From 9efdaf0998bcb480c56c3e61fb7829e5af12a8c4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Peter=20Draho=C5=A1?= Date: Mon, 9 Dec 2013 16:03:27 +0100 Subject: [luadist-git] add lua-5.2.3-Windows-x86_64 [ci skip] --- bin/liblua.dll | Bin 0 -> 170496 bytes bin/lua.exe | Bin 0 -> 141824 bytes bin/luac.exe | Bin 0 -> 289792 bytes bin/wlua.exe | Bin 0 -> 142848 bytes dist.info | 52 + include/lauxlib.h | 212 + include/lua.h | 444 ++ include/lua.hpp | 9 + include/luaconf.h | 497 ++ include/lualib.h | 55 + lib/liblua.dll.a | Bin 0 -> 91190 bytes share/lua/README.md | 6 + share/lua/doc/contents.html | 533 ++ share/lua/doc/logo.gif | Bin 0 -> 4232 bytes share/lua/doc/lua.1 | 116 + share/lua/doc/lua.css | 96 + share/lua/doc/luac.1 | 118 + share/lua/doc/manual.css | 27 + share/lua/doc/manual.html | 10507 ++++++++++++++++++++++++++++++++ share/lua/doc/osi-certified-72x60.png | Bin 0 -> 3774 bytes share/lua/doc/readme.html | 413 ++ share/lua/etc/lua.ico | Bin 0 -> 116114 bytes share/lua/etc/lua_lang.ico | Bin 0 -> 119793 bytes 23 files changed, 13085 insertions(+) create mode 100644 bin/liblua.dll create mode 100644 bin/lua.exe create mode 100644 bin/luac.exe create mode 100644 bin/wlua.exe create mode 100644 dist.info create mode 100644 include/lauxlib.h create mode 100644 include/lua.h create mode 100644 include/lua.hpp create mode 100644 include/luaconf.h create mode 100644 include/lualib.h create mode 100644 lib/liblua.dll.a create mode 100644 share/lua/README.md create mode 100644 share/lua/doc/contents.html create mode 100644 share/lua/doc/logo.gif create mode 100644 share/lua/doc/lua.1 create mode 100644 share/lua/doc/lua.css create mode 100644 share/lua/doc/luac.1 create mode 100644 share/lua/doc/manual.css create mode 100644 share/lua/doc/manual.html create mode 100644 share/lua/doc/osi-certified-72x60.png create mode 100644 share/lua/doc/readme.html create mode 100644 share/lua/etc/lua.ico create mode 100644 share/lua/etc/lua_lang.ico diff --git a/bin/liblua.dll b/bin/liblua.dll new file mode 100644 index 0000000..f660040 Binary files /dev/null and b/bin/liblua.dll differ diff --git a/bin/lua.exe b/bin/lua.exe new file mode 100644 index 0000000..c288ed8 Binary files /dev/null and b/bin/lua.exe differ diff --git a/bin/luac.exe b/bin/luac.exe new file mode 100644 index 0000000..0c841b0 Binary files /dev/null and b/bin/luac.exe differ diff --git a/bin/wlua.exe b/bin/wlua.exe new file mode 100644 index 0000000..a7eca2d Binary files /dev/null and b/bin/wlua.exe differ diff --git a/dist.info b/dist.info new file mode 100644 index 0000000..cdfea60 --- /dev/null +++ b/dist.info @@ -0,0 +1,52 @@ +license = "MIT/X11" +maintainer = "Peter Drahoš" +url = "http://www.lua.org" +type = "x86_64" +version = "5.2.3" +author = "Roberto Ierusalimschy, Waldemar Celes, Luiz Henrique de Figueiredo" +files = { +Header = { +[[include\lua.h]], +[[include\lualib.h]], +[[include\lauxlib.h]], +[[include\lua.hpp]], +[[include\luaconf.h]], +} +, +Data = { +[[share\lua\README.md]], +} +, +Library = { +[[lib\liblua.dll.a]], +} +, +Other = { +[[share\lua\etc\\lua.ico]], +[[share\lua\etc\\lua_lang.ico]], +} +, +Documentation = { +[[share\lua\doc\\contents.html]], +[[share\lua\doc\\logo.gif]], +[[share\lua\doc\\lua.1]], +[[share\lua\doc\\lua.css]], +[[share\lua\doc\\luac.1]], +[[share\lua\doc\\manual.css]], +[[share\lua\doc\\manual.html]], +[[share\lua\doc\\osi-certified-72x60.png]], +[[share\lua\doc\\readme.html]], +} +, +Runtime = { +[[bin\wlua.exe]], +[[bin\lua.exe]], +[[bin\luac.exe]], +[[bin\liblua.dll]], +} +, +} + +arch = "Windows" +name = "lua" +desc = "Lua is a powerful, fast, light-weight, embeddable scripting language." diff --git a/include/lauxlib.h b/include/lauxlib.h new file mode 100644 index 0000000..0fb023b --- /dev/null +++ b/include/lauxlib.h @@ -0,0 +1,212 @@ +/* +** $Id: lauxlib.h,v 1.120.1.1 2013/04/12 18:48:47 roberto Exp $ +** Auxiliary functions for building Lua libraries +** See Copyright Notice in lua.h +*/ + + +#ifndef lauxlib_h +#define lauxlib_h + + +#include +#include + +#include "lua.h" + + + +/* extra error code for `luaL_load' */ +#define LUA_ERRFILE (LUA_ERRERR+1) + + +typedef struct luaL_Reg { + const char *name; + lua_CFunction func; +} luaL_Reg; + + +LUALIB_API void (luaL_checkversion_) (lua_State *L, lua_Number ver); +#define luaL_checkversion(L) luaL_checkversion_(L, LUA_VERSION_NUM) + +LUALIB_API int (luaL_getmetafield) (lua_State *L, int obj, const char *e); +LUALIB_API int (luaL_callmeta) (lua_State *L, int obj, const char *e); +LUALIB_API const char *(luaL_tolstring) (lua_State *L, int idx, size_t *len); +LUALIB_API int (luaL_argerror) (lua_State *L, int numarg, const char *extramsg); +LUALIB_API const char *(luaL_checklstring) (lua_State *L, int numArg, + size_t *l); +LUALIB_API const char *(luaL_optlstring) (lua_State *L, int numArg, + const char *def, size_t *l); +LUALIB_API lua_Number (luaL_checknumber) (lua_State *L, int numArg); +LUALIB_API lua_Number (luaL_optnumber) (lua_State *L, int nArg, lua_Number def); + +LUALIB_API lua_Integer (luaL_checkinteger) (lua_State *L, int numArg); +LUALIB_API lua_Integer (luaL_optinteger) (lua_State *L, int nArg, + lua_Integer def); +LUALIB_API lua_Unsigned (luaL_checkunsigned) (lua_State *L, int numArg); +LUALIB_API lua_Unsigned (luaL_optunsigned) (lua_State *L, int numArg, + lua_Unsigned def); + +LUALIB_API void (luaL_checkstack) (lua_State *L, int sz, const char *msg); +LUALIB_API void (luaL_checktype) (lua_State *L, int narg, int t); +LUALIB_API void (luaL_checkany) (lua_State *L, int narg); + +LUALIB_API int (luaL_newmetatable) (lua_State *L, const char *tname); +LUALIB_API void (luaL_setmetatable) (lua_State *L, const char *tname); +LUALIB_API void *(luaL_testudata) (lua_State *L, int ud, const char *tname); +LUALIB_API void *(luaL_checkudata) (lua_State *L, int ud, const char *tname); + +LUALIB_API void (luaL_where) (lua_State *L, int lvl); +LUALIB_API int (luaL_error) (lua_State *L, const char *fmt, ...); + +LUALIB_API int (luaL_checkoption) (lua_State *L, int narg, const char *def, + const char *const lst[]); + +LUALIB_API int (luaL_fileresult) (lua_State *L, int stat, const char *fname); +LUALIB_API int (luaL_execresult) (lua_State *L, int stat); + +/* pre-defined references */ +#define LUA_NOREF (-2) +#define LUA_REFNIL (-1) + +LUALIB_API int (luaL_ref) (lua_State *L, int t); +LUALIB_API void (luaL_unref) (lua_State *L, int t, int ref); + +LUALIB_API int (luaL_loadfilex) (lua_State *L, const char *filename, + const char *mode); + +#define luaL_loadfile(L,f) luaL_loadfilex(L,f,NULL) + +LUALIB_API int (luaL_loadbufferx) (lua_State *L, const char *buff, size_t sz, + const char *name, const char *mode); +LUALIB_API int (luaL_loadstring) (lua_State *L, const char *s); + +LUALIB_API lua_State *(luaL_newstate) (void); + +LUALIB_API int (luaL_len) (lua_State *L, int idx); + +LUALIB_API const char *(luaL_gsub) (lua_State *L, const char *s, const char *p, + const char *r); + +LUALIB_API void (luaL_setfuncs) (lua_State *L, const luaL_Reg *l, int nup); + +LUALIB_API int (luaL_getsubtable) (lua_State *L, int idx, const char *fname); + +LUALIB_API void (luaL_traceback) (lua_State *L, lua_State *L1, + const char *msg, int level); + +LUALIB_API void (luaL_requiref) (lua_State *L, const char *modname, + lua_CFunction openf, int glb); + +/* +** =============================================================== +** some useful macros +** =============================================================== +*/ + + +#define luaL_newlibtable(L,l) \ + lua_createtable(L, 0, sizeof(l)/sizeof((l)[0]) - 1) + +#define luaL_newlib(L,l) (luaL_newlibtable(L,l), luaL_setfuncs(L,l,0)) + +#define luaL_argcheck(L, cond,numarg,extramsg) \ + ((void)((cond) || luaL_argerror(L, (numarg), (extramsg)))) +#define luaL_checkstring(L,n) (luaL_checklstring(L, (n), NULL)) +#define luaL_optstring(L,n,d) (luaL_optlstring(L, (n), (d), NULL)) +#define luaL_checkint(L,n) ((int)luaL_checkinteger(L, (n))) +#define luaL_optint(L,n,d) ((int)luaL_optinteger(L, (n), (d))) +#define luaL_checklong(L,n) ((long)luaL_checkinteger(L, (n))) +#define luaL_optlong(L,n,d) ((long)luaL_optinteger(L, (n), (d))) + +#define luaL_typename(L,i) lua_typename(L, lua_type(L,(i))) + +#define luaL_dofile(L, fn) \ + (luaL_loadfile(L, fn) || lua_pcall(L, 0, LUA_MULTRET, 0)) + +#define luaL_dostring(L, s) \ + (luaL_loadstring(L, s) || lua_pcall(L, 0, LUA_MULTRET, 0)) + +#define luaL_getmetatable(L,n) (lua_getfield(L, LUA_REGISTRYINDEX, (n))) + +#define luaL_opt(L,f,n,d) (lua_isnoneornil(L,(n)) ? (d) : f(L,(n))) + +#define luaL_loadbuffer(L,s,sz,n) luaL_loadbufferx(L,s,sz,n,NULL) + + +/* +** {====================================================== +** Generic Buffer manipulation +** ======================================================= +*/ + +typedef struct luaL_Buffer { + char *b; /* buffer address */ + size_t size; /* buffer size */ + size_t n; /* number of characters in buffer */ + lua_State *L; + char initb[LUAL_BUFFERSIZE]; /* initial buffer */ +} luaL_Buffer; + + +#define luaL_addchar(B,c) \ + ((void)((B)->n < (B)->size || luaL_prepbuffsize((B), 1)), \ + ((B)->b[(B)->n++] = (c))) + +#define luaL_addsize(B,s) ((B)->n += (s)) + +LUALIB_API void (luaL_buffinit) (lua_State *L, luaL_Buffer *B); +LUALIB_API char *(luaL_prepbuffsize) (luaL_Buffer *B, size_t sz); +LUALIB_API void (luaL_addlstring) (luaL_Buffer *B, const char *s, size_t l); +LUALIB_API void (luaL_addstring) (luaL_Buffer *B, const char *s); +LUALIB_API void (luaL_addvalue) (luaL_Buffer *B); +LUALIB_API void (luaL_pushresult) (luaL_Buffer *B); +LUALIB_API void (luaL_pushresultsize) (luaL_Buffer *B, size_t sz); +LUALIB_API char *(luaL_buffinitsize) (lua_State *L, luaL_Buffer *B, size_t sz); + +#define luaL_prepbuffer(B) luaL_prepbuffsize(B, LUAL_BUFFERSIZE) + +/* }====================================================== */ + + + +/* +** {====================================================== +** File handles for IO library +** ======================================================= +*/ + +/* +** A file handle is a userdata with metatable 'LUA_FILEHANDLE' and +** initial structure 'luaL_Stream' (it may contain other fields +** after that initial structure). +*/ + +#define LUA_FILEHANDLE "FILE*" + + +typedef struct luaL_Stream { + FILE *f; /* stream (NULL for incompletely created streams) */ + lua_CFunction closef; /* to close stream (NULL for closed streams) */ +} luaL_Stream; + +/* }====================================================== */ + + + +/* compatibility with old module system */ +#if defined(LUA_COMPAT_MODULE) + +LUALIB_API void (luaL_pushmodule) (lua_State *L, const char *modname, + int sizehint); +LUALIB_API void (luaL_openlib) (lua_State *L, const char *libname, + const luaL_Reg *l, int nup); + +#define luaL_register(L,n,l) (luaL_openlib(L,(n),(l),0)) + +#endif + + +#endif + + diff --git a/include/lua.h b/include/lua.h new file mode 100644 index 0000000..149a2c3 --- /dev/null +++ b/include/lua.h @@ -0,0 +1,444 @@ +/* +** $Id: lua.h,v 1.285.1.2 2013/11/11 12:09:16 roberto Exp $ +** Lua - A Scripting Language +** Lua.org, PUC-Rio, Brazil (http://www.lua.org) +** See Copyright Notice at the end of this file +*/ + + +#ifndef lua_h +#define lua_h + +#include +#include + + +#include "luaconf.h" + + +#define LUA_VERSION_MAJOR "5" +#define LUA_VERSION_MINOR "2" +#define LUA_VERSION_NUM 502 +#define LUA_VERSION_RELEASE "3" + +#define LUA_VERSION "Lua " LUA_VERSION_MAJOR "." LUA_VERSION_MINOR +#define LUA_RELEASE LUA_VERSION "." LUA_VERSION_RELEASE +#define LUA_COPYRIGHT LUA_RELEASE " Copyright (C) 1994-2013 Lua.org, PUC-Rio" +#define LUA_AUTHORS "R. Ierusalimschy, L. H. de Figueiredo, W. Celes" + + +/* mark for precompiled code ('Lua') */ +#define LUA_SIGNATURE "\033Lua" + +/* option for multiple returns in 'lua_pcall' and 'lua_call' */ +#define LUA_MULTRET (-1) + + +/* +** pseudo-indices +*/ +#define LUA_REGISTRYINDEX LUAI_FIRSTPSEUDOIDX +#define lua_upvalueindex(i) (LUA_REGISTRYINDEX - (i)) + + +/* thread status */ +#define LUA_OK 0 +#define LUA_YIELD 1 +#define LUA_ERRRUN 2 +#define LUA_ERRSYNTAX 3 +#define LUA_ERRMEM 4 +#define LUA_ERRGCMM 5 +#define LUA_ERRERR 6 + + +typedef struct lua_State lua_State; + +typedef int (*lua_CFunction) (lua_State *L); + + +/* +** functions that read/write blocks when loading/dumping Lua chunks +*/ +typedef const char * (*lua_Reader) (lua_State *L, void *ud, size_t *sz); + +typedef int (*lua_Writer) (lua_State *L, const void* p, size_t sz, void* ud); + + +/* +** prototype for memory-allocation functions +*/ +typedef void * (*lua_Alloc) (void *ud, void *ptr, size_t osize, size_t nsize); + + +/* +** basic types +*/ +#define LUA_TNONE (-1) + +#define LUA_TNIL 0 +#define LUA_TBOOLEAN 1 +#define LUA_TLIGHTUSERDATA 2 +#define LUA_TNUMBER 3 +#define LUA_TSTRING 4 +#define LUA_TTABLE 5 +#define LUA_TFUNCTION 6 +#define LUA_TUSERDATA 7 +#define LUA_TTHREAD 8 + +#define LUA_NUMTAGS 9 + + + +/* minimum Lua stack available to a C function */ +#define LUA_MINSTACK 20 + + +/* predefined values in the registry */ +#define LUA_RIDX_MAINTHREAD 1 +#define LUA_RIDX_GLOBALS 2 +#define LUA_RIDX_LAST LUA_RIDX_GLOBALS + + +/* type of numbers in Lua */ +typedef LUA_NUMBER lua_Number; + + +/* type for integer functions */ +typedef LUA_INTEGER lua_Integer; + +/* unsigned integer type */ +typedef LUA_UNSIGNED lua_Unsigned; + + + +/* +** generic extra include file +*/ +#if defined(LUA_USER_H) +#include LUA_USER_H +#endif + + +/* +** RCS ident string +*/ +extern const char lua_ident[]; + + +/* +** state manipulation +*/ +LUA_API lua_State *(lua_newstate) (lua_Alloc f, void *ud); +LUA_API void (lua_close) (lua_State *L); +LUA_API lua_State *(lua_newthread) (lua_State *L); + +LUA_API lua_CFunction (lua_atpanic) (lua_State *L, lua_CFunction panicf); + + +LUA_API const lua_Number *(lua_version) (lua_State *L); + + +/* +** basic stack manipulation +*/ +LUA_API int (lua_absindex) (lua_State *L, int idx); +LUA_API int (lua_gettop) (lua_State *L); +LUA_API void (lua_settop) (lua_State *L, int idx); +LUA_API void (lua_pushvalue) (lua_State *L, int idx); +LUA_API void (lua_remove) (lua_State *L, int idx); +LUA_API void (lua_insert) (lua_State *L, int idx); +LUA_API void (lua_replace) (lua_State *L, int idx); +LUA_API void (lua_copy) (lua_State *L, int fromidx, int toidx); +LUA_API int (lua_checkstack) (lua_State *L, int sz); + +LUA_API void (lua_xmove) (lua_State *from, lua_State *to, int n); + + +/* +** access functions (stack -> C) +*/ + +LUA_API int (lua_isnumber) (lua_State *L, int idx); +LUA_API int (lua_isstring) (lua_State *L, int idx); +LUA_API int (lua_iscfunction) (lua_State *L, int idx); +LUA_API int (lua_isuserdata) (lua_State *L, int idx); +LUA_API int (lua_type) (lua_State *L, int idx); +LUA_API const char *(lua_typename) (lua_State *L, int tp); + +LUA_API lua_Number (lua_tonumberx) (lua_State *L, int idx, int *isnum); +LUA_API lua_Integer (lua_tointegerx) (lua_State *L, int idx, int *isnum); +LUA_API lua_Unsigned (lua_tounsignedx) (lua_State *L, int idx, int *isnum); +LUA_API int (lua_toboolean) (lua_State *L, int idx); +LUA_API const char *(lua_tolstring) (lua_State *L, int idx, size_t *len); +LUA_API size_t (lua_rawlen) (lua_State *L, int idx); +LUA_API lua_CFunction (lua_tocfunction) (lua_State *L, int idx); +LUA_API void *(lua_touserdata) (lua_State *L, int idx); +LUA_API lua_State *(lua_tothread) (lua_State *L, int idx); +LUA_API const void *(lua_topointer) (lua_State *L, int idx); + + +/* +** Comparison and arithmetic functions +*/ + +#define LUA_OPADD 0 /* ORDER TM */ +#define LUA_OPSUB 1 +#define LUA_OPMUL 2 +#define LUA_OPDIV 3 +#define LUA_OPMOD 4 +#define LUA_OPPOW 5 +#define LUA_OPUNM 6 + +LUA_API void (lua_arith) (lua_State *L, int op); + +#define LUA_OPEQ 0 +#define LUA_OPLT 1 +#define LUA_OPLE 2 + +LUA_API int (lua_rawequal) (lua_State *L, int idx1, int idx2); +LUA_API int (lua_compare) (lua_State *L, int idx1, int idx2, int op); + + +/* +** push functions (C -> stack) +*/ +LUA_API void (lua_pushnil) (lua_State *L); +LUA_API void (lua_pushnumber) (lua_State *L, lua_Number n); +LUA_API void (lua_pushinteger) (lua_State *L, lua_Integer n); +LUA_API void (lua_pushunsigned) (lua_State *L, lua_Unsigned n); +LUA_API const char *(lua_pushlstring) (lua_State *L, const char *s, size_t l); +LUA_API const char *(lua_pushstring) (lua_State *L, const char *s); +LUA_API const char *(lua_pushvfstring) (lua_State *L, const char *fmt, + va_list argp); +LUA_API const char *(lua_pushfstring) (lua_State *L, const char *fmt, ...); +LUA_API void (lua_pushcclosure) (lua_State *L, lua_CFunction fn, int n); +LUA_API void (lua_pushboolean) (lua_State *L, int b); +LUA_API void (lua_pushlightuserdata) (lua_State *L, void *p); +LUA_API int (lua_pushthread) (lua_State *L); + + +/* +** get functions (Lua -> stack) +*/ +LUA_API void (lua_getglobal) (lua_State *L, const char *var); +LUA_API void (lua_gettable) (lua_State *L, int idx); +LUA_API void (lua_getfield) (lua_State *L, int idx, const char *k); +LUA_API void (lua_rawget) (lua_State *L, int idx); +LUA_API void (lua_rawgeti) (lua_State *L, int idx, int n); +LUA_API void (lua_rawgetp) (lua_State *L, int idx, const void *p); +LUA_API void (lua_createtable) (lua_State *L, int narr, int nrec); +LUA_API void *(lua_newuserdata) (lua_State *L, size_t sz); +LUA_API int (lua_getmetatable) (lua_State *L, int objindex); +LUA_API void (lua_getuservalue) (lua_State *L, int idx); + + +/* +** set functions (stack -> Lua) +*/ +LUA_API void (lua_setglobal) (lua_State *L, const char *var); +LUA_API void (lua_settable) (lua_State *L, int idx); +LUA_API void (lua_setfield) (lua_State *L, int idx, const char *k); +LUA_API void (lua_rawset) (lua_State *L, int idx); +LUA_API void (lua_rawseti) (lua_State *L, int idx, int n); +LUA_API void (lua_rawsetp) (lua_State *L, int idx, const void *p); +LUA_API int (lua_setmetatable) (lua_State *L, int objindex); +LUA_API void (lua_setuservalue) (lua_State *L, int idx); + + +/* +** 'load' and 'call' functions (load and run Lua code) +*/ +LUA_API void (lua_callk) (lua_State *L, int nargs, int nresults, int ctx, + lua_CFunction k); +#define lua_call(L,n,r) lua_callk(L, (n), (r), 0, NULL) + +LUA_API int (lua_getctx) (lua_State *L, int *ctx); + +LUA_API int (lua_pcallk) (lua_State *L, int nargs, int nresults, int errfunc, + int ctx, lua_CFunction k); +#define lua_pcall(L,n,r,f) lua_pcallk(L, (n), (r), (f), 0, NULL) + +LUA_API int (lua_load) (lua_State *L, lua_Reader reader, void *dt, + const char *chunkname, + const char *mode); + +LUA_API int (lua_dump) (lua_State *L, lua_Writer writer, void *data); + + +/* +** coroutine functions +*/ +LUA_API int (lua_yieldk) (lua_State *L, int nresults, int ctx, + lua_CFunction k); +#define lua_yield(L,n) lua_yieldk(L, (n), 0, NULL) +LUA_API int (lua_resume) (lua_State *L, lua_State *from, int narg); +LUA_API int (lua_status) (lua_State *L); + +/* +** garbage-collection function and options +*/ + +#define LUA_GCSTOP 0 +#define LUA_GCRESTART 1 +#define LUA_GCCOLLECT 2 +#define LUA_GCCOUNT 3 +#define LUA_GCCOUNTB 4 +#define LUA_GCSTEP 5 +#define LUA_GCSETPAUSE 6 +#define LUA_GCSETSTEPMUL 7 +#define LUA_GCSETMAJORINC 8 +#define LUA_GCISRUNNING 9 +#define LUA_GCGEN 10 +#define LUA_GCINC 11 + +LUA_API int (lua_gc) (lua_State *L, int what, int data); + + +/* +** miscellaneous functions +*/ + +LUA_API int (lua_error) (lua_State *L); + +LUA_API int (lua_next) (lua_State *L, int idx); + +LUA_API void (lua_concat) (lua_State *L, int n); +LUA_API void (lua_len) (lua_State *L, int idx); + +LUA_API lua_Alloc (lua_getallocf) (lua_State *L, void **ud); +LUA_API void (lua_setallocf) (lua_State *L, lua_Alloc f, void *ud); + + + +/* +** =============================================================== +** some useful macros +** =============================================================== +*/ + +#define lua_tonumber(L,i) lua_tonumberx(L,i,NULL) +#define lua_tointeger(L,i) lua_tointegerx(L,i,NULL) +#define lua_tounsigned(L,i) lua_tounsignedx(L,i,NULL) + +#define lua_pop(L,n) lua_settop(L, -(n)-1) + +#define lua_newtable(L) lua_createtable(L, 0, 0) + +#define lua_register(L,n,f) (lua_pushcfunction(L, (f)), lua_setglobal(L, (n))) + +#define lua_pushcfunction(L,f) lua_pushcclosure(L, (f), 0) + +#define lua_isfunction(L,n) (lua_type(L, (n)) == LUA_TFUNCTION) +#define lua_istable(L,n) (lua_type(L, (n)) == LUA_TTABLE) +#define lua_islightuserdata(L,n) (lua_type(L, (n)) == LUA_TLIGHTUSERDATA) +#define lua_isnil(L,n) (lua_type(L, (n)) == LUA_TNIL) +#define lua_isboolean(L,n) (lua_type(L, (n)) == LUA_TBOOLEAN) +#define lua_isthread(L,n) (lua_type(L, (n)) == LUA_TTHREAD) +#define lua_isnone(L,n) (lua_type(L, (n)) == LUA_TNONE) +#define lua_isnoneornil(L, n) (lua_type(L, (n)) <= 0) + +#define lua_pushliteral(L, s) \ + lua_pushlstring(L, "" s, (sizeof(s)/sizeof(char))-1) + +#define lua_pushglobaltable(L) \ + lua_rawgeti(L, LUA_REGISTRYINDEX, LUA_RIDX_GLOBALS) + +#define lua_tostring(L,i) lua_tolstring(L, (i), NULL) + + + +/* +** {====================================================================== +** Debug API +** ======================================================================= +*/ + + +/* +** Event codes +*/ +#define LUA_HOOKCALL 0 +#define LUA_HOOKRET 1 +#define LUA_HOOKLINE 2 +#define LUA_HOOKCOUNT 3 +#define LUA_HOOKTAILCALL 4 + + +/* +** Event masks +*/ +#define LUA_MASKCALL (1 << LUA_HOOKCALL) +#define LUA_MASKRET (1 << LUA_HOOKRET) +#define LUA_MASKLINE (1 << LUA_HOOKLINE) +#define LUA_MASKCOUNT (1 << LUA_HOOKCOUNT) + +typedef struct lua_Debug lua_Debug; /* activation record */ + + +/* Functions to be called by the debugger in specific events */ +typedef void (*lua_Hook) (lua_State *L, lua_Debug *ar); + + +LUA_API int (lua_getstack) (lua_State *L, int level, lua_Debug *ar); +LUA_API int (lua_getinfo) (lua_State *L, const char *what, lua_Debug *ar); +LUA_API const char *(lua_getlocal) (lua_State *L, const lua_Debug *ar, int n); +LUA_API const char *(lua_setlocal) (lua_State *L, const lua_Debug *ar, int n); +LUA_API const char *(lua_getupvalue) (lua_State *L, int funcindex, int n); +LUA_API const char *(lua_setupvalue) (lua_State *L, int funcindex, int n); + +LUA_API void *(lua_upvalueid) (lua_State *L, int fidx, int n); +LUA_API void (lua_upvaluejoin) (lua_State *L, int fidx1, int n1, + int fidx2, int n2); + +LUA_API int (lua_sethook) (lua_State *L, lua_Hook func, int mask, int count); +LUA_API lua_Hook (lua_gethook) (lua_State *L); +LUA_API int (lua_gethookmask) (lua_State *L); +LUA_API int (lua_gethookcount) (lua_State *L); + + +struct lua_Debug { + int event; + const char *name; /* (n) */ + const char *namewhat; /* (n) 'global', 'local', 'field', 'method' */ + const char *what; /* (S) 'Lua', 'C', 'main', 'tail' */ + const char *source; /* (S) */ + int currentline; /* (l) */ + int linedefined; /* (S) */ + int lastlinedefined; /* (S) */ + unsigned char nups; /* (u) number of upvalues */ + unsigned char nparams;/* (u) number of parameters */ + char isvararg; /* (u) */ + char istailcall; /* (t) */ + char short_src[LUA_IDSIZE]; /* (S) */ + /* private part */ + struct CallInfo *i_ci; /* active function */ +}; + +/* }====================================================================== */ + + +/****************************************************************************** +* Copyright (C) 1994-2013 Lua.org, PUC-Rio. +* +* Permission is hereby granted, free of charge, to any person obtaining +* a copy of this software and associated documentation files (the +* "Software"), to deal in the Software without restriction, including +* without limitation the rights to use, copy, modify, merge, publish, +* distribute, sublicense, and/or sell copies of the Software, and to +* permit persons to whom the Software is furnished to do so, subject to +* the following conditions: +* +* The above copyright notice and this permission notice shall be +* included in all copies or substantial portions of the Software. +* +* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. +* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY +* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, +* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE +* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. +******************************************************************************/ + + +#endif diff --git a/include/lua.hpp b/include/lua.hpp new file mode 100644 index 0000000..ec417f5 --- /dev/null +++ b/include/lua.hpp @@ -0,0 +1,9 @@ +// lua.hpp +// Lua header files for C++ +// <> not supplied automatically because Lua also compiles as C++ + +extern "C" { +#include "lua.h" +#include "lualib.h" +#include "lauxlib.h" +} diff --git a/include/luaconf.h b/include/luaconf.h new file mode 100644 index 0000000..e769d6f --- /dev/null +++ b/include/luaconf.h @@ -0,0 +1,497 @@ +/* +** $Id: luaconf.h,v 1.176.1.1 2013/04/12 18:48:47 roberto Exp $ +** Configuration file for Lua +** See Copyright Notice in lua.h +*/ + + +#ifndef lconfig_h +#define lconfig_h + +#include +#include + + +/* +** ================================================================== +** Search for "@@" to find all configurable definitions. +** =================================================================== +*/ + + +/* +@@ LUA_ANSI controls the use of non-ansi features. +** CHANGE it (define it) if you want Lua to avoid the use of any +** non-ansi feature or library. +*/ +/* #undef LUA_ANSI */ +#define LUA_WIN + +#if defined(LUA_WIN) +#define LUA_DL_DLL +#define LUA_USE_AFORMAT /* assume 'printf' handles 'aA' specifiers */ +#endif + +/* #undef LUA_USE_POSIX */ +/* #undef LUA_USE_DLOPEN */ +/* #undef LUA_USE_READLINE */ +/* #undef LUA_USE_STRTODHEX */ +/* #undef LUA_USE_AFORMAT */ +/* #undef LUA_USE_LONGLONG */ +/* #undef LUA_USE_MKSTEMP */ +/* #undef LUA_USE_ISATTY */ +/* #undef LUA_USE_POPEN */ +/* #undef LUA_USE_ULONGJMP */ + + +/* +@@ LUA_PATH_DEFAULT is the default path that Lua uses to look for +@* Lua libraries. +@@ LUA_CPATH_DEFAULT is the default path that Lua uses to look for +@* C libraries. +** CHANGE them if your machine has a non-conventional directory +** hierarchy or if you want to install your libraries in +** non-conventional directories. +*/ +#define LUA_MODULE_SUFFIX ".dll" +#define LUA_DIR "!/../" +#define LUA_LDIR "lib\\lua" +#define LUA_CDIR "lib\\lua" + +#define LUA_PATH_DEFAULT ".\\?.lua;!\\..\\lib\\lua\\?.lua;!\\..\\lib\\lua\\?\\init.lua" +#define LUA_CPATH_DEFAULT ".\\?.dll;!\\..\\lib\\lua\\?.dll;!\\..\\lib\\lua\\loadall.dll" + +/* +@@ LUA_DIRSEP is the directory separator (for submodules). +** CHANGE it if your machine does not use "/" as the directory separator +** and is not Windows. (On Windows Lua automatically uses "\".) +*/ +#define LUA_DIRSEP "\\" + +/* +@@ LUA_ENV is the name of the variable that holds the current +@@ environment, used to access global names. +** CHANGE it if you do not like this name. +*/ +#define LUA_ENV "_ENV" + + +/* +@@ LUA_API is a mark for all core API functions. +@@ LUALIB_API is a mark for all auxiliary library functions. +@@ LUAMOD_API is a mark for all standard library opening functions. +** CHANGE them if you need to define those functions in some special way. +** For instance, if you want to create one Windows DLL with the core and +** the libraries, you may want to use the following definition (define +** LUA_BUILD_AS_DLL to get it). +*/ +#if defined(LUA_BUILD_AS_DLL) /* { */ + +#if defined(LUA_CORE) || defined(LUA_LIB) /* { */ +#define LUA_API __declspec(dllexport) +#else /* }{ */ +#define LUA_API __declspec(dllimport) +#endif /* } */ + +#else /* }{ */ + +#define LUA_API extern + +#endif /* } */ + + +/* more often than not the libs go together with the core */ +#define LUALIB_API LUA_API +#define LUAMOD_API LUALIB_API + + +/* +@@ LUAI_FUNC is a mark for all extern functions that are not to be +@* exported to outside modules. +@@ LUAI_DDEF and LUAI_DDEC are marks for all extern (const) variables +@* that are not to be exported to outside modules (LUAI_DDEF for +@* definitions and LUAI_DDEC for declarations). +** CHANGE them if you need to mark them in some special way. Elf/gcc +** (versions 3.2 and later) mark them as "hidden" to optimize access +** when Lua is compiled as a shared library. Not all elf targets support +** this attribute. Unfortunately, gcc does not offer a way to check +** whether the target offers that support, and those without support +** give a warning about it. To avoid these warnings, change to the +** default definition. +*/ +#if defined(__GNUC__) && ((__GNUC__*100 + __GNUC_MINOR__) >= 302) && \ + defined(__ELF__) /* { */ +#define LUAI_FUNC __attribute__((visibility("hidden"))) extern +#define LUAI_DDEC LUAI_FUNC +#define LUAI_DDEF /* empty */ + +#else /* }{ */ +#define LUAI_FUNC extern +#define LUAI_DDEC extern +#define LUAI_DDEF /* empty */ +#endif /* } */ + + + +/* +@@ LUA_QL describes how error messages quote program elements. +** CHANGE it if you want a different appearance. +*/ +#define LUA_QL(x) "'" x "'" +#define LUA_QS LUA_QL("%s") + + +/* +@@ LUA_IDSIZE gives the maximum size for the description of the source +@* of a function in debug information. +** CHANGE it if you want a different size. +*/ +#define LUA_IDSIZE 60 + + +/* +@@ luai_writestring/luai_writeline define how 'print' prints its results. +** They are only used in libraries and the stand-alone program. (The #if +** avoids including 'stdio.h' everywhere.) +*/ +#if defined(LUA_LIB) || defined(lua_c) +#include +#define luai_writestring(s,l) fwrite((s), sizeof(char), (l), stdout) +#define luai_writeline() (luai_writestring("\n", 1), fflush(stdout)) +#endif + +/* +@@ luai_writestringerror defines how to print error messages. +** (A format string with one argument is enough for Lua...) +*/ +#define luai_writestringerror(s,p) \ + (fprintf(stderr, (s), (p)), fflush(stderr)) + + +/* +@@ LUAI_MAXSHORTLEN is the maximum length for short strings, that is, +** strings that are internalized. (Cannot be smaller than reserved words +** or tags for metamethods, as these strings must be internalized; +** #("function") = 8, #("__newindex") = 10.) +*/ +#define LUAI_MAXSHORTLEN 40 + + + +/* +** {================================================================== +** Compatibility with previous versions +** =================================================================== +*/ + +/* +@@ LUA_COMPAT_ALL controls all compatibility options. +** You can define it to get all options, or change specific options +** to fit your specific needs. +*/ +#define LUA_COMPAT_ALL +#if defined(LUA_COMPAT_ALL) /* { */ + +/* +@@ LUA_COMPAT_UNPACK controls the presence of global 'unpack'. +** You can replace it with 'table.unpack'. +*/ +#define LUA_COMPAT_UNPACK + +/* +@@ LUA_COMPAT_LOADERS controls the presence of table 'package.loaders'. +** You can replace it with 'package.searchers'. +*/ +#define LUA_COMPAT_LOADERS + +/* +@@ macro 'lua_cpcall' emulates deprecated function lua_cpcall. +** You can call your C function directly (with light C functions). +*/ +#define lua_cpcall(L,f,u) \ + (lua_pushcfunction(L, (f)), \ + lua_pushlightuserdata(L,(u)), \ + lua_pcall(L,1,0,0)) + + +/* +@@ LUA_COMPAT_LOG10 defines the function 'log10' in the math library. +** You can rewrite 'log10(x)' as 'log(x, 10)'. +*/ +#define LUA_COMPAT_LOG10 + +/* +@@ LUA_COMPAT_LOADSTRING defines the function 'loadstring' in the base +** library. You can rewrite 'loadstring(s)' as 'load(s)'. +*/ +#define LUA_COMPAT_LOADSTRING + +/* +@@ LUA_COMPAT_MAXN defines the function 'maxn' in the table library. +*/ +#define LUA_COMPAT_MAXN + +/* +@@ The following macros supply trivial compatibility for some +** changes in the API. The macros themselves document how to +** change your code to avoid using them. +*/ +#define lua_strlen(L,i) lua_rawlen(L, (i)) + +#define lua_objlen(L,i) lua_rawlen(L, (i)) + +#define lua_equal(L,idx1,idx2) lua_compare(L,(idx1),(idx2),LUA_OPEQ) +#define lua_lessthan(L,idx1,idx2) lua_compare(L,(idx1),(idx2),LUA_OPLT) + +/* +@@ LUA_COMPAT_MODULE controls compatibility with previous +** module functions 'module' (Lua) and 'luaL_register' (C). +*/ +#define LUA_COMPAT_MODULE + +#endif /* } */ + +/* }================================================================== */ + + + +/* +@@ LUAI_BITSINT defines the number of bits in an int. +** CHANGE here if Lua cannot automatically detect the number of bits of +** your machine. Probably you do not need to change this. +*/ +/* avoid overflows in comparison */ +#if INT_MAX-20 < 32760 /* { */ +#define LUAI_BITSINT 16 +#elif INT_MAX > 2147483640L /* }{ */ +/* int has at least 32 bits */ +#define LUAI_BITSINT 32 +#else /* }{ */ +#error "you must define LUA_BITSINT with number of bits in an integer" +#endif /* } */ + + +/* +@@ LUA_INT32 is an signed integer with exactly 32 bits. +@@ LUAI_UMEM is an unsigned integer big enough to count the total +@* memory used by Lua. +@@ LUAI_MEM is a signed integer big enough to count the total memory +@* used by Lua. +** CHANGE here if for some weird reason the default definitions are not +** good enough for your machine. Probably you do not need to change +** this. +*/ +#if LUAI_BITSINT >= 32 /* { */ +#define LUA_INT32 int +#define LUAI_UMEM size_t +#define LUAI_MEM ptrdiff_t +#else /* }{ */ +/* 16-bit ints */ +#define LUA_INT32 long +#define LUAI_UMEM unsigned long +#define LUAI_MEM long +#endif /* } */ + + +/* +@@ LUAI_MAXSTACK limits the size of the Lua stack. +** CHANGE it if you need a different limit. This limit is arbitrary; +** its only purpose is to stop Lua to consume unlimited stack +** space (and to reserve some numbers for pseudo-indices). +*/ +#if LUAI_BITSINT >= 32 +#define LUAI_MAXSTACK 1000000 +#else +#define LUAI_MAXSTACK 15000 +#endif + +/* reserve some space for error handling */ +#define LUAI_FIRSTPSEUDOIDX (-LUAI_MAXSTACK - 1000) + + + + +/* +@@ LUAL_BUFFERSIZE is the buffer size used by the lauxlib buffer system. +** CHANGE it if it uses too much C-stack space. +*/ +#define LUAL_BUFFERSIZE BUFSIZ + + + + +/* +** {================================================================== +@@ LUA_NUMBER is the type of numbers in Lua. +** CHANGE the following definitions only if you want to build Lua +** with a number type different from double. You may also need to +** change lua_number2int & lua_number2integer. +** =================================================================== +*/ + +#define LUA_NUMBER_DOUBLE +#define LUA_NUMBER double + +/* +@@ LUAI_UACNUMBER is the result of an 'usual argument conversion' +@* over a number. +*/ +#define LUAI_UACNUMBER double + + +/* +@@ LUA_NUMBER_SCAN is the format for reading numbers. +@@ LUA_NUMBER_FMT is the format for writing numbers. +@@ lua_number2str converts a number to a string. +@@ LUAI_MAXNUMBER2STR is maximum size of previous conversion. +*/ +#define LUA_NUMBER_SCAN "%lf" +#define LUA_NUMBER_FMT "%.14g" +#define lua_number2str(s,n) sprintf((s), LUA_NUMBER_FMT, (n)) +#define LUAI_MAXNUMBER2STR 32 /* 16 digits, sign, point, and \0 */ + + +/* +@@ l_mathop allows the addition of an 'l' or 'f' to all math operations +*/ +#define l_mathop(x) (x) + + +/* +@@ lua_str2number converts a decimal numeric string to a number. +@@ lua_strx2number converts an hexadecimal numeric string to a number. +** In C99, 'strtod' does both conversions. C89, however, has no function +** to convert floating hexadecimal strings to numbers. For these +** systems, you can leave 'lua_strx2number' undefined and Lua will +** provide its own implementation. +*/ +#define lua_str2number(s,p) strtod((s), (p)) + +#if defined(LUA_USE_STRTODHEX) +#define lua_strx2number(s,p) strtod((s), (p)) +#endif + + +/* +@@ The luai_num* macros define the primitive operations over numbers. +*/ + +/* the following operations need the math library */ +#if defined(lobject_c) || defined(lvm_c) +#include +#define luai_nummod(L,a,b) ((a) - l_mathop(floor)((a)/(b))*(b)) +#define luai_numpow(L,a,b) (l_mathop(pow)(a,b)) +#endif + +/* these are quite standard operations */ +#if defined(LUA_CORE) +#define luai_numadd(L,a,b) ((a)+(b)) +#define luai_numsub(L,a,b) ((a)-(b)) +#define luai_nummul(L,a,b) ((a)*(b)) +#define luai_numdiv(L,a,b) ((a)/(b)) +#define luai_numunm(L,a) (-(a)) +#define luai_numeq(a,b) ((a)==(b)) +#define luai_numlt(L,a,b) ((a)<(b)) +#define luai_numle(L,a,b) ((a)<=(b)) +#define luai_numisnan(L,a) (!luai_numeq((a), (a))) +#endif + + + +/* +@@ LUA_INTEGER is the integral type used by lua_pushinteger/lua_tointeger. +** CHANGE that if ptrdiff_t is not adequate on your machine. (On most +** machines, ptrdiff_t gives a good choice between int or long.) +*/ +#define LUA_INTEGER ptrdiff_t + +/* +@@ LUA_UNSIGNED is the integral type used by lua_pushunsigned/lua_tounsigned. +** It must have at least 32 bits. +*/ +#define LUA_UNSIGNED unsigned LUA_INT32 + + + +/* +** Some tricks with doubles +*/ + +#if defined(LUA_NUMBER_DOUBLE) && !defined(LUA_ANSI) /* { */ +/* +** The next definitions activate some tricks to speed up the +** conversion from doubles to integer types, mainly to LUA_UNSIGNED. +** +@@ LUA_MSASMTRICK uses Microsoft assembler to avoid clashes with a +** DirectX idiosyncrasy. +** +@@ LUA_IEEE754TRICK uses a trick that should work on any machine +** using IEEE754 with a 32-bit integer type. +** +@@ LUA_IEEELL extends the trick to LUA_INTEGER; should only be +** defined when LUA_INTEGER is a 32-bit integer. +** +@@ LUA_IEEEENDIAN is the endianness of doubles in your machine +** (0 for little endian, 1 for big endian); if not defined, Lua will +** check it dynamically for LUA_IEEE754TRICK (but not for LUA_NANTRICK). +** +@@ LUA_NANTRICK controls the use of a trick to pack all types into +** a single double value, using NaN values to represent non-number +** values. The trick only works on 32-bit machines (ints and pointers +** are 32-bit values) with numbers represented as IEEE 754-2008 doubles +** with conventional endianess (12345678 or 87654321), in CPUs that do +** not produce signaling NaN values (all NaNs are quiet). +*/ + +/* Microsoft compiler on a Pentium (32 bit) ? */ +#if defined(LUA_WIN) && defined(_MSC_VER) && defined(_M_IX86) /* { */ + +#define LUA_MSASMTRICK +#define LUA_IEEEENDIAN 0 +#define LUA_NANTRICK + + +/* pentium 32 bits? */ +#elif defined(__i386__) || defined(__i386) || defined(__X86__) /* }{ */ + +#define LUA_IEEE754TRICK +#define LUA_IEEELL +#define LUA_IEEEENDIAN 0 +#define LUA_NANTRICK + +/* pentium 64 bits? */ +#elif defined(__x86_64) /* }{ */ + +#define LUA_IEEE754TRICK +#define LUA_IEEEENDIAN 0 + +#elif defined(__POWERPC__) || defined(__ppc__) /* }{ */ + +#define LUA_IEEE754TRICK +#define LUA_IEEEENDIAN 1 + +#else /* }{ */ + +/* assume IEEE754 and a 32-bit integer type */ +#define LUA_IEEE754TRICK + +#endif /* } */ + +#endif /* } */ + +/* }================================================================== */ + + + + +/* =================================================================== */ + +/* +** Local configuration. You can use this space to add your redefinitions +** without modifying the main part of the file. +*/ + + + +#endif + diff --git a/include/lualib.h b/include/lualib.h new file mode 100644 index 0000000..da82005 --- /dev/null +++ b/include/lualib.h @@ -0,0 +1,55 @@ +/* +** $Id: lualib.h,v 1.43.1.1 2013/04/12 18:48:47 roberto Exp $ +** Lua standard libraries +** See Copyright Notice in lua.h +*/ + + +#ifndef lualib_h +#define lualib_h + +#include "lua.h" + + + +LUAMOD_API int (luaopen_base) (lua_State *L); + +#define LUA_COLIBNAME "coroutine" +LUAMOD_API int (luaopen_coroutine) (lua_State *L); + +#define LUA_TABLIBNAME "table" +LUAMOD_API int (luaopen_table) (lua_State *L); + +#define LUA_IOLIBNAME "io" +LUAMOD_API int (luaopen_io) (lua_State *L); + +#define LUA_OSLIBNAME "os" +LUAMOD_API int (luaopen_os) (lua_State *L); + +#define LUA_STRLIBNAME "string" +LUAMOD_API int (luaopen_string) (lua_State *L); + +#define LUA_BITLIBNAME "bit32" +LUAMOD_API int (luaopen_bit32) (lua_State *L); + +#define LUA_MATHLIBNAME "math" +LUAMOD_API int (luaopen_math) (lua_State *L); + +#define LUA_DBLIBNAME "debug" +LUAMOD_API int (luaopen_debug) (lua_State *L); + +#define LUA_LOADLIBNAME "package" +LUAMOD_API int (luaopen_package) (lua_State *L); + + +/* open all previous libraries */ +LUALIB_API void (luaL_openlibs) (lua_State *L); + + + +#if !defined(lua_assert) +#define lua_assert(x) ((void)0) +#endif + + +#endif diff --git a/lib/liblua.dll.a b/lib/liblua.dll.a new file mode 100644 index 0000000..a4aae39 Binary files /dev/null and b/lib/liblua.dll.a differ diff --git a/share/lua/README.md b/share/lua/README.md new file mode 100644 index 0000000..49033ad --- /dev/null +++ b/share/lua/README.md @@ -0,0 +1,6 @@ + +This is Lua 5.2.3, released on 11 Nov 2013. + +For installation instructions, license details, and +further information about Lua, see doc/readme.html. + diff --git a/share/lua/doc/contents.html b/share/lua/doc/contents.html new file mode 100644 index 0000000..0ce297d --- /dev/null +++ b/share/lua/doc/contents.html @@ -0,0 +1,533 @@ + + + +Lua 5.2 Reference Manual - contents + + + + + + + +
+

