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diff --git a/readline/doc/rltech.texinfo b/readline/doc/rltech.texinfo new file mode 100644 index 00000000000..bce508717ac --- /dev/null +++ b/readline/doc/rltech.texinfo @@ -0,0 +1,1548 @@ +@comment %**start of header (This is for running Texinfo on a region.) +@setfilename rltech.info +@comment %**end of header (This is for running Texinfo on a region.) +@setchapternewpage odd + +@ifinfo +This document describes the GNU Readline Library, a utility for aiding +in the consitency of user interface across discrete programs that need +to provide a command line interface. + +Copyright (C) 1988, 1994, 1996 Free Software Foundation, Inc. + +Permission is granted to make and distribute verbatim copies of +this manual provided the copyright notice and this permission notice +pare preserved on all copies. + +@ignore +Permission is granted to process this file through TeX and print the +results, provided the printed document carries copying permission +notice identical to this one except for the removal of this paragraph +(this paragraph not being relevant to the printed manual). +@end ignore + +Permission is granted to copy and distribute modified versions of this +manual under the conditions for verbatim copying, provided that the entire +resulting derived work is distributed under the terms of a permission +notice identical to this one. + +Permission is granted to copy and distribute translations of this manual +into another language, under the above conditions for modified versions, +except that this permission notice may be stated in a translation approved +by the Foundation. +@end ifinfo + +@node Programming with GNU Readline +@chapter Programming with GNU Readline + +This chapter describes the interface between the GNU Readline Library and +other programs. If you are a programmer, and you wish to include the +features found in GNU Readline +such as completion, line editing, and interactive history manipulation +in your own programs, this section is for you. + +@menu +* Basic Behavior:: Using the default behavior of Readline. +* Custom Functions:: Adding your own functions to Readline. +* Readline Variables:: Variables accessible to custom + functions. +* Readline Convenience Functions:: Functions which Readline supplies to + aid in writing your own +* Custom Completers:: Supplanting or supplementing Readline's + completion functions. +@end menu + +@node Basic Behavior +@section Basic Behavior + +Many programs provide a command line interface, such as @code{mail}, +@code{ftp}, and @code{sh}. For such programs, the default behaviour of +Readline is sufficient. This section describes how to use Readline in +the simplest way possible, perhaps to replace calls in your code to +@code{gets()} or @code{fgets ()}. + +@findex readline +@cindex readline, function +The function @code{readline ()} prints a prompt and then reads and returns +a single line of text from the user. The line @code{readline} +returns is allocated with @code{malloc ()}; you should @code{free ()} +the line when you are done with it. The declaration for @code{readline} +in ANSI C is + +@example +@code{char *readline (char *@var{prompt});} +@end example + +@noindent +So, one might say +@example +@code{char *line = readline ("Enter a line: ");} +@end example +@noindent +in order to read a line of text from the user. +The line returned has the final newline removed, so only the +text remains. + +If @code{readline} encounters an @code{EOF} while reading the line, and the +line is empty at that point, then @code{(char *)NULL} is returned. +Otherwise, the line is ended just as if a newline had been typed. + +If you want the user to be able to get at the line later, (with +@key{C-p} for example), you must call @code{add_history ()} to save the +line away in a @dfn{history} list of such lines. + +@example +@code{add_history (line)}; +@end example + +@noindent +For full details on the GNU History Library, see the associated manual. + +It is preferable to avoid saving empty lines on the history list, since +users rarely have a burning need to reuse a blank line. Here is +a function which usefully replaces the standard @code{gets ()} library +function, and has the advantage of no static buffer to overflow: + +@example +/* A static variable for holding the line. */ +static char *line_read = (char *)NULL; + +/* Read a string, and return a pointer to it. Returns NULL on EOF. */ +char * +rl_gets () +@{ + /* If the buffer has already been allocated, return the