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/* extern.c - external declarations (K & R p218-9) */
#include "def.h"
#include "globvar.h"
#include "symbol.h"
struct typestruct *declarator();
struct typestruct *extypespec();
int paramlist();
struct typestruct *typespec();
/*=============================================================================
-- notation is 1st attempt at EBNF (see Modula-2 book)
program = { type-definition | function-or-data-definition }.
type-definition = "typedef" type-definition-list.
=============================================================================*/
program()
{
nextsym();
while ( sym != EOFSYM )
{
if ( sym = TYPEDEFDECL )
deftypes();
else
functordata();
}
}
/*=============================================================================
type-definition-list. -- not implemented
=============================================================================*/
deftypes()
{}
/*=============================================================================
function-or-data-definition = external-type-specification
( function-definition | init-declarators ).
function-definition = "(" parameter-list ")" arg-list compound-statement.
-- this is different from K & R who omit typedefs and static functions
=============================================================================*/
functordata()
{
struct typestruct *type;
int nargs;
type = extypespec();
if ( sym == LPAREN )
{
nextsym();
nargs = paramlist();
need( RPAREN );
arglist( nargs );
need( LBRACE );
compound( 1 + locptr-pstartloc );/* 1 = function flag, rest = nargs */
oldlevel();
}
else
initdecl( type );
}
/*=============================================================================
external-type-specification = extern-sc type-specifier declarator.
extern-sc = [ extern | static ].
=============================================================================*/
struct typestruct *extypespec()
{
int sc;
switch( sym )
{
case EXTERNDECL:
case STATICDECL:
sc = sym; nextsym(); break;
default:
sc = EXTERNDECL; break;
}
return declarator( typespec() );
}
/*=============================================================================
parameter-list = [identifier { "," identifier }].
=============================================================================*/
int paramlist()
{
int nargs;
locptr = pstartloc;
newlevel();
nargs = 0;
while ( sym == IDENT )
{
addloc( gsname, itype, 0 ); /* fix up types and offsets later */
nextsym();
++nargs;
if ( sym != COMMA )
break;
nextsym();
}
return nargs;
}
/*=============================================================================
arg-list =
=============================================================================*/
arglist( nargs )
int nargs;
{
struct symstruct *symptr;
int argsize, argsp;
int lastsym;
struct typestruct *basetype;
char declflag;
declflag = TRUE;
do
{
switch( sym )
{
case TYPEDECL:
basetype = gsymptr->type;
nextsym();
getarg1( basetype );
break;
case STRUCTDECL:
case UNIONDECL:
lastsym = sym;
nextsym();
getarg( declsu( lastsym ) );
break;
case AUTODECL:
case EXTERNDECL:
case REGDECL:
case STATICDECL:
case SEMICOLON:
nextsym();
break;
default:
declflag = FALSE;
break;
}
}
while ( declflag );
argsp = -2;
symptr = pstartloc;
while ( nargs && symptr < locptr ) /* convert arg sizes to offsets */
{
argsize = symptr->offset;
if ( symptr->type == ctype )
{
++argsp;
--argsize;
}
symptr->offset = argsp;
argsp += argsize;
if ( symptr == pstartloc )
argsp += 2;
--nargs;
++symptr;
}
if ( nargs )
error( "arguments not all declared" );
}
/* getarg( basetype ) - fill in argument types and sizes */
getarg1( basetype )
struct typestruct *basetype;
{
char sname[NAMESIZE];
struct typestruct *type;
int size;
struct symstruct *symptr;
if ( sym != SEMICOLON )
while ( TRUE )
{
type = basetype;
size = getvar( sname, &type );
if ( (symptr = findlorg( sname )) == NULL || symptr->level != ARGLEVEL )
error( "variable not in argument list" );
else if ( symptr->offset != 0 ) /* already in arg list */
multidecl( sname, type, symptr );
else
{
if ( size < 2 || type->typeop == ATYPEOP )
size = 2;
symptr->offset = size;
symptr->type = type;
}
if ( sym == COMMA )
nextsym();
else
break;
}
ns();
}
struct typestruct *declarator( basetype )
struct typestruct *basetype;
{
char sname[NAMESIZE];
int size;
struct symstruct *multi;
size = getvar( sname, &type );
if ( multi = findlorg( sname ) )
multidecl( sname, type, multi );
else
addglb( sname, type, size );
nextsym();
}
struct typestruct *typespec()
{
int lastsym;
switch( sym )
{
case TYPEDECL:
nextsym();
return gsymptr->type;
case STRUCTDECL:
case UNIONDECL:
lastsym = sym;
nextsym();
return declsu( lastsym );
default:
return itype;
}
}
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