+ +Lua 5.2 Reference Manual +

+ +

+The reference manual is the official definition of the Lua language. +For a complete introduction to Lua programming, see the book +Programming in Lua. + +

+start +· +contents +· +index +

+ +Copyright © 2011–2013 Lua.org, PUC-Rio. +Freely available under the terms of the +Lua license. + + +

Contents

+ + +

Index

+ + + + + + + +
+

Lua functions

+

+_G
+_VERSION
+ +

+assert
+collectgarbage
+dofile
+error
+getmetatable
+ipairs
+load
+loadfile
+next
+pairs
+pcall
+print
+rawequal
+rawget
+rawlen
+rawset
+require
+select
+setmetatable
+tonumber
+tostring
+type
+xpcall
+ +

+bit32.arshift
+bit32.band
+bit32.bnot
+bit32.bor
+bit32.btest
+bit32.bxor
+bit32.extract
+bit32.lrotate
+bit32.lshift
+bit32.replace
+bit32.rrotate
+bit32.rshift
+ +

+coroutine.create
+coroutine.resume
+coroutine.running
+coroutine.status
+coroutine.wrap
+coroutine.yield
+ +

+debug.debug
+debug.getuservalue
+debug.gethook
+debug.getinfo
+debug.getlocal
+debug.getmetatable
+debug.getregistry
+debug.getupvalue
+debug.setuservalue
+debug.sethook
+debug.setlocal
+debug.setmetatable
+debug.setupvalue
+debug.traceback
+debug.upvalueid
+debug.upvaluejoin
+ +

+file:close
+file:flush
+file:lines
+file:read
+file:seek
+file:setvbuf
+file:write
+ +

+io.close
+io.flush
+io.input
+io.lines
+io.open
+io.output
+io.popen
+io.read
+io.stderr
+io.stdin
+io.stdout
+io.tmpfile
+io.type
+io.write
+ +

 +

 

+

+math.abs
+math.acos
+math.asin
+math.atan
+math.atan2
+math.ceil
+math.cos
+math.cosh
+math.deg
+math.exp
+math.floor
+math.fmod
+math.frexp
+math.huge
+math.ldexp
+math.log
+math.max
+math.min
+math.modf
+math.pi
+math.pow
+math.rad
+math.random
+math.randomseed
+math.sin
+math.sinh
+math.sqrt
+math.tan
+math.tanh
+ +

+os.clock
+os.date
+os.difftime
+os.execute
+os.exit
+os.getenv
+os.remove
+os.rename
+os.setlocale
+os.time
+os.tmpname
+ +

+package.config
+package.cpath
+package.loaded
+package.loadlib
+package.path
+package.preload
+package.searchers
+package.searchpath
+ +

+string.byte
+string.char
+string.dump
+string.find
+string.format
+string.gmatch
+string.gsub
+string.len
+string.lower
+string.match
+string.rep
+string.reverse
+string.sub
+string.upper
+ +

+table.concat
+table.insert
+table.pack
+table.remove
+table.sort
+table.unpack
+ +

 +

C API

+

+lua_Alloc
+lua_CFunction
+lua_Debug
+lua_Hook
+lua_Integer
+lua_Number
+lua_Reader
+lua_State
+lua_Unsigned
+lua_Writer
+ +

+lua_absindex
+lua_arith
+lua_atpanic
+lua_call
+lua_callk
+lua_checkstack
+lua_close
+lua_compare
+lua_concat
+lua_copy
+lua_createtable
+lua_dump
+lua_error
+lua_gc
+lua_getallocf
+lua_getctx
+lua_getfield
+lua_getglobal
+lua_gethook
+lua_gethookcount
+lua_gethookmask
+lua_getinfo
+lua_getlocal
+lua_getmetatable
+lua_getstack
+lua_gettable
+lua_gettop
+lua_getupvalue
+lua_getuservalue
+lua_insert
+lua_isboolean
+lua_iscfunction
+lua_isfunction
+lua_islightuserdata
+lua_isnil
+lua_isnone
+lua_isnoneornil
+lua_isnumber
+lua_isstring
+lua_istable
+lua_isthread
+lua_isuserdata
+lua_len
+lua_load
+lua_newstate
+lua_newtable
+lua_newthread
+lua_newuserdata
+lua_next
+lua_pcall
+lua_pcallk
+lua_pop
+lua_pushboolean
+lua_pushcclosure
+lua_pushcfunction
+lua_pushfstring
+lua_pushglobaltable
+lua_pushinteger
+lua_pushlightuserdata
+lua_pushliteral
+lua_pushlstring
+lua_pushnil
+lua_pushnumber
+lua_pushstring
+lua_pushthread
+lua_pushunsigned
+lua_pushvalue
+lua_pushvfstring
+lua_rawequal
+lua_rawget
+lua_rawgeti
+lua_rawgetp
+lua_rawlen
+lua_rawset
+lua_rawseti
+lua_rawsetp
+lua_register
+lua_remove
+lua_replace
+lua_resume
+lua_setallocf
+lua_setfield
+lua_setglobal
+lua_sethook
+lua_setlocal
+lua_setmetatable
+lua_settable
+lua_settop
+lua_setupvalue
+lua_setuservalue
+lua_status
+lua_toboolean
+lua_tocfunction
+lua_tointeger
+lua_tointegerx
+lua_tolstring
+lua_tonumber
+lua_tonumberx
+lua_topointer
+lua_tostring
+lua_tothread
+lua_tounsigned
+lua_tounsignedx
+lua_touserdata
+lua_type
+lua_typename
+lua_upvalueid
+lua_upvalueindex
+lua_upvaluejoin
+lua_version
+lua_xmove
+lua_yield
+lua_yieldk
+ +

 +

auxiliary library

+

+luaL_Buffer
+luaL_Reg
+ +

+luaL_addchar
+luaL_addlstring
+luaL_addsize
+luaL_addstring
+luaL_addvalue
+luaL_argcheck
+luaL_argerror
+luaL_buffinit
+luaL_buffinitsize
+luaL_callmeta
+luaL_checkany
+luaL_checkint
+luaL_checkinteger
+luaL_checklong
+luaL_checklstring
+luaL_checknumber
+luaL_checkoption
+luaL_checkstack
+luaL_checkstring
+luaL_checktype
+luaL_checkudata
+luaL_checkunsigned
+luaL_checkversion
+luaL_dofile
+luaL_dostring
+luaL_error
+luaL_execresult
+luaL_fileresult
+luaL_getmetafield
+luaL_getmetatable
+luaL_getsubtable
+luaL_gsub
+luaL_len
+luaL_loadbuffer
+luaL_loadbufferx
+luaL_loadfile
+luaL_loadfilex
+luaL_loadstring
+luaL_newlib
+luaL_newlibtable
+luaL_newmetatable
+luaL_newstate
+luaL_openlibs
+luaL_optint
+luaL_optinteger
+luaL_optlong
+luaL_optlstring
+luaL_optnumber
+luaL_optstring
+luaL_optunsigned
+luaL_prepbuffer
+luaL_prepbuffsize
+luaL_pushresult
+luaL_pushresultsize
+luaL_ref
+luaL_requiref
+luaL_setfuncs
+luaL_setmetatable
+luaL_testudata
+luaL_tolstring
+luaL_traceback
+luaL_typename
+luaL_unref
+luaL_where
+ +

+ +
+ +Last update: +Tue Mar 12 11:22:18 BRT 2013 + + + + + diff --git a/share/lua/doc/logo.gif b/share/lua/doc/logo.gif new file mode 100644 index 0000000..2f5e4ac Binary files /dev/null and b/share/lua/doc/logo.gif differ diff --git a/share/lua/doc/lua.1 b/share/lua/doc/lua.1 new file mode 100644 index 0000000..1dbf043 --- /dev/null +++ b/share/lua/doc/lua.1 @@ -0,0 +1,116 @@ +.\" $Id: lua.man,v 1.13 2011/11/16 17:16:53 lhf Exp $ +.TH LUA 1 "$Date: 2011/11/16 17:16:53 $" +.SH NAME +lua \- Lua interpreter +.SH SYNOPSIS +.B lua +[ +.I options +] +[ +.I script +[ +.I args +] +] +.SH DESCRIPTION +.B lua +is the standalone Lua interpreter. +It loads and executes Lua programs, +either in textual source form or +in precompiled binary form. +(Precompiled binaries are output by +.BR luac , +the Lua compiler.) +.B lua +can be used as a batch interpreter and also interactively. +.LP +The given +.I options +are handled in order and then +the Lua program in file +.I script +is loaded and executed. +The given +.I args +are available to +.I script +as strings in a global table named +.BR arg . +If no options or arguments are given, +then +.B "\-v \-i" +is assumed when the standard input is a terminal; +otherwise, +.B "\-" +is assumed. +.LP +In interactive mode, +.B lua +prompts the user, +reads lines from the standard input, +and executes them as they are read. +If a line does not contain a complete statement, +then a secondary prompt is displayed and +lines are read until a complete statement is formed or +a syntax error is found. +If a line starts with +.BR '=' , +then +.B lua +evaluates and displays +the values of the expressions in the remainder of the line. +.LP +At the very start, +before even handling the command line, +.B lua +checks the contents of the environment variables +.B LUA_INIT_5_2 +or +.BR LUA_INIT , +in that order. +If the contents is of the form +.RI '@ filename ', +then +.I filename +is executed. +Otherwise, the string is assumed to be a Lua statement and is executed. +.SH OPTIONS +.TP +.BI \-e " stat" +execute statement +.IR stat . +.TP +.B \-i +enter interactive mode after executing +.IR script . +.TP +.BI \-l " name" +execute the equivalent of +.IB name =require(' name ') +before executing +.IR script . +.TP +.B \-v +show version information. +.TP +.B \-E +ignore environment variables. +.TP +.B \-\- +stop handling options. +.TP +.B \- +stop handling options and execute the standard input as a file. +.SH "SEE ALSO" +.BR luac (1) +.br +The documentation at lua.org, +especially section 7 of the reference manual. +.SH DIAGNOSTICS +Error messages should be self explanatory. +.SH AUTHORS +R. Ierusalimschy, +L. H. de Figueiredo, +W. Celes +.\" EOF diff --git a/share/lua/doc/lua.css b/share/lua/doc/lua.css new file mode 100644 index 0000000..3d2443a --- /dev/null +++ b/share/lua/doc/lua.css @@ -0,0 +1,96 @@ +html { + background-color: #F8F8F8 ; +} + +body { + border: solid #a0a0a0 1px ; + border-radius: 20px ; + padding: 26px ; + margin: 16px ; + color: #000000 ; + background-color: #FFFFFF ; + font-family: Helvetica, Arial, sans-serif ; + text-align: justify ; +} + +h1, h2, h3, h4 { + font-family: Verdana, Geneva, sans-serif ; + font-weight: normal ; + font-style: normal ; +} + +h2 { + padding-top: 0.4em ; + padding-bottom: 0.4em ; + padding-left: 0.8em ; + padding-right: 0.8em ; + background-color: #D0D0FF ; + border-radius: 8px ; + border: solid #a0a0a0 1px ; +} + +h3 { + padding-left: 0.5em ; + border-left: solid #D0D0FF 1em ; +} + +table h3 { + padding-left: 0px ; + border-left: none ; +} + +a:link { + color: #000080 ; + background-color: inherit ; + text-decoration: none ; +} + +a:visited { + background-color: inherit ; + text-decoration: none ; +} + +a:link:hover, a:visited:hover { + color: #000080 ; + background-color: #D0D0FF ; +} + +a:link:active, a:visited:active { + color: #FF0000 ; +} + +hr { + border: 0 ; + height: 1px ; + color: #a0a0a0 ; + background-color: #a0a0a0 ; + display: none ; +} + +table hr { + display: block ; +} + +:target { + background-color: #F8F8F8 ; + padding: 8px ; + border: solid #a0a0a0 2px ; + border-radius: 8px ; +} + +.footer { + color: gray ; + font-size: x-small ; +} + +input[type=text] { + border: solid #a0a0a0 2px ; + border-radius: 2em ; + -moz-border-radius: 2em ; + background-image: url('images/search.png') ; + background-repeat: no-repeat; + background-position: 4px center ; + padding-left: 20px ; + height: 2em ; +} + diff --git a/share/lua/doc/luac.1 b/share/lua/doc/luac.1 new file mode 100644 index 0000000..33a4ed0 --- /dev/null +++ b/share/lua/doc/luac.1 @@ -0,0 +1,118 @@ +.\" $Id: luac.man,v 1.29 2011/11/16 13:53:40 lhf Exp $ +.TH LUAC 1 "$Date: 2011/11/16 13:53:40 $" +.SH NAME +luac \- Lua compiler +.SH SYNOPSIS +.B luac +[ +.I options +] [ +.I filenames +] +.SH DESCRIPTION +.B luac +is the Lua compiler. +It translates programs written in the Lua programming language +into binary files containing precompiled chunks +that can be later loaded and executed. +.LP +The main advantages of precompiling chunks are: +faster loading, +protecting source code from accidental user changes, +and +off-line syntax checking. +Precompiling does not imply faster execution +because in Lua chunks are always compiled into bytecodes before being executed. +.B luac +simply allows those bytecodes to be saved in a file for later execution. +Precompiled chunks are not necessarily smaller than the corresponding source. +The main goal in precompiling is faster loading. +.LP +In the command line, +you can mix +text files containing Lua source and +binary files containing precompiled chunks. +.B luac +produces a single output file containing the combined bytecodes +for all files given. +Executing the combined file is equivalent to executing the given files. +By default, +the output file is named +.BR luac.out , +but you can change this with the +.B \-o +option. +.LP +Precompiled chunks are +.I not +portable across different architectures. +Moreover, +the internal format of precompiled chunks +is likely to change when a new version of Lua is released. +Make sure you save the source files of all Lua programs that you precompile. +.LP +.SH OPTIONS +.TP +.B \-l +produce a listing of the compiled bytecode for Lua's virtual machine. +Listing bytecodes is useful to learn about Lua's virtual machine. +If no files are given, then +.B luac +loads +.B luac.out +and lists its contents. +Use +.B \-l \-l +for a full listing. +.TP +.BI \-o " file" +output to +.IR file , +instead of the default +.BR luac.out . +(You can use +.B "'\-'" +for standard output, +but not on platforms that open standard output in text mode.) +The output file may be one of the given files because +all files are loaded before the output file is written. +Be careful not to overwrite precious files. +.TP +.B \-p +load files but do not generate any output file. +Used mainly for syntax checking and for testing precompiled chunks: +corrupted files will probably generate errors when loaded. +If no files are given, then +.B luac +loads +.B luac.out +and tests its contents. +No messages are displayed if the file loads without errors. +.TP +.B \-s +strip debug information before writing the output file. +This saves some space in very large chunks, +but if errors occur when running a stripped chunk, +then the error messages may not contain the full information they usually do. +In particular, +line numbers and names of local variables are lost. +.TP +.B \-v +show version information. +.TP +.B \-\- +stop handling options. +.TP +.B \- +stop handling options and process standard input. +.SH "SEE ALSO" +.BR lua (1) +.br +The documentation at lua.org. +.SH DIAGNOSTICS +Error messages should be self explanatory. +.SH AUTHORS +R. Ierusalimschy, +L. H. de Figueiredo, +W. Celes +.\" EOF diff --git a/share/lua/doc/manual.css b/share/lua/doc/manual.css new file mode 100644 index 0000000..ca613cd --- /dev/null +++ b/share/lua/doc/manual.css @@ -0,0 +1,27 @@ +h3 code { + font-family: inherit ; + font-size: inherit ; +} + +pre, code { + font-size: 12pt ; +} + +span.apii { + float: right ; + font-family: inherit ; + font-style: normal ; + font-size: small ; + color: gray ; +} + +p+h1, ul+h1 { + font-style: normal ; + padding-top: 0.4em ; + padding-bottom: 0.4em ; + padding-left: 16px ; + margin-left: -16px ; + background-color: #D0D0FF ; + border-radius: 8px ; + border: solid #000080 1px ; +} diff --git a/share/lua/doc/manual.html b/share/lua/doc/manual.html new file mode 100644 index 0000000..8536536 --- /dev/null +++ b/share/lua/doc/manual.html @@ -0,0 +1,10507 @@ + + + + +Lua 5.2 Reference Manual + + + + + + + +
+

+ +Lua 5.2 Reference Manual +

+ +by Roberto Ierusalimschy, Luiz Henrique de Figueiredo, Waldemar Celes +

+ +Copyright © 2011–2013 Lua.org, PUC-Rio. +Freely available under the terms of the +Lua license. + +

+

+ +contents +· +index + + +

+ + + + + + +

1 – Introduction

+ +

+Lua is an extension programming language designed to support +general procedural programming with data description +facilities. +It also offers good support for object-oriented programming, +functional programming, and data-driven programming. +Lua is intended to be used as a powerful, lightweight, +embeddable scripting language for any program that needs one. +Lua is implemented as a library, written in clean C, +the common subset of Standard C and C++. + + +

+Being an extension language, Lua has no notion of a "main" program: +it only works embedded in a host client, +called the embedding program or simply the host. +The host program can invoke functions to execute a piece of Lua code, +can write and read Lua variables, +and can register C functions to be called by Lua code. +Through the use of C functions, Lua can be augmented to cope with +a wide range of different domains, +thus creating customized programming languages sharing a syntactical framework. +The Lua distribution includes a sample host program called lua, +which uses the Lua library to offer a complete, standalone Lua interpreter, +for interactive or batch use. + + +

+Lua is free software, +and is provided as usual with no guarantees, +as stated in its license. +The implementation described in this manual is available +at Lua's official web site, www.lua.org. + + +

+Like any other reference manual, +this document is dry in places. +For a discussion of the decisions behind the design of Lua, +see the technical papers available at Lua's web site. +For a detailed introduction to programming in Lua, +see Roberto's book, Programming in Lua. + + + +

2 – Basic Concepts

+ +

+This section describes the basic concepts of the language. + + + +

2.1 – Values and Types

+ +

+Lua is a dynamically typed language. +This means that +variables do not have types; only values do. +There are no type definitions in the language. +All values carry their own type. + + +

+All values in Lua are first-class values. +This means that all values can be stored in variables, +passed as arguments to other functions, and returned as results. + + +

+There are eight basic types in Lua: +nil, boolean, number, +string, function, userdata, +thread, and table. +Nil is the type of the value nil, +whose main property is to be different from any other value; +it usually represents the absence of a useful value. +Boolean is the type of the values false and true. +Both nil and false make a condition false; +any other value makes it true. +Number represents real (double-precision floating-point) numbers. +Operations on numbers follow the same rules of +the underlying C implementation, +which, in turn, usually follows the IEEE 754 standard. +(It is easy to build Lua interpreters that use other +internal representations for numbers, +such as single-precision floats or long integers; +see file luaconf.h.) +String represents immutable sequences of bytes. + +Lua is 8-bit clean: +strings can contain any 8-bit value, +including embedded zeros ('\0'). + + +

+Lua can call (and manipulate) functions written in Lua and +functions written in C +(see §3.4.9). + + +

+The type userdata is provided to allow arbitrary C data to +be stored in Lua variables. +A userdata value is a pointer to a block of raw memory. +There are two kinds of userdata: +full userdata, where the block of memory is managed by Lua, +and light userdata, where the block of memory is managed by the host. +Userdata has no predefined operations in Lua, +except assignment and identity test. +By using metatables, +the programmer can define operations for full userdata values +(see §2.4). +Userdata values cannot be created or modified in Lua, +only through the C API. +This guarantees the integrity of data owned by the host program. + + +

+The type thread represents independent threads of execution +and it is used to implement coroutines (see §2.6). +Do not confuse Lua threads with operating-system threads. +Lua supports coroutines on all systems, +even those that do not support threads. + + +

+The type table implements associative arrays, +that is, arrays that can be indexed not only with numbers, +but with any Lua value except nil and NaN +(Not a Number, a special numeric value used to represent +undefined or unrepresentable results, such as 0/0). +Tables can be heterogeneous; +that is, they can contain values of all types (except nil). +Any key with value nil is not considered part of the table. +Conversely, any key that is not part of a table has +an associated value nil. + + +

+Tables are the sole data structuring mechanism in Lua; +they can be used to represent ordinary arrays, sequences, +symbol tables, sets, records, graphs, trees, etc. +To represent records, Lua uses the field name as an index. +The language supports this representation by +providing a.name as syntactic sugar for a["name"]. +There are several convenient ways to create tables in Lua +(see §3.4.8). + + +

+We use the term sequence to denote a table where +the set of all positive numeric keys is equal to {1..n} +for some integer n, +which is called the length of the sequence (see §3.4.6). + + +

+Like indices, +the values of table fields can be of any type. +In particular, +because functions are first-class values, +table fields can contain functions. +Thus tables can also carry methods (see §3.4.10). + + +

+The indexing of tables follows +the definition of raw equality in the language. +The expressions a[i] and a[j] +denote the same table element +if and only if i and j are raw equal +(that is, equal without metamethods). + + +

+Tables, functions, threads, and (full) userdata values are objects: +variables do not actually contain these values, +only references to them. +Assignment, parameter passing, and function returns +always manipulate references to such values; +these operations do not imply any kind of copy. + + +

+The library function type returns a string describing the type +of a given value (see §6.1). + + + + + +

2.2 – Environments and the Global Environment

+ +

+As will be discussed in §3.2 and §3.3.3, +any reference to a global name var is syntactically translated +to _ENV.var. +Moreover, every chunk is compiled in the scope of +an external local variable called _ENV (see §3.3.2), +so _ENV itself is never a global name in a chunk. + + +