memory + to the free pool. */ + if (line_read) + @{ + free (line_read); + line_read = (char *)NULL; + @} + + /* Get a line from the user. */ + line_read = readline (""); + + /* If the line has any text in it, save it on the history. */ + if (line_read && *line_read) + add_history (line_read); + + return (line_read); +@} +@end example + +This function gives the user the default behaviour of @key{TAB} +completion: completion on file names. If you do not want Readline to +complete on filenames, you can change the binding of the @key{TAB} key +with @code{rl_bind_key ()}. + +@example +@code{int rl_bind_key (int @var{key}, int (*@var{function})());} +@end example + +@code{rl_bind_key ()} takes two arguments: @var{key} is the character that +you want to bind, and @var{function} is the address of the function to +call when @var{key} is pressed. Binding @key{TAB} to @code{rl_insert ()} +makes @key{TAB} insert itself. +@code{rl_bind_key ()} returns non-zero if @var{key} is not a valid +ASCII character code (between 0 and 255). + +Thus, to disable the default @key{TAB} behavior, the following suffices: +@example +@code{rl_bind_key ('\t', rl_insert);} +@end example + +This code should be executed once at the start of your program; you +might write a function called @code{initialize_readline ()} which +performs this and other desired initializations, such as installing +custom completers (@pxref{Custom Completers}). + +@node Custom Functions +@section Custom Functions + +Readline provides many functions for manipulating the text of +the line, but it isn't possible to anticipate the needs of all +programs. This section describes the various functions and variables +defined within the Readline library which allow a user program to add +customized functionality to Readline. + +@menu +* The Function Type:: C declarations to make code readable. +* Function Writing:: Variables and calling conventions. +@end menu + +@node The Function Type +@subsection The Function Type + +For readabilty, we declare a new type of object, called +@dfn{Function}. A @code{Function} is a C function which +returns an @code{int}. The type declaration for @code{Function} is: + +@noindent +@code{typedef int Function ();} + +The reason for declaring this new type is to make it easier to write +code describing pointers to C functions. Let us say we had a variable +called @var{func} which was a pointer to a function. Instead of the +classic C declaration + +@code{int (*)()func;} + +@noindent +we may write + +@code{Function *func;} + +@noindent +Similarly, there are + +@example +typedef void VFunction (); +typedef char *CPFunction (); @r{and} +typedef char **CPPFunction (); +@end example + +@noindent +for functions returning no value, @code{pointer to char}, and +@code{pointer to pointer to char}, respectively. + +@node Function Writing +@subsection Writing a New Function + +In order to write new functions for Readline, you need to know the +calling conventions for keyboard-invoked functions, and the names of the +variables that describe the current state of the line read so far. + +The calling sequence for a command @code{foo} looks like + +@example +@code{foo (int count, int key)} +@end example + +@noindent +where @var{count} is the numeric argument (or 1 if defaulted) and +@var{key} is the key that invoked this function. + +It is completely up to the function as to what should be done with the +numeric argument. Some functions use it as a repeat count, some +as a flag, and others to choose alternate behavior (refreshing the current +line as opposed to refreshing the screen, for example). Some choose to +ignore it. In general, if a +function uses the numeric argument as a repeat count, it should be able +to do something useful with both negative and positive arguments. +At the very least, it should be aware that it can be passed a +negative argument. + +@node Readline Variables +@section Readline Variables + +These variables are available to function writers. + +@deftypevar {char *} rl_line_buffer +This is the line gathered so far. You are welcome to modify the +contents of the line, but see @ref{Allowing Undoing}. +@end deftypevar + +@deftypevar int rl_point +The offset of the current cursor position in @code{rl_line_buffer} +(the @emph{point}). +@end deftypevar + +@deftypevar int rl_end +The number of characters present in @code{rl_line_buffer}. When +@code{rl_point} is at the end of the line, @code{rl_point} and +@code{rl_end} are equal. +@end deftypevar + +@deftypevar int rl_mark +The mark (saved position) in the current line. If set, the mark +and point define a @emph{region}. +@end deftypevar + +@deftypevar int rl_done +Setting this to a non-zero value causes Readline to return the current +line immediately. +@end deftypevar + +@deftypevar int rl_pending_input +Setting this to a value makes it the next keystroke read. This is a +way to stuff a single character into the input stream. +@end deftypevar + +@deftypevar {char *} rl_prompt +The prompt Readline uses. This is set from the argument to +@code{readline ()}, and should not be assigned to directly. +@end deftypevar + +@deftypevar {char *} rl_library_version +The version number of this revision of the library. +@end deftypevar + +@deftypevar {char *} rl_terminal_name +The terminal type, used for initialization. +@end deftypevar + +@deftypevar {char *} rl_readline_name +This variable is set to a unique name by each application using Readline. +The value allows conditional parsing of the inputrc file +(@pxref{Conditional Init Constructs}). +@end deftypevar + +@deftypevar {FILE *} rl_instream +The stdio stream from which Readline reads input. +@end deftypevar + +@deftypevar {FILE *} rl_outstream +The stdio stream to which Readline performs output. +@end deftypevar + +@deftypevar {Function *} rl_startup_hook +If non-zero, this is the address of a function to call just +before @code{readline} prints the first prompt. +@end deftypevar + +@deftypevar {Function *} rl_event_hook +If non-zero, this is the address of a function to call periodically +when readline is waiting for terminal input. +@end deftypevar + +@deftypevar {Function *} rl_getc_function +If non-zero, @code{readline} will call indirectly through this pointer +to get a character from the input stream. By default, it is set to +@code{rl_getc}, the default @code{readline} character input function +(@pxref{Utility Functions}). +@end deftypevar + +@deftypevar {VFunction *} rl_redisplay_function +If non-zero, @code{readline} will call indirectly through this pointer +to update the display with the current contents of the editing buffer. +By default, it is set to @code{rl_redisplay}, the default @code{readline} +redisplay function (@pxref{Redisplay}). +@end deftypevar + +@deftypevar {Keymap} rl_executing_keymap +This variable is set to the keymap (@pxref{Keymaps}) in which the +currently executing readline function was found. +@end deftypevar + +@deftypevar {Keymap} rl_binding_keymap +This variable is set to the keymap (@pxref{Keymaps}) in which the +last key binding occurred. +@end deftypevar + +@node Readline Convenience Functions +@section Readline Convenience Functions + +@menu +* Function Naming:: How to give a function you write a name. +* Keymaps:: Making keymaps. +* Binding Keys:: Changing Keymaps. +* Associating Function Names and Bindings:: Translate function names to + key sequences. +* Allowing Undoing:: How to make your functions undoable. +* Redisplay:: Functions to control line display. +* Modifying Text:: Functions to modify @code{rl_line_buffer}. +* Utility Functions:: Generally useful functions and hooks. +* Alternate Interface:: Using Readline in a `callback' fashion. +@end menu + +@node Function Naming +@subsection Naming a Function + +The user can dynamically change the bindings of keys while using +Readline. This is done by representing the function with a descriptive +name. The user is able to type the descriptive name when referring to +the function. Thus, in an init file, one might find + +@example +Meta-Rubout: backward-kill-word +@end example + +This binds the keystroke @key{Meta-Rubout} to the function +@emph{descriptively} named @code{backward-kill-word}. You, as the +programmer, should bind the functions you write to descriptive names as +well. Readline provides a function for doing that: + +@deftypefun int rl_add_defun (char *name, Function *function, int key) +Add @var{name} to the list of named functions. Make @var{function} be +the function that gets called. If @var{key} is not -1, then bind it to +@var{function} using @code{rl_bind_key ()}. +@end deftypefun + +Using this function alone is sufficient for most applications. It is +the recommended way to add a few functions to the default functions that +Readline has built in. If you need to do something other +than adding a function to Readline, you may need to use the +underlying functions described below. + +@node Keymaps +@subsection Selecting a Keymap + +Key bindings take place on a @dfn{keymap}. The keymap is the +association between the keys that the user types