+Despite the existence of this external _ENV variable and +the translation of global names, +_ENV is a completely regular name. +In particular, +you can define new variables and parameters with that name. +Each reference to a global name uses the _ENV that is +visible at that point in the program, +following the usual visibility rules of Lua (see §3.5). + + +

+Any table used as the value of _ENV is called an environment. + + +

+Lua keeps a distinguished environment called the global environment. +This value is kept at a special index in the C registry (see §4.5). +In Lua, the variable _G is initialized with this same value. + + +

+When Lua compiles a chunk, +it initializes the value of its _ENV upvalue +with the global environment (see load). +Therefore, by default, +global variables in Lua code refer to entries in the global environment. +Moreover, all standard libraries are loaded in the global environment +and several functions there operate on that environment. +You can use load (or loadfile) +to load a chunk with a different environment. +(In C, you have to load the chunk and then change the value +of its first upvalue.) + + +

+If you change the global environment in the registry +(through C code or the debug library), +all chunks loaded after the change will get the new environment. +Previously loaded chunks are not affected, however, +as each has its own reference to the environment in its _ENV variable. +Moreover, the variable _G +(which is stored in the original global environment) +is never updated by Lua. + + + + + +

2.3 – Error Handling

+ +

+Because Lua is an embedded extension language, +all Lua actions start from C code in the host program +calling a function from the Lua library (see lua_pcall). +Whenever an error occurs during +the compilation or execution of a Lua chunk, +control returns to the host, +which can take appropriate measures +(such as printing an error message). + + +

+Lua code can explicitly generate an error by calling the +error function. +If you need to catch errors in Lua, +you can use pcall or xpcall +to call a given function in protected mode. + + +

+Whenever there is an error, +an error object (also called an error message) +is propagated with information about the error. +Lua itself only generates errors where the error object is a string, +but programs may generate errors with +any value for the error object. + + +

+When you use xpcall or lua_pcall, +you may give a message handler +to be called in case of errors. +This function is called with the original error message +and returns a new error message. +It is called before the error unwinds the stack, +so that it can gather more information about the error, +for instance by inspecting the stack and creating a stack traceback. +This message handler is still protected by the protected call; +so, an error inside the message handler +will call the message handler again. +If this loop goes on, Lua breaks it and returns an appropriate message. + + + + + +

2.4 – Metatables and Metamethods

+ +

+Every value in Lua can have a metatable. +This metatable is an ordinary Lua table +that defines the behavior of the original value +under certain special operations. +You can change several aspects of the behavior +of operations over a value by setting specific fields in its metatable. +For instance, when a non-numeric value is the operand of an addition, +Lua checks for a function in the field "__add" of the value's metatable. +If it finds one, +Lua calls this function to perform the addition. + + +

+The keys in a metatable are derived from the event names; +the corresponding values are called metamethods. +In the previous example, the event is "add" +and the metamethod is the function that performs the addition. + + +

+You can query the metatable of any value +using the getmetatable function. + + +

+You can replace the metatable of tables +using the setmetatable function. +You cannot change the metatable of other types from Lua +(except by using the debug library); +you must use the C API for that. + + +

+Tables and full userdata have individual metatables +(although multiple tables and userdata can share their metatables). +Values of all other types share one single metatable per type; +that is, there is one single metatable for all numbers, +one for all strings, etc. +By default, a value has no metatable, +but the string library sets a metatable for the string type (see §6.4). + + +

+A metatable controls how an object behaves in arithmetic operations, +order comparisons, concatenation, length operation, and indexing. +A metatable also can define a function to be called +when a userdata or a table is garbage collected. +When Lua performs one of these operations over a value, +it checks whether this value has a metatable with the corresponding event. +If so, the value associated with that key (the metamethod) +controls how Lua will perform the operation. + + +

+Metatables control the operations listed next. +Each operation is identified by its corresponding name. +The key for each operation is a string with its name prefixed by +two underscores, '__'; +for instance, the key for operation "add" is the +string "__add". + + +

+The semantics of these operations is better explained by a Lua function +describing how the interpreter executes the operation. +The code shown here in Lua is only illustrative; +the real behavior is hard coded in the interpreter +and it is much more efficient than this simulation. +All functions used in these descriptions +(rawget, tonumber, etc.) +are described in §6.1. +In particular, to retrieve the metamethod of a given object, +we use the expression + +

+     metatable(obj)[event]
+

+This should be read as + +

+     rawget(getmetatable(obj) or {}, event)
+

+This means that the access to a metamethod does not invoke other metamethods, +and access to objects with no metatables does not fail +(it simply results in nil). + + +

+For the unary - and # operators, +the metamethod is called with a dummy second argument. +This extra argument is only to simplify Lua's internals; +it may be removed in future versions and therefore it is not present +in the following code. +(For most uses this extra argument is irrelevant.) + + + +

    + +
  • "add": +the + operation. + + + +

    +The function getbinhandler below defines how Lua chooses a handler +for a binary operation. +First, Lua tries the first operand. +If its type does not define a handler for the operation, +then Lua tries the second operand. + +

    +     function getbinhandler (op1, op2, event)
+       return metatable(op1)[event] or metatable(op2)[event]
+     end
+

    +By using this function, +the behavior of the op1 + op2 is + +

    +     function add_event (op1, op2)
+       local o1, o2 = tonumber(op1), tonumber(op2)
+       if o1 and o2 then  -- both operands are numeric?
+         return o1 + o2   -- '+' here is the primitive 'add'
+       else  -- at least one of the operands is not numeric
+         local h = getbinhandler(op1, op2, "__add")
+         if h then
+           -- call the handler with both operands
+           return (h(op1, op2))
+         else  -- no handler available: default behavior
+           error(···)
+         end
+       end
+     end
+

    +

    • + +
  • "sub": +the - operation. + +Behavior similar to the "add" operation. +
    • + +
  • "mul": +the * operation. + +Behavior similar to the "add" operation. +
    • + +
  • "div": +the / operation. + +Behavior similar to the "add" operation. +
    • + +
  • "mod": +the % operation. + +Behavior similar to the "add" operation, +with the operation +o1 - floor(o1/o2)*o2 as the primitive operation. +
    • + +
  • "pow": +the ^ (exponentiation) operation. + +Behavior similar to the "add" operation, +with the function pow (from the C math library) +as the primitive operation. +
    • + +
  • "unm": +the unary - operation. + + +
    +     function unm_event (op)
+       local o = tonumber(op)
+       if o then  -- operand is numeric?
+         return -o  -- '-' here is the primitive 'unm'
+       else  -- the operand is not numeric.
+         -- Try to get a handler from the operand
+         local h = metatable(op).__unm
+         if h then
+           -- call the handler with the operand
+           return (h(op))
+         else  -- no handler available: default behavior
+           error(···)
+         end
+       end
+     end
+

    +

    • + +
  • "concat": +the .. (concatenation) operation. + + +
    +     function concat_event (op1, op2)
+       if (type(op1) == "string" or type(op1) == "number") and
+          (type(op2) == "string" or type(op2) == "number") then
+         return op1 .. op2  -- primitive string concatenation
+       else
+         local h = getbinhandler(op1, op2, "__concat")
+         if h then
+           return (h(op1, op2))
+         else
+           error(···)
+         end
+       end
+     end
+

    +

    • + +
  • "len": +the # operation. + + +
    +     function len_event (op)
+       if type(op) == "string" then
+         return strlen(op)      -- primitive string length
+       else
+         local h = metatable(op).__len
+         if h then
+           return (h(op))       -- call handler with the operand
+         elseif type(op) == "table" then
+           return #op              -- primitive table length
+         else  -- no handler available: error
+           error(···)
+         end
+       end
+     end
+

    +See §3.4.6 for a description of the length of a table. +

    • + +
  • "eq": +the == operation. + +The function getequalhandler defines how Lua chooses a metamethod +for equality. +A metamethod is selected only when both values +being compared have the same type +and the same metamethod for the selected operation, +and the values are either tables or full userdata. + +
    +     function getequalhandler (op1, op2)
+       if type(op1) ~= type(op2) or
+          (type(op1) ~= "table" and type(op1) ~= "userdata") then
+         return nil     -- different values
+       end
+       local mm1 = metatable(op1).__eq
+       local mm2 = metatable(op2).__eq
+       if mm1 == mm2 then return mm1 else return nil end
+     end
+

    +The "eq" event is defined as follows: + +

    +     function eq_event (op1, op2)
+       if op1 == op2 then   -- primitive equal?
+         return true   -- values are equal
+       end
+       -- try metamethod
+       local h = getequalhandler(op1, op2)
+       if h then
+         return not not h(op1, op2)
+       else
+         return false
+       end
+     end
+

    +Note that the result is always a boolean. +

    • + +
  • "lt": +the < operation. + + +
    +     function lt_event (op1, op2)
+       if type(op1) == "number" and type(op2) == "number" then
+         return op1 < op2   -- numeric comparison
+       elseif type(op1) == "string" and type(op2) == "string" then
+         return op1 < op2   -- lexicographic comparison
+       else
+         local h = getbinhandler(op1, op2, "__lt")
+         if h then
+           return not not h(op1, op2)
+         else
+           error(···)
+         end
+       end
+     end
+

    +Note that the result is always a boolean. +

    • + +
  • "le": +the <= operation. + + +
    +     function le_event (op1, op2)
+       if type(op1) == "number" and type(op2) == "number" then
+         return op1 <= op2   -- numeric comparison
+       elseif type(op1) == "string" and type(op2) == "string" then
+         return op1 <= op2   -- lexicographic comparison
+       else
+         local h = getbinhandler(op1, op2, "__le")
+         if h then
+           return not not h(op1, op2)
+         else
+           h = getbinhandler(op1, op2, "__lt")
+           if h then
+             return not h(op2, op1)
+           else
+             error(···)
+           end
+         end
+       end
+     end
+

    +Note that, in the absence of a "le" metamethod, +Lua tries the "lt", assuming that a <= b is +equivalent to not (b < a). + + +

    +As with the other comparison operators, +the result is always a boolean. +

    • + +
  • "index": +The indexing access table[key]. +Note that the metamethod is tried only +when key is not present in table. +(When table is not a table, +no key is ever present, +so the metamethod is always tried.) + + +
    +     function gettable_event (table, key)
+       local h
+       if type(table) == "table" then
+         local v = rawget(table, key)
+         -- if key is present, return raw value
+         if v ~= nil then return v end
+         h = metatable(table).__index
+         if h == nil then return nil end
+       else
+         h = metatable(table).__index
+         if h == nil then
+           error(···)
+         end
+       end
+       if type(h) == "function" then
+         return (h(table, key))     -- call the handler
+       else return h[key]           -- or repeat operation on it
+       end
+     end
+

    +

    • + +
  • "newindex": +The indexing assignment table[key] = value. +Note that the metamethod is tried only +when key is not present in table. + + +
    +     function settable_event (table, key, value)
+       local h
+       if type(table) == "table" then
+         local v = rawget(table, key)
+         -- if key is present, do raw assignment
+         if v ~= nil then rawset(table, key, value); return end
+         h = metatable(table).__newindex
+         if h == nil then rawset(table, key, value); return end
+       else
+         h = metatable(table).__newindex
+         if h == nil then
+           error(···)
+         end
+       end
+       if type(h) == "function" then
+         h(table, key,value)           -- call the handler
+       else h[key] = value             -- or repeat operation on it
+       end
+     end
+

    +

    • + +
  • "call": +called when Lua calls a value. + + +
    +     function function_event (func, ...)
+       if type(func) == "function" then
+         return func(...)   -- primitive call
+       else
+         local h = metatable(func).__call
+         if h then
+           return h(func, ...)
+         else
+           error(···)
+         end
+       end
+     end
+

    +

    • + +
+ + + + +

2.5 – Garbage Collection

+ +

+Lua performs automatic memory management. +This means that +you have to worry neither about allocating memory for new objects +nor about freeing it when the objects are no longer needed. +Lua manages memory automatically by running +a garbage collector to collect all dead objects +(that is, objects that are no longer accessible from Lua). +All memory used by Lua is subject to automatic management: +strings, tables, userdata, functions, threads, internal structures, etc. + + +

+Lua implements an incremental mark-and-sweep collector. +It uses two numbers to control its garbage-collection cycles: +the garbage-collector pause and +the garbage-collector step multiplier. +Both use percentage points as units +(e.g., a value of 100 means an internal value of 1). + + +

+The garbage-collector pause +controls how long the collector waits before starting a new cycle. +Larger values make the collector less aggressive. +Values smaller than 100 mean the collector will not wait to +start a new cycle. +A value of 200 means that the collector waits for the total memory in use +to double before starting a new cycle. + + +

+The garbage-collector step multiplier +controls the relative speed of the collector relative to +memory allocation. +Larger values make the collector more aggressive but also increase +the size of each incremental step. +Values smaller than 100 make the collector too slow and +can result in the collector never finishing a cycle. +The default is 200, +which means that the collector runs at "twice" +the speed of memory allocation. + + +

+If you set the step multiplier to a very large number +(larger than 10% of the maximum number of +bytes that the program may use), +the collector behaves like a stop-the-world collector. +If you then set the pause to 200, +the collector behaves as in old Lua versions, +doing a complete collection every time Lua doubles its +memory usage. + + +

+You can change these numbers by calling lua_gc in C +or collectgarbage in Lua. +You can also use these functions to control +the collector directly (e.g., stop and restart it). + + +

+As an experimental feature in Lua 5.2, +you can change the collector's operation mode +from incremental to generational. +A generational collector assumes that most objects die young, +and therefore it traverses only young (recently created) objects. +This behavior can reduce the time used by the collector, +but also increases memory usage (as old dead objects may accumulate). +To mitigate this second problem, +from time to time the generational collector performs a full collection. +Remember that this is an experimental feature; +you are welcome to try it, +but check your gains. + + + +

2.5.1 – Garbage-Collection Metamethods

+ +

+You can set garbage-collector metamethods for tables +and, using the C API, +for full userdata (see §2.4). +These metamethods are also called finalizers. +Finalizers allow you to coordinate Lua's garbage collection +with external resource management +(such as closing files, network or database connections, +or freeing your own memory). + + +

+For an object (table or userdata) to be finalized when collected, +you must mark it for finalization. + +You mark an object for finalization when you set its metatable +and the metatable has a field indexed by the string "__gc". +Note that if you set a metatable without a __gc field +and later create that field in the metatable, +the object will not be marked for finalization. +However, after an object is marked, +you can freely change the __gc field of its metatable. + + +

+When a marked object becomes garbage, +it is not collected immediately by the garbage collector. +Instead, Lua puts it in a list. +After the collection, +Lua does the equivalent of the following function +for each object in that list: + +

+     function gc_event (obj)
+       local h = metatable(obj).__gc
+       if type(h) == "function" then
+         h(obj)
+       end
+     end
+
+ +

+At the end of each garbage-collection cycle, +the finalizers for objects are called in +the reverse order that they were marked for collection, +among those collected in that cycle; +that is, the first finalizer to be called is the one associated +with the object marked last in the program. +The execution of each finalizer may occur at any point during +the execution of the regular code. + + +

+Because the object being collected must still be used by the finalizer, +it (and other objects accessible only through it) +must be resurrected by Lua. +Usually, this resurrection is transient, +and the object memory is freed in the next garbage-collection cycle. +However, if the finalizer stores the object in some global place +(e.g., a global variable), +then there is a permanent resurrection. +In any case, +the object memory is freed only when it becomes completely inaccessible; +its finalizer will never be called twice. + + +

+When you close a state (see lua_close), +Lua calls the finalizers of all objects marked for finalization, +following the reverse order that they were marked. +If any finalizer marks new objects for collection during that phase, +these new objects will not be finalized. + + + + + +

2.5.2 – Weak Tables

+ +

+A weak table is a table whose elements are +weak references. +A weak reference is ignored by the garbage collector. +In other words, +if the only references to an object are weak references, +then the garbage collector will collect that object. + + +

+A weak table can have weak keys, weak values, or both. +A table with weak keys allows the collection of its keys, +but prevents the collection of its values. +A table with both weak keys and weak values allows the collection of +both keys and values. +In any case, if either the key or the value is collected, +the whole pair is removed from the table. +The weakness of a table is controlled by the +__mode field of its metatable. +If the __mode field is a string containing the character 'k', +the keys in the table are weak. +If __mode contains 'v', +the values in the table are weak. + + +

+A table with weak keys and strong values +is also called an ephemeron table. +In an ephemeron table, +a value is considered reachable only if its key is reachable. +In particular, +if the only reference to a key comes through its value, +the pair is removed. + + +

+Any change in the weakness of a table may take effect only +at the next collect cycle. +In particular, if you change the weakness to a stronger mode, +Lua may still collect some items from that table +before the change takes effect. + + +

+Only objects that have an explicit construction +are removed from weak tables. +Values, such as numbers and light C functions, +are not subject to garbage collection, +and therefore are not removed from weak tables +(unless its associated value is collected). +Although strings are subject to garbage collection, +they do not have an explicit construction, +and therefore are not removed from weak tables. + + +

+Resurrected objects +(that is, objects being finalized +and objects accessible only through objects being finalized) +have a special behavior in weak tables. +They are removed from weak values before running their finalizers, +but are removed from weak keys only in the next collection +after running their finalizers, when such objects are actually freed. +This behavior allows the finalizer to access properties +associated with the object through weak tables. + + +

+If a weak table is among the resurrected objects in a collection cycle, +it may not be properly cleared until the next cycle. + + + + + + + +

2.6 – Coroutines

+ +

+Lua supports coroutines, +also called collaborative multithreading. +A coroutine in Lua represents an independent thread of execution. +Unlike threads in multithread systems, however, +a coroutine only suspends its execution by explicitly calling +a yield function. + + +

+You create a coroutine by calling coroutine.create. +Its sole argument is a function +that is the main function of the coroutine. +The create function only creates a new coroutine and +returns a handle to it (an object of type thread); +it does not start the coroutine. + + +

+You execute a coroutine by calling coroutine.resume. +When you first call coroutine.resume, +passing as its first argument +a thread returned by coroutine.create, +the coroutine starts its execution, +at the first line of its main function. +Extra arguments passed to coroutine.resume are passed on +to the coroutine main function. +After the coroutine starts running, +it runs until it terminates or yields. + + +

+A coroutine can terminate its execution in two ways: +normally, when its main function returns +(explicitly or implicitly, after the last instruction); +and abnormally, if there is an unprotected error. +In the first case, coroutine.resume returns true, +plus any values returned by the coroutine main function. +In case of errors, coroutine.resume returns false +plus an error message. + + +

+A coroutine yields by calling coroutine.yield. +When a coroutine yields, +the corresponding coroutine.resume returns immediately, +even if the yield happens inside nested function calls +(that is, not in the main function, +but in a function directly or indirectly called by the main function). +In the case of a yield, coroutine.resume also returns true, +plus any values passed to coroutine.yield. +The next time you resume the same coroutine, +it continues its execution from the point where it yielded, +with the call to coroutine.yield returning any extra +arguments passed to coroutine.resume. + + +

+Like coroutine.create, +the coroutine.wrap function also creates a coroutine, +but instead of returning the coroutine itself, +it returns a function that, when called, resumes the coroutine. +Any arguments passed to this function +go as extra arguments to coroutine.resume. +coroutine.wrap returns all the values returned by coroutine.resume, +except the first one (the boolean error code). +Unlike coroutine.resume, +coroutine.wrap does not catch errors; +any error is propagated to the caller. + + +

+As an example of how coroutines work, +consider the following code: + +

+     function foo (a)
+       print("foo", a)
+       return coroutine.yield(2*a)
+     end
+     
+     co = coroutine.create(function (a,b)
+           print("co-body", a, b)
+           local r = foo(a+1)
+           print("co-body", r)
+           local r, s = coroutine.yield(a+b, a-b)
+           print("co-body", r, s)
+           return b, "end"
+     end)
+     
+     print("main", coroutine.resume(co, 1, 10))
+     print("main", coroutine.resume(co, "r"))
+     print("main", coroutine.resume(co, "x", "y"))
+     print("main", coroutine.resume(co, "x", "y"))
+

+When you run it, it produces the following output: + +

+     co-body 1       10
+     foo     2
+     main    true    4
+     co-body r
+     main    true    11      -9
+     co-body x       y
+     main    true    10      end
+     main    false   cannot resume dead coroutine
+
+ +

+You can also create and manipulate coroutines through the C API: +see functions lua_newthread, lua_resume, +and lua_yield. + + + + + +

3 – The Language

+ +

+This section describes the lexis, the syntax, and the semantics of Lua. +In other words, +this section describes +which tokens are valid, +how they can be combined, +and what their combinations mean. + + +

+Language constructs will be explained using the usual extended BNF notation, +in which +{a} means 0 or more a's, and +[a] means an optional a. +Non-terminals are shown like non-terminal, +keywords are shown like kword, +and other terminal symbols are shown like ‘=’. +The complete syntax of Lua can be found in §9 +at the end of this manual. + + + +

3.1 – Lexical Conventions

+ +

+Lua is a free-form language. +It ignores spaces (including new lines) and comments +between lexical elements (tokens), +except as delimiters between names and keywords. + + +

+Names +(also called identifiers) +in Lua can be any string of letters, +digits, and underscores, +not beginning with a digit. +Identifiers are used to name variables, table fields, and labels. + + +

+The following keywords are reserved +and cannot be used as names: + + +

+     and       break     do        else      elseif    end
+     false     for       function  goto      if        in
+     local     nil       not       or        repeat    return
+     then      true      until     while
+
+ +

+Lua is a case-sensitive language: +and is a reserved word, but And and AND +are two different, valid names. +As a convention, names starting with an underscore followed by +uppercase letters (such as _VERSION) +are reserved for variables used by Lua. + + +

+The following strings denote other tokens: + +

+     +     -     *     /     %     ^     #
+     ==    ~=    <=    >=    <     >     =
+     (     )     {     }     [     ]     ::
+     ;     :     ,     .     ..    ...
+
+ +

+Literal strings +can be delimited by matching single or double quotes, +and can contain the following C-like escape sequences: +'\a' (bell), +'\b' (backspace), +'\f' (form feed), +'\n' (newline), +'\r' (carriage return), +'\t' (horizontal tab), +'\v' (vertical tab), +'\\' (backslash), +'\"' (quotation mark [double quote]), +and '\'' (apostrophe [single quote]). +A backslash followed by a real newline +results in a newline in the string. +The escape sequence '\z' skips the following span +of white-space characters, +including line breaks; +it is particularly useful to break and indent a long literal string +into multiple lines without adding the newlines and spaces +into the string contents. + + +

+A byte in a literal string can also be specified by its numerical value. +This can be done with the escape sequence \xXX, +where XX is a sequence of exactly two hexadecimal digits, +or with the escape sequence \ddd, +where ddd is a sequence of up to three decimal digits. +(Note that if a decimal escape is to be followed by a digit, +it must be expressed using exactly three digits.) +Strings in Lua can contain any 8-bit value, including embedded zeros, +which can be specified as '\0'. + + +

+Literal strings can also be defined using a long format +enclosed by long brackets. +We define an opening long bracket of level n as an opening +square bracket followed by n equal signs followed by another +opening square bracket. +So, an opening long bracket of level 0 is written as [[, +an opening long bracket of level 1 is written as [=[, +and so on. +A closing long bracket is defined similarly; +for instance, a closing long bracket of level 4 is written as ]====]. +A long literal starts with an opening long bracket of any level and +ends at the first closing long bracket of the same level. +It can contain any text except a closing bracket of the proper level. +Literals in this bracketed form can run for several lines, +do not interpret any escape sequences, +and ignore long brackets of any other level. +Any kind of end-of-line sequence +(carriage return, newline, carriage return followed by newline, +or newline followed by carriage return) +is converted to a simple newline. + + +

+Any byte in a literal string not +explicitly affected by the previous rules represents itself. +However, Lua opens files for parsing in text mode, +and the system file functions may have problems with +some control characters. +So, it is safer to represent +non-text data as a quoted literal with +explicit escape sequences for non-text characters. + + +

+For convenience, +when the opening long bracket is immediately followed by a newline, +the newline is not included in the string. +As an example, in a system using ASCII +(in which 'a' is coded as 97, +newline is coded as 10, and '1' is coded as 49), +the five literal strings below denote the same string: + +

+     a = 'alo\n123"'
+     a = "alo\n123\""
+     a = '\97lo\10\04923"'
+     a = [[alo
+     123"]]
+     a = [==[
+     alo
+     123"]==]
+
+ +

+A numerical constant can be written with an optional fractional part +and an optional decimal exponent, +marked by a letter 'e' or 'E'. +Lua also accepts hexadecimal constants, +which start with 0x or 0X. +Hexadecimal constants also accept an optional fractional part +plus an optional binary exponent, +marked by a letter 'p' or 'P'. +Examples of valid numerical constants are + +

+     3     3.0     3.1416     314.16e-2     0.31416E1
+     0xff  0x0.1E  0xA23p-4   0X1.921FB54442D18P+1
+
+ +

+A comment starts with a double hyphen (--) +anywhere outside a string. +If the text immediately after -- is not an opening long bracket, +the comment is a short comment, +which runs until the end of the line. +Otherwise, it is a long comment, +which runs until the corresponding closing long bracket. +Long comments are frequently used to disable code temporarily. + + + + + +

3.2 – Variables

+ +

+Variables are places that store values. +There are three kinds of variables in Lua: +global variables, local variables, and table fields. + + +

+A single name can denote a global variable or a local variable +(or a function's formal parameter, +which is a particular kind of local variable): + +

+	var ::= Name
+

+Name denotes identifiers, as defined in §3.1. + + +

+Any variable name is assumed to be global unless explicitly declared +as a local (see §3.3.7). +Local variables are lexically scoped: +local variables can be freely accessed by functions +defined inside their scope (see §3.5). + + +

+Before the first assignment to a variable, its value is nil. + + +

+Square brackets are used to index a table: + +

+	var ::= prefixexp ‘[’ exp ‘]’
+

+The meaning of accesses to table fields can be changed via metatables. +An access to an indexed variable t[i] is equivalent to +a call gettable_event(t,i). +(See §2.4 for a complete description of the +gettable_event function. +This function is not defined or callable in Lua. +We use it here only for explanatory purposes.) + + +

+The syntax var.Name is just syntactic sugar for +var["Name"]: + +

+	var ::= prefixexp ‘.’ Name
+
+ +

+An access to a global variable x +is equivalent to _ENV.x. +Due to the way that chunks are compiled, +_ENV is never a global name (see §2.2). + + + + + +

3.3 – Statements

+ +

+Lua supports an almost conventional set of statements, +similar to those in Pascal or C. +This set includes +assignments, control structures, function calls, +and variable declarations. + + + +

3.3.1 – Blocks

+ +

+A block is a list of statements, +which are executed sequentially: + +

+	block ::= {stat}
+

+Lua has empty statements +that allow you to separate statements with semicolons, +start a block with a semicolon +or write two semicolons in sequence: + +

+	stat ::= ‘;’
+
+ +

+Function calls and assignments +can start with an open parenthesis. +This possibility leads to an ambiguity in Lua's grammar. +Consider the following fragment: + +

+     a = b + c
+     (print or io.write)('done')
+

+The grammar could see it in two ways: + +

+     a = b + c(print or io.write)('done')
+     
+     a = b + c; (print or io.write)('done')
+

+The current parser always sees such constructions +in the first way, +interpreting the open parenthesis +as the start of the arguments to a call. +To avoid this ambiguity, +it is a good practice to always precede with a semicolon +statements that start with a parenthesis: + +

+     ;(print or io.write)('done')
+
+ +

+A block can be explicitly delimited to produce a single statement: + +

+	stat ::= do block end
+

+Explicit blocks are useful +to control the scope of variable declarations. +Explicit blocks are also sometimes used to +add a return statement in the middle +of another block (see §3.3.4). + + + + + +

3.3.2 – Chunks

+ +

+The unit of compilation of Lua is called a chunk. +Syntactically, +a chunk is simply a block: + +

+	chunk ::= block
+
+ +

+Lua handles a chunk as the body of an anonymous function +with a variable number of arguments +(see §3.4.10). +As such, chunks can define local variables, +receive arguments, and return values. +Moreover, such anonymous function is compiled as in the +scope of an external local variable called _ENV (see §2.2). +The resulting function always has _ENV as its only upvalue, +even if it does not use that variable. + + +

+A chunk can be stored in a file or in a string inside the host program. +To execute a chunk, +Lua first precompiles the chunk into instructions for a virtual machine, +and then it executes the compiled code +with an interpreter for the virtual machine. + + +

+Chunks can also be precompiled into binary form; +see program luac for details. +Programs in source and compiled forms are interchangeable; +Lua automatically detects the file type and acts accordingly. + + + + + + +

3.3.3 – Assignment

+ +

+Lua allows multiple assignments. +Therefore, the syntax for assignment +defines a list of variables on the left side +and a list of expressions on the right side. +The elements in both lists are separated by commas: + +

+	stat ::= varlist ‘=’ explist
+	varlist ::= var {‘,’ var}
+	explist ::= exp {‘,’ exp}
+

+Expressions are discussed in §3.4. + + +

+Before the assignment, +the list of values is adjusted to the length of +the list of variables. +If there are more values than needed, +the excess values are thrown away. +If there are fewer values than needed, +the list is extended with as many nil's as needed. +If the list of expressions ends with a function call, +then all values returned by that call enter the list of values, +before the adjustment +(except when the call is enclosed in parentheses; see §3.4). + + +

+The assignment statement first evaluates all its expressions +and only then are the assignments performed. +Thus the code + +

+     i = 3
+     i, a[i] = i+1, 20
+

+sets a[3] to 20, without affecting a[4] +because the i in a[i] is evaluated (to 3) +before it is assigned 4. +Similarly, the line + +

+     x, y = y, x
+

+exchanges the values of x and y, +and + +

+     x, y, z = y, z, x
+

+cyclically permutes the values of x, y, and z. + + +

+The meaning of assignments to global variables +and table fields can be changed via metatables. +An assignment to an indexed variable t[i] = val is equivalent to +settable_event(t,i,val). +(See §2.4 for a complete description of the +settable_event function. +This function is not defined or callable in Lua. +We use it here only for explanatory purposes.) + + +

+An assignment to a global variable x = val +is equivalent to the assignment +_ENV.x = val (see §2.2). + + + + + +

3.3.4 – Control Structures

+The control structures +if, while, and repeat have the usual meaning and +familiar syntax: + + + + +

+	stat ::= while exp do block end
+	stat ::= repeat block until exp
+	stat ::= if exp then block {elseif exp then block} [else block] end
+

+Lua also has a for statement, in two flavors (see §3.3.5). + + +

+The condition expression of a +control structure can return any value. +Both false and nil are considered false. +All values different from nil and false are considered true +(in particular, the number 0 and the empty string are also true). + + +

+In the repeat–until loop, +the inner block does not end at the until keyword, +but only after the condition. +So, the condition can refer to local variables +declared inside the loop block. + + +

+The goto statement transfers the program control to a label. +For syntactical reasons, +labels in Lua are considered statements too: + + + +

+	stat ::= goto Name
+	stat ::= label
+	label ::= ‘::’ Name ‘::’
+
+ +

+A label is visible in the entire block where it is defined, +except +inside nested blocks where a label with the same name is defined and +inside nested functions. +A goto may jump to any visible label as long as it does not +enter into the scope of a local variable. + + +

+Labels and empty statements are called void statements, +as they perform no actions. + + +

+The break statement terminates the execution of a +while, repeat, or for loop, +skipping to the next statement after the loop: + + +

+	stat ::= break
+

+A break ends the innermost enclosing loop. + + +

+The return statement is used to return values +from a function or a chunk (which is a function in disguise). + +Functions can return more than one value, +so the syntax for the return statement is + +

+	stat ::= return [explist] [‘;’]
+
+ +

+The return statement can only be written +as the last statement of a block. +If it is really necessary to return in the middle of a block, +then an explicit inner block can be used, +as in the idiom do return end, +because now return is the last statement in its (inner) block. + + + + + +

3.3.5 – For Statement

+ +

+ +The for statement has two forms: +one numeric and one generic. + + +

+The numeric for loop repeats a block of code while a +control variable runs through an arithmetic progression. +It has the following syntax: + +

+	stat ::= for Name ‘=’ exp ‘,’ exp [‘,’ exp] do block end
+

+The block is repeated for name starting at the value of +the first exp, until it passes the second exp by steps of the +third exp. +More precisely, a for statement like + +

+     for v = e1, e2, e3 do block end
+

+is equivalent to the code: + +

+     do
+       local var, limit, step = tonumber(e1), tonumber(e2), tonumber(e3)
+       if not (var and limit and step) then error() end
+       while (step > 0 and var <= limit) or (step <= 0 and var >= limit) do
+         local v = var
+         block
+         var = var + step
+       end
+     end
+

+Note the following: + +

    + +
  • +All three control expressions are evaluated only once, +before the loop starts. +They must all result in numbers. +
    • + +
  • +var, limit, and step are invisible variables. +The names shown here are for explanatory purposes only. +
    • + +
  • +If the third expression (the step) is absent, +then a step of 1 is used. +
    • + +
  • +You can use break to exit a for loop. +
    • + +
  • +The loop variable v is local to the loop; +you cannot use its value after the for ends or is broken. +If you need this value, +assign it to another variable before breaking or exiting the loop. +
    • + +
+ +

+The generic for statement works over functions, +called iterators. +On each iteration, the iterator function is called to produce a new value, +stopping when this new value is nil. +The generic for loop has the following syntax: + +

+	stat ::= for namelist in explist do block end
+	namelist ::= Name {‘,’ Name}
+

+A for statement like + +

+     for var_1, ···, var_n in explist do block end
+

+is equivalent to the code: + +

+     do
+       local f, s, var = explist
+       while true do
+         local var_1, ···, var_n = f(s, var)
+         if var_1 == nil then break end
+         var = var_1
+         block
+       end
+     end
+

+Note the following: + +

    + +
  • +explist is evaluated only once. +Its results are an iterator function, +a state, +and an initial value for the first iterator variable. +
    • + +
  • +f, s, and var are invisible variables. +The names are here for explanatory purposes only. +
    • + +
  • +You can use break to exit a for loop. +
    • + +
  • +The loop variables var_i are local to the loop; +you cannot use their values after the for ends. +If you need these values, +then assign them to other variables before breaking or exiting the loop. +
    • + +
+ + + + +

3.3.6 – Function Calls as Statements

+To allow possible side-effects, +function calls can be executed as statements: + +

+	stat ::= functioncall
+

+In this case, all returned values are thrown away. +Function calls are explained in §3.4.9. + + + + + +

3.3.7 – Local Declarations

+Local variables can be declared anywhere inside a block. +The declaration can include an initial assignment: + +

+	stat ::= local namelist [‘=’ explist]
+

+If present, an initial assignment has the same semantics +of a multiple assignment (see §3.3.3). +Otherwise, all variables are initialized with nil. + + +

+A chunk is also a block (see §3.3.2), +and so local variables can be declared in a chunk outside any explicit block. + + +