and the functions that +get run. You can make your own keymaps, copy existing keymaps, and tell +Readline which keymap to use. + +@deftypefun Keymap rl_make_bare_keymap () +Returns a new, empty keymap. The space for the keymap is allocated with +@code{malloc ()}; you should @code{free ()} it when you are done. +@end deftypefun + +@deftypefun Keymap rl_copy_keymap (Keymap map) +Return a new keymap which is a copy of @var{map}. +@end deftypefun + +@deftypefun Keymap rl_make_keymap () +Return a new keymap with the printing characters bound to rl_insert, +the lowercase Meta characters bound to run their equivalents, and +the Meta digits bound to produce numeric arguments. +@end deftypefun + +@deftypefun void rl_discard_keymap (Keymap keymap) +Free the storage associated with @var{keymap}. +@end deftypefun + +Readline has several internal keymaps. These functions allow you to +change which keymap is active. + +@deftypefun Keymap rl_get_keymap () +Returns the currently active keymap. +@end deftypefun + +@deftypefun void rl_set_keymap (Keymap keymap) +Makes @var{keymap} the currently active keymap. +@end deftypefun + +@deftypefun Keymap rl_get_keymap_by_name (char *name) +Return the keymap matching @var{name}. @var{name} is one which would +be supplied in a @code{set keymap} inputrc line (@pxref{Readline Init File}). +@end deftypefun + +@deftypefun {char *} rl_get_keymap_name (Keymap keymap) +Return the name matching @var{keymap}. @var{name} is one which would +be supplied in a @code{set keymap} inputrc line (@pxref{Readline Init File}). +@end deftypefun + +@node Binding Keys +@subsection Binding Keys + +You associate keys with functions through the keymap. Readline has +several internal keymaps: @code{emacs_standard_keymap}, +@code{emacs_meta_keymap}, @code{emacs_ctlx_keymap}, +@code{vi_movement_keymap}, and @code{vi_insertion_keymap}. +@code{emacs_standard_keymap} is the default, and the examples in +this manual assume that. + +These functions manage key bindings. + +@deftypefun int rl_bind_key (int key, Function *function) +Binds @var{key} to @var{function} in the currently active keymap. +Returns non-zero in the case of an invalid @var{key}. +@end deftypefun + +@deftypefun int rl_bind_key_in_map (int key, Function *function, Keymap map) +Bind @var{key} to @var{function} in @var{map}. Returns non-zero in the case +of an invalid @var{key}. +@end deftypefun + +@deftypefun int rl_unbind_key (int key) +Bind @var{key} to the null function in the currently active keymap. +Returns non-zero in case of error. +@end deftypefun + +@deftypefun int rl_unbind_key_in_map (int key, Keymap map) +Bind @var{key} to the null function in @var{map}. +Returns non-zero in case of error. +@end deftypefun + +@deftypefun int rl_unbind_function_in_map (Function *function, Keymap map) +Unbind all keys that execute @var{function} in @var{map}. +@end deftypefun + +@deftypefun int rl_unbind_command_in_map (char *command, Keymap map) +Unbind all keys that are bound to @var{command} in @var{map}. +@end deftypefun + +@deftypefun int rl_generic_bind (int type, char *keyseq, char *data, Keymap map) +Bind the key sequence represented by the string @var{keyseq} to the arbitrary +pointer @var{data}. @var{type} says what kind of data is pointed to by +@var{data}; this can be a function (@code{ISFUNC}), a macro +(@code{ISMACR}), or a keymap (@code{ISKMAP}). This makes new keymaps as +necessary. The initial keymap in which to do bindings is @var{map}. +@end deftypefun + +@deftypefun int rl_parse_and_bind (char *line) +Parse @var{line} as if it had been read from the @code{inputrc} file and +perform any key bindings and variable assignments found +(@pxref{Readline Init File}). +@end deftypefun + +@deftypefun int rl_read_init_file (char *filename) +Read keybindings and variable assignments from @var{filename} +(@pxref{Readline Init File}). +@end deftypefun + +@node Associating Function Names and Bindings +@subsection Associating Function Names and Bindings + +These functions allow you to find out what keys invoke named functions +and the functions invoked by a particular key sequence. + +@deftypefun {Function *} rl_named_function (char *name) +Return the function with name @var{name}. +@end deftypefun + +@deftypefun {Function *} rl_function_of_keyseq (char *keyseq, Keymap map, int *type) +Return the function invoked by @var{keyseq} in keymap @var{map}. +If @var{map} is NULL, the current keymap is used. If @var{type} is +not NULL, the type of the object is returned in it (one of @code{ISFUNC}, +@code{ISKMAP}, or @code{ISMACR}). +@end deftypefun + +@deftypefun {char **} rl_invoking_keyseqs (Function *function) +Return an array of strings representing the key sequences used to +invoke @var{function} in the current keymap. +@end deftypefun + +@deftypefun {char **} rl_invoking_keyseqs_in_map (Function *function, Keymap map) +Return an array of strings representing the key sequences used to +invoke @var{function} in the keymap @var{map}. +@end deftypefun + +@deftypefun void rl_function_dumper (int readable) +Print the readline function names and the key sequences currently +bound to them to @code{rl_outstream}. If @var{readable} is non-zero, +the list is formatted in such a way that it can be made part of an +@code{inputrc} file and re-read. +@end deftypefun + +@deftypefun void rl_list_funmap_names () +Print the names of all bindable Readline functions to @code{rl_outstream}. +@end deftypefun + +@node Allowing Undoing +@subsection Allowing Undoing + +Supporting the undo command is a painless thing, and makes your +functions much more useful. It is certainly easy to try +something if you know you can undo it. I could use an undo function for +the stock market. + +If your function simply inserts text once, or deletes text once, and +uses @code{rl_insert_text ()} or @code{rl_delete_text ()} to do it, then +undoing is already done for you automatically. + +If you do multiple insertions or multiple deletions, or any combination +of these operations, you should group them together into one operation. +This is done with @code{rl_begin_undo_group ()} and +@code{rl_end_undo_group ()}. + +The types of events that can be undone are: + +@example +enum undo_code @{ UNDO_DELETE, UNDO_INSERT, UNDO_BEGIN, UNDO_END @}; +@end example + +Notice that @code{UNDO_DELETE} means to insert some text, and +@code{UNDO_INSERT} means to delete some text. That is, the undo code +tells undo what to undo, not how to undo it. @code{UNDO_BEGIN} and +@code{UNDO_END} are tags added by @code{rl_begin_undo_group ()} and +@code{rl_end_undo_group ()}. + +@deftypefun int rl_begin_undo_group () +Begins saving undo information in a group construct. The undo +information usually comes from calls to @code{rl_insert_text ()} and +@code{rl_delete_text ()}, but could be the result of calls to +@code{rl_add_undo ()}. +@end deftypefun + +@deftypefun int rl_end_undo_group () +Closes the current undo group started with @code{rl_begin_undo_group +()}. There should be one call to @code{rl_end_undo_group ()} +for each call to @code{rl_begin_undo_group ()}. +@end deftypefun + +@deftypefun void rl_add_undo (enum undo_code what, int start, int end, char *text) +Remember how to undo an event (according to @var{what}). The affected +text runs from @var{start} to @var{end}, and encompasses @var{text}. +@end deftypefun + +@deftypefun void free_undo_list () +Free the existing undo list. +@end deftypefun + +@deftypefun int rl_do_undo () +Undo the first thing on the undo list. Returns @code{0} if there was +nothing to undo, non-zero if something was undone. +@end deftypefun + +Finally, if you neither insert nor delete text, but directly modify the +existing text (e.g., change its case), call @code{rl_modifying ()} +once, just before you modify the text. You must supply the indices of +the text range that you are going to modify. + +@deftypefun int rl_modifying (int start, int end) +Tell Readline to save the text between @var{start} and @var{end} as a +single undo unit. It is assumed that you will subsequently modify +that text. +@end deftypefun + +@node Redisplay +@subsection Redisplay + +@deftypefun void rl_redisplay () +Change what's displayed on the screen to reflect the current contents +of @code{rl_line_buffer}. +@end deftypefun + +@deftypefun int rl_forced_update_display () +Force the line to be updated and redisplayed, whether or not +Readline thinks the screen display is correct. +@end deftypefun + +@deftypefun int rl_on_new_line () +Tell the update routines that we have moved onto a new (empty) line, +usually after ouputting a newline. +@end deftypefun + +@deftypefun int rl_reset_line_state () +Reset the display state to a clean state and redisplay the current line +starting on a new line. +@end deftypefun + +@deftypefun int rl_message (va_alist) +The arguments are a string as would be supplied to @code{printf}. The +resulting string is displayed in the @dfn{echo area}. The echo area +is also used to display numeric arguments and search strings. +@end deftypefun + +@deftypefun int rl_clear_message () +Clear the message