+The visibility rules for local variables are explained in §3.5. + + + + + + + +

3.4 – Expressions

+ +

+The basic expressions in Lua are the following: + +

+	exp ::= prefixexp
+	exp ::= nil | false | true
+	exp ::= Number
+	exp ::= String
+	exp ::= functiondef
+	exp ::= tableconstructor
+	exp ::= ‘...’
+	exp ::= exp binop exp
+	exp ::= unop exp
+	prefixexp ::= var | functioncall | ‘(’ exp ‘)’
+
+ +

+Numbers and literal strings are explained in §3.1; +variables are explained in §3.2; +function definitions are explained in §3.4.10; +function calls are explained in §3.4.9; +table constructors are explained in §3.4.8. +Vararg expressions, +denoted by three dots ('...'), can only be used when +directly inside a vararg function; +they are explained in §3.4.10. + + +

+Binary operators comprise arithmetic operators (see §3.4.1), +relational operators (see §3.4.3), logical operators (see §3.4.4), +and the concatenation operator (see §3.4.5). +Unary operators comprise the unary minus (see §3.4.1), +the unary not (see §3.4.4), +and the unary length operator (see §3.4.6). + + +

+Both function calls and vararg expressions can result in multiple values. +If a function call is used as a statement (see §3.3.6), +then its return list is adjusted to zero elements, +thus discarding all returned values. +If an expression is used as the last (or the only) element +of a list of expressions, +then no adjustment is made +(unless the expression is enclosed in parentheses). +In all other contexts, +Lua adjusts the result list to one element, +either discarding all values except the first one +or adding a single nil if there are no values. + + +

+Here are some examples: + +

+     f()                -- adjusted to 0 results
+     g(f(), x)          -- f() is adjusted to 1 result
+     g(x, f())          -- g gets x plus all results from f()
+     a,b,c = f(), x     -- f() is adjusted to 1 result (c gets nil)
+     a,b = ...          -- a gets the first vararg parameter, b gets
+                        -- the second (both a and b can get nil if there
+                        -- is no corresponding vararg parameter)
+     
+     a,b,c = x, f()     -- f() is adjusted to 2 results
+     a,b,c = f()        -- f() is adjusted to 3 results
+     return f()         -- returns all results from f()
+     return ...         -- returns all received vararg parameters
+     return x,y,f()     -- returns x, y, and all results from f()
+     {f()}              -- creates a list with all results from f()
+     {...}              -- creates a list with all vararg parameters
+     {f(), nil}         -- f() is adjusted to 1 result
+
+ +

+Any expression enclosed in parentheses always results in only one value. +Thus, +(f(x,y,z)) is always a single value, +even if f returns several values. +(The value of (f(x,y,z)) is the first value returned by f +or nil if f does not return any values.) + + + +

3.4.1 – Arithmetic Operators

+Lua supports the usual arithmetic operators: +the binary + (addition), +- (subtraction), * (multiplication), +/ (division), % (modulo), and ^ (exponentiation); +and unary - (mathematical negation). +If the operands are numbers, or strings that can be converted to +numbers (see §3.4.2), +then all operations have the usual meaning. +Exponentiation works for any exponent. +For instance, x^(-0.5) computes the inverse of the square root of x. +Modulo is defined as + +

+     a % b == a - math.floor(a/b)*b
+

+That is, it is the remainder of a division that rounds +the quotient towards minus infinity. + + + + + +

3.4.2 – Coercion

+ +

+Lua provides automatic conversion between +string and number values at run time. +Any arithmetic operation applied to a string tries to convert +this string to a number, following the rules of the Lua lexer. +(The string may have leading and trailing spaces and a sign.) +Conversely, whenever a number is used where a string is expected, +the number is converted to a string, in a reasonable format. +For complete control over how numbers are converted to strings, +use the format function from the string library +(see string.format). + + + + + +

3.4.3 – Relational Operators

+The relational operators in Lua are + +

+     ==    ~=    <     >     <=    >=
+

+These operators always result in false or true. + + +

+Equality (==) first compares the type of its operands. +If the types are different, then the result is false. +Otherwise, the values of the operands are compared. +Numbers and strings are compared in the usual way. +Tables, userdata, and threads +are compared by reference: +two objects are considered equal only if they are the same object. +Every time you create a new object +(a table, userdata, or thread), +this new object is different from any previously existing object. +Closures with the same reference are always equal. +Closures with any detectable difference +(different behavior, different definition) are always different. + + +

+You can change the way that Lua compares tables and userdata +by using the "eq" metamethod (see §2.4). + + +

+The conversion rules of §3.4.2 +do not apply to equality comparisons. +Thus, "0"==0 evaluates to false, +and t[0] and t["0"] denote different +entries in a table. + + +

+The operator ~= is exactly the negation of equality (==). + + +

+The order operators work as follows. +If both arguments are numbers, then they are compared as such. +Otherwise, if both arguments are strings, +then their values are compared according to the current locale. +Otherwise, Lua tries to call the "lt" or the "le" +metamethod (see §2.4). +A comparison a > b is translated to b < a +and a >= b is translated to b <= a. + + + + + +

3.4.4 – Logical Operators

+The logical operators in Lua are +and, or, and not. +Like the control structures (see §3.3.4), +all logical operators consider both false and nil as false +and anything else as true. + + +

+The negation operator not always returns false or true. +The conjunction operator and returns its first argument +if this value is false or nil; +otherwise, and returns its second argument. +The disjunction operator or returns its first argument +if this value is different from nil and false; +otherwise, or returns its second argument. +Both and and or use short-cut evaluation; +that is, +the second operand is evaluated only if necessary. +Here are some examples: + +

+     10 or 20            --> 10
+     10 or error()       --> 10
+     nil or "a"          --> "a"
+     nil and 10          --> nil
+     false and error()   --> false
+     false and nil       --> false
+     false or nil        --> nil
+     10 and 20           --> 20
+

+(In this manual, +--> indicates the result of the preceding expression.) + + + + + +

3.4.5 – Concatenation

+The string concatenation operator in Lua is +denoted by two dots ('..'). +If both operands are strings or numbers, then they are converted to +strings according to the rules mentioned in §3.4.2. +Otherwise, the __concat metamethod is called (see §2.4). + + + + + +

3.4.6 – The Length Operator

+ +

+The length operator is denoted by the unary prefix operator #. +The length of a string is its number of bytes +(that is, the usual meaning of string length when each +character is one byte). + + +

+A program can modify the behavior of the length operator for +any value but strings through the __len metamethod (see §2.4). + + +

+Unless a __len metamethod is given, +the length of a table t is only defined if the +table is a sequence, +that is, +the set of its positive numeric keys is equal to {1..n} +for some integer n. +In that case, n is its length. +Note that a table like + +

+     {10, 20, nil, 40}
+

+is not a sequence, because it has the key 4 +but does not have the key 3. +(So, there is no n such that the set {1..n} is equal +to the set of positive numeric keys of that table.) +Note, however, that non-numeric keys do not interfere +with whether a table is a sequence. + + + + + +

3.4.7 – Precedence

+Operator precedence in Lua follows the table below, +from lower to higher priority: + +

+     or
+     and
+     <     >     <=    >=    ~=    ==
+     ..
+     +     -
+     *     /     %
+     not   #     - (unary)
+     ^
+

+As usual, +you can use parentheses to change the precedences of an expression. +The concatenation ('..') and exponentiation ('^') +operators are right associative. +All other binary operators are left associative. + + + + + +

3.4.8 – Table Constructors

+Table constructors are expressions that create tables. +Every time a constructor is evaluated, a new table is created. +A constructor can be used to create an empty table +or to create a table and initialize some of its fields. +The general syntax for constructors is + +

+	tableconstructor ::= ‘{’ [fieldlist] ‘}’
+	fieldlist ::= field {fieldsep field} [fieldsep]
+	field ::= ‘[’ exp ‘]’ ‘=’ exp | Name ‘=’ exp | exp
+	fieldsep ::= ‘,’ | ‘;’
+
+ +

+Each field of the form [exp1] = exp2 adds to the new table an entry +with key exp1 and value exp2. +A field of the form name = exp is equivalent to +["name"] = exp. +Finally, fields of the form exp are equivalent to +[i] = exp, where i are consecutive numerical integers, +starting with 1. +Fields in the other formats do not affect this counting. +For example, + +

+     a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 }
+

+is equivalent to + +

+     do
+       local t = {}
+       t[f(1)] = g
+       t[1] = "x"         -- 1st exp
+       t[2] = "y"         -- 2nd exp
+       t.x = 1            -- t["x"] = 1
+       t[3] = f(x)        -- 3rd exp
+       t[30] = 23
+       t[4] = 45          -- 4th exp
+       a = t
+     end
+
+ +

+If the last field in the list has the form exp +and the expression is a function call or a vararg expression, +then all values returned by this expression enter the list consecutively +(see §3.4.9). + + +

+The field list can have an optional trailing separator, +as a convenience for machine-generated code. + + + + + +

3.4.9 – Function Calls

+A function call in Lua has the following syntax: + +

+	functioncall ::= prefixexp args
+

+In a function call, +first prefixexp and args are evaluated. +If the value of prefixexp has type function, +then this function is called +with the given arguments. +Otherwise, the prefixexp "call" metamethod is called, +having as first parameter the value of prefixexp, +followed by the original call arguments +(see §2.4). + + +

+The form + +

+	functioncall ::= prefixexp ‘:’ Name args
+

+can be used to call "methods". +A call v:name(args) +is syntactic sugar for v.name(v,args), +except that v is evaluated only once. + + +

+Arguments have the following syntax: + +

+	args ::= ‘(’ [explist] ‘)’
+	args ::= tableconstructor
+	args ::= String
+

+All argument expressions are evaluated before the call. +A call of the form f{fields} is +syntactic sugar for f({fields}); +that is, the argument list is a single new table. +A call of the form f'string' +(or f"string" or f[[string]]) +is syntactic sugar for f('string'); +that is, the argument list is a single literal string. + + +

+A call of the form return functioncall is called +a tail call. +Lua implements proper tail calls +(or proper tail recursion): +in a tail call, +the called function reuses the stack entry of the calling function. +Therefore, there is no limit on the number of nested tail calls that +a program can execute. +However, a tail call erases any debug information about the +calling function. +Note that a tail call only happens with a particular syntax, +where the return has one single function call as argument; +this syntax makes the calling function return exactly +the returns of the called function. +So, none of the following examples are tail calls: + +

+     return (f(x))        -- results adjusted to 1
+     return 2 * f(x)
+     return x, f(x)       -- additional results
+     f(x); return         -- results discarded
+     return x or f(x)     -- results adjusted to 1
+
+ + + + +

3.4.10 – Function Definitions

+ +

+The syntax for function definition is + +

+	functiondef ::= function funcbody
+	funcbody ::= ‘(’ [parlist] ‘)’ block end
+
+ +

+The following syntactic sugar simplifies function definitions: + +

+	stat ::= function funcname funcbody
+	stat ::= local function Name funcbody
+	funcname ::= Name {‘.’ Name} [‘:’ Name]
+

+The statement + +

+     function f () body end
+

+translates to + +

+     f = function () body end
+

+The statement + +

+     function t.a.b.c.f () body end
+

+translates to + +

+     t.a.b.c.f = function () body end
+

+The statement + +

+     local function f () body end
+

+translates to + +

+     local f; f = function () body end
+

+not to + +

+     local f = function () body end
+

+(This only makes a difference when the body of the function +contains references to f.) + + +

+A function definition is an executable expression, +whose value has type function. +When Lua precompiles a chunk, +all its function bodies are precompiled too. +Then, whenever Lua executes the function definition, +the function is instantiated (or closed). +This function instance (or closure) +is the final value of the expression. + + +

+Parameters act as local variables that are +initialized with the argument values: + +

+	parlist ::= namelist [‘,’ ‘...’] | ‘...’
+

+When a function is called, +the list of arguments is adjusted to +the length of the list of parameters, +unless the function is a vararg function, +which is indicated by three dots ('...') +at the end of its parameter list. +A vararg function does not adjust its argument list; +instead, it collects all extra arguments and supplies them +to the function through a vararg expression, +which is also written as three dots. +The value of this expression is a list of all actual extra arguments, +similar to a function with multiple results. +If a vararg expression is used inside another expression +or in the middle of a list of expressions, +then its return list is adjusted to one element. +If the expression is used as the last element of a list of expressions, +then no adjustment is made +(unless that last expression is enclosed in parentheses). + + +

+As an example, consider the following definitions: + +

+     function f(a, b) end
+     function g(a, b, ...) end
+     function r() return 1,2,3 end
+

+Then, we have the following mapping from arguments to parameters and +to the vararg expression: + +

+     CALL            PARAMETERS
+     
+     f(3)             a=3, b=nil
+     f(3, 4)          a=3, b=4
+     f(3, 4, 5)       a=3, b=4
+     f(r(), 10)       a=1, b=10
+     f(r())           a=1, b=2
+     
+     g(3)             a=3, b=nil, ... -->  (nothing)
+     g(3, 4)          a=3, b=4,   ... -->  (nothing)
+     g(3, 4, 5, 8)    a=3, b=4,   ... -->  5  8
+     g(5, r())        a=5, b=1,   ... -->  2  3
+
+ +

+Results are returned using the return statement (see §3.3.4). +If control reaches the end of a function +without encountering a return statement, +then the function returns with no results. + + +

+ +There is a system-dependent limit on the number of values +that a function may return. +This limit is guaranteed to be larger than 1000. + + +

+The colon syntax +is used for defining methods, +that is, functions that have an implicit extra parameter self. +Thus, the statement + +

+     function t.a.b.c:f (params) body end
+

+is syntactic sugar for + +

+     t.a.b.c.f = function (self, params) body end
+
+ + + + + + +

3.5 – Visibility Rules

+ +

+ +Lua is a lexically scoped language. +The scope of a local variable begins at the first statement after +its declaration and lasts until the last non-void statement +of the innermost block that includes the declaration. +Consider the following example: + +

+     x = 10                -- global variable
+     do                    -- new block
+       local x = x         -- new 'x', with value 10
+       print(x)            --> 10
+       x = x+1
+       do                  -- another block
+         local x = x+1     -- another 'x'
+         print(x)          --> 12
+       end
+       print(x)            --> 11
+     end
+     print(x)              --> 10  (the global one)
+
+ +

+Notice that, in a declaration like local x = x, +the new x being declared is not in scope yet, +and so the second x refers to the outside variable. + + +

+Because of the lexical scoping rules, +local variables can be freely accessed by functions +defined inside their scope. +A local variable used by an inner function is called +an upvalue, or external local variable, +inside the inner function. + + +

+Notice that each execution of a local statement +defines new local variables. +Consider the following example: + +

+     a = {}
+     local x = 20
+     for i=1,10 do
+       local y = 0
+       a[i] = function () y=y+1; return x+y end
+     end
+

+The loop creates ten closures +(that is, ten instances of the anonymous function). +Each of these closures uses a different y variable, +while all of them share the same x. + + + + + +

4 – The Application Program Interface

+ +

+ +This section describes the C API for Lua, that is, +the set of C functions available to the host program to communicate +with Lua. +All API functions and related types and constants +are declared in the header file lua.h. + + +

+Even when we use the term "function", +any facility in the API may be provided as a macro instead. +Except where stated otherwise, +all such macros use each of their arguments exactly once +(except for the first argument, which is always a Lua state), +and so do not generate any hidden side-effects. + + +

+As in most C libraries, +the Lua API functions do not check their arguments for validity or consistency. +However, you can change this behavior by compiling Lua +with the macro LUA_USE_APICHECK defined. + + + +

4.1 – The Stack

+ +

+Lua uses a virtual stack to pass values to and from C. +Each element in this stack represents a Lua value +(nil, number, string, etc.). + + +

+Whenever Lua calls C, the called function gets a new stack, +which is independent of previous stacks and of stacks of +C functions that are still active. +This stack initially contains any arguments to the C function +and it is where the C function pushes its results +to be returned to the caller (see lua_CFunction). + + +

+For convenience, +most query operations in the API do not follow a strict stack discipline. +Instead, they can refer to any element in the stack +by using an index: +A positive index represents an absolute stack position +(starting at 1); +a negative index represents an offset relative to the top of the stack. +More specifically, if the stack has n elements, +then index 1 represents the first element +(that is, the element that was pushed onto the stack first) +and +index n represents the last element; +index -1 also represents the last element +(that is, the element at the top) +and index -n represents the first element. + + + + + +

4.2 – Stack Size

+ +

+When you interact with the Lua API, +you are responsible for ensuring consistency. +In particular, +you are responsible for controlling stack overflow. +You can use the function lua_checkstack +to ensure that the stack has extra slots when pushing new elements. + + +

+Whenever Lua calls C, +it ensures that the stack has at least LUA_MINSTACK extra slots. +LUA_MINSTACK is defined as 20, +so that usually you do not have to worry about stack space +unless your code has loops pushing elements onto the stack. + + +

+When you call a Lua function +without a fixed number of results (see lua_call), +Lua ensures that the stack has enough size for all results, +but it does not ensure any extra space. +So, before pushing anything in the stack after such a call +you should use lua_checkstack. + + + + + +

4.3 – Valid and Acceptable Indices

+ +

+Any function in the API that receives stack indices +works only with valid indices or acceptable indices. + + +

+A valid index is an index that refers to a +real position within the stack, that is, +its position lies between 1 and the stack top +(1 ≤ abs(index) ≤ top). + +Usually, functions that can modify the value at an index +require valid indices. + + +

+Unless otherwise noted, +any function that accepts valid indices also accepts pseudo-indices, +which represent some Lua values that are accessible to C code +but which are not in the stack. +Pseudo-indices are used to access the registry +and the upvalues of a C function (see §4.4). + + +

+Functions that do not need a specific stack position, +but only a value in the stack (e.g., query functions), +can be called with acceptable indices. +An acceptable index can be any valid index, +including the pseudo-indices, +but it also can be any positive index after the stack top +within the space allocated for the stack, +that is, indices up to the stack size. +(Note that 0 is never an acceptable index.) +Except when noted otherwise, +functions in the API work with acceptable indices. + + +

+Acceptable indices serve to avoid extra tests +against the stack top when querying the stack. +For instance, a C function can query its third argument +without the need to first check whether there is a third argument, +that is, without the need to check whether 3 is a valid index. + + +

+For functions that can be called with acceptable indices, +any non-valid index is treated as if it +contains a value of a virtual type LUA_TNONE, +which behaves like a nil value. + + + + + +

4.4 – C Closures

+ +

+When a C function is created, +it is possible to associate some values with it, +thus creating a C closure +(see lua_pushcclosure); +these values are called upvalues and are +accessible to the function whenever it is called. + + +

+Whenever a C function is called, +its upvalues are located at specific pseudo-indices. +These pseudo-indices are produced by the macro +lua_upvalueindex. +The first value associated with a function is at position +lua_upvalueindex(1), and so on. +Any access to lua_upvalueindex(n), +where n is greater than the number of upvalues of the +current function (but not greater than 256), +produces an acceptable but invalid index. + + + + + +

4.5 – Registry

+ +

+Lua provides a registry, +a predefined table that can be used by any C code to +store whatever Lua values it needs to store. +The registry table is always located at pseudo-index +LUA_REGISTRYINDEX, +which is a valid index. +Any C library can store data into this table, +but it should take care to choose keys +that are different from those used +by other libraries, to avoid collisions. +Typically, you should use as key a string containing your library name, +or a light userdata with the address of a C object in your code, +or any Lua object created by your code. +As with global names, +string keys starting with an underscore followed by +uppercase letters are reserved for Lua. + + +

+The integer keys in the registry are used by the reference mechanism, +implemented by the auxiliary library, +and by some predefined values. +Therefore, integer keys should not be used for other purposes. + + +

+When you create a new Lua state, +its registry comes with some predefined values. +These predefined values are indexed with integer keys +defined as constants in lua.h. +The following constants are defined: + +

    +
  • LUA_RIDX_MAINTHREAD: At this index the registry has +the main thread of the state. +(The main thread is the one created together with the state.) +
    • + +
  • LUA_RIDX_GLOBALS: At this index the registry has +the global environment. +
    • +
+ + + + +

4.6 – Error Handling in C

+ +

+Internally, Lua uses the C longjmp facility to handle errors. +(You can also choose to use exceptions if you compile Lua as C++; +search for LUAI_THROW in the source code.) +When Lua faces any error +(such as a memory allocation error, type errors, syntax errors, +and runtime errors) +it raises an error; +that is, it does a long jump. +A protected environment uses setjmp +to set a recovery point; +any error jumps to the most recent active recovery point. + + +

+If an error happens outside any protected environment, +Lua calls a panic function (see lua_atpanic) +and then calls abort, +thus exiting the host application. +Your panic function can avoid this exit by +never returning +(e.g., doing a long jump to your own recovery point outside Lua). + + +

+The panic function runs as if it were a message handler (see §2.3); +in particular, the error message is at the top of the stack. +However, there is no guarantees about stack space. +To push anything on the stack, +the panic function should first check the available space (see §4.2). + + +

+Most functions in the API can throw an error, +for instance due to a memory allocation error. +The documentation for each function indicates whether +it can throw errors. + + +

+Inside a C function you can throw an error by calling lua_error. + + + + + +

4.7 – Handling Yields in C

+ +

+Internally, Lua uses the C longjmp facility to yield a coroutine. +Therefore, if a function foo calls an API function +and this API function yields +(directly or indirectly by calling another function that yields), +Lua cannot return to foo any more, +because the longjmp removes its frame from the C stack. + + +

+To avoid this kind of problem, +Lua raises an error whenever it tries to yield across an API call, +except for three functions: +lua_yieldk, lua_callk, and lua_pcallk. +All those functions receive a continuation function +(as a parameter called k) to continue execution after a yield. + + +

+We need to set some terminology to explain continuations. +We have a C function called from Lua which we will call +the original function. +This original function then calls one of those three functions in the C API, +which we will call the callee function, +that then yields the current thread. +(This can happen when the callee function is lua_yieldk, +or when the callee function is either lua_callk or lua_pcallk +and the function called by them yields.) + + +

+Suppose the running thread yields while executing the callee function. +After the thread resumes, +it eventually will finish running the callee function. +However, +the callee function cannot return to the original function, +because its frame in the C stack was destroyed by the yield. +Instead, Lua calls a continuation function, +which was given as an argument to the callee function. +As the name implies, +the continuation function should continue the task +of the original function. + + +

+Lua treats the continuation function as if it were the original function. +The continuation function receives the same Lua stack +from the original function, +in the same state it would be if the callee function had returned. +(For instance, +after a lua_callk the function and its arguments are +removed from the stack and replaced by the results from the call.) +It also has the same upvalues. +Whatever it returns is handled by Lua as if it were the return +of the original function. + + +

+The only difference in the Lua state between the original function +and its continuation is the result of a call to lua_getctx. + + + + + +

4.8 – Functions and Types

+ +

+Here we list all functions and types from the C API in +alphabetical order. +Each function has an indicator like this: +[-o, +p, x] + + +

+The first field, o, +is how many elements the function pops from the stack. +The second field, p, +is how many elements the function pushes onto the stack. +(Any function always pushes its results after popping its arguments.) +A field in the form x|y means the function can push (or pop) +x or y elements, +depending on the situation; +an interrogation mark '?' means that +we cannot know how many elements the function pops/pushes +by looking only at its arguments +(e.g., they may depend on what is on the stack). +The third field, x, +tells whether the function may throw errors: +'-' means the function never throws any error; +'e' means the function may throw errors; +'v' means the function may throw an error on purpose. + + + +

lua_absindex

+[-0, +0, –] +

int lua_absindex (lua_State *L, int idx);
+ +

+Converts the acceptable index idx into an absolute index +(that is, one that does not depend on the stack top). + + + + + +

lua_Alloc

+
typedef void * (*lua_Alloc) (void *ud,
+                             void *ptr,
+                             size_t osize,
+                             size_t nsize);
+ +

+The type of the memory-allocation function used by Lua states. +The allocator function must provide a +functionality similar to realloc, +but not exactly the same. +Its arguments are +ud, an opaque pointer passed to lua_newstate; +ptr, a pointer to the block being allocated/reallocated/freed; +osize, the original size of the block or some code about what +is being allocated; +nsize, the new size of the block. + + +

+When ptr is not NULL, +osize is the size of the block pointed by ptr, +that is, the size given when it was allocated or reallocated. + + +

+When ptr is NULL, +osize encodes the kind of object that Lua is allocating. +osize is any of +LUA_TSTRING, LUA_TTABLE, LUA_TFUNCTION, +LUA_TUSERDATA, or LUA_TTHREAD when (and only when) +Lua is creating a new object of that type. +When osize is some other value, +Lua is allocating memory for something else. + + +

+Lua assumes the following behavior from the allocator function: + + +

+When nsize is zero, +the allocator should behave like free +and return NULL. + + +

+When nsize is not zero, +the allocator should behave like realloc. +The allocator returns NULL +if and only if it cannot fulfill the request. +Lua assumes that the allocator never fails when +osize >= nsize. + + +

+Here is a simple implementation for the allocator function. +It is used in the auxiliary library by luaL_newstate. + +

+     static void *l_alloc (void *ud, void *ptr, size_t osize,
+                                                size_t nsize) {
+       (void)ud;  (void)osize;  /* not used */
+       if (nsize == 0) {
+         free(ptr);
+         return NULL;
+       }
+       else
+         return realloc(ptr, nsize);
+     }
+

+Note that Standard C ensures +that free(NULL) has no effect and that +realloc(NULL, size) is equivalent to malloc(size). +This code assumes that realloc does not fail when shrinking a block. +(Although Standard C does not ensure this behavior, +it seems to be a safe assumption.) + + + + + +

lua_arith

+[-(2|1), +1, e] +

void lua_arith (lua_State *L, int op);
+ +

+Performs an arithmetic operation over the two values +(or one, in the case of negation) +at the top of the stack, +with the value at the top being the second operand, +pops these values, and pushes the result of the operation. +The function follows the semantics of the corresponding Lua operator +(that is, it may call metamethods). + + +

+The value of op must be one of the following constants: + +

+ + + + +

lua_atpanic

+[-0, +0, –] +

lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf);
+ +

+Sets a new panic function and returns the old one (see §4.6). + + + + + +

lua_call

+[-(nargs+1), +nresults, e] +

void lua_call (lua_State *L, int nargs, int nresults);
+ +

+Calls a function. + + +

+To call a function you must use the following protocol: +first, the function to be called is pushed onto the stack; +then, the arguments to the function are pushed +in direct order; +that is, the first argument is pushed first. +Finally you call lua_call; +nargs is the number of arguments that you pushed onto the stack. +All arguments and the function value are popped from the stack +when the function is called. +The function results are pushed onto the stack when the function returns. +The number of results is adjusted to nresults, +unless nresults is LUA_MULTRET. +In this case, all results from the function are pushed. +Lua takes care that the returned values fit into the stack space. +The function results are pushed onto the stack in direct order +(the first result is pushed first), +so that after the call the last result is on the top of the stack. + + +

+Any error inside the called function is propagated upwards +(with a longjmp). + + +

+The following example shows how the host program can do the +equivalent to this Lua code: + +

+     a = f("how", t.x, 14)
+

+Here it is in C: + +

+     lua_getglobal(L, "f");                  /* function to be called */
+     lua_pushstring(L, "how");                        /* 1st argument */
+     lua_getglobal(L, "t");                    /* table to be indexed */
+     lua_getfield(L, -1, "x");        /* push result of t.x (2nd arg) */
+     lua_remove(L, -2);                  /* remove 't' from the stack */
+     lua_pushinteger(L, 14);                          /* 3rd argument */
+     lua_call(L, 3, 1);     /* call 'f' with 3 arguments and 1 result */
+     lua_setglobal(L, "a");                         /* set global 'a' */
+

+Note that the code above is "balanced": +at its end, the stack is back to its original configuration. +This is considered good programming practice. + + + + + +

lua_callk

+[-(nargs + 1), +nresults, e] +

void lua_callk (lua_State *L, int nargs, int nresults, int ctx,
+                lua_CFunction k);
+ +

+This function behaves exactly like lua_call, +but allows the called function to yield (see §4.7). + + + + + +

lua_CFunction

+
typedef int (*lua_CFunction) (lua_State *L);
+ +

+Type for C functions. + + +

+In order to communicate properly with Lua, +a C function must use the following protocol, +which defines the way parameters and results are passed: +a C function receives its arguments from Lua in its stack +in direct order (the first argument is pushed first). +So, when the function starts, +lua_gettop(L) returns the number of arguments received by the function. +The first argument (if any) is at index 1 +and its last argument is at index lua_gettop(L). +To return values to Lua, a C function just pushes them onto the stack, +in direct order (the first result is pushed first), +and returns the number of results. +Any other value in the stack below the results will be properly +discarded by Lua. +Like a Lua function, a C function called by Lua can also return +many results. + + +

+As an example, the following function receives a variable number +of numerical arguments and returns their average and sum: + +

+     static int foo (lua_State *L) {
+       int n = lua_gettop(L);    /* number of arguments */
+       lua_Number sum = 0;
+       int i;
+       for (i = 1; i <= n; i++) {
+         if (!lua_isnumber(L, i)) {
+           lua_pushstring(L, "incorrect argument");
+           lua_error(L);
+         }
+         sum += lua_tonumber(L, i);
+       }
+       lua_pushnumber(L, sum/n);        /* first result */
+       lua_pushnumber(L, sum);         /* second result */
+       return 2;                   /* number of results */
+     }
+
+ + + + +

lua_checkstack

+[-0, +0, –] +

int lua_checkstack (lua_State *L, int extra);
+ +

+Ensures that there are at least extra free stack slots in the stack. +It returns false if it cannot fulfill the request, +because it would cause the stack to be larger than a fixed maximum size +(typically at least a few thousand elements) or +because it cannot allocate memory for the new stack size. +This function never shrinks the stack; +if the stack is already larger than the new size, +it is left unchanged. + + + + + +

lua_close

+[-0, +0, –] +

void lua_close (lua_State *L);
+ +

+Destroys all objects in the given Lua state +(calling the corresponding garbage-collection metamethods, if any) +and frees all dynamic memory used by this state. +On several platforms, you may not need to call this function, +because all resources are naturally released when the host program ends. +On the other hand, long-running programs that create multiple states, +such as daemons or web servers, +might need to close states as soon as they are not needed. + + + + + +

lua_compare

+[-0, +0, e] +

int lua_compare (lua_State *L, int index1, int index2, int op);
+ +

+Compares two Lua values. +Returns 1 if the value at index index1 satisfies op +when compared with the value at index index2, +following the semantics of the corresponding Lua operator +(that is, it may call metamethods). +Otherwise returns 0. +Also returns 0 if any of the indices is non valid. + + +

+The value of op must be one of the following constants: + +

    + +
  • LUA_OPEQ: compares for equality (==)
    • +
  • LUA_OPLT: compares for less than (<)
    • +
  • LUA_OPLE: compares for less or equal (<=)
    • + +
+ + + + +

lua_concat

+[-n, +1, e] +

void lua_concat (lua_State *L, int n);
+ +

+Concatenates the n values at the top of the stack, +pops them, and leaves the result at the top. +If n is 1, the result is the single value on the stack +(that is, the function does nothing); +if n is 0, the result is the empty string. +Concatenation is performed following the usual semantics of Lua +(see §3.4.5). + + + + + +

lua_copy

+[-0, +0, –] +

void lua_copy (lua_State *L, int fromidx, int toidx);
+ +

+Moves the element at index fromidx +into the valid index toidx +without shifting any element +(therefore replacing the value at that position). + + + + + +

lua_createtable

+[-0, +1, e] +

void lua_createtable (lua_State *L, int narr, int nrec);
+ +

+Creates a new empty table and pushes it onto the stack. +Parameter narr is a hint for how many elements the table +will have as a sequence; +parameter nrec is a hint for how many other elements +the table will have. +Lua may use these hints to preallocate memory for the new table. +This pre-allocation is useful for performance when you know in advance +how many elements the table will have. +Otherwise you can use the function lua_newtable. + + + + + +

lua_dump

+[-0, +0, e] +

int lua_dump (lua_State *L, lua_Writer writer, void *data);
+ +

+Dumps a function as a binary chunk. +Receives a Lua function on the top of the stack +and produces a binary chunk that, +if loaded again, +results in a function equivalent to the one dumped. +As it produces parts of the chunk, +lua_dump calls function writer (see lua_Writer) +with the given data +to write them. + + +

+The value returned is the error code returned by the last +call to the writer; +0 means no errors. + + +

+This function does not pop the Lua function from the stack. + + + + + +

lua_error

+[-1, +0, v] +

int lua_error (lua_State *L);
+ +

+Generates a Lua error. +The error message (which can actually be a Lua value of any type) +must be on the stack top. +This function does a long jump, +and therefore never returns +(see luaL_error). + + + + + +

lua_gc

+[-0, +0, e] +

int lua_gc (lua_State *L, int what, int data);
+ +

+Controls the garbage collector. + + +

+This function performs several tasks, +according to the value of the parameter what: + +

    + +
  • LUA_GCSTOP: +stops the garbage collector. +
    • + +
  • LUA_GCRESTART: +restarts the garbage collector. +
    • + +
  • LUA_GCCOLLECT: +performs a full garbage-collection cycle. +
    • + +
  • LUA_GCCOUNT: +returns the current amount of memory (in Kbytes) in use by Lua. +
    • + +
  • LUA_GCCOUNTB: +returns the remainder of dividing the current amount of bytes of +memory in use by Lua by 1024. +
    • + +
  • LUA_GCSTEP: +performs an incremental step of garbage collection. +The step "size" is controlled by data +(larger values mean more steps) in a non-specified way. +If you want to control the step size +you must experimentally tune the value of data. +The function returns 1 if the step finished a +garbage-collection cycle. +
    • + +
  • LUA_GCSETPAUSE: +sets data as the new value +for the pause of the collector (see §2.5). +The function returns the previous value of the pause. +
    • + +
  • LUA_GCSETSTEPMUL: +sets data as the new value for the step multiplier of +the collector (see §2.5). +The function returns the previous value of the step multiplier. +
    • + +
  • LUA_GCISRUNNING: +returns a boolean that tells whether the collector is running +(i.e., not stopped). +
    • + +
  • LUA_GCGEN: +changes the collector to generational mode +(see §2.5). +
    • + +
  • LUA_GCINC: +changes the collector to incremental mode. +This is the default mode. +
    • + +
+ +

+For more details about these options, +see collectgarbage. + + + + + +

lua_getallocf

+[-0, +0, –] +

lua_Alloc lua_getallocf (lua_State *L, void **ud);
+ +

+Returns the memory-allocation function of a given state. +If ud is not NULL, Lua stores in *ud the +opaque pointer passed to lua_newstate. + + + + + +

lua_getctx

+[-0, +0, –] +

int lua_getctx (lua_State *L, int *ctx);
+ +

+This function is called by a continuation function (see §4.7) +to retrieve the status of the thread and a context information. + + +

+When called in the original function, +lua_getctx always returns LUA_OK +and does not change the value of its argument ctx. +When called inside a continuation function, +lua_getctx returns LUA_YIELD and sets +the value of ctx to be the context information +(the value passed as the ctx argument +to the callee together with the continuation function). + + +

+When the callee is lua_pcallk, +Lua may also call its continuation function +to handle errors during the call. +That is, upon an error in the function called by lua_pcallk, +Lua may not return to the original function +but instead may call the continuation function. +In that case, a call to lua_getctx will return the error code +(the value that would be returned by lua_pcallk); +the value of ctx will be set to the context information, +as in the case of a yield. + + + + + +

lua_getfield

+[-0, +1, e] +

void lua_getfield (lua_State *L, int index, const char *k);
+ +

+Pushes onto the stack the value t[k], +where t is the value at the given index. +As in Lua, this function may trigger a metamethod +for the "index" event (see §2.4). + + + + + +

lua_getglobal

+[-0, +1, e] +

void lua_getglobal (lua_State *L, const char *name);
+ +

+Pushes onto the stack the value of the global name. + + + + + +

lua_getmetatable

+[-0, +(0|1), –] +

int lua_getmetatable (lua_State *L, int index);
+ +

+Pushes onto the stack the metatable of the value at the given index. +If the value does not have a metatable, +the function returns 0 and pushes nothing on the stack. + + + + + +

lua_gettable

+[-1, +1, e] +

void lua_gettable (lua_State *L, int index);
+ +

+Pushes onto the stack the value t[k], +where t is the value at the given index +and k is the value at the top of the stack. + + +

+This function pops the key from the stack +(putting the resulting value in its place). +As in Lua, this function may trigger a metamethod +for the "index" event (see §2.4). + + + + + +

lua_gettop

+[-0, +0, –] +

int lua_gettop (lua_State *L);
+ +

+Returns the index of the top element in the stack. +Because indices start at 1, +this result is equal to the number of elements in the stack +(and so 0 means an empty stack). + + + + + +

lua_getuservalue

+[-0, +1, –] +

void lua_getuservalue (lua_State *L, int index);
+ +

+Pushes onto the stack the Lua value associated with the userdata +at the given index. +This Lua value must be a table or nil. + + + + + +

lua_insert

+[-1, +1, –] +

void lua_insert (lua_State *L, int index);
+ +

+Moves the top element into the given valid index, +shifting up the elements above this index to open space. +This function cannot be called with a pseudo-index, +because a pseudo-index is not an actual stack position. + + + + + +

lua_Integer

+
typedef ptrdiff_t lua_Integer;
+ +

+The type used by the Lua API to represent signed integral values. + + +

+By default it is a ptrdiff_t, +which is usually the largest signed integral type the machine handles +"comfortably". + + + + + +

lua_isboolean

+[-0, +0, –] +

int lua_isboolean (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is a boolean, +and 0 otherwise. + + + + + +

lua_iscfunction

+[-0, +0, –] +

int lua_iscfunction (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is a C function, +and 0 otherwise. + + + + + +

lua_isfunction

+[-0, +0, –] +

int lua_isfunction (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is a function +(either C or Lua), and 0 otherwise. + + + + + +

lua_islightuserdata

+[-0, +0, –] +

int lua_islightuserdata (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is a light userdata, +and 0 otherwise. + + + + + +

lua_isnil

+[-0, +0, –] +

int lua_isnil (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is nil, +and 0 otherwise. + + + + + +

lua_isnone

+[-0, +0, –] +

int lua_isnone (lua_State *L, int index);
+ +

+Returns 1 if the given index is not valid, +and 0 otherwise. + + + + + +

lua_isnoneornil

+[-0, +0, –] +

int lua_isnoneornil (lua_State *L, int index);
+ +

+Returns 1 if the given index is not valid +or if the value at this index is nil, +and 0 otherwise. + + + + + +

lua_isnumber

+[-0, +0, –] +

int lua_isnumber (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is a number +or a string convertible to a number, +and 0 otherwise. + + + + + +

lua_isstring

+[-0, +0, –] +

int lua_isstring (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is a string +or a number (which is always convertible to a string), +and 0 otherwise. + + + + + +

lua_istable

+[-0, +0, –] +

int lua_istable (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is a table, +and 0 otherwise. + + + + + +

lua_isthread

+[-0, +0, –] +

int lua_isthread (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is a thread, +and 0 otherwise. + + + + + +

lua_isuserdata

+[-0, +0, –] +

int lua_isuserdata (lua_State *L, int index);
+ +

+Returns 1 if the value at the given index is a userdata +(either full or light), and 0 otherwise. + + + + + +

lua_len

+[-0, +1, e] +

void lua_len (lua_State *L, int index);
+ +

+Returns the "length" of the value at the given index; +it is equivalent to the '#' operator in Lua (see §3.4.6). +The result is pushed on the stack. + + + + + +

lua_load

+[-0, +1, –] +

int lua_load (lua_State *L,
+              lua_Reader reader,
+              void *data,
+              const char *source,
+              const char *mode);
+ +

+Loads a Lua chunk (without running it). +If there are no errors, +lua_load pushes the compiled chunk as a Lua +function on top of the stack. +Otherwise, it pushes an error message. + + +

+The return values of lua_load are: + +

    + +
  • LUA_OK: no errors;
    • + +
  • LUA_ERRSYNTAX: +syntax error during precompilation;
    • + +
  • LUA_ERRMEM: +memory allocation error;
    • + +
  • LUA_ERRGCMM: +error while running a __gc metamethod. +(This error has no relation with the chunk being loaded. +It is generated by the garbage collector.) +
    • + +
+ +

+The lua_load function uses a user-supplied reader function +to read the chunk (see lua_Reader). +The data argument is an opaque value passed to the reader function. + + +

+The source argument gives a name to the chunk, +which is used for error messages and in debug information (see §4.9). + + +

+lua_load automatically detects whether the chunk is text or binary +and loads it accordingly (see program luac). +The string mode works as in function load, +with the addition that +a NULL value is equivalent to the string "bt". + + +

+lua_load uses the stack internally, +so the reader function should always leave the stack +unmodified when returning. + + +

+If the resulting function has one upvalue, +this upvalue is set to the value of the global environment +stored at index LUA_RIDX_GLOBALS in the registry (see §4.5). +When loading main chunks, +this upvalue will be the _ENV variable (see §2.2). + + + + + +

lua_newstate

+[-0, +0, –] +

lua_State *lua_newstate (lua_Alloc f, void *ud);
+ +

+Creates a new thread running in a new, independent state. +Returns NULL if cannot create the thread or the state +(due to lack of memory). +The argument f is the allocator function; +Lua does all memory allocation for this state through this function. +The second argument, ud, is an opaque pointer that Lua +passes to the allocator in every call. + + + + + +

lua_newtable

+[-0, +1, e] +

void lua_newtable (lua_State *L);
+ +

+Creates a new empty table and pushes it onto the stack. +It is equivalent to lua_createtable(L, 0, 0). + + + + + +

lua_newthread

+[-0, +1, e] +

lua_State *lua_newthread (lua_State *L);
+ +

+Creates a new thread, pushes it on the stack, +and returns a pointer to a lua_State that represents this new thread. +The new thread returned by this function shares with the original thread +its global environment, +but has an independent execution stack. + + +

+There is no explicit function to close or to destroy a thread. +Threads are subject to garbage collection, +like any Lua object. + + + + + +

lua_newuserdata

+[-0, +1, e] +

void *lua_newuserdata (lua_State *L, size_t size);
+ +

+This function allocates a new block of memory with the given size, +pushes onto the stack a new full userdata with the block address, +and returns this address. +The host program can freely use this memory. + + + + + +

lua_next

+[-1, +(2|0), e] +

int lua_next (lua_State *L, int index);
+ +

+Pops a key from the stack, +and pushes a key–value pair from the table at the given index +(the "next" pair after the given key). +If there are no more elements in the table, +then lua_next returns 0 (and pushes nothing). + + +

+A typical traversal looks like this: + +

+     /* table is in the stack at index 't' */
+     lua_pushnil(L);  /* first key */
+     while (lua_next(L, t) != 0) {
+       /* uses 'key' (at index -2) and 'value' (at index -1) */
+       printf("%s - %s\n",
+              lua_typename(L, lua_type(L, -2)),
+              lua_typename(L, lua_type(L, -1)));
+       /* removes 'value'; keeps 'key' for next iteration */
+       lua_pop(L, 1);
+     }
+
+ +

+While traversing a table, +do not call lua_tolstring directly on a key, +unless you know that the key is actually a string. +Recall that lua_tolstring may change +the value at the given index; +this confuses the next call to lua_next. + + +

+See function next for the caveats of modifying +the table during its traversal. + + + + + +

lua_Number

+
typedef double lua_Number;
+ +

+The type of numbers in Lua. +By default, it is double, but that can be changed in luaconf.h. +Through this configuration file you can change +Lua to operate with another type for numbers (e.g., float or long). + + + + + +

lua_pcall

+[-(nargs + 1), +(nresults|1), –] +

int lua_pcall (lua_State *L, int nargs, int nresults, int msgh);
+ +

+Calls a function in protected mode. + + +

+Both nargs and nresults have the same meaning as +in lua_call. +If there are no errors during the call, +lua_pcall behaves exactly like lua_call. +However, if there is any error, +lua_pcall catches it, +pushes a single value on the stack (the error message), +and returns an error code. +Like lua_call, +lua_pcall always removes the function +and its arguments from the stack. + + +

+If msgh is 0, +then the error message returned on the stack +is exactly the original error message. +Otherwise, msgh is the stack index of a +message handler. +(In the current implementation, this index cannot be a pseudo-index.) +In case of runtime errors, +this function will be called with the error message +and its return value will be the message +returned on the stack by lua_pcall. + + +

+Typically, the message handler is used to add more debug +information to the error message, such as a stack traceback. +Such information cannot be gathered after the return of lua_pcall, +since by then the stack has unwound. + + +

+The lua_pcall function returns one of the following codes +(defined in lua.h): + +

    + +
  • LUA_OK (0): +success.
    • + +
  • LUA_ERRRUN: +a runtime error. +
    • + +
  • LUA_ERRMEM: +memory allocation error. +For such errors, Lua does not call the message handler. +
    • + +
  • LUA_ERRERR: +error while running the message handler. +
    • + +
  • LUA_ERRGCMM: +error while running a __gc metamethod. +(This error typically has no relation with the function being called. +It is generated by the garbage collector.) +
    • + +
+ + + + +

lua_pcallk

+[-(nargs + 1), +(nresults|1), –] +

int lua_pcallk (lua_State *L,
+                int nargs,
+                int nresults,
+                int errfunc,
+                int ctx,
+                lua_CFunction k);
+ +

+This function behaves exactly like lua_pcall, +but allows the called function to yield (see §4.7). + + + + + +

lua_pop

+[-n, +0, –] +

void lua_pop (lua_State *L, int n);
+ +

+Pops n elements from the stack. + + + + + +

lua_pushboolean

+[-0, +1, –] +

void lua_pushboolean (lua_State *L, int b);
+ +

+Pushes a boolean value with value b onto the stack. + + + + + +

lua_pushcclosure

+[-n, +1, e] +

void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n);
+ +

+Pushes a new C closure onto the stack. + + +

+When a C function is created, +it is possible to associate some values with it, +thus creating a C closure (see §4.4); +these values are then accessible to the function whenever it is called. +To associate values with a C function, +first these values should be pushed onto the stack +(when there are multiple values, the first value is pushed first). +Then lua_pushcclosure +is called to create and push the C function onto the stack, +with the argument n telling how many values should be +associated with the function. +lua_pushcclosure also pops these values from the stack. + + +

+The maximum value for n is 255. + + +

+When n is zero, +this function creates a light C function, +which is just a pointer to the C function. +In that case, it never throws a memory error. + + + + + +

lua_pushcfunction

+[-0, +1, –] +

void lua_pushcfunction (lua_State *L, lua_CFunction f);
+ +

+Pushes a C function onto the stack. +This function receives a pointer to a C function +and pushes onto the stack a Lua value of type function that, +when called, invokes the corresponding C function. + + +

+Any function to be registered in Lua must +follow the correct protocol to receive its parameters +and return its results (see lua_CFunction). + + +

+lua_pushcfunction is defined as a macro: + +

+     #define lua_pushcfunction(L,f)  lua_pushcclosure(L,f,0)
+

+Note that f is used twice. + + + + + +

lua_pushfstring

+[-0, +1, e] +

const char *lua_pushfstring (lua_State *L, const char *fmt, ...);
+ +

+Pushes onto the stack a formatted string +and returns a pointer to this string. +It is similar to the ANSI C function sprintf, +but has some important differences: + +

    + +
  • +You do not have to allocate space for the result: +the result is a Lua string and Lua takes care of memory allocation +(and deallocation, through garbage collection). +
    • + +
  • +The conversion specifiers are quite restricted. +There are no flags, widths, or precisions. +The conversion specifiers can only be +'%%' (inserts a '%' in the string), +'%s' (inserts a zero-terminated string, with no size restrictions), +'%f' (inserts a lua_Number), +'%p' (inserts a pointer as a hexadecimal numeral), +'%d' (inserts an int), and +'%c' (inserts an int as a byte). +
    • + +
+ + + + +

lua_pushglobaltable

+[-0, +1, –] +

void lua_pushglobaltable (lua_State *L);
+ +

+Pushes the global environment onto the stack. + + + + + +

lua_pushinteger

+[-0, +1, –] +

void lua_pushinteger (lua_State *L, lua_Integer n);
+ +

+Pushes a number with value n onto the stack. + + + + + +

lua_pushlightuserdata

+[-0, +1, –] +

void lua_pushlightuserdata (lua_State *L, void *p);
+ +

+Pushes a light userdata onto the stack. + + +

+Userdata represent C values in Lua. +A light userdata represents a pointer, a void*. +It is a value (like a number): +you do not create it, it has no individual metatable, +and it is not collected (as it was never created). +A light userdata is equal to "any" +light userdata with the same C address. + + + + + +

lua_pushliteral

+[-0, +1, e] +

const char *lua_pushliteral (lua_State *L, const char *s);
+ +

+This macro is equivalent to lua_pushlstring, +but can be used only when s is a literal string. +It automatically provides the string length. + + + + + +

lua_pushlstring

+[-0, +1, e] +

const char *lua_pushlstring (lua_State *L, const char *s, size_t len);
+ +

+Pushes the string pointed to by s with size len +onto the stack. +Lua makes (or reuses) an internal copy of the given string, +so the memory at s can be freed or reused immediately after +the function returns. +The string can contain any binary data, +including embedded zeros. + + +

+Returns a pointer to the internal copy of the string. + + + + + +

lua_pushnil

+[-0, +1, –] +

void lua_pushnil (lua_State *L);
+ +

+Pushes a nil value onto the stack. + + + + + +

lua_pushnumber

+[-0, +1, –] +

void lua_pushnumber (lua_State *L, lua_Number n);
+ +

+Pushes a number with value n onto the stack. + + + + + +

lua_pushstring

+[-0, +1, e] +

const char *lua_pushstring (lua_State *L, const char *s);
+ +

+Pushes the zero-terminated string pointed to by s +onto the stack. +Lua makes (or reuses) an internal copy of the given string, +so the memory at s can be freed or reused immediately after +the function returns. + + +

+Returns a pointer to the internal copy of the string. + + +

+If s is NULL, pushes nil and returns NULL. + + + + + +

lua_pushthread

+[-0, +1, –] +

int lua_pushthread (lua_State *L);
+ +

+Pushes the thread represented by L onto the stack. +Returns 1 if this thread is the main thread of its state. + + + + + +

lua_pushunsigned

+[-0, +1, –] +

void lua_pushunsigned (lua_State *L, lua_Unsigned n);
+ +

+Pushes a number with value n onto the stack. + + + + + +

lua_pushvalue

+[-0, +1, –] +

void lua_pushvalue (lua_State *L, int index);
+ +

+Pushes a copy of the element at the given index +onto the stack. + + + + + +

lua_pushvfstring

+[-0, +1, e] +

const char *lua_pushvfstring (lua_State *L,
+                              const char *fmt,
+                              va_list argp);
+ +

+Equivalent to lua_pushfstring, except that it receives a va_list +instead of a variable number of arguments. + + + + + +

lua_rawequal

+[-0, +0, –] +

int lua_rawequal (lua_State *L, int index1, int index2);
+ +

+Returns 1 if the two values in indices index1 and +index2 are primitively equal +(that is, without calling metamethods). +Otherwise returns 0. +Also returns 0 if any of the indices are non valid. + + + + + +

lua_rawget

+[-1, +1, –] +

void lua_rawget (lua_State *L, int index);
+ +

+Similar to lua_gettable, but does a raw access +(i.e., without metamethods). + + + + + +

lua_rawgeti

+[-0, +1, –] +

void lua_rawgeti (lua_State *L, int index, int n);
+ +

+Pushes onto the stack the value t[n], +where t is the table at the given index. +The access is raw; +that is, it does not invoke metamethods. + + + + + +

lua_rawgetp

+[-0, +1, –] +

void lua_rawgetp (lua_State *L, int index, const void *p);
+ +

+Pushes onto the stack the value t[k], +where t is the table at the given index and +k is the pointer p represented as a light userdata. +The access is raw; +that is, it does not invoke metamethods. + + + + + +

lua_rawlen

+[-0, +0, –] +

size_t lua_rawlen (lua_State *L, int index);
+ +

+Returns the raw "length" of the value at the given index: +for strings, this is the string length; +for tables, this is the result of the length operator ('#') +with no metamethods; +for userdata, this is the size of the block of memory allocated +for the userdata; +for other values, it is 0. + + + + + +

lua_rawset

+[-2, +0, e] +

void lua_rawset (lua_State *L, int index);
+ +

+Similar to lua_settable, but does a raw assignment +(i.e., without metamethods). + + + + + +

lua_rawseti

+[-1, +0, e] +

void lua_rawseti (lua_State *L, int index, int n);
+ +

+Does the equivalent of t[n] = v, +where t is the table at the given index +and v is the value at the top of the stack. + + +

+This function pops the value from the stack. +The assignment is raw; +that is, it does not invoke metamethods. + + + + + +

lua_rawsetp

+[-1, +0, e] +

void lua_rawsetp (lua_State *L, int index, const void *p);
+ +

+Does the equivalent of t[k] = v, +where t is the table at the given index, +k is the pointer p represented as a light userdata, +and v is the value at the top of the stack. + + +

+This function pops the value from the stack. +The assignment is raw; +that is, it does not invoke metamethods. + + + + + +

lua_Reader

+
typedef const char * (*lua_Reader) (lua_State *L,
+                                    void *data,
+                                    size_t *size);
+ +

+The reader function used by lua_load. +Every time it needs another piece of the chunk, +lua_load calls the reader, +passing along its data parameter. +The reader must return a pointer to a block of memory +with a new piece of the chunk +and set size to the block size. +The block must exist until the reader function is called again. +To signal the end of the chunk, +the reader must return NULL or set size to zero. +The reader function may return pieces of any size greater than zero. + + + + + +

lua_register

+[-0, +0, e] +

void lua_register (lua_State *L, const char *name, lua_CFunction f);
+ +

+Sets the C function f as the new value of global name. +It is defined as a macro: + +

+     #define lua_register(L,n,f) \
+            (lua_pushcfunction(L, f), lua_setglobal(L, n))
+
+ + + + +

lua_remove

+[-1, +0, –] +

void lua_remove (lua_State *L, int index);
+ +

+Removes the element at the given valid index, +shifting down the elements above this index to fill the gap. +This function cannot be called with a pseudo-index, +because a pseudo-index is not an actual stack position. + + + + + +

lua_replace

+[-1, +0, –] +

void lua_replace (lua_State *L, int index);
+ +

+Moves the top element into the given valid index +without shifting any element +(therefore replacing the value at the given index), +and then pops the top element. + + + + + +

lua_resume

+[-?, +?, –] +

int lua_resume (lua_State *L, lua_State *from, int nargs);
+ +

+Starts and resumes a coroutine in a given thread. + + +

+To start a coroutine, +you push onto the thread stack the main function plus any arguments; +then you call lua_resume, +with nargs being the number of arguments. +This call returns when the coroutine suspends or finishes its execution. +When it returns, the stack contains all values passed to lua_yield, +or all values returned by the body function. +lua_resume returns +LUA_YIELD if the coroutine yields, +LUA_OK if the coroutine finishes its execution +without errors, +or an error code in case of errors (see lua_pcall). + + +

+In case of errors, +the stack is not unwound, +so you can use the debug API over it. +The error message is on the top of the stack. + + +

+To resume a coroutine, +you remove any results from the last lua_yield, +put on its stack only the values to +be passed as results from yield, +and then call lua_resume. + + +

+The parameter from represents the coroutine that is resuming L. +If there is no such coroutine, +this parameter can be NULL. + + + + + +

lua_setallocf

+[-0, +0, –] +

void lua_setallocf (lua_State *L, lua_Alloc f, void *ud);
+ +

+Changes the allocator function of a given state to f +with user data ud. + + + + + +

lua_setfield

+[-1, +0, e] +

void lua_setfield (lua_State *L, int index, const char *k);
+ +

+Does the equivalent to t[k] = v, +where t is the value at the given index +and v is the value at the top of the stack. + + +

+This function pops the value from the stack. +As in Lua, this function may trigger a metamethod +for the "newindex" event (see §2.4). + + + + + +

lua_setglobal

+[-1, +0, e] +

void lua_setglobal (lua_State *L, const char *name);
+ +

+Pops a value from the stack and +sets it as the new value of global name. + + + + + +

lua_setmetatable

+[-1, +0, –] +

void lua_setmetatable (lua_State *L, int index);
+ +

+Pops a table from the stack and +sets it as the new metatable for the value at the given index. + + + + + +

lua_settable

+[-2, +0, e] +

void lua_settable (lua_State *L, int index);
+ +

+Does the equivalent to t[k] = v, +where t is the value at the given index, +v is the value at the top of the stack, +and k is the value just below the top. + + +

+This function pops both the key and the value from the stack. +As in Lua, this function may trigger a metamethod +for the "newindex" event (see §2.4). + + + + + +

lua_settop

+[-?, +?, –] +

void lua_settop (lua_State *L, int index);
+ +

+Accepts any index, or 0, +and sets the stack top to this index. +If the new top is larger than the old one, +then the new elements are filled with nil. +If index is 0, then all stack elements are removed. + + + + + +

lua_setuservalue

+[-1, +0, –] +

void lua_setuservalue (lua_State *L, int index);
+ +

+Pops a table or nil from the stack and sets it as +the new value associated to the userdata at the given index. + + + + + +

lua_State

+
typedef struct lua_State lua_State;
+ +

+An opaque structure that points to a thread and indirectly +(through the thread) to the whole state of a Lua interpreter. +The Lua library is fully reentrant: +it has no global variables. +All information about a state is accessible through this structure. + + +

+A pointer to this structure must be passed as the first argument to +every function in the library, except to lua_newstate, +which creates a Lua state from scratch. + + + + + +

lua_status

+[-0, +0, –] +

int lua_status (lua_State *L);
+ +

+Returns the status of the thread L. + + +

+The status can be 0 (LUA_OK) for a normal thread, +an error code if the thread finished the execution +of a lua_resume with an error, +or LUA_YIELD if the thread is suspended. + + +

+You can only call functions in threads with status LUA_OK. +You can resume threads with status LUA_OK +(to start a new coroutine) or LUA_YIELD +(to resume a coroutine). + + + + + +

lua_toboolean

+[-0, +0, –] +

int lua_toboolean (lua_State *L, int index);
+ +

+Converts the Lua value at the given index to a C boolean +value (0 or 1). +Like all tests in Lua, +lua_toboolean returns true for any Lua value +different from false and nil; +otherwise it returns false. +(If you want to accept only actual boolean values, +use lua_isboolean to test the value's type.) + + + + + +

lua_tocfunction

+[-0, +0, –] +

lua_CFunction lua_tocfunction (lua_State *L, int index);
+ +

+Converts a value at the given index to a C function. +That value must be a C function; +otherwise, returns NULL. + + + + + +

lua_tointeger

+[-0, +0, –] +

lua_Integer lua_tointeger (lua_State *L, int index);
+ +

+Equivalent to lua_tointegerx with isnum equal to NULL. + + + + + +

lua_tointegerx

+[-0, +0, –] +

lua_Integer lua_tointegerx (lua_State *L, int index, int *isnum);
+ +

+Converts the Lua value at the given index +to the signed integral type lua_Integer. +The Lua value must be a number or a string convertible to a number +(see §3.4.2); +otherwise, lua_tointegerx returns 0. + + +

+If the number is not an integer, +it is truncated in some non-specified way. + + +

+If isnum is not NULL, +its referent is assigned a boolean value that +indicates whether the operation succeeded. + + + + + +

lua_tolstring

+[-0, +0, e] +

const char *lua_tolstring (lua_State *L, int index, size_t *len);
+ +

+Converts the Lua value at the given index to a C string. +If len is not NULL, +it also sets *len with the string length. +The Lua value must be a string or a number; +otherwise, the function returns NULL. +If the value is a number, +then lua_tolstring also +changes the actual value in the stack to a string. +(This change confuses lua_next +when lua_tolstring is applied to keys during a table traversal.) + + +

+lua_tolstring returns a fully aligned pointer +to a string inside the Lua state. +This string always has a zero ('\0') +after its last character (as in C), +but can contain other zeros in its body. +Because Lua has garbage collection, +there is no guarantee that the pointer returned by lua_tolstring +will be valid after the corresponding value is removed from the stack. + + + + + +

lua_tonumber

+[-0, +0, –] +

lua_Number lua_tonumber (lua_State *L, int index);
+ +

+Equivalent to lua_tonumberx with isnum equal to NULL. + + + + + +

lua_tonumberx

+[-0, +0, –] +

lua_Number lua_tonumberx (lua_State *L, int index, int *isnum);
+ +

+Converts the Lua value at the given index +to the C type lua_Number (see lua_Number). +The Lua value must be a number or a string convertible to a number +(see §3.4.2); +otherwise, lua_tonumberx returns 0. + + +

+If isnum is not NULL, +its referent is assigned a boolean value that +indicates whether the operation succeeded. + + + + + +

lua_topointer

+[-0, +0, –] +

const void *lua_topointer (lua_State *L, int index);
+ +

+Converts the value at the given index to a generic +C pointer (void*). +The value can be a userdata, a table, a thread, or a function; +otherwise, lua_topointer returns NULL. +Different objects will give different pointers. +There is no way to convert the pointer back to its original value. + + +

+Typically this function is used only for debug information. + + + + + +

lua_tostring

+[-0, +0, e] +

const char *lua_tostring (lua_State *L, int index);
+ +

+Equivalent to lua_tolstring with len equal to NULL. + + + + + +

lua_tothread

+[-0, +0, –] +

lua_State *lua_tothread (lua_State *L, int index);
+ +

+Converts the value at the given index to a Lua thread +(represented as lua_State*). +This value must be a thread; +otherwise, the function returns NULL. + + + + + +

lua_tounsigned

+[-0, +0, –] +

lua_Unsigned lua_tounsigned (lua_State *L, int index);
+ +

+Equivalent to lua_tounsignedx with isnum equal to NULL. + + + + + +

lua_tounsignedx

+[-0, +0, –] +

lua_Unsigned lua_tounsignedx (lua_State *L, int index, int *isnum);
+ +

+Converts the Lua value at the given index +to the unsigned integral type lua_Unsigned. +The Lua value must be a number or a string convertible to a number +(see §3.4.2); +otherwise, lua_tounsignedx returns 0. + + +

+If the number is not an integer, +it is truncated in some non-specified way. +If the number is outside the range of representable values, +it is normalized to the remainder of its division by +one more than the maximum representable value. + + +

+If isnum is not NULL, +its referent is assigned a boolean value that +indicates whether the operation succeeded. + + + + + +

lua_touserdata

+[-0, +0, –] +

void *lua_touserdata (lua_State *L, int index);
+ +

+If the value at the given index is a full userdata, +returns its block address. +If the value is a light userdata, +returns its pointer. +Otherwise, returns NULL. + + + + + +

lua_type

+[-0, +0, –] +

int lua_type (lua_State *L, int index);
+ +

+Returns the type of the value in the given valid index, +or LUA_TNONE for a non-valid (but acceptable) index. +The types returned by lua_type are coded by the following constants +defined in lua.h: +LUA_TNIL, +LUA_TNUMBER, +LUA_TBOOLEAN, +LUA_TSTRING, +LUA_TTABLE, +LUA_TFUNCTION, +LUA_TUSERDATA, +LUA_TTHREAD, +and +LUA_TLIGHTUSERDATA. + + + + + +

lua_typename

+[-0, +0, –] +

const char *lua_typename (lua_State *L, int tp);
+ +

+Returns the name of the type encoded by the value tp, +which must be one the values returned by lua_type. + + + + + +

lua_Unsigned

+
typedef unsigned long lua_Unsigned;
+ +

+The type used by the Lua API to represent unsigned integral values. +It must have at least 32 bits. + + +

+By default it is an unsigned int or an unsigned long, +whichever can hold 32-bit values. + + + + + +

lua_upvalueindex

+[-0, +0, –] +

int lua_upvalueindex (int i);
+ +

+Returns the pseudo-index that represents the i-th upvalue of +the running function (see §4.4). + + + + + +

lua_version

+[-0, +0, v] +

const lua_Number *lua_version (lua_State *L);
+ +

+Returns the address of the version number stored in the Lua core. +When called with a valid lua_State, +returns the address of the version used to create that state. +When called with NULL, +returns the address of the version running the call. + + + + + +

lua_Writer

+
typedef int (*lua_Writer) (lua_State *L,
+                           const void* p,
+                           size_t sz,
+                           void* ud);
+ +

+The type of the writer function used by lua_dump. +Every time it produces another piece of chunk, +lua_dump calls the writer, +passing along the buffer to be written (p), +its size (sz), +and the data parameter supplied to lua_dump. + + +

+The writer returns an error code: +0 means no errors; +any other value means an error and stops lua_dump from +calling the writer again. + + + + + +

lua_xmove

+[-?, +?, –] +

void lua_xmove (lua_State *from, lua_State *to, int n);
+ +

+Exchange values between different threads of the same state. + + +

+This function pops n values from the stack from, +and pushes them onto the stack to. + + + + + +

lua_yield

+[-?, +?, –] +

int lua_yield (lua_State *L, int nresults);
+ +

+This function is equivalent to lua_yieldk, +but it has no continuation (see §4.7). +Therefore, when the thread resumes, +it returns to the function that called +the function calling lua_yield. + + + + + +

lua_yieldk

+[-?, +?, –] +

int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k);
+ +

+Yields a coroutine. + + +

+This function should only be called as the +return expression of a C function, as follows: + +

+     return lua_yieldk (L, n, i, k);
+

+When a C function calls lua_yieldk in that way, +the running coroutine suspends its execution, +and the call to lua_resume that started this coroutine returns. +The parameter nresults is the number of values from the stack +that are passed as results to lua_resume. + + +

+When the coroutine is resumed again, +Lua calls the given continuation function k to continue +the execution of the C function that yielded (see §4.7). +This continuation function receives the same stack +from the previous function, +with the results removed and +replaced by the arguments passed to lua_resume. +Moreover, +the continuation function may access the value ctx +by calling lua_getctx. + + + + + + + +

4.9 – The Debug Interface

+ +

+Lua has no built-in debugging facilities. +Instead, it offers a special interface +by means of functions and hooks. +This interface allows the construction of different +kinds of debuggers, profilers, and other tools +that need "inside information" from the interpreter. + + + +

lua_Debug

+
typedef struct lua_Debug {
+  int event;
+  const char *name;           /* (n) */
+  const char *namewhat;       /* (n) */
+  const char *what;           /* (S) */
+  const char *source;         /* (S) */
+  int currentline;            /* (l) */
+  int linedefined;            /* (S) */
+  int lastlinedefined;        /* (S) */
+  unsigned char nups;         /* (u) number of upvalues */
+  unsigned char nparams;      /* (u) number of parameters */
+  char isvararg;              /* (u) */
+  char istailcall;            /* (t) */
+  char short_src[LUA_IDSIZE]; /* (S) */
+  /* private part */
+  other fields
+} lua_Debug;
+ +

+A structure used to carry different pieces of +information about a function or an activation record. +lua_getstack fills only the private part +of this structure, for later use. +To fill the other fields of lua_Debug with useful information, +call lua_getinfo. + + +

+The fields of lua_Debug have the following meaning: + +

    + +
  • source: +the source of the chunk that created the function. +If source starts with a '@', +it means that the function was defined in a file where +the file name follows the '@'. +If source starts with a '=', +the remainder of its contents describe the source in a user-dependent manner. +Otherwise, +the function was defined in a string where +source is that string. +
    • + +
  • short_src: +a "printable" version of source, to be used in error messages. +
    • + +
  • linedefined: +the line number where the definition of the function starts. +
    • + +
  • lastlinedefined: +the line number where the definition of the function ends. +
    • + +
  • what: +the string "Lua" if the function is a Lua function, +"C" if it is a C function, +"main" if it is the main part of a chunk. +
    • + +
  • currentline: +the current line where the given function is executing. +When no line information is available, +currentline is set to -1. +
    • + +
  • name: +a reasonable name for the given function. +Because functions in Lua are first-class values, +they do not have a fixed name: +some functions can be the value of multiple global variables, +while others can be stored only in a table field. +The lua_getinfo function checks how the function was +called to find a suitable name. +If it cannot find a name, +then name is set to NULL. +
    • + +
  • namewhat: +explains the name field. +The value of namewhat can be +"global", "local", "method", +"field", "upvalue", or "" (the empty string), +according to how the function was called. +(Lua uses the empty string when no other option seems to apply.) +
    • + +
  • istailcall: +true if this function invocation was called by a tail call. +In this case, the caller of this level is not in the stack. +
    • + +
  • nups: +the number of upvalues of the function. +
    • + +
  • nparams: +the number of fixed parameters of the function +(always 0 for C functions). +
    • + +
  • isvararg: +true if the function is a vararg function +(always true for C functions). +
    • + +
+ + + + +

lua_gethook

+[-0, +0, –] +

lua_Hook lua_gethook (lua_State *L);
+ +

+Returns the current hook function. + + + + + +

lua_gethookcount

+[-0, +0, –] +

int lua_gethookcount (lua_State *L);
+ +

+Returns the current hook count. + + + + + +

lua_gethookmask

+[-0, +0, –] +

int lua_gethookmask (lua_State *L);
+ +

+Returns the current hook mask. + + + + + +

lua_getinfo

+[-(0|1), +(0|1|2), e] +

int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar);
+ +

+Gets information about a specific function or function invocation. + + +

+To get information about a function invocation, +the parameter ar must be a valid activation record that was +filled by a previous call to lua_getstack or +given as argument to a hook (see lua_Hook). + + +

+To get information about a function you push it onto the stack +and start the what string with the character '>'. +(In that case, +lua_getinfo pops the function from the top of the stack.) +For instance, to know in which line a function f was defined, +you can write the following code: + +

+     lua_Debug ar;
+     lua_getglobal(L, "f");  /* get global 'f' */
+     lua_getinfo(L, ">S", &ar);
+     printf("%d\n", ar.linedefined);
+
+ +

+Each character in the string what +selects some fields of the structure ar to be filled or +a value to be pushed on the stack: + +