in the echo area. +@end deftypefun + +@node Modifying Text +@subsection Modifying Text + +@deftypefun int rl_insert_text (char *text) +Insert @var{text} into the line at the current cursor position. +@end deftypefun + +@deftypefun int rl_delete_text (int start, int end) +Delete the text between @var{start} and @var{end} in the current line. +@end deftypefun + +@deftypefun {char *} rl_copy_text (int start, int end) +Return a copy of the text between @var{start} and @var{end} in +the current line. +@end deftypefun + +@deftypefun int rl_kill_text (int start, int end) +Copy the text between @var{start} and @var{end} in the current line +to the kill ring, appending or prepending to the last kill if the +last command was a kill command. The text is deleted. +If @var{start} is less than @var{end}, +the text is appended, otherwise prepended. If the last command was +not a kill, a new kill ring slot is used. +@end deftypefun + +@node Utility Functions +@subsection Utility Functions + +@deftypefun int rl_read_key () +Return the next character available. This handles input inserted into +the input stream via @var{pending input} (@pxref{Readline Variables}) +and @code{rl_stuff_char ()}, macros, and characters read from the keyboard. +@end deftypefun + +@deftypefun int rl_getc (FILE *) +Return the next character available from the keyboard. +@end deftypefun + +@deftypefun int rl_stuff_char (int c) +Insert @var{c} into the Readline input stream. It will be "read" +before Readline attempts to read characters from the terminal with +@code{rl_read_key ()}. +@end deftypefun + +@deftypefun rl_extend_line_buffer (int len) +Ensure that @code{rl_line_buffer} has enough space to hold @var{len} +characters, possibly reallocating it if necessary. +@end deftypefun + +@deftypefun int rl_initialize () +Initialize or re-initialize Readline's internal state. +@end deftypefun + +@deftypefun int rl_reset_terminal (char *terminal_name) +Reinitialize Readline's idea of the terminal settings using +@var{terminal_name} as the terminal type (e.g., @code{vt100}). +@end deftypefun + +@deftypefun int alphabetic (int c) +Return 1 if @var{c} is an alphabetic character. +@end deftypefun + +@deftypefun int numeric (int c) +Return 1 if @var{c} is a numeric character. +@end deftypefun + +@deftypefun int ding () +Ring the terminal bell, obeying the setting of @code{bell-style}. +@end deftypefun + +The following are implemented as macros, defined in @code{chartypes.h}. + +@deftypefun int uppercase_p (int c) +Return 1 if @var{c} is an uppercase alphabetic character. +@end deftypefun + +@deftypefun int lowercase_p (int c) +Return 1 if @var{c} is a lowercase alphabetic character. +@end deftypefun + +@deftypefun int digit_p (int c) +Return 1 if @var{c} is a numeric character. +@end deftypefun + +@deftypefun int to_upper (int c) +If @var{c} is a lowercase alphabetic character, return the corresponding +uppercase character. +@end deftypefun + +@deftypefun int to_lower (int c) +If @var{c} is an uppercase alphabetic character, return the corresponding +lowercase character. +@end deftypefun + +@deftypefun int digit_value (int c) +If @var{c} is a number, return the value it represents. +@end deftypefun + +@node Alternate Interface +@subsection Alternate Interface + +An alternate interface is available to plain @code{readline()}. Some +applications need to interleave keyboard I/O with file, device, or +window system I/O, typically by using a main loop to @code{select()} +on various file descriptors. To accomodate this need, readline can +also be invoked as a `callback' function from an event loop. There +are functions available to make this easy. + +@deftypefun void rl_callback_handler_install (char *prompt, Vfunction *lhandler) +Set up the terminal for readline I/O and display the initial +expanded value of @var{prompt}. Save the value of @var{lhandler} to +use as a callback when a complete line of input has been entered. +@end deftypefun + +@deftypefun void rl_callback_read_char () +Whenever an application determines that keyboard input is available, it +should call @code{rl_callback_read_char()}, which will read the next +character from the current input source. If that character completes the +line, @code{rl_callback_read_char} will invoke the @var{lhandler} +function saved by @code{rl_callback_handler_install} to process the +line. @code{EOF} is indicated by calling @var{lhandler} with a +@code{NULL} line. +@end deftypefun + +@deftypefun void rl_callback_handler_remove () +Restore the terminal to its initial