    + +
  • 'n': fills in the field name and namewhat; +
    • + +
  • 'S': +fills in the fields source, short_src, +linedefined, lastlinedefined, and what; +
    • + +
  • 'l': fills in the field currentline; +
    • + +
  • 't': fills in the field istailcall; +
    • + +
  • 'u': fills in the fields +nups, nparams, and isvararg; +
    • + +
  • 'f': +pushes onto the stack the function that is +running at the given level; +
    • + +
  • 'L': +pushes onto the stack a table whose indices are the +numbers of the lines that are valid on the function. +(A valid line is a line with some associated code, +that is, a line where you can put a break point. +Non-valid lines include empty lines and comments.) +
    • + +
+ +

+This function returns 0 on error +(for instance, an invalid option in what). + + + + + +

lua_getlocal

+[-0, +(0|1), –] +

const char *lua_getlocal (lua_State *L, lua_Debug *ar, int n);
+ +

+Gets information about a local variable of +a given activation record or a given function. + + +

+In the first case, +the parameter ar must be a valid activation record that was +filled by a previous call to lua_getstack or +given as argument to a hook (see lua_Hook). +The index n selects which local variable to inspect; +see debug.getlocal for details about variable indices +and names. + + +

+lua_getlocal pushes the variable's value onto the stack +and returns its name. + + +

+In the second case, ar should be NULL and the function +to be inspected must be at the top of the stack. +In this case, only parameters of Lua functions are visible +(as there is no information about what variables are active) +and no values are pushed onto the stack. + + +

+Returns NULL (and pushes nothing) +when the index is greater than +the number of active local variables. + + + + + +

lua_getstack

+[-0, +0, –] +

int lua_getstack (lua_State *L, int level, lua_Debug *ar);
+ +

+Gets information about the interpreter runtime stack. + + +

+This function fills parts of a lua_Debug structure with +an identification of the activation record +of the function executing at a given level. +Level 0 is the current running function, +whereas level n+1 is the function that has called level n +(except for tail calls, which do not count on the stack). +When there are no errors, lua_getstack returns 1; +when called with a level greater than the stack depth, +it returns 0. + + + + + +

lua_getupvalue

+[-0, +(0|1), –] +

const char *lua_getupvalue (lua_State *L, int funcindex, int n);
+ +

+Gets information about a closure's upvalue. +(For Lua functions, +upvalues are the external local variables that the function uses, +and that are consequently included in its closure.) +lua_getupvalue gets the index n of an upvalue, +pushes the upvalue's value onto the stack, +and returns its name. +funcindex points to the closure in the stack. +(Upvalues have no particular order, +as they are active through the whole function. +So, they are numbered in an arbitrary order.) + + +

+Returns NULL (and pushes nothing) +when the index is greater than the number of upvalues. +For C functions, this function uses the empty string "" +as a name for all upvalues. + + + + + +

lua_Hook

+
typedef void (*lua_Hook) (lua_State *L, lua_Debug *ar);
+ +

+Type for debugging hook functions. + + +

+Whenever a hook is called, its ar argument has its field +event set to the specific event that triggered the hook. +Lua identifies these events with the following constants: +LUA_HOOKCALL, LUA_HOOKRET, +LUA_HOOKTAILCALL, LUA_HOOKLINE, +and LUA_HOOKCOUNT. +Moreover, for line events, the field currentline is also set. +To get the value of any other field in ar, +the hook must call lua_getinfo. + + +

+For call events, event can be LUA_HOOKCALL, +the normal value, or LUA_HOOKTAILCALL, for a tail call; +in this case, there will be no corresponding return event. + + +

+While Lua is running a hook, it disables other calls to hooks. +Therefore, if a hook calls back Lua to execute a function or a chunk, +this execution occurs without any calls to hooks. + + +

+Hook functions cannot have continuations, +that is, they cannot call lua_yieldk, +lua_pcallk, or lua_callk with a non-null k. + + +

+Hook functions can yield under the following conditions: +Only count and line events can yield +and they cannot yield any value; +to yield a hook function must finish its execution +calling lua_yield with nresults equal to zero. + + + + + +

lua_sethook

+[-0, +0, –] +

int lua_sethook (lua_State *L, lua_Hook f, int mask, int count);
+ +

+Sets the debugging hook function. + + +

+Argument f is the hook function. +mask specifies on which events the hook will be called: +it is formed by a bitwise or of the constants +LUA_MASKCALL, +LUA_MASKRET, +LUA_MASKLINE, +and LUA_MASKCOUNT. +The count argument is only meaningful when the mask +includes LUA_MASKCOUNT. +For each event, the hook is called as explained below: + +

    + +
  • The call hook: is called when the interpreter calls a function. +The hook is called just after Lua enters the new function, +before the function gets its arguments. +
    • + +
  • The return hook: is called when the interpreter returns from a function. +The hook is called just before Lua leaves the function. +There is no standard way to access the values +to be returned by the function. +
    • + +
  • The line hook: is called when the interpreter is about to +start the execution of a new line of code, +or when it jumps back in the code (even to the same line). +(This event only happens while Lua is executing a Lua function.) +
    • + +
  • The count hook: is called after the interpreter executes every +count instructions. +(This event only happens while Lua is executing a Lua function.) +
    • + +
+ +

+A hook is disabled by setting mask to zero. + + + + + +

lua_setlocal

+[-(0|1), +0, –] +

const char *lua_setlocal (lua_State *L, lua_Debug *ar, int n);
+ +

+Sets the value of a local variable of a given activation record. +Parameters ar and n are as in lua_getlocal +(see lua_getlocal). +lua_setlocal assigns the value at the top of the stack +to the variable and returns its name. +It also pops the value from the stack. + + +

+Returns NULL (and pops nothing) +when the index is greater than +the number of active local variables. + + + + + +

lua_setupvalue

+[-(0|1), +0, –] +

const char *lua_setupvalue (lua_State *L, int funcindex, int n);
+ +

+Sets the value of a closure's upvalue. +It assigns the value at the top of the stack +to the upvalue and returns its name. +It also pops the value from the stack. +Parameters funcindex and n are as in the lua_getupvalue +(see lua_getupvalue). + + +

+Returns NULL (and pops nothing) +when the index is greater than the number of upvalues. + + + + + +

lua_upvalueid

+[-0, +0, –] +

void *lua_upvalueid (lua_State *L, int funcindex, int n);
+ +

+Returns an unique identifier for the upvalue numbered n +from the closure at index funcindex. +Parameters funcindex and n are as in the lua_getupvalue +(see lua_getupvalue) +(but n cannot be greater than the number of upvalues). + + +

+These unique identifiers allow a program to check whether different +closures share upvalues. +Lua closures that share an upvalue +(that is, that access a same external local variable) +will return identical ids for those upvalue indices. + + + + + +

lua_upvaluejoin

+[-0, +0, –] +

void lua_upvaluejoin (lua_State *L, int funcindex1, int n1,
+                                    int funcindex2, int n2);
+ +

+Make the n1-th upvalue of the Lua closure at index funcindex1 +refer to the n2-th upvalue of the Lua closure at index funcindex2. + + + + + + + +

5 – The Auxiliary Library

+ +

+ +The auxiliary library provides several convenient functions +to interface C with Lua. +While the basic API provides the primitive functions for all +interactions between C and Lua, +the auxiliary library provides higher-level functions for some +common tasks. + + +

+All functions and types from the auxiliary library +are defined in header file lauxlib.h and +have a prefix luaL_. + + +

+All functions in the auxiliary library are built on +top of the basic API, +and so they provide nothing that cannot be done with that API. +Nevertheless, the use of the auxiliary library ensures +more consistency to your code. + + +

+Several functions in the auxiliary library use internally some +extra stack slots. +When a function in the auxiliary library uses less than five slots, +it does not check the stack size; +it simply assumes that there are enough slots. + + +

+Several functions in the auxiliary library are used to +check C function arguments. +Because the error message is formatted for arguments +(e.g., "bad argument #1"), +you should not use these functions for other stack values. + + +

+Functions called luaL_check* +always throw an error if the check is not satisfied. + + + +

5.1 – Functions and Types

+ +

+Here we list all functions and types from the auxiliary library +in alphabetical order. + + + +

luaL_addchar

+[-?, +?, e] +

void luaL_addchar (luaL_Buffer *B, char c);
+ +

+Adds the byte c to the buffer B +(see luaL_Buffer). + + + + + +

luaL_addlstring

+[-?, +?, e] +

void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l);
+ +

+Adds the string pointed to by s with length l to +the buffer B +(see luaL_Buffer). +The string can contain embedded zeros. + + + + + +

luaL_addsize

+[-?, +?, e] +

void luaL_addsize (luaL_Buffer *B, size_t n);
+ +

+Adds to the buffer B (see luaL_Buffer) +a string of length n previously copied to the +buffer area (see luaL_prepbuffer). + + + + + +

luaL_addstring

+[-?, +?, e] +

void luaL_addstring (luaL_Buffer *B, const char *s);
+ +

+Adds the zero-terminated string pointed to by s +to the buffer B +(see luaL_Buffer). +The string cannot contain embedded zeros. + + + + + +

luaL_addvalue

+[-1, +?, e] +

void luaL_addvalue (luaL_Buffer *B);
+ +

+Adds the value at the top of the stack +to the buffer B +(see luaL_Buffer). +Pops the value. + + +

+This is the only function on string buffers that can (and must) +be called with an extra element on the stack, +which is the value to be added to the buffer. + + + + + +

luaL_argcheck

+[-0, +0, v] +

void luaL_argcheck (lua_State *L,
+                    int cond,
+                    int arg,
+                    const char *extramsg);
+ +

+Checks whether cond is true. +If not, raises an error with a standard message. + + + + + +

luaL_argerror

+[-0, +0, v] +

int luaL_argerror (lua_State *L, int arg, const char *extramsg);
+ +

+Raises an error with a standard message +that includes extramsg as a comment. + + +

+This function never returns, +but it is an idiom to use it in C functions +as return luaL_argerror(args). + + + + + +

luaL_Buffer

+
typedef struct luaL_Buffer luaL_Buffer;
+ +

+Type for a string buffer. + + +

+A string buffer allows C code to build Lua strings piecemeal. +Its pattern of use is as follows: + +

    + +
  • First declare a variable b of type luaL_Buffer.
    • + +
  • Then initialize it with a call luaL_buffinit(L, &b).
    • + +
  • +Then add string pieces to the buffer calling any of +the luaL_add* functions. +
    • + +
  • +Finish by calling luaL_pushresult(&b). +This call leaves the final string on the top of the stack. +
    • + +
+ +

+If you know beforehand the total size of the resulting string, +you can use the buffer like this: + +

    + +
  • First declare a variable b of type luaL_Buffer.
    • + +
  • Then initialize it and preallocate a space of +size sz with a call luaL_buffinitsize(L, &b, sz).
    • + +
  • Then copy the string into that space.
    • + +
  • +Finish by calling luaL_pushresultsize(&b, sz), +where sz is the total size of the resulting string +copied into that space. +
    • + +
+ +

+During its normal operation, +a string buffer uses a variable number of stack slots. +So, while using a buffer, you cannot assume that you know where +the top of the stack is. +You can use the stack between successive calls to buffer operations +as long as that use is balanced; +that is, +when you call a buffer operation, +the stack is at the same level +it was immediately after the previous buffer operation. +(The only exception to this rule is luaL_addvalue.) +After calling luaL_pushresult the stack is back to its +level when the buffer was initialized, +plus the final string on its top. + + + + + +

luaL_buffinit

+[-0, +0, –] +

void luaL_buffinit (lua_State *L, luaL_Buffer *B);
+ +

+Initializes a buffer B. +This function does not allocate any space; +the buffer must be declared as a variable +(see luaL_Buffer). + + + + + +

luaL_buffinitsize

+[-?, +?, e] +

char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz);
+ +

+Equivalent to the sequence +luaL_buffinit, luaL_prepbuffsize. + + + + + +

luaL_callmeta

+[-0, +(0|1), e] +

int luaL_callmeta (lua_State *L, int obj, const char *e);
+ +

+Calls a metamethod. + + +

+If the object at index obj has a metatable and this +metatable has a field e, +this function calls this field passing the object as its only argument. +In this case this function returns true and pushes onto the +stack the value returned by the call. +If there is no metatable or no metamethod, +this function returns false (without pushing any value on the stack). + + + + + +

luaL_checkany

+[-0, +0, v] +

void luaL_checkany (lua_State *L, int arg);
+ +

+Checks whether the function has an argument +of any type (including nil) at position arg. + + + + + +

luaL_checkint

+[-0, +0, v] +

int luaL_checkint (lua_State *L, int arg);
+ +

+Checks whether the function argument arg is a number +and returns this number cast to an int. + + + + + +

luaL_checkinteger

+[-0, +0, v] +

lua_Integer luaL_checkinteger (lua_State *L, int arg);
+ +

+Checks whether the function argument arg is a number +and returns this number cast to a lua_Integer. + + + + + +

luaL_checklong

+[-0, +0, v] +

long luaL_checklong (lua_State *L, int arg);
+ +

+Checks whether the function argument arg is a number +and returns this number cast to a long. + + + + + +

luaL_checklstring

+[-0, +0, v] +

const char *luaL_checklstring (lua_State *L, int arg, size_t *l);
+ +

+Checks whether the function argument arg is a string +and returns this string; +if l is not NULL fills *l +with the string's length. + + +

+This function uses lua_tolstring to get its result, +so all conversions and caveats of that function apply here. + + + + + +

luaL_checknumber

+[-0, +0, v] +

lua_Number luaL_checknumber (lua_State *L, int arg);
+ +

+Checks whether the function argument arg is a number +and returns this number. + + + + + +

luaL_checkoption

+[-0, +0, v] +

int luaL_checkoption (lua_State *L,
+                      int arg,
+                      const char *def,
+                      const char *const lst[]);
+ +

+Checks whether the function argument arg is a string and +searches for this string in the array lst +(which must be NULL-terminated). +Returns the index in the array where the string was found. +Raises an error if the argument is not a string or +if the string cannot be found. + + +

+If def is not NULL, +the function uses def as a default value when +there is no argument arg or when this argument is nil. + + +

+This is a useful function for mapping strings to C enums. +(The usual convention in Lua libraries is +to use strings instead of numbers to select options.) + + + + + +

luaL_checkstack

+[-0, +0, v] +

void luaL_checkstack (lua_State *L, int sz, const char *msg);
+ +

+Grows the stack size to top + sz elements, +raising an error if the stack cannot grow to that size. +msg is an additional text to go into the error message +(or NULL for no additional text). + + + + + +

luaL_checkstring

+[-0, +0, v] +

const char *luaL_checkstring (lua_State *L, int arg);
+ +

+Checks whether the function argument arg is a string +and returns this string. + + +

+This function uses lua_tolstring to get its result, +so all conversions and caveats of that function apply here. + + + + + +

luaL_checktype

+[-0, +0, v] +

void luaL_checktype (lua_State *L, int arg, int t);
+ +

+Checks whether the function argument arg has type t. +See lua_type for the encoding of types for t. + + + + + +

luaL_checkudata

+[-0, +0, v] +

void *luaL_checkudata (lua_State *L, int arg, const char *tname);
+ +

+Checks whether the function argument arg is a userdata +of the type tname (see luaL_newmetatable) and +returns the userdata address (see lua_touserdata). + + + + + +

luaL_checkunsigned

+[-0, +0, v] +

lua_Unsigned luaL_checkunsigned (lua_State *L, int arg);
+ +

+Checks whether the function argument arg is a number +and returns this number cast to a lua_Unsigned. + + + + + +

luaL_checkversion

+[-0, +0, –] +

void luaL_checkversion (lua_State *L);
+ +

+Checks whether the core running the call, +the core that created the Lua state, +and the code making the call are all using the same version of Lua. +Also checks whether the core running the call +and the core that created the Lua state +are using the same address space. + + + + + +

luaL_dofile

+[-0, +?, e] +

int luaL_dofile (lua_State *L, const char *filename);
+ +

+Loads and runs the given file. +It is defined as the following macro: + +

+     (luaL_loadfile(L, filename) || lua_pcall(L, 0, LUA_MULTRET, 0))
+

+It returns false if there are no errors +or true in case of errors. + + + + + +

luaL_dostring

+[-0, +?, –] +

int luaL_dostring (lua_State *L, const char *str);
+ +

+Loads and runs the given string. +It is defined as the following macro: + +

+     (luaL_loadstring(L, str) || lua_pcall(L, 0, LUA_MULTRET, 0))
+

+It returns false if there are no errors +or true in case of errors. + + + + + +

luaL_error

+[-0, +0, v] +

int luaL_error (lua_State *L, const char *fmt, ...);
+ +

+Raises an error. +The error message format is given by fmt +plus any extra arguments, +following the same rules of lua_pushfstring. +It also adds at the beginning of the message the file name and +the line number where the error occurred, +if this information is available. + + +

+This function never returns, +but it is an idiom to use it in C functions +as return luaL_error(args). + + + + + +

luaL_execresult

+[-0, +3, e] +

int luaL_execresult (lua_State *L, int stat);
+ +

+This function produces the return values for +process-related functions in the standard library +(os.execute and io.close). + + + + + +

luaL_fileresult

+[-0, +(1|3), e] +

int luaL_fileresult (lua_State *L, int stat, const char *fname);
+ +

+This function produces the return values for +file-related functions in the standard library +(io.open, os.rename, file:seek, etc.). + + + + + +

luaL_getmetafield

+[-0, +(0|1), e] +

int luaL_getmetafield (lua_State *L, int obj, const char *e);
+ +

+Pushes onto the stack the field e from the metatable +of the object at index obj. +If the object does not have a metatable, +or if the metatable does not have this field, +returns false and pushes nothing. + + + + + +

luaL_getmetatable

+[-0, +1, –] +

void luaL_getmetatable (lua_State *L, const char *tname);
+ +

+Pushes onto the stack the metatable associated with name tname +in the registry (see luaL_newmetatable). + + + + + +

luaL_getsubtable

+[-0, +1, e] +

int luaL_getsubtable (lua_State *L, int idx, const char *fname);
+ +

+Ensures that the value t[fname], +where t is the value at index idx, +is a table, +and pushes that table onto the stack. +Returns true if it finds a previous table there +and false if it creates a new table. + + + + + +

luaL_gsub

+[-0, +1, e] +

const char *luaL_gsub (lua_State *L,
+                       const char *s,
+                       const char *p,
+                       const char *r);
+ +

+Creates a copy of string s by replacing +any occurrence of the string p +with the string r. +Pushes the resulting string on the stack and returns it. + + + + + +

luaL_len

+[-0, +0, e] +

int luaL_len (lua_State *L, int index);
+ +

+Returns the "length" of the value at the given index +as a number; +it is equivalent to the '#' operator in Lua (see §3.4.6). +Raises an error if the result of the operation is not a number. +(This case only can happen through metamethods.) + + + + + +

luaL_loadbuffer

+[-0, +1, –] +

int luaL_loadbuffer (lua_State *L,
+                     const char *buff,
+                     size_t sz,
+                     const char *name);
+ +

+Equivalent to luaL_loadbufferx with mode equal to NULL. + + + + + +

luaL_loadbufferx

+[-0, +1, –] +

int luaL_loadbufferx (lua_State *L,
+                      const char *buff,
+                      size_t sz,
+                      const char *name,
+                      const char *mode);
+ +

+Loads a buffer as a Lua chunk. +This function uses lua_load to load the chunk in the +buffer pointed to by buff with size sz. + + +

+This function returns the same results as lua_load. +name is the chunk name, +used for debug information and error messages. +The string mode works as in function lua_load. + + + + + +

luaL_loadfile

+[-0, +1, e] +

int luaL_loadfile (lua_State *L, const char *filename);
+ +

+Equivalent to luaL_loadfilex with mode equal to NULL. + + + + + +

luaL_loadfilex

+[-0, +1, e] +

int luaL_loadfilex (lua_State *L, const char *filename,
+                                            const char *mode);
+ +

+Loads a file as a Lua chunk. +This function uses lua_load to load the chunk in the file +named filename. +If filename is NULL, +then it loads from the standard input. +The first line in the file is ignored if it starts with a #. + + +

+The string mode works as in function lua_load. + + +

+This function returns the same results as lua_load, +but it has an extra error code LUA_ERRFILE +if it cannot open/read the file or the file has a wrong mode. + + +

+As lua_load, this function only loads the chunk; +it does not run it. + + + + + +

luaL_loadstring

+[-0, +1, –] +

int luaL_loadstring (lua_State *L, const char *s);
+ +

+Loads a string as a Lua chunk. +This function uses lua_load to load the chunk in +the zero-terminated string s. + + +

+This function returns the same results as lua_load. + + +

+Also as lua_load, this function only loads the chunk; +it does not run it. + + + + + +

luaL_newlib

+[-0, +1, e] +

void luaL_newlib (lua_State *L, const luaL_Reg *l);
+ +

+Creates a new table and registers there +the functions in list l. +It is implemented as the following macro: + +

+     (luaL_newlibtable(L,l), luaL_setfuncs(L,l,0))
+
+ + + + +

luaL_newlibtable

+[-0, +1, e] +

void luaL_newlibtable (lua_State *L, const luaL_Reg l[]);
+ +

+Creates a new table with a size optimized +to store all entries in the array l +(but does not actually store them). +It is intended to be used in conjunction with luaL_setfuncs +(see luaL_newlib). + + +

+It is implemented as a macro. +The array l must be the actual array, +not a pointer to it. + + + + + +

luaL_newmetatable

+[-0, +1, e] +

int luaL_newmetatable (lua_State *L, const char *tname);
+ +

+If the registry already has the key tname, +returns 0. +Otherwise, +creates a new table to be used as a metatable for userdata, +adds it to the registry with key tname, +and returns 1. + + +

+In both cases pushes onto the stack the final value associated +with tname in the registry. + + + + + +

luaL_newstate

+[-0, +0, –] +

lua_State *luaL_newstate (void);
+ +

+Creates a new Lua state. +It calls lua_newstate with an +allocator based on the standard C realloc function +and then sets a panic function (see §4.6) that prints +an error message to the standard error output in case of fatal +errors. + + +

+Returns the new state, +or NULL if there is a memory allocation error. + + + + + +

luaL_openlibs

+[-0, +0, e] +

void luaL_openlibs (lua_State *L);
+ +

+Opens all standard Lua libraries into the given state. + + + + + +

luaL_optint

+[-0, +0, v] +

int luaL_optint (lua_State *L, int arg, int d);
+ +

+If the function argument arg is a number, +returns this number cast to an int. +If this argument is absent or is nil, +returns d. +Otherwise, raises an error. + + + + + +

luaL_optinteger

+[-0, +0, v] +

lua_Integer luaL_optinteger (lua_State *L,
+                             int arg,
+                             lua_Integer d);
+ +

+If the function argument arg is a number, +returns this number cast to a lua_Integer. +If this argument is absent or is nil, +returns d. +Otherwise, raises an error. + + + + + +

luaL_optlong

+[-0, +0, v] +

long luaL_optlong (lua_State *L, int arg, long d);
+ +

+If the function argument arg is a number, +returns this number cast to a long. +If this argument is absent or is nil, +returns d. +Otherwise, raises an error. + + + + + +

luaL_optlstring

+[-0, +0, v] +

const char *luaL_optlstring (lua_State *L,
+                             int arg,
+                             const char *d,
+                             size_t *l);
+ +

+If the function argument arg is a string, +returns this string. +If this argument is absent or is nil, +returns d. +Otherwise, raises an error. + + +

+If l is not NULL, +fills the position *l with the result's length. + + + + + +

luaL_optnumber

+[-0, +0, v] +

lua_Number luaL_optnumber (lua_State *L, int arg, lua_Number d);
+ +

+If the function argument arg is a number, +returns this number. +If this argument is absent or is nil, +returns d. +Otherwise, raises an error. + + + + + +

luaL_optstring

+[-0, +0, v] +

const char *luaL_optstring (lua_State *L,
+                            int arg,
+                            const char *d);
+ +

+If the function argument arg is a string, +returns this string. +If this argument is absent or is nil, +returns d. +Otherwise, raises an error. + + + + + +

luaL_optunsigned

+[-0, +0, v] +

lua_Unsigned luaL_optunsigned (lua_State *L,
+                               int arg,
+                               lua_Unsigned u);
+ +

+If the function argument arg is a number, +returns this number cast to a lua_Unsigned. +If this argument is absent or is nil, +returns u. +Otherwise, raises an error. + + + + + +

luaL_prepbuffer

+[-?, +?, e] +

char *luaL_prepbuffer (luaL_Buffer *B);
+ +

+Equivalent to luaL_prepbuffsize +with the predefined size LUAL_BUFFERSIZE. + + + + + +

luaL_prepbuffsize

+[-?, +?, e] +

char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz);
+ +

+Returns an address to a space of size sz +where you can copy a string to be added to buffer B +(see luaL_Buffer). +After copying the string into this space you must call +luaL_addsize with the size of the string to actually add +it to the buffer. + + + + + +

luaL_pushresult

+[-?, +1, e] +

void luaL_pushresult (luaL_Buffer *B);
+ +

+Finishes the use of buffer B leaving the final string on +the top of the stack. + + + + + +

luaL_pushresultsize

+[-?, +1, e] +

void luaL_pushresultsize (luaL_Buffer *B, size_t sz);
+ +

+Equivalent to the sequence luaL_addsize, luaL_pushresult. + + + + + +

luaL_ref

+[-1, +0, e] +

int luaL_ref (lua_State *L, int t);
+ +

+Creates and returns a reference, +in the table at index t, +for the object at the top of the stack (and pops the object). + + +

+A reference is a unique integer key. +As long as you do not manually add integer keys into table t, +luaL_ref ensures the uniqueness of the key it returns. +You can retrieve an object referred by reference r +by calling lua_rawgeti(L, t, r). +Function luaL_unref frees a reference and its associated object. + + +

+If the object at the top of the stack is nil, +luaL_ref returns the constant LUA_REFNIL. +The constant LUA_NOREF is guaranteed to be different +from any reference returned by luaL_ref. + + + + + +

luaL_Reg

+
typedef struct luaL_Reg {
+  const char *name;
+  lua_CFunction func;
+} luaL_Reg;
+ +

+Type for arrays of functions to be registered by +luaL_setfuncs. +name is the function name and func is a pointer to +the function. +Any array of luaL_Reg must end with an sentinel entry +in which both name and func are NULL. + + + + + +

luaL_requiref

+[-0, +1, e] +

void luaL_requiref (lua_State *L, const char *modname,
+                    lua_CFunction openf, int glb);
+ +

+Calls function openf with string modname as an argument +and sets the call result in package.loaded[modname], +as if that function has been called through require. + + +

+If glb is true, +also stores the result into global modname. + + +

+Leaves a copy of that result on the stack. + + + + + +

luaL_setfuncs

+[-nup, +0, e] +

void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup);
+ +

+Registers all functions in the array l +(see luaL_Reg) into the table on the top of the stack +(below optional upvalues, see next). + + +

+When nup is not zero, +all functions are created sharing nup upvalues, +which must be previously pushed on the stack +on top of the library table. +These values are popped from the stack after the registration. + + + + + +

luaL_setmetatable

+[-0, +0, –] +

void luaL_setmetatable (lua_State *L, const char *tname);
+ +

+Sets the metatable of the object at the top of the stack +as the metatable associated with name tname +in the registry (see luaL_newmetatable). + + + + + +

luaL_testudata

+[-0, +0, e] +

void *luaL_testudata (lua_State *L, int arg, const char *tname);
+ +

+This function works like luaL_checkudata, +except that, when the test fails, +it returns NULL instead of throwing an error. + + + + + +

luaL_tolstring

+[-0, +1, e] +

const char *luaL_tolstring (lua_State *L, int idx, size_t *len);
+ +

+Converts any Lua value at the given index to a C string +in a reasonable format. +The resulting string is pushed onto the stack and also +returned by the function. +If len is not NULL, +the function also sets *len with the string length. + + +

+If the value has a metatable with a "__tostring" field, +then luaL_tolstring calls the corresponding metamethod +with the value as argument, +and uses the result of the call as its result. + + + + + +

luaL_traceback

+[-0, +1, e] +

void luaL_traceback (lua_State *L, lua_State *L1, const char *msg,
+                     int level);
+ +

+Creates and pushes a traceback of the stack L1. +If msg is not NULL it is appended +at the beginning of the traceback. +The level parameter tells at which level +to start the traceback. + + + + + +

luaL_typename

+[-0, +0, –] +

const char *luaL_typename (lua_State *L, int index);
+ +

+Returns the name of the type of the value at the given index. + + + + + +

luaL_unref

+[-0, +0, –] +

void luaL_unref (lua_State *L, int t, int ref);
+ +

+Releases reference ref from the table at index t +(see luaL_ref). +The entry is removed from the table, +so that the referred object can be collected. +The reference ref is also freed to be used again. + + +

+If ref is LUA_NOREF or LUA_REFNIL, +luaL_unref does nothing. + + + + + +

luaL_where

+[-0, +1, e] +

void luaL_where (lua_State *L, int lvl);
+ +

+Pushes onto the stack a string identifying the current position +of the control at level lvl in the call stack. +Typically this string has the following format: + +

+     chunkname:currentline:
+

+Level 0 is the running function, +level 1 is the function that called the running function, +etc. + + +

+This function is used to build a prefix for error messages. + + + + + + + +

6 – Standard Libraries

+ +

+The standard Lua libraries provide useful functions +that are implemented directly through the C API. +Some of these functions provide essential services to the language +(e.g., type and getmetatable); +others provide access to "outside" services (e.g., I/O); +and others could be implemented in Lua itself, +but are quite useful or have critical performance requirements that +deserve an implementation in C (e.g., table.sort). + + +

+All libraries are implemented through the official C API +and are provided as separate C modules. +Currently, Lua has the following standard libraries: + +

    + +
  • basic library (§6.1);
    • + +
  • coroutine library (§6.2);
    • + +
  • package library (§6.3);
    • + +
  • string manipulation (§6.4);
    • + +
  • table manipulation (§6.5);
    • + +
  • mathematical functions (§6.6) (sin, log, etc.);
    • + +
  • bitwise operations (§6.7);
    • + +
  • input and output (§6.8);
    • + +
  • operating system facilities (§6.9);
    • + +
  • debug facilities (§6.10).
    • + +

+Except for the basic and the package libraries, +each library provides all its functions as fields of a global table +or as methods of its objects. + + +

+To have access to these libraries, +the C host program should call the luaL_openlibs function, +which opens all standard libraries. +Alternatively, +the host program can open them individually by using +luaL_requiref to call +luaopen_base (for the basic library), +luaopen_package (for the package library), +luaopen_coroutine (for the coroutine library), +luaopen_string (for the string library), +luaopen_table (for the table library), +luaopen_math (for the mathematical library), +luaopen_bit32 (for the bit library), +luaopen_io (for the I/O library), +luaopen_os (for the Operating System library), +and luaopen_debug (for the debug library). +These functions are declared in lualib.h. + + + +

6.1 – Basic Functions

+ +

+The basic library provides core functions to Lua. +If you do not include this library in your application, +you should check carefully whether you need to provide +implementations for some of its facilities. + + +

+

assert (v [, message])

+Issues an error when +the value of its argument v is false (i.e., nil or false); +otherwise, returns all its arguments. +message is an error message; +when absent, it defaults to "assertion failed!" + + + + +

+

collectgarbage ([opt [, arg]])

+ + +

+This function is a generic interface to the garbage collector. +It performs different functions according to its first argument, opt: + +

    + +
  • "collect": +performs a full garbage-collection cycle. +This is the default option. +
    • + +
  • "stop": +stops automatic execution of the garbage collector. +The collector will run only when explicitly invoked, +until a call to restart it. +
    • + +
  • "restart": +restarts automatic execution of the garbage collector. +
    • + +
  • "count": +returns the total memory in use by Lua (in Kbytes) and +a second value with the total memory in bytes modulo 1024. +The first value has a fractional part, +so the following equality is always true: + +
    +     k, b = collectgarbage("count")
+     assert(k*1024 == math.floor(k)*1024 + b)
+

    +(The second result is useful when Lua is compiled +with a non floating-point type for numbers.) +

    • + +
  • "step": +performs a garbage-collection step. +The step "size" is controlled by arg +(larger values mean more steps) in a non-specified way. +If you want to control the step size +you must experimentally tune the value of arg. +Returns true if the step finished a collection cycle. +
    • + +
  • "setpause": +sets arg as the new value for the pause of +the collector (see §2.5). +Returns the previous value for pause. +
    • + +
  • "setstepmul": +sets arg as the new value for the step multiplier of +the collector (see §2.5). +Returns the previous value for step. +
    • + +
  • "isrunning": +returns a boolean that tells whether the collector is running +(i.e., not stopped). +
    • + +
  • "generational": +changes the collector to generational mode. +This is an experimental feature (see §2.5). +
    • + +
  • "incremental": +changes the collector to incremental mode. +This is the default mode. +
    • + +
+ + + +

+

dofile ([filename])

+Opens the named file and executes its contents as a Lua chunk. +When called without arguments, +dofile executes the contents of the standard input (stdin). +Returns all values returned by the chunk. +In case of errors, dofile propagates the error +to its caller (that is, dofile does not run in protected mode). + + + + +

+

error (message [, level])

+Terminates the last protected function called +and returns message as the error message. +Function error never returns. + + +

+Usually, error adds some information about the error position +at the beginning of the message, if the message is a string. +The level argument specifies how to get the error position. +With level 1 (the default), the error position is where the +error function was called. +Level 2 points the error to where the function +that called error was called; and so on. +Passing a level 0 avoids the addition of error position information +to the message. + + + + +

+

_G

+A global variable (not a function) that +holds the global environment (see §2.2). +Lua itself does not use this variable; +changing its value does not affect any environment, +nor vice-versa. + + + + +

+

getmetatable (object)

+ + +

+If object does not have a metatable, returns nil. +Otherwise, +if the object's metatable has a "__metatable" field, +returns the associated value. +Otherwise, returns the metatable of the given object. + + + + +

+

ipairs (t)

+ + +

+If t has a metamethod __ipairs, +calls it with t as argument and returns the first three +results from the call. + + +

+Otherwise, +returns three values: an iterator function, the table t, and 0, +so that the construction + +

+     for i,v in ipairs(t) do body end
+

+will iterate over the pairs (1,t[1]), (2,t[2]), ..., +up to the first integer key absent from the table. + + + + +

+

load (ld [, source [, mode [, env]]])

+ + +

+Loads a chunk. + + +

+If ld is a string, the chunk is this string. +If ld is a function, +load calls it repeatedly to get the chunk pieces. +Each call to ld must return a string that concatenates +with previous results. +A return of an empty string, nil, or no value signals the end of the chunk. + + +

+If there are no syntactic errors, +returns the compiled chunk as a function; +otherwise, returns nil plus the error message. + + +

+If the resulting function has upvalues, +the first upvalue is set to the value of env, +if that parameter is given, +or to the value of the global environment. +(When you load a main chunk, +the resulting function will always have exactly one upvalue, +the _ENV variable (see §2.2). +When you load a binary chunk created from a function (see string.dump), +the resulting function can have arbitrary upvalues.) + + +

+source is used as the source of the chunk for error messages +and debug information (see §4.9). +When absent, +it defaults to ld, if ld is a string, +or to "=(load)" otherwise. + + +

+The string mode controls whether the chunk can be text or binary +(that is, a precompiled chunk). +It may be the string "b" (only binary chunks), +"t" (only text chunks), +or "bt" (both binary and text). +The default is "bt". + + + + +

+

loadfile ([filename [, mode [, env]]])

+ + +

+Similar to load, +but gets the chunk from file filename +or from the standard input, +if no file name is given. + + + + +

+

next (table [, index])

+ + +

+Allows a program to traverse all fields of a table. +Its first argument is a table and its second argument +is an index in this table. +next returns the next index of the table +and its associated value. +When called with nil as its second argument, +next returns an initial index +and its associated value. +When called with the last index, +or with nil in an empty table, +next returns nil. +If the second argument is absent, then it is interpreted as nil. +In particular, +you can use next(t) to check whether a table is empty. + + +

+The order in which the indices are enumerated is not specified, +even for numeric indices. +(To traverse a table in numeric order, +use a numerical for.) + + +

+The behavior of next is undefined if, +during the traversal, +you assign any value to a non-existent field in the table. +You may however modify existing fields. +In particular, you may clear existing fields. + + + + +

+

pairs (t)

+ + +

+If t has a metamethod __pairs, +calls it with t as argument and returns the first three +results from the call. + + +

+Otherwise, +returns three values: the next function, the table t, and nil, +so that the construction + +

+     for k,v in pairs(t) do body end
+

+will iterate over all key–value pairs of table t. + + +

+See function next for the caveats of modifying +the table during its traversal. + + + + +

+

pcall (f [, arg1, ···])

+ + +

+Calls function f with +the given arguments in protected mode. +This means that any error inside f is not propagated; +instead, pcall catches the error +and returns a status code. +Its first result is the status code (a boolean), +which is true if the call succeeds without errors. +In such case, pcall also returns all results from the call, +after this first result. +In case of any error, pcall returns false plus the error message. + + + + +

+

print (···)

+Receives any number of arguments +and prints their values to stdout, +using the tostring function to convert each argument to a string. +print is not intended for formatted output, +but only as a quick way to show a value, +for instance for debugging. +For complete control over the output, +use string.format and io.write. + + + + +

+

rawequal (v1, v2)

+Checks whether v1 is equal to v2, +without invoking any metamethod. +Returns a boolean. + + + + +

+

rawget (table, index)

+Gets the real value of table[index], +without invoking any metamethod. +table must be a table; +index may be any value. + + + + +

+

rawlen (v)

+Returns the length of the object v, +which must be a table or a string, +without invoking any metamethod. +Returns an integer number. + + + + +

+

rawset (table, index, value)

+Sets the real value of table[index] to value, +without invoking any metamethod. +table must be a table, +index any value different from nil and NaN, +and value any Lua value. + + +

+This function returns table. + + + + +

+

select (index, ···)

+ + +

+If index is a number, +returns all arguments after argument number index; +a negative number indexes from the end (-1 is the last argument). +Otherwise, index must be the string "#", +and select returns the total number of extra arguments it received. + + + + +

+

setmetatable (table, metatable)

+ + +

+Sets the metatable for the given table. +(You cannot change the metatable of other types from Lua, only from C.) +If metatable is nil, +removes the metatable of the given table. +If the original metatable has a "__metatable" field, +raises an error. + + +

+This function returns table. + + + + +

+

tonumber (e [, base])

+ + +

+When called with no base, +tonumber tries to convert its argument to a number. +If the argument is already a number or +a string convertible to a number (see §3.4.2), +then tonumber returns this number; +otherwise, it returns nil. + + +

+When called with base, +then e should be a string to be interpreted as +an integer numeral in that base. +The base may be any integer between 2 and 36, inclusive. +In bases above 10, the letter 'A' (in either upper or lower case) +represents 10, 'B' represents 11, and so forth, +with 'Z' representing 35. +If the string e is not a valid numeral in the given base, +the function returns nil. + + + + +

+

tostring (v)

+Receives a value of any type and +converts it to a string in a reasonable format. +(For complete control of how numbers are converted, +use string.format.) + + +

+If the metatable of v has a "__tostring" field, +then tostring calls the corresponding value +with v as argument, +and uses the result of the call as its result. + + + + +

+

type (v)

+Returns the type of its only argument, coded as a string. +The possible results of this function are +"nil" (a string, not the value nil), +"number", +"string", +"boolean", +"table", +"function", +"thread", +and "userdata". + + + + +

+

_VERSION

+A global variable (not a function) that +holds a string containing the current interpreter version. +The current contents of this variable is "Lua 5.2". + + + + +

+

xpcall (f, msgh [, arg1, ···])

+ + +

+This function is similar to pcall, +except that it sets a new message handler msgh. + + + + + + + +

6.2 – Coroutine Manipulation

+ +

+The operations related to coroutines comprise a sub-library of +the basic library and come inside the table coroutine. +See §2.6 for a general description of coroutines. + + +

+

coroutine.create (f)

+ + +

+Creates a new coroutine, with body f. +f must be a Lua function. +Returns this new coroutine, +an object with type "thread". + + + + +

+

coroutine.resume (co [, val1, ···])

+ + +

+Starts or continues the execution of coroutine co. +The first time you resume a coroutine, +it starts running its body. +The values val1, ... are passed +as the arguments to the body function. +If the coroutine has yielded, +resume restarts it; +the values val1, ... are passed +as the results from the yield. + + +

+If the coroutine runs without any errors, +resume returns true plus any values passed to yield +(if the coroutine yields) or any values returned by the body function +(if the coroutine terminates). +If there is any error, +resume returns false plus the error message. + + + + +

+

coroutine.running ()

+ + +

+Returns the running coroutine plus a boolean, +true when the running coroutine is the main one. + + + + +

+

coroutine.status (co)

+ + +

+Returns the status of coroutine co, as a string: +"running", +if the coroutine is running (that is, it called status); +"suspended", if the coroutine is suspended in a call to yield, +or if it has not started running yet; +"normal" if the coroutine is active but not running +(that is, it has resumed another coroutine); +and "dead" if the coroutine has finished its body function, +or if it has stopped with an error. + + + + +

+

coroutine.wrap (f)

+ + +

+Creates a new coroutine, with body f. +f must be a Lua function. +Returns a function that resumes the coroutine each time it is called. +Any arguments passed to the function behave as the +extra arguments to resume. +Returns the same values returned by resume, +except the first boolean. +In case of error, propagates the error. + + + + +

+

coroutine.yield (···)

+ + +

+Suspends the execution of the calling coroutine. +Any arguments to yield are passed as extra results to resume. + + + + + + + +

6.3 – Modules

+ +

+The package library provides basic +facilities for loading modules in Lua. +It exports one function directly in the global environment: +require. +Everything else is exported in a table package. + + +

+

require (modname)

+ + +

+Loads the given module. +The function starts by looking into the package.loaded table +to determine whether modname is already loaded. +If it is, then require returns the value stored +at package.loaded[modname]. +Otherwise, it tries to find a loader for the module. + + +

+To find a loader, +require is guided by the package.searchers sequence. +By changing this sequence, +we can change how require looks for a module. +The following explanation is based on the default configuration +for package.searchers. + + +

+First require queries package.preload[modname]. +If it has a value, +this value (which should be a function) is the loader. +Otherwise require searches for a Lua loader using the +path stored in package.path. +If that also fails, it searches for a C loader using the +path stored in package.cpath. +If that also fails, +it tries an all-in-one loader (see package.searchers). + + +

+Once a loader is found, +require calls the loader with two arguments: +modname and an extra value dependent on how it got the loader. +(If the loader came from a file, +this extra value is the file name.) +If the loader returns any non-nil value, +require assigns the returned value to package.loaded[modname]. +If the loader does not return a non-nil value and +has not assigned any value to package.loaded[modname], +then require assigns true to this entry. +In any case, require returns the +final value of package.loaded[modname]. + + +

+If there is any error loading or running the module, +or if it cannot find any loader for the module, +then require raises an error. + + + + +

+

package.config

+ + +

+A string describing some compile-time configurations for packages. +This string is a sequence of lines: + +

    + +
  • The first line is the directory separator string. +Default is '\' for Windows and '/' for all other systems.
    • + +
  • The second line is the character that separates templates in a path. +Default is ';'.
    • + +
  • The third line is the string that marks the +substitution points in a template. +Default is '?'.
    • + +
  • The fourth line is a string that, in a path in Windows, +is replaced by the executable's directory. +Default is '!'.
    • + +
  • The fifth line is a mark to ignore all text before it +when building the luaopen_ function name. +Default is '-'.
    • + +
+ + + +

+

package.cpath

+ + +

+The path used by require to search for a C loader. + + +

+Lua initializes the C path package.cpath in the same way +it initializes the Lua path package.path, +using the environment variable LUA_CPATH_5_2 +or the environment variable LUA_CPATH +or a default path defined in luaconf.h. + + + + +

+

package.loaded

+ + +

+A table used by require to control which +modules are already loaded. +When you require a module modname and +package.loaded[modname] is not false, +require simply returns the value stored there. + + +

+This variable is only a reference to the real table; +assignments to this variable do not change the +table used by require. + + + + +

+

package.loadlib (libname, funcname)

+ + +

+Dynamically links the host program with the C library libname. + + +

+If funcname is "*", +then it only links with the library, +making the symbols exported by the library +available to other dynamically linked libraries. +Otherwise, +it looks for a function funcname inside the library +and returns this function as a C function. +So, funcname must follow the lua_CFunction prototype +(see lua_CFunction). + + +

+This is a low-level function. +It completely bypasses the package and module system. +Unlike require, +it does not perform any path searching and +does not automatically adds extensions. +libname must be the complete file name of the C library, +including if necessary a path and an extension. +funcname must be the exact name exported by the C library +(which may depend on the C compiler and linker used). + + +

+This function is not supported by Standard C. +As such, it is only available on some platforms +(Windows, Linux, Mac OS X, Solaris, BSD, +plus other Unix systems that support the dlfcn standard). + + + + +

+

package.path

+ + +

+The path used by require to search for a Lua loader. + + +

+At start-up, Lua initializes this variable with +the value of the environment variable LUA_PATH_5_2 or +the environment variable LUA_PATH or +with a default path defined in luaconf.h, +if those environment variables are not defined. +Any ";;" in the value of the environment variable +is replaced by the default path. + + + + +

+

package.preload

+ + +

+A table to store loaders for specific modules +(see require). + + +

+This variable is only a reference to the real table; +assignments to this variable do not change the +table used by require. + + + + +

+

package.searchers

+ + +

+A table used by require to control how to load modules. + + +

+Each entry in this table is a searcher function. +When looking for a module, +require calls each of these searchers in ascending order, +with the module name (the argument given to require) as its +sole parameter. +The function can return another function (the module loader) +plus an extra value that will be passed to that loader, +or a string explaining why it did not find that module +(or nil if it has nothing to say). + + +

+Lua initializes this table with four searcher functions. + + +

+The first searcher simply looks for a loader in the +package.preload table. + + +

+The second searcher looks for a loader as a Lua library, +using the path stored at package.path. +The search is done as described in function package.searchpath. + + +

+The third searcher looks for a loader as a C library, +using the path given by the variable package.cpath. +Again, +the search is done as described in function package.searchpath. +For instance, +if the C path is the string + +

+     "./?.so;./?.dll;/usr/local/?/init.so"
+

+the searcher for module foo +will try to open the files ./foo.so, ./foo.dll, +and /usr/local/foo/init.so, in that order. +Once it finds a C library, +this searcher first uses a dynamic link facility to link the +application with the library. +Then it tries to find a C function inside the library to +be used as the loader. +The name of this C function is the string "luaopen_" +concatenated with a copy of the module name where each dot +is replaced by an underscore. +Moreover, if the module name has a hyphen, +its prefix up to (and including) the first hyphen is removed. +For instance, if the module name is a.v1-b.c, +the function name will be luaopen_b_c. + + +

+The fourth searcher tries an all-in-one loader. +It searches the C path for a library for +the root name of the given module. +For instance, when requiring a.b.c, +it will search for a C library for a. +If found, it looks into it for an open function for +the submodule; +in our example, that would be luaopen_a_b_c. +With this facility, a package can pack several C submodules +into one single library, +with each submodule keeping its original open function. + + +

+All searchers except the first one (preload) return as the extra value +the file name where the module was found, +as returned by package.searchpath. +The first searcher returns no extra value. + + + + +

+

package.searchpath (name, path [, sep [, rep]])

+ + +

+Searches for the given name in the given path. + + +

+A path is a string containing a sequence of +templates separated by semicolons. +For each template, +the function replaces each interrogation mark (if any) +in the template with a copy of name +wherein all occurrences of sep +(a dot, by default) +were replaced by rep +(the system's directory separator, by default), +and then tries to open the resulting file name. + + +

+For instance, if the path is the string + +

+     "./?.lua;./?.lc;/usr/local/?/init.lua"
+

+the search for the name foo.a +will try to open the files +./foo/a.lua, ./foo/a.lc, and +/usr/local/foo/a/init.lua, in that order. + + +

+Returns the resulting name of the first file that it can +open in read mode (after closing the file), +or nil plus an error message if none succeeds. +(This error message lists all file names it tried to open.) + + + + + + + +

6.4 – String Manipulation

+ +

+This library provides generic functions for string manipulation, +such as finding and extracting substrings, and pattern matching. +When indexing a string in Lua, the first character is at position 1 +(not at 0, as in C). +Indices are allowed to be negative and are interpreted as indexing backwards, +from the end of the string. +Thus, the last character is at position -1, and so on. + + +

+The string library provides all its functions inside the table +string. +It also sets a metatable for strings +where the __index field points to the string table. +Therefore, you can use the string functions in object-oriented style. +For instance, string.byte(s,i) +can be written as s:byte(i). + + +

+The string library assumes one-byte character encodings. + + +

+

string.byte (s [, i [, j]])

+Returns the internal numerical codes of the characters s[i], +s[i+1], ..., s[j]. +The default value for i is 1; +the default value for j is i. +These indices are corrected +following the same rules of function string.sub. + + +

+Numerical codes are not necessarily portable across platforms. + + + + +

+

string.char (···)

+Receives zero or more integers. +Returns a string with length equal to the number of arguments, +in which each character has the internal numerical code equal +to its corresponding argument. + + +

+Numerical codes are not necessarily portable across platforms. + + + + +

+

string.dump (function)

+ + +

+Returns a string containing a binary representation of the given function, +so that a later load on this string returns +a copy of the function (but with new upvalues). + + + + +

+

string.find (s, pattern [, init [, plain]])

+ + +

+Looks for the first match of +pattern in the string s. +If it finds a match, then find returns the indices of s +where this occurrence starts and ends; +otherwise, it returns nil. +A third, optional numerical argument init specifies +where to start the search; +its default value is 1 and can be negative. +A value of true as a fourth, optional argument plain +turns off the pattern matching facilities, +so the function does a plain "find substring" operation, +with no characters in pattern being considered magic. +Note that if plain is given, then init must be given as well. + + +

+If the pattern has captures, +then in a successful match +the captured values are also returned, +after the two indices. + + + + +

+

string.format (formatstring, ···)

+ + +

+Returns a formatted version of its variable number of arguments +following the description given in its first argument (which must be a string). +The format string follows the same rules as the ANSI C function sprintf. +The only differences are that the options/modifiers +*, h, L, l, n, +and p are not supported +and that there is an extra option, q. +The q option formats a string between double quotes, +using escape sequences when necessary to ensure that +it can safely be read back by the Lua interpreter. +For instance, the call + +

+     string.format('%q', 'a string with "quotes" and \n new line')
+

+may produce the string: + +

+     "a string with \"quotes\" and \
+      new line"
+
+ +

+Options +A and a (when available), +E, e, f, +G, and g all expect a number as argument. +Options c, d, +i, o, u, X, and x +also expect a number, +but the range of that number may be limited by +the underlying C implementation. +For options o, u, X, and x, +the number cannot be negative. +Option q expects a string; +option s expects a string without embedded zeros. +If the argument to option s is not a string, +it is converted to one following the same rules of tostring. + + + + +

+

string.gmatch (s, pattern)

+Returns an iterator function that, +each time it is called, +returns the next captures from pattern over the string s. +If pattern specifies no captures, +then the whole match is produced in each call. + + +

+As an example, the following loop +will iterate over all the words from string s, +printing one per line: + +

+     s = "hello world from Lua"
+     for w in string.gmatch(s, "%a+") do
+       print(w)
+     end
+

+The next example collects all pairs key=value from the +given string into a table: + +

+     t = {}
+     s = "from=world, to=Lua"
+     for k, v in string.gmatch(s, "(%w+)=(%w+)") do
+       t[k] = v
+     end
+
+ +

+For this function, a caret '^' at the start of a pattern does not +work as an anchor, as this would prevent the iteration. + + + + +

+

string.gsub (s, pattern, repl [, n])

+Returns a copy of s +in which all (or the first n, if given) +occurrences of the pattern have been +replaced by a replacement string specified by repl, +which can be a string, a table, or a function. +gsub also returns, as its second value, +the total number of matches that occurred. +The name gsub comes from Global SUBstitution. + + +

+If repl is a string, then its value is used for replacement. +The character % works as an escape character: +any sequence in repl of the form %d, +with d between 1 and 9, +stands for the value of the d-th captured substring. +The sequence %0 stands for the whole match. +The sequence %% stands for a single %. + + +

+If repl is a table, then the table is queried for every match, +using the first capture as the key. + + +

+If repl is a function, then this function is called every time a +match occurs, with all captured substrings passed as arguments, +in order. + + +

+In any case, +if the pattern specifies no captures, +then it behaves as if the whole pattern was inside a capture. + + +

+If the value returned by the table query or by the function call +is a string or a number, +then it is used as the replacement string; +otherwise, if it is false or nil, +then there is no replacement +(that is, the original match is kept in the string). + + +

+Here are some examples: + +

+     x = string.gsub("hello world", "(%w+)", "%1 %1")
+     --> x="hello hello world world"
+     
+     x = string.gsub("hello world", "%w+", "%0 %0", 1)
+     --> x="hello hello world"
+     
+     x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1")
+     --> x="world hello Lua from"
+     
+     x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv)
+     --> x="home = /home/roberto, user = roberto"
+     
+     x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s)
+           return load(s)()
+         end)
+     --> x="4+5 = 9"
+     
+     local t = {name="lua", version="5.2"}
+     x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t)
+     --> x="lua-5.2.tar.gz"
+
+ + + +

+

string.len (s)

+Receives a string and returns its length. +The empty string "" has length 0. +Embedded zeros are counted, +so "a\000bc\000" has length 5. + + + + +

+

string.lower (s)

+Receives a string and returns a copy of this string with all +uppercase letters changed to lowercase. +All other characters are left unchanged. +The definition of what an uppercase letter is depends on the current locale. + + + + +

+

string.match (s, pattern [, init])

+Looks for the first match of +pattern in the string s. +If it finds one, then match returns +the captures from the pattern; +otherwise it returns nil. +If pattern specifies no captures, +then the whole match is returned. +A third, optional numerical argument init specifies +where to start the search; +its default value is 1 and can be negative. + + + + +

+

string.rep (s, n [, sep])

+Returns a string that is the concatenation of n copies of +the string s separated by the string sep. +The default value for sep is the empty string +(that is, no separator). + + + + +

+

string.reverse (s)

+Returns a string that is the string s reversed. + + + + +

+

string.sub (s, i [, j])

+Returns the substring of s that +starts at i and continues until j; +i and j can be negative. +If j is absent, then it is assumed to be equal to -1 +(which is the same as the string length). +In particular, +the call string.sub(s,1,j) returns a prefix of s +with length j, +and string.sub(s, -i) returns a suffix of s +with length i. + + +

+If, after the translation of negative indices, +i is less than 1, +it is corrected to 1. +If j is greater than the string length, +it is corrected to that length. +If, after these corrections, +i is greater than j, +the function returns the empty string. + + + + +

+

string.upper (s)

+Receives a string and returns a copy of this string with all +lowercase letters changed to uppercase. +All other characters are left unchanged. +The definition of what a lowercase letter is depends on the current locale. + + + +

6.4.1 – Patterns

+ + +

Character Class:

+A character class is used to represent a set of characters. +The following combinations are allowed in describing a character class: + +

    + +
  • x: +(where x is not one of the magic characters +^$()%.[]*+-?) +represents the character x itself. +
    • + +
  • .: (a dot) represents all characters.
    • + +
  • %a: represents all letters.
    • + +
  • %c: represents all control characters.
    • + +
  • %d: represents all digits.
    • + +
  • %g: represents all printable characters except space.
    • + +
  • %l: represents all lowercase letters.
    • + +
  • %p: represents all punctuation characters.
    • + +
  • %s: represents all space characters.
    • + +
  • %u: represents all uppercase letters.
    • + +
  • %w: represents all alphanumeric characters.
    • + +
  • %x: represents all hexadecimal digits.
    • + +
  • %x: (where x is any non-alphanumeric character) +represents the character x. +This is the standard way to escape the magic characters. +Any punctuation character (even the non magic) +can be preceded by a '%' +when used to represent itself in a pattern. +
    • + +
  • [set]: +represents the class which is the union of all +characters in set. +A range of characters can be specified by +separating the end characters of the range, +in ascending order, with a '-', +All classes %x described above can also be used as +components in set. +All other characters in set represent themselves. +For example, [%w_] (or [_%w]) +represents all alphanumeric characters plus the underscore, +[0-7] represents the octal digits, +and [0-7%l%-] represents the octal digits plus +the lowercase letters plus the '-' character. + + +

    +The interaction between ranges and classes is not defined. +Therefore, patterns like [%a-z] or [a-%%] +have no meaning. +

    • + +
  • [^set]: +represents the complement of set, +where set is interpreted as above. +
    • + +

+For all classes represented by single letters (%a, %c, etc.), +the corresponding uppercase letter represents the complement of the class. +For instance, %S represents all non-space characters. + + +

+The definitions of letter, space, and other character groups +depend on the current locale. +In particular, the class [a-z] may not be equivalent to %l. + + + + + +

Pattern Item:

+A pattern item can be + +

    + +
  • +a single character class, +which matches any single character in the class; +
    • + +
  • +a single character class followed by '*', +which matches 0 or more repetitions of characters in the class. +These repetition items will always match the longest possible sequence; +
    • + +
  • +a single character class followed by '+', +which matches 1 or more repetitions of characters in the class. +These repetition items will always match the longest possible sequence; +
    • + +
  • +a single character class followed by '-', +which also matches 0 or more repetitions of characters in the class. +Unlike '*', +these repetition items will always match the shortest possible sequence; +
    • + +
  • +a single character class followed by '?', +which matches 0 or 1 occurrence of a character in the class; +
    • + +
  • +%n, for n between 1 and 9; +such item matches a substring equal to the n-th captured string +(see below); +
    • + +
  • +%bxy, where x and y are two distinct characters; +such item matches strings that start with x, end with y, +and where the x and y are balanced. +This means that, if one reads the string from left to right, +counting +1 for an x and -1 for a y, +the ending y is the first y where the count reaches 0. +For instance, the item %b() matches expressions with +balanced parentheses. +
    • + +
  • +%f[set], a frontier pattern; +such item matches an empty string at any position such that +the next character belongs to set +and the previous character does not belong to set. +The set set is interpreted as previously described. +The beginning and the end of the subject are handled as if +they were the character '\0'. +
    • + +
+ + + + +

Pattern:

+A pattern is a sequence of pattern items. +A caret '^' at the beginning of a pattern anchors the match at the +beginning of the subject string. +A '$' at the end of a pattern anchors the match at the +end of the subject string. +At other positions, +'^' and '$' have no special meaning and represent themselves. + + + + + +

Captures:

+A pattern can contain sub-patterns enclosed in parentheses; +they describe captures. +When a match succeeds, the substrings of the subject string +that match captures are stored (captured) for future use. +Captures are numbered according to their left parentheses. +For instance, in the pattern "(a*(.)%w(%s*))", +the part of the string matching "a*(.)%w(%s*)" is +stored as the first capture (and therefore has number 1); +the character matching "." is captured with number 2, +and the part matching "%s*" has number 3. + + +

+As a special case, the empty capture () captures +the current string position (a number). +For instance, if we apply the pattern "()aa()" on the +string "flaaap", there will be two captures: 3 and 5. + + + + + + + + + + + +

6.5 – Table Manipulation

+ +

+This library provides generic functions for table manipulation. +It provides all its functions inside the table table. + + +

+Remember that, whenever an operation needs the length of a table, +the table should be a proper sequence +or have a __len metamethod (see §3.4.6). +All functions ignore non-numeric keys +in tables given as arguments. + + +

+For performance reasons, +all table accesses (get/set) performed by these functions are raw. + + +

+

table.concat (list [, sep [, i [, j]]])

+ + +

+Given a list where all elements are strings or numbers, +returns the string list[i]..sep..list[i+1] ··· sep..list[j]. +The default value for sep is the empty string, +the default for i is 1, +and the default for j is #list. +If i is greater than j, returns the empty string. + + + + +

+

table.insert (list, [pos,] value)

+ + +

+Inserts element value at position pos in list, +shifting up the elements +list[pos], list[pos+1], ···, list[#list]. +The default value for pos is #list+1, +so that a call table.insert(t,x) inserts x at the end +of list t. + + + + +

+

table.pack (···)

+ + +

+Returns a new table with all parameters stored into keys 1, 2, etc. +and with a field "n" with the total number of parameters. +Note that the resulting table may not be a sequence. + + + + +

+

table.remove (list [, pos])

+ + +

+Removes from list the element at position pos, +returning the value of the removed element. +When pos is an integer between 1 and #list, +it shifts down the elements +list[pos+1], list[pos+2], ···, list[#list] +and erases element list[#list]; +The index pos can also be 0 when #list is 0, +or #list + 1; +in those cases, the function erases the element list[pos]. + + +

+The default value for pos is #list, +so that a call table.remove(t) removes the last element +of list t. + + + + +

+

table.sort (list [, comp])

+ + +

+Sorts list elements in a given order, in-place, +from list[1] to list[#list]. +If comp is given, +then it must be a function that receives two list elements +and returns true when the first element must come +before the second in the final order +(so that not comp(list[i+1],list[i]) will be true after the sort). +If comp is not given, +then the standard Lua operator < is used instead. + + +

+The sort algorithm is not stable; +that is, elements considered equal by the given order +may have their relative positions changed by the sort. + + + + +

+

table.unpack (list [, i [, j]])

+ + +

+Returns the elements from the given table. +This function is equivalent to + +

+     return list[i], list[i+1], ···, list[j]
+

+By default, i is 1 and j is #list. + + + + + + + +

6.6 – Mathematical Functions

+ +

+This library is an interface to the standard C math library. +It provides all its functions inside the table math. + + +

+

math.abs (x)

+ + +

+Returns the absolute value of x. + + + + +

+

math.acos (x)

+ + +

+Returns the arc cosine of x (in radians). + + + + +

+

math.asin (x)

+ + +

+Returns the arc sine of x (in radians). + + + + +

+

math.atan (x)

+ + +

+Returns the arc tangent of x (in radians). + + + + +

+

math.atan2 (y, x)

+ + +

+Returns the arc tangent of y/x (in radians), +but uses the signs of both parameters to find the +quadrant of the result. +(It also handles correctly the case of x being zero.) + + + + +

+

math.ceil (x)

+ + +

+Returns the smallest integer larger than or equal to x. + + + + +

+

math.cos (x)

+ + +

+Returns the cosine of x (assumed to be in radians). + + + + +

+

math.cosh (x)

+ + +

+Returns the hyperbolic cosine of x. + + + + +

+

math.deg (x)

+ + +

+Returns the angle x (given in radians) in degrees. + + + + +

+

math.exp (x)

+ + +

+Returns the value ex. + + + + +

+

math.floor (x)

+ + +

+Returns the largest integer smaller than or equal to x. + + + + +

+

math.fmod (x, y)

+ + +

+Returns the remainder of the division of x by y +that rounds the quotient towards zero. + + + + +

+

math.frexp (x)

+ + +

+Returns m and e such that x = m2e, +e is an integer and the absolute value of m is +in the range [0.5, 1) +(or zero when x is zero). + + + + +

+

math.huge

+ + +

+The value HUGE_VAL, +a value larger than or equal to any other numerical value. + + + + +

+

math.ldexp (m, e)

+ + +

+Returns m2e (e should be an integer). + + + + +

+

math.log (x [, base])

+ + +

+Returns the logarithm of x in the given base. +The default for base is e +(so that the function returns the natural logarithm of x). + + + + +

+

math.max (x, ···)

+ + +

+Returns the maximum value among its arguments. + + + + +

+

math.min (x, ···)

+ + +

+Returns the minimum value among its arguments. + + + + +

+

math.modf (x)

+ + +

+Returns two numbers, +the integral part of x and the fractional part of x. + + + + +

+

math.pi

+ + +

+The value of π. + + + + +

+

math.pow (x, y)

+ + +

+Returns xy. +(You can also use the expression x^y to compute this value.) + + + + +

+

math.rad (x)

+ + +

+Returns the angle x (given in degrees) in radians. + + + + +

+

math.random ([m [, n]])

+ + +

+This function is an interface to the simple +pseudo-random generator function rand provided by Standard C. +(No guarantees can be given for its statistical properties.) + + +

+When called without arguments, +returns a uniform pseudo-random real number +in the range [0,1). +When called with an integer number m, +math.random returns +a uniform pseudo-random integer in the range [1, m]. +When called with two integer numbers m and n, +math.random returns a uniform pseudo-random +integer in the range [m, n]. + + + + +

+

math.randomseed (x)

+ + +

+Sets x as the "seed" +for the pseudo-random generator: +equal seeds produce equal sequences of numbers. + + + + +

+

math.sin (x)

+ + +

+Returns the sine of x (assumed to be in radians). + + + + +

+

math.sinh (x)

+ + +

+Returns the hyperbolic sine of x. + + + + +

+

math.sqrt (x)

+ + +

+Returns the square root of x. +(You can also use the expression x^0.5 to compute this value.) + + + + +

+

math.tan (x)

+ + +

+Returns the tangent of x (assumed to be in radians). + + + + +

+

math.tanh (x)

+ + +

+Returns the hyperbolic tangent of x. + + + + + + + +

6.7 – Bitwise Operations

+ +

+This library provides bitwise operations. +It provides all its functions inside the table bit32. + + +

+Unless otherwise stated, +all functions accept numeric arguments in the range +(-251,+251); +each argument is normalized to +the remainder of its division by 232 +and truncated to an integer (in some unspecified way), +so that its final value falls in the range [0,232 - 1]. +Similarly, all results are in the range [0,232 - 1]. +Note that bit32.bnot(0) is 0xFFFFFFFF, +which is different from -1. + + +

+

bit32.arshift (x, disp)

+ + +

+Returns the number x shifted disp bits to the right. +The number disp may be any representable integer. +Negative displacements shift to the left. + + +

+This shift operation is what is called arithmetic shift. +Vacant bits on the left are filled +with copies of the higher bit of x; +vacant bits on the right are filled with zeros. +In particular, +displacements with absolute values higher than 31 +result in zero or 0xFFFFFFFF (all original bits are shifted out). + + + + +

+

bit32.band (···)

+ + +

+Returns the bitwise and of its operands. + + + + +

+

bit32.bnot (x)

+ + +

+Returns the bitwise negation of x. +For any integer x, +the following identity holds: + +

+     assert(bit32.bnot(x) == (-1 - x) % 2^32)
+
+ + + +

+

bit32.bor (···)

+ + +

+Returns the bitwise or of its operands. + + + + +

+

bit32.btest (···)

+ + +

+Returns a boolean signaling +whether the bitwise and of its operands is different from zero. + + + + +

+

bit32.bxor (···)

+ + +

+Returns the bitwise exclusive or of its operands. + + + + +

+

bit32.extract (n, field [, width])

+ + +

+Returns the unsigned number formed by the bits +field to field + width - 1 from n. +Bits are numbered from 0 (least significant) to 31 (most significant). +All accessed bits must be in the range [0, 31]. + + +

+The default for width is 1. + + + + +

+

bit32.replace (n, v, field [, width])

+ + +

+Returns a copy of n with +the bits field to field + width - 1 +replaced by the value v. +See bit32.extract for details about field and width. + + + + +

+

bit32.lrotate (x, disp)

+ + +

+Returns the number x rotated disp bits to the left. +The number disp may be any representable integer. + + +

+For any valid displacement, +the following identity holds: + +

+     assert(bit32.lrotate(x, disp) == bit32.lrotate(x, disp % 32))
+

+In particular, +negative displacements rotate to the right. + + + + +

+

bit32.lshift (x, disp)

+ + +

+Returns the number x shifted disp bits to the left. +The number disp may be any representable integer. +Negative displacements shift to the right. +In any direction, vacant bits are filled with zeros. +In particular, +displacements with absolute values higher than 31 +result in zero (all bits are shifted out). + + +

+For positive displacements, +the following equality holds: + +

+     assert(bit32.lshift(b, disp) == (b * 2^disp) % 2^32)
+
+ + + +

+

bit32.rrotate (x, disp)

+ + +

+Returns the number x rotated disp bits to the right. +The number disp may be any representable integer. + + +

+For any valid displacement, +the following identity holds: + +

+     assert(bit32.rrotate(x, disp) == bit32.rrotate(x, disp % 32))
+

+In particular, +negative displacements rotate to the left. + + + + +

+

bit32.rshift (x, disp)

+ + +

+Returns the number x shifted disp bits to the right. +The number disp may be any representable integer. +Negative displacements shift to the left. +In any direction, vacant bits are filled with zeros. +In particular, +displacements with absolute values higher than 31 +result in zero (all bits are shifted out). + + +

+For positive displacements, +the following equality holds: + +

+     assert(bit32.rshift(b, disp) == math.floor(b % 2^32 / 2^disp))
+
+ +

+This shift operation is what is called logical shift. + + + + + + + +

6.8 – Input and Output Facilities

+ +

+The I/O library provides two different styles for file manipulation. +The first one uses implicit file descriptors; +that is, there are operations to set a default input file and a +default output file, +and all input/output operations are over these default files. +The second style uses explicit file descriptors. + + +

+When using implicit file descriptors, +all operations are supplied by table io. +When using explicit file descriptors, +the operation io.open returns a file descriptor +and then all operations are supplied as methods of the file descriptor. + + +

+The table io also provides +three predefined file descriptors with their usual meanings from C: +io.stdin, io.stdout, and io.stderr. +The I/O library never closes these files. + + +

+Unless otherwise stated, +all I/O functions return nil on failure +(plus an error message as a second result and +a system-dependent error code as a third result) +and some value different from nil on success. +On non-Posix systems, +the computation of the error message and error code +in case of errors +may be not thread safe, +because they rely on the global C variable errno. + + +

+

io.close ([file])

+ + +

+Equivalent to file:close(). +Without a file, closes the default output file. + + + + +

+

io.flush ()

+ + +

+Equivalent to io.output():flush(). + + + + +

+

io.input ([file])

+ + +

+When called with a file name, it opens the named file (in text mode), +and sets its handle as the default input file. +When called with a file handle, +it simply sets this file handle as the default input file. +When called without parameters, +it returns the current default input file. + + +

+In case of errors this function raises the error, +instead of returning an error code. + + + + +

+

io.lines ([filename ···])

+ + +

+Opens the given file name in read mode +and returns an iterator function that +works like file:lines(···) over the opened file. +When the iterator function detects the end of file, +it returns nil (to finish the loop) and automatically closes the file. + + +

+The call io.lines() (with no file name) is equivalent +to io.input():lines(); +that is, it iterates over the lines of the default input file. +In this case it does not close the file when the loop ends. + + +

+In case of errors this function raises the error, +instead of returning an error code. + + + + +

+

io.open (filename [, mode])

+ + +

+This function opens a file, +in the mode specified in the string mode. +It returns a new file handle, +or, in case of errors, nil plus an error message. + + +

+The mode string can be any of the following: + +

    +
  • "r": read mode (the default);
    • +
  • "w": write mode;
    • +
  • "a": append mode;
    • +
  • "r+": update mode, all previous data is preserved;
    • +
  • "w+": update mode, all previous data is erased;
    • +
  • "a+": append update mode, previous data is preserved, + writing is only allowed at the end of file.
    • +

+The mode string can also have a 'b' at the end, +which is needed in some systems to open the file in binary mode. + + + + +

+

io.output ([file])

+ + +

+Similar to io.input, but operates over the default output file. + + + + +

+

io.popen (prog [, mode])

+ + +

+This function is system dependent and is not available +on all platforms. + + +

+Starts program prog in a separated process and returns +a file handle that you can use to read data from this program +(if mode is "r", the default) +or to write data to this program +(if mode is "w"). + + + + +

+

io.read (···)

+ + +

+Equivalent to io.input():read(···). + + + + +

+

io.tmpfile ()

+ + +

+Returns a handle for a temporary file. +This file is opened in update mode +and it is automatically removed when the program ends. + + + + +

+

io.type (obj)

+ + +

+Checks whether obj is a valid file handle. +Returns the string "file" if obj is an open file handle, +"closed file" if obj is a closed file handle, +or nil if obj is not a file handle. + + + + +

+

io.write (···)

+ + +

+Equivalent to io.output():write(···). + + + + +

+

file:close ()

+ + +

+Closes file. +Note that files are automatically closed when +their handles are garbage collected, +but that takes an unpredictable amount of time to happen. + + +

+When closing a file handle created with io.popen, +file:close returns the same values +returned by os.execute. + + + + +

+

file:flush ()

+ + +

+Saves any written data to file. + + + + +

+

file:lines (···)

+ + +

+Returns an iterator function that, +each time it is called, +reads the file according to the given formats. +When no format is given, +uses "*l" as a default. +As an example, the construction + +

+     for c in file:lines(1) do body end
+

+will iterate over all characters of the file, +starting at the current position. +Unlike io.lines, this function does not close the file +when the loop ends. + + +

+In case of errors this function raises the error, +instead of returning an error code. + + + + +

+

file:read (···)

+ + +

+Reads the file file, +according to the given formats, which specify what to read. +For each format, +the function returns a string (or a number) with the characters read, +or nil if it cannot read data with the specified format. +When called without formats, +it uses a default format that reads the next line +(see below). + + +

+The available formats are + +

    + +
  • "*n": +reads a number; +this is the only format that returns a number instead of a string. +
    • + +
  • "*a": +reads the whole file, starting at the current position. +On end of file, it returns the empty string. +
    • + +
  • "*l": +reads the next line skipping the end of line, +returning nil on end of file. +This is the default format. +
    • + +
  • "*L": +reads the next line keeping the end of line (if present), +returning nil on end of file. +
    • + +
  • number: +reads a string with up to this number of bytes, +returning nil on end of file. +If number is zero, +it reads nothing and returns an empty string, +or nil on end of file. +
    • + +
+ + + +

+

file:seek ([whence [, offset]])

+ + +

+Sets and gets the file position, +measured from the beginning of the file, +to the position given by offset plus a base +specified by the string whence, as follows: + +

    +
  • "set": base is position 0 (beginning of the file);
    • +
  • "cur": base is current position;
    • +
  • "end": base is end of file;
    • +

+In case of success, seek returns the final file position, +measured in bytes from the beginning of the file. +If seek fails, it returns nil, +plus a string describing the error. + + +

+The default value for whence is "cur", +and for offset is 0. +Therefore, the call file:seek() returns the current +file position, without changing it; +the call file:seek("set") sets the position to the +beginning of the file (and returns 0); +and the call file:seek("end") sets the position to the +end of the file, and returns its size. + + + + +

+

file:setvbuf (mode [, size])

+ + +

+Sets the buffering mode for an output file. +There are three available modes: + +

    + +
  • "no": +no buffering; the result of any output operation appears immediately. +
    • + +
  • "full": +full buffering; output operation is performed only +when the buffer is full or when +you explicitly flush the file (see io.flush). +
    • + +
  • "line": +line buffering; output is buffered until a newline is output +or there is any input from some special files +(such as a terminal device). +
    • + +

+For the last two cases, size +specifies the size of the buffer, in bytes. +The default is an appropriate size. + + + + +

+

file:write (···)

+ + +

+Writes the value of each of its arguments to file. +The arguments must be strings or numbers. + + +

+In case of success, this function returns file. +Otherwise it returns nil plus a string describing the error. + + + + + + + +

6.9 – Operating System Facilities

+ +

+This library is implemented through table os. + + +

+

os.clock ()

+ + +

+Returns an approximation of the amount in seconds of CPU time +used by the program. + + + + +

+

os.date ([format [, time]])

+ + +

+Returns a string or a table containing date and time, +formatted according to the given string format. + + +

+If the time argument is present, +this is the time to be formatted +(see the os.time function for a description of this value). +Otherwise, date formats the current time. + + +

+If format starts with '!', +then the date is formatted in Coordinated Universal Time. +After this optional character, +if format is the string "*t", +then date returns a table with the following fields: +year (four digits), month (1–12), day (1–31), +hour (0–23), min (0–59), sec (0–61), +wday (weekday, Sunday is 1), +yday (day of the year), +and isdst (daylight saving flag, a boolean). +This last field may be absent +if the information is not available. + + +

+If format is not "*t", +then date returns the date as a string, +formatted according to the same rules as the ANSI C function strftime. + + +

+When called without arguments, +date returns a reasonable date and time representation that depends on +the host system and on the current locale +(that is, os.date() is equivalent to os.date("%c")). + + +

+On non-Posix systems, +this function may be not thread safe +because of its reliance on C function gmtime and C function localtime. + + + + +

+

os.difftime (t2, t1)

+ + +

+Returns the number of seconds from time t1 to time t2. +In POSIX, Windows, and some other systems, +this value is exactly t2-t1. + + + + +

+

os.execute ([command])

+ + +

+This function is equivalent to the ANSI C function system. +It passes command to be executed by an operating system shell. +Its first result is true +if the command terminated successfully, +or nil otherwise. +After this first result +the function returns a string and a number, +as follows: + +

    + +
  • "exit": +the command terminated normally; +the following number is the exit status of the command. +
    • + +
  • "signal": +the command was terminated by a signal; +the following number is the signal that terminated the command. +
    • + +
+ +

+When called without a command, +os.execute returns a boolean that is true if a shell is available. + + + + +

+

os.exit ([code [, close])

+ + +

+Calls the ANSI C function exit to terminate the host program. +If code is true, +the returned status is EXIT_SUCCESS; +if code is false, +the returned status is EXIT_FAILURE; +if code is a number, +the returned status is this number. +The default value for code is true. + + +

+If the optional second argument close is true, +closes the Lua state before exiting. + + + + +

+

os.getenv (varname)

+ + +

+Returns the value of the process environment variable varname, +or nil if the variable is not defined. + + + + +

+

os.remove (filename)

+ + +

+Deletes the file (or empty directory, on POSIX systems) +with the given name. +If this function fails, it returns nil, +plus a string describing the error and the error code. + + + + +

+

os.rename (oldname, newname)

+ + +

+Renames file or directory named oldname to newname. +If this function fails, it returns nil, +plus a string describing the error and the error code. + + + + +

+

os.setlocale (locale [, category])

+ + +

+Sets the current locale of the program. +locale is a system-dependent string specifying a locale; +category is an optional string describing which category to change: +"all", "collate", "ctype", +"monetary", "numeric", or "time"; +the default category is "all". +The function returns the name of the new locale, +or nil if the request cannot be honored. + + +

+If locale is the empty string, +the current locale is set to an implementation-defined native locale. +If locale is the string "C", +the current locale is set to the standard C locale. + + +

+When called with nil as the first argument, +this function only returns the name of the current locale +for the given category. + + +

+This function may be not thread safe +because of its reliance on C function setlocale. + + + + +

+

os.time ([table])

+ + +

+Returns the current time when called without arguments, +or a time representing the date and time specified by the given table. +This table must have fields year, month, and day, +and may have fields +hour (default is 12), +min (default is 0), +sec (default is 0), +and isdst (default is nil). +For a description of these fields, see the os.date function. + + +

+The returned value is a number, whose meaning depends on your system. +In POSIX, Windows, and some other systems, +this number counts the number +of seconds since some given start time (the "epoch"). +In other systems, the meaning is not specified, +and the number returned by time can be used only as an argument to +os.date and os.difftime. + + + + +

+

os.tmpname ()

+ + +

+Returns a string with a file name that can +be used for a temporary file. +The file must be explicitly opened before its use +and explicitly removed when no longer needed. + + +

+On POSIX systems, +this function also creates a file with that name, +to avoid security risks. +(Someone else might create the file with wrong permissions +in the time between getting the name and creating the file.) +You still have to open the file to use it +and to remove it (even if you do not use it). + + +

+When possible, +you may prefer to use io.tmpfile, +which automatically removes the file when the program ends. + + + + + + + +

6.10 – The Debug Library

+ +

+This library provides +the functionality of the debug interface (§4.9) to Lua programs. +You should exert care when using this library. +Several of its functions +violate basic assumptions about Lua code +(e.g., that variables local to a function +cannot be accessed from outside; +that userdata metatables cannot be changed by Lua code; +that Lua programs do not crash) +and therefore can compromise otherwise secure code. +Moreover, some functions in this library may be slow. + + +

+All functions in this library are provided +inside the debug table. +All functions that operate over a thread +have an optional first argument which is the +thread to operate over. +The default is always the current thread. + + +

+

debug.debug ()

+ + +

+Enters an interactive mode with the user, +running each string that the user enters. +Using simple commands and other debug facilities, +the user can inspect global and local variables, +change their values, evaluate expressions, and so on. +A line containing only the word cont finishes this function, +so that the caller continues its execution. + + +

+Note that commands for debug.debug are not lexically nested +within any function and so have no direct access to local variables. + + + + +

+

debug.gethook ([thread])

+ + +

+Returns the current hook settings of the thread, as three values: +the current hook function, the current hook mask, +and the current hook count +(as set by the debug.sethook function). + + + + +

+

debug.getinfo ([thread,] f [, what])

+ + +

+Returns a table with information about a function. +You can give the function directly +or you can give a number as the value of f, +which means the function running at level f of the call stack +of the given thread: +level 0 is the current function (getinfo itself); +level 1 is the function that called getinfo +(except for tail calls, which do not count on the stack); +and so on. +If f is a number larger than the number of active functions, +then getinfo returns nil. + + +

+The returned table can contain all the fields returned by lua_getinfo, +with the string what describing which fields to fill in. +The default for what is to get all information available, +except the table of valid lines. +If present, +the option 'f' +adds a field named func with the function itself. +If present, +the option 'L' +adds a field named activelines with the table of +valid lines. + + +

+For instance, the expression debug.getinfo(1,"n").name returns +a table with a name for the current function, +if a reasonable name can be found, +and the expression debug.getinfo(print) +returns a table with all available information +about the print function. + + + + +

+

debug.getlocal ([thread,] f, local)

+ + +

+This function returns the name and the value of the local variable +with index local of the function at level f of the stack. +This function accesses not only explicit local variables, +but also parameters, temporaries, etc. + + +

+The first parameter or local variable has index 1, and so on, +until the last active variable. +Negative indices refer to vararg parameters; +-1 is the first vararg parameter. +The function returns nil if there is no variable with the given index, +and raises an error when called with a level out of range. +(You can call debug.getinfo to check whether the level is valid.) + + +

+Variable names starting with '(' (open parenthesis) +represent internal variables +(loop control variables, temporaries, varargs, and C function locals). + + +

+The parameter f may also be a function. +In that case, getlocal returns only the name of function parameters. + + + + +

+

debug.getmetatable (value)

+ + +

+Returns the metatable of the given value +or nil if it does not have a metatable. + + + + +

+

debug.getregistry ()

+ + +

+Returns the registry table (see §4.5). + + + + +

+

debug.getupvalue (f, up)

+ + +

+This function returns the name and the value of the upvalue +with index up of the function f. +The function returns nil if there is no upvalue with the given index. + + + + +

+

debug.getuservalue (u)

+ + +

+Returns the Lua value associated to u. +If u is not a userdata, +returns nil. + + + + +

+

debug.sethook ([thread,] hook, mask [, count])

+ + +

+Sets the given function as a hook. +The string mask and the number count describe +when the hook will be called. +The string mask may have the following characters, +with the given meaning: + +

    +
  • 'c': the hook is called every time Lua calls a function;
    • +
  • 'r': the hook is called every time Lua returns from a function;
    • +
  • 'l': the hook is called every time Lua enters a new line of code.
    • +

+With a count different from zero, +the hook is called after every count instructions. + + +

+When called without arguments, +debug.sethook turns off the hook. + + +

+When the hook is called, its first parameter is a string +describing the event that has triggered its call: +"call" (or "tail call"), +"return", +"line", and "count". +For line events, +the hook also gets the new line number as its second parameter. +Inside a hook, +you can call getinfo with level 2 to get more information about +the running function +(level 0 is the getinfo function, +and level 1 is the hook function). + + + + +

+

debug.setlocal ([thread,] level, local, value)

+ + +

+This function assigns the value value to the local variable +with index local of the function at level level of the stack. +The function returns nil if there is no local +variable with the given index, +and raises an error when called with a level out of range. +(You can call getinfo to check whether the level is valid.) +Otherwise, it returns the name of the local variable. + + +

+See debug.getlocal for more information about +variable indices and names. + + + + +

+

debug.setmetatable (value, table)

+ + +

+Sets the metatable for the given value to the given table +(which can be nil). +Returns value. + + + + +

+

debug.setupvalue (f, up, value)

+ + +

+This function assigns the value value to the upvalue +with index up of the function f. +The function returns nil if there is no upvalue +with the given index. +Otherwise, it returns the name of the upvalue. + + + + +

+

debug.setuservalue (udata, value)

+ + +

+Sets the given value as +the Lua value associated to the given udata. +value must be a table or nil; +udata must be a full userdata. + + +

+Returns udata. + + + + +

+

debug.traceback ([thread,] [message [, level]])

+ + +

+If message is present but is neither a string nor nil, +this function returns message without further processing. +Otherwise, +it returns a string with a traceback of the call stack. +An optional message string is appended +at the beginning of the traceback. +An optional level number tells at which level +to start the traceback +(default is 1, the function calling traceback). + + + + +

+

debug.upvalueid (f, n)

+ + +

+Returns an unique identifier (as a light userdata) +for the upvalue numbered n +from the given function. + + +

+These unique identifiers allow a program to check whether different +closures share upvalues. +Lua closures that share an upvalue +(that is, that access a same external local variable) +will return identical ids for those upvalue indices. + + + + +

+

debug.upvaluejoin (f1, n1, f2, n2)

+ + +

+Make the n1-th upvalue of the Lua closure f1 +refer to the n2-th upvalue of the Lua closure f2. + + + + + + + +

7 – Lua Standalone

+ +

+Although Lua has been designed as an extension language, +to be embedded in a host C program, +it is also frequently used as a standalone language. +An interpreter for Lua as a standalone language, +called simply lua, +is provided with the standard distribution. +The standalone interpreter includes +all standard libraries, including the debug library. +Its usage is: + +

+     lua [options] [script [args]]
+

+The options are: + +

    +
  • -e stat: executes string stat;
    • +
  • -l mod: "requires" mod;
    • +
  • -i: enters interactive mode after running script;
    • +
  • -v: prints version information;
    • +
  • -E: ignores environment variables;
    • +
  • --: stops handling options;
    • +
  • -: executes stdin as a file and stops handling options.
    • +

+After handling its options, lua runs the given script, +passing to it the given args as string arguments. +When called without arguments, +lua behaves as lua -v -i +when the standard input (stdin) is a terminal, +and as lua - otherwise. + + +

+When called without option -E, +the interpreter checks for an environment variable LUA_INIT_5_2 +(or LUA_INIT if it is not defined) +before running any argument. +If the variable content has the format @filename, +then lua executes the file. +Otherwise, lua executes the string itself. + + +

+When called with option -E, +besides ignoring LUA_INIT, +Lua also ignores +the values of LUA_PATH and LUA_CPATH, +setting the values of +package.path and package.cpath +with the default paths defined in luaconf.h. + + +

+All options are handled in order, except -i and -E. +For instance, an invocation like + +

+     $ lua -e'a=1' -e 'print(a)' script.lua
+

+will first set a to 1, then print the value of a, +and finally run the file script.lua with no arguments. +(Here $ is the shell prompt. Your prompt may be different.) + + +

+Before starting to run the script, +lua collects all arguments in the command line +in a global table called arg. +The script name is stored at index 0, +the first argument after the script name goes to index 1, +and so on. +Any arguments before the script name +(that is, the interpreter name plus the options) +go to negative indices. +For instance, in the call + +

+     $ lua -la b.lua t1 t2
+

+the interpreter first runs the file a.lua, +then creates a table + +

+     arg = { [-2] = "lua", [-1] = "-la",
+             [0] = "b.lua",
+             [1] = "t1", [2] = "t2" }
+

+and finally runs the file b.lua. +The script is called with arg[1], arg[2], ... +as arguments; +it can also access these arguments with the vararg expression '...'. + + +

+In interactive mode, +if you write an incomplete statement, +the interpreter waits for its completion +by issuing a different prompt. + + +

+In case of unprotected errors in the script, +the interpreter reports the error to the standard error stream. +If the error object is a string, +the interpreter adds a stack traceback to it. +Otherwise, if the error object has a metamethod __tostring, +the interpreter calls this metamethod to produce the final message. +Finally, if the error object is nil, +the interpreter does not report the error. + + +

+When finishing normally, +the interpreter closes its main Lua state +(see lua_close). +The script can avoid this step by +calling os.exit to terminate. + + +

+To allow the use of Lua as a +script interpreter in Unix systems, +the standalone interpreter skips +the first line of a chunk if it starts with #. +Therefore, Lua scripts can be made into executable programs +by using chmod +x and the #! form, +as in + +

+     #!/usr/local/bin/lua
+

+(Of course, +the location of the Lua interpreter may be different in your machine. +If lua is in your PATH, +then + +

+     #!/usr/bin/env lua
+

+is a more portable solution.) + + + +

8 – Incompatibilities with the Previous Version

+ +

+Here we list the incompatibilities that you may find when moving a program +from Lua 5.1 to Lua 5.2. +You can avoid some incompatibilities by compiling Lua with +appropriate options (see file luaconf.h). +However, +all these compatibility options will be removed in the next version of Lua. +Similarly, +all features marked as deprecated in Lua 5.1 +have been removed in Lua 5.2. + + + +

8.1 – Changes in the Language

+
    + +
  • +The concept of environment changed. +Only Lua functions have environments. +To set the environment of a Lua function, +use the variable _ENV or the function load. + + +

    +C functions no longer have environments. +Use an upvalue with a shared table if you need to keep +shared state among several C functions. +(You may use luaL_setfuncs to open a C library +with all functions sharing a common upvalue.) + + +

    +To manipulate the "environment" of a userdata +(which is now called user value), +use the new functions +lua_getuservalue and lua_setuservalue. +

    • + +
  • +Lua identifiers cannot use locale-dependent letters. +
    • + +
  • +Doing a step or a full collection in the garbage collector +does not restart the collector if it has been stopped. +
    • + +
  • +Weak tables with weak keys now perform like ephemeron tables. +
    • + +
  • +The event tail return in debug hooks was removed. +Instead, tail calls generate a special new event, +tail call, so that the debugger can know that +there will not be a corresponding return event. +
    • + +
  • +Equality between function values has changed. +Now, a function definition may not create a new value; +it may reuse some previous value if there is no +observable difference to the new function. +
    • + +
+ + + + +

8.2 – Changes in the Libraries

+
    + +
  • +Function module is deprecated. +It is easy to set up a module with regular Lua code. +Modules are not expected to set global variables. +
    • + +
  • +Functions setfenv and getfenv were removed, +because of the changes in environments. +
    • + +
  • +Function math.log10 is deprecated. +Use math.log with 10 as its second argument, instead. +
    • + +
  • +Function loadstring is deprecated. +Use load instead; it now accepts string arguments +and are exactly equivalent to loadstring. +
    • + +
  • +Function table.maxn is deprecated. +Write it in Lua if you really need it. +
    • + +
  • +Function os.execute now returns true when command +terminates successfully and nil plus error information +otherwise. +
    • + +
  • +Function unpack was moved into the table library +and therefore must be called as table.unpack. +
    • + +
  • +Character class %z in patterns is deprecated, +as now patterns may contain '\0' as a regular character. +
    • + +
  • +The table package.loaders was renamed package.searchers. +
    • + +
  • +Lua does not have bytecode verification anymore. +So, all functions that load code +(load and loadfile) +are potentially insecure when loading untrusted binary data. +(Actually, those functions were already insecure because +of flaws in the verification algorithm.) +When in doubt, +use the mode argument of those functions +to restrict them to loading textual chunks. +
    • + +
  • +The standard paths in the official distribution may +change between versions. +
    • + +
+ + + + +

8.3 – Changes in the API

+
    + +
  • +Pseudoindex LUA_GLOBALSINDEX was removed. +You must get the global environment from the registry +(see §4.5). +
    • + +
  • +Pseudoindex LUA_ENVIRONINDEX +and functions lua_getfenv/lua_setfenv +were removed, +as C functions no longer have environments. +
    • + +
  • +Function luaL_register is deprecated. +Use luaL_setfuncs so that your module does not create globals. +(Modules are not expected to set global variables anymore.) +
    • + +
  • +The osize argument to the allocation function +may not be zero when creating a new block, +that is, when ptr is NULL +(see lua_Alloc). +Use only the test ptr == NULL to check whether +the block is new. +
    • + +
  • +Finalizers (__gc metamethods) for userdata are called in the +reverse order that they were marked for finalization, +not that they were created (see §2.5.1). +(Most userdata are marked immediately after they are created.) +Moreover, +if the metatable does not have a __gc field when set, +the finalizer will not be called, +even if it is set later. +
    • + +
  • +luaL_typerror was removed. +Write your own version if you need it. +
    • + +
  • +Function lua_cpcall is deprecated. +You can simply push the function with lua_pushcfunction +and call it with lua_pcall. +
    • + +
  • +Functions lua_equal and lua_lessthan are deprecated. +Use the new lua_compare with appropriate options instead. +
    • + +
  • +Function lua_objlen was renamed lua_rawlen. +
    • + +
  • +Function lua_load has an extra parameter, mode. +Pass NULL to simulate the old behavior. +
    • + +
  • +Function lua_resume has an extra parameter, from. +Pass NULL or the thread doing the call. +
    • + +
+ + + + +

9 – The Complete Syntax of Lua

+ +

+Here is the complete syntax of Lua in extended BNF. +(It does not describe operator precedences.) + + + + +

+
+	chunk ::= block
+
+	block ::= {stat} [retstat]
+
+	stat ::=  ‘;’ | 
+		 varlist ‘=’ explist | 
+		 functioncall | 
+		 label | 
+		 break | 
+		 goto Name | 
+		 do block end | 
+		 while exp do block end | 
+		 repeat block until exp | 
+		 if exp then block {elseif exp then block} [else block] end | 
+		 for Name ‘=’ exp ‘,’ exp [‘,’ exp] do block end | 
+		 for namelist in explist do block end | 
+		 function funcname funcbody | 
+		 local function Name funcbody | 
+		 local namelist [‘=’ explist] 
+
+	retstat ::= return [explist] [‘;’]
+
+	label ::= ‘::’ Name ‘::’
+
+	funcname ::= Name {‘.’ Name} [‘:’ Name]
+
+	varlist ::= var {‘,’ var}
+
+	var ::=  Name | prefixexp ‘[’ exp ‘]’ | prefixexp ‘.’ Name 
+
+	namelist ::= Name {‘,’ Name}
+
+	explist ::= exp {‘,’ exp}
+
+	exp ::=  nil | false | true | Number | String | ‘...’ | functiondef | 
+		 prefixexp | tableconstructor | exp binop exp | unop exp 
+
+	prefixexp ::= var | functioncall | ‘(’ exp ‘)’
+
+	functioncall ::=  prefixexp args | prefixexp ‘:’ Name args 
+
+	args ::=  ‘(’ [explist] ‘)’ | tableconstructor | String 
+
+	functiondef ::= function funcbody
+
+	funcbody ::= ‘(’ [parlist] ‘)’ block end
+
+	parlist ::= namelist [‘,’ ‘...’] | ‘...’
+
+	tableconstructor ::= ‘{’ [fieldlist] ‘}’
+
+	fieldlist ::= field {fieldsep field} [fieldsep]
+
+	field ::= ‘[’ exp ‘]’ ‘=’ exp | Name ‘=’ exp | exp
+
+	fieldsep ::= ‘,’ | ‘;’
+
+	binop ::= ‘+’ | ‘-’ | ‘*’ | ‘/’ | ‘^’ | ‘%’ | ‘..’ | 
+		 ‘<’ | ‘<=’ | ‘>’ | ‘>=’ | ‘==’ | ‘~=’ | 
+		 and | or
+
+	unop ::= ‘-’ | not | ‘#’
+
+
+ +

+ + + + + + + +

+ +Last update: +Thu Mar 21 12:58:59 BRT 2013 + + + + + diff --git a/share/lua/doc/osi-certified-72x60.png b/share/lua/doc/osi-certified-72x60.png new file mode 100644 index 0000000..07df5f6 Binary files /dev/null and b/share/lua/doc/osi-certified-72x60.png differ diff --git a/share/lua/doc/readme.html b/share/lua/doc/readme.html new file mode 100644 index 0000000..8acec87 --- /dev/null +++ b/share/lua/doc/readme.html @@ -0,0 +1,413 @@ + + + +Lua 5.2 readme + + + + + + + +
+

+Lua +Welcome to Lua 5.2 +

+ +

+about +· +installation +· +changes +· +license +· +reference manual + +

About Lua

+ +

+Lua is a powerful, fast, lightweight, embeddable scripting language +developed by a +team +at +PUC-Rio, +the Pontifical Catholic University of Rio de Janeiro in Brazil. +Lua is +free software +used in many products and projects around the world. + +

+Lua's +official web site +provides complete information +about Lua, +including +an +executive summary +and +updated +documentation, +especially the +reference manual, +which may differ slightly from the +local copy +distributed in this package. + +

Installing Lua

+ +

+Lua is distributed in +source +form. +You need to build it before using it. +Building Lua should be straightforward +because +Lua is implemented in pure ANSI C and compiles unmodified in all known +platforms that have an ANSI C compiler. +Lua also compiles unmodified as C++. +The instructions given below for building Lua are for Unix-like platforms. +See also +instructions for other systems +and +customization options. + +

+If you don't have the time or the inclination to compile Lua yourself, +get a binary from +LuaBinaries. +Try also +Lua for Windows, +an easy-to-use distribution of Lua that includes many useful libraries. + +

Building Lua

+ +

+In most Unix-like platforms, simply do "make" with a suitable target. +Here are the details. + +

    +
  1. +Open a terminal window and move to +the top-level directory, which is named lua-5.2.3. +The Makefile there controls both the build process and the installation process. +

    +

  2. + Do "make" and see if your platform is listed. + The platforms currently supported are: +

    +

    + aix ansi bsd freebsd generic linux macosx mingw posix solaris +

    +

    + If your platform is listed, just do "make xxx", where xxx + is your platform name. +

    + If your platform is not listed, try the closest one or posix, generic, + ansi, in this order. +

    +

  3. +The compilation takes only a few moments +and produces three files in the src directory: +lua (the interpreter), +luac (the compiler), +and liblua.a (the library). +

    +

  4. + To check that Lua has been built correctly, do "make test" + after building Lua. This will run the interpreter and print its version string. +
+

+If you're running Linux and get compilation errors, +make sure you have installed the readline development package. +If you get link errors after that, +then try "make linux MYLIBS=-ltermcap". + +

Installing Lua

+

+ Once you have built Lua, you may want to install it in an official + place in your system. In this case, do "make install". The official + place and the way to install files are defined in the Makefile. You'll + probably need the right permissions to install files. + +

+ To build and install Lua in one step, do "make xxx install", + where xxx is your platform name. + +

+ To install Lua locally, do "make local". + This will create a directory install with subdirectories + bin, include, lib, man, + and install Lua as listed below. + + To install Lua locally, but in some other directory, do + "make install INSTALL_TOP=xxx", where xxx is your chosen directory. + +

+
+ bin: +
+ lua luac +
+ include: +
+ lua.h luaconf.h lualib.h lauxlib.h lua.hpp +
+ lib: +
+ liblua.a +
+ man/man1: +
+ lua.1 luac.1 +
+ +

+ These are the only directories you need for development. + If you only want to run Lua programs, + you only need the files in bin and man. + The files in include and lib are needed for + embedding Lua in C or C++ programs. + +

Customization

+

+ Three kinds of things can be customized by editing a file: +

    +
  • Where and how to install Lua — edit Makefile. +
  • How to build Lua — edit src/Makefile. +
  • Lua features — edit src/luaconf.h. +
+ +

+ You don't actually need to edit the Makefiles because you may set the + relevant variables in the command line when invoking make. + Nevertheless, it's probably best to edit and save the Makefiles to + record the changes you need. + +

+ On the other hand, if you need to customize some Lua features, you'll need + to edit src/luaconf.h before building and installing Lua. + The edited file will be the one installed, and + it will be used by any Lua clients that you build, to ensure consistency. + Further customization is available to experts by editing the Lua sources. + +

+ We strongly recommend that you enable dynamic loading in src/luaconf.h. + This is done automatically for all platforms listed above that have + this feature and also for Windows. + +

Building Lua on other systems

+ +

+ If you're not using the usual Unix tools, then the instructions for + building Lua depend on the compiler you use. You'll need to create + projects (or whatever your compiler uses) for building the library, + the interpreter, and the compiler, as follows: + +

+
+library: +
+lapi.c lcode.c lctype.c ldebug.c ldo.c ldump.c lfunc.c lgc.c llex.c +lmem.c lobject.c lopcodes.c lparser.c lstate.c lstring.c ltable.c +ltm.c lundump.c lvm.c lzio.c +lauxlib.c lbaselib.c lbitlib.c lcorolib.c ldblib.c liolib.c +lmathlib.c loslib.c lstrlib.c ltablib.c loadlib.c linit.c +
+interpreter: +
+ library, lua.c +
+compiler: +
+ library, luac.c +
+ +

+ To use Lua as a library in your own programs you'll need to know how to + create and use libraries with your compiler. Moreover, to dynamically load + C libraries for Lua you'll need to know how to create dynamic libraries + and you'll need to make sure that the Lua API functions are accessible to + those dynamic libraries — but don't link the Lua library + into each dynamic library. For Unix, we recommend that the Lua library + be linked statically into the host program and its symbols exported for + dynamic linking; src/Makefile does this for the Lua interpreter. + For Windows, we recommend that the Lua library be a DLL. + +

+ As mentioned above, you may edit src/luaconf.h to customize + some features before building Lua. + +

Changes since Lua 5.1

+ +

+Here are the main changes introduced in Lua 5.2. +The +reference manual +lists the +incompatibilities that had to be introduced. + +

Main changes

+
    +
  • yieldable pcall and metamethods +
  • new lexical scheme for globals +
  • ephemeron tables +
  • new library for bitwise operations +
  • light C functions +
  • emergency garbage collector +
  • goto statement +
  • finalizers for tables +
+ +Here are the other changes introduced in Lua 5.2: +

Language

+
    +
  • no more fenv for threads or functions +
  • tables honor the __len metamethod +
  • hex and \z escapes in strings +
  • support for hexadecimal floats +
  • order metamethods work for different types +
  • no more verification of opcode consistency +
  • hook event "tail return" replaced by "tail call" +
  • empty statement +
  • break statement may appear in the middle of a block +
+ +

Libraries

+
    +
  • arguments for function called through xpcall +
  • optional 'mode' argument to load and loadfile (to control binary x text) +
  • optional 'env' argument to load and loadfile (environment for loaded chunk) +
  • loadlib may load libraries with global names (RTLD_GLOBAL) +
  • new function package.searchpath +
  • modules receive their paths when loaded +
  • optional base in math.log +
  • optional separator in string.rep +
  • file:write returns file +
  • closing a pipe returns exit status +
  • os.exit may close state +
  • new metamethods __pairs and __ipairs +
  • new option 'isrunning' for collectgarbage and lua_gc +
  • frontier patterns +
  • \0 in patterns +
  • new option *L for io.read +
  • options for io.lines +
  • debug.getlocal can access function varargs +
+ +

C API

+
    +
  • main thread predefined in the registry +
  • new functions +lua_absindex, +lua_arith, +lua_compare, +lua_copy, +lua_len, +lua_rawgetp, +lua_rawsetp, +lua_upvalueid, +lua_upvaluejoin, +lua_version. +
  • new functions +luaL_checkversion, +luaL_setmetatable, +luaL_testudata, +luaL_tolstring. +
  • lua_pushstring and pushlstring return string +
  • nparams and isvararg available in debug API +
  • new lua_Unsigned +
+ +

Implementation

+
    +
  • max constants per function raised to 226 +
  • generational mode for garbage collection (experimental) +
  • NaN trick (experimental) +
  • internal (immutable) version of ctypes +
  • simpler implementation for string buffers +
  • parser uses much less C-stack space (no more auto arrays) +
+ +

Lua standalone interpreter

+
    +
  • new -E option to avoid environment variables +
  • handling of non-string error messages +
+ +

License

+ +[osi certified] + + +

+Lua is free software distributed under the terms of the +MIT license +reproduced below; +it may be used for any purpose, including commercial purposes, +at absolutely no cost without having to ask us. + +The only requirement is that if you do use Lua, +then you should give us credit by including the appropriate copyright notice somewhere in your product or its documentation. + +For details, see +this. + +

+Copyright © 1994–2013 Lua.org, PUC-Rio. + +

+Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +

+The above copyright notice and this permission notice shall be included in +all copies or substantial portions of the Software. + +

+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +THE SOFTWARE. +

+

+ +

+ +Last update: +Sat Nov 9 22:39:16 BRST 2013 + + + + + diff --git a/share/lua/etc/lua.ico b/share/lua/etc/lua.ico new file mode 100644 index 0000000..1dd0d0d Binary files /dev/null and b/share/lua/etc/lua.ico differ diff --git a/share/lua/etc/lua_lang.ico b/share/lua/etc/lua_lang.ico new file mode 100644 index 0000000..b189462 Binary files /dev/null and b/share/lua/etc/lua_lang.ico differ -- cgit v1.2.1