state and remove the line handler. +This may be called from within a callback as well as independently. +@end deftypefun + +@subsection An Example + +Here is a function which changes lowercase characters to their uppercase +equivalents, and uppercase characters to lowercase. If +this function was bound to @samp{M-c}, then typing @samp{M-c} would +change the case of the character under point. Typing @samp{M-1 0 M-c} +would change the case of the following 10 characters, leaving the cursor on +the last character changed. + +@example +/* Invert the case of the COUNT following characters. */ +int +invert_case_line (count, key) + int count, key; +@{ + register int start, end, i; + + start = rl_point; + + if (rl_point >= rl_end) + return (0); + + if (count < 0) + @{ + direction = -1; + count = -count; + @} + else + direction = 1; + + /* Find the end of the range to modify. */ + end = start + (count * direction); + + /* Force it to be within range. */ + if (end > rl_end) + end = rl_end; + else if (end < 0) + end = 0; + + if (start == end) + return (0); + + if (start > end) + @{ + int temp = start; + start = end; + end = temp; + @} + + /* Tell readline that we are modifying the line, so it will save + the undo information. */ + rl_modifying (start, end); + + for (i = start; i != end; i++) + @{ + if (uppercase_p (rl_line_buffer[i])) + rl_line_buffer[i] = to_lower (rl_line_buffer[i]); + else if (lowercase_p (rl_line_buffer[i])) + rl_line_buffer[i] = to_upper (rl_line_buffer[i]); + @} + /* Move point to on top of the last character changed. */ + rl_point = (direction == 1) ? end - 1 : start; + return (0); +@} +@end example + +@node Custom Completers +@section Custom Completers + +Typically, a program that reads commands from the user has a way of +disambiguating commands and data. If your program is one of these, then +it can provide completion for commands, data, or both. +The following sections describe how your program and Readline +cooperate to provide this service. + +@menu +* How Completing Works:: The logic used to do completion. +* Completion Functions:: Functions provided by Readline. +* Completion Variables:: Variables which control completion. +* A Short Completion Example:: An example of writing completer subroutines. +@end menu + +@node How Completing Works +@subsection How Completing Works + +In order to complete some text, the full list of possible completions +must be available. That is, it is not possible to accurately +expand a partial word without knowing all of the possible words +which make sense in that context. The Readline library provides +the user interface to completion, and two of the most common +completion functions: filename and username. For completing other types +of text, you must write your own completion function. This section +describes exactly what such functions must do, and provides an example. + +There are three major functions used to perform completion: + +@enumerate +@item +The user-interface function @code{rl_complete ()}. This function is +called with the same arguments as other Readline +functions intended for interactive use: @var{count} and +@var{invoking_key}. It isolates the word to be completed and calls +@code{completion_matches ()} to generate a list of possible completions. +It then either lists the possible completions, inserts the possible +completions, or actually performs the +completion, depending on which behavior is desired. + +@item +The internal function @code{completion_matches ()} uses your +@dfn{generator} function to generate the list of possible matches, and +then returns the array of these matches. You should place the address +of your generator function in @code{rl_completion_entry_function}. + +@item +The generator function is called repeatedly from +@code{completion_matches ()}, returning a string each time. The +arguments to the generator function are @var{text} and @var{state}. +@var{text} is the partial word to be completed. @var{state} is zero the +first time the function is called, allowing the generator to perform +any necessary initialization, and a positive non-zero integer for +each subsequent call. When the generator function returns +@code{(char *)NULL} this signals @code{completion_matches ()} that there are +no more possibilities left. Usually the generator function computes the +list of possible completions when @var{state} is zero, and returns them +one at a time on subsequent calls. Each string the generator function +returns as a match must be allocated with @code{malloc()}; Readline +frees the strings when it has finished with them. + +@end enumerate + +@deftypefun int rl_complete (int ignore, int invoking_key) +Complete the word at or before point. You have supplied the function +that does the initial simple matching selection algorithm (see +@code{completion_matches ()}). The default is to do filename completion. +@end deftypefun + +@deftypevar {Function *} rl_completion_entry_function +This is a pointer to the generator function for @code{completion_matches +()}. If the value of @code{rl_completion_entry_function} is +@code{(Function *)NULL} then the default filename generator function, +@code{filename_completion_function ()}, is used. +@end deftypevar + +@node Completion Functions +@subsection Completion Functions + +Here is the complete list of callable completion functions present in +Readline. + +@deftypefun int rl_complete_internal (int what_to_do) +Complete the word at or before point. @var{what_to_do} says what to do +with the completion. A value of @samp{?} means list the possible +completions. @samp{TAB} means do standard completion. @samp{*} means +insert all of the possible completions. @samp{!} means to display +all of the possible completions, if there is more than one, as well as +performing partial completion. +@end deftypefun + +@deftypefun int rl_complete (int ignore, int invoking_key) +Complete the word at or before point. You have supplied the function +that does the initial simple matching selection algorithm (see +@code{completion_matches ()} and @code{rl_completion_entry_function}). +The default is to do filename +completion. This calls @code{rl_complete_internal ()} with an +argument depending on @var{invoking_key}. +@end deftypefun + +@deftypefun int rl_possible_completions (int count, int invoking_key)) +List the possible completions. See description of @code{rl_complete +()}. This calls @code{rl_complete_internal ()} with an argument of +@samp{?}. +@end deftypefun + +@deftypefun int rl_insert_completions (int count, int invoking_key)) +Insert the list of possible completions into the line, deleting the +partially-completed word. See description of @code{rl_complete ()}. +This calls @code{rl_complete_internal ()} with an argument of @samp{*}. +@end deftypefun + +@deftypefun {char **} completion_matches (char *text, CPFunction *entry_func) +Returns an array of @code{(char *)} which is a list of completions for +@var{text}. If there are no completions, returns @code{(char **)NULL}. +The first entry in the returned array is the substitution for @var{text}. +The remaining entries are the possible completions. The array is +terminated with a @code{NULL} pointer. + +@var{entry_func} is a function of two args, and returns a +@code{(char *)}. The first argument is @var{text}. The second is a +state argument; it is zero on the first call, and non-zero on subsequent +calls. @var{entry_func} returns a @code{NULL} pointer to the caller +when there are no more matches. +@end deftypefun + +@deftypefun {char *} filename_completion_function (char *text, int state) +A generator function for filename completion in the general case. Note +that completion in Bash is a little different because of all +the pathnames that must be followed when looking up completions for a +command. The Bash source is a useful reference for writing custom +completion functions. +@end deftypefun + +@deftypefun {char *} username_completion_function (char *text, int state) +A completion generator for usernames. @var{text} contains a partial +username preceded by a random character (usually @samp{~}). As with all +completion generators, @var{state} is zero on the first call and non-zero +for subsequent calls. +@end deftypefun + +@node Completion Variables +@subsection Completion Variables + +@deftypevar {Function *} rl_completion_entry_function +A pointer to the generator function for @code{completion_matches ()}. +@code{NULL} means to use @code{filename_entry_function ()}, the default +filename completer. +@end deftypevar + +@deftypevar {CPPFunction *} rl_attempted_completion_function +A pointer to an alternative function to create matches. +The function is called with @var{text}, @var{start}, and @var{end}. +@var{start} and @var{end} are indices in @code{rl_line_buffer} saying +what the boundaries of @var{text} are. If this function exists and +returns @code{NULL}, or if this variable is set to @code{NULL}, then +@code{rl_complete ()} will call the value of +@code{rl_completion_entry_function} to generate matches, otherwise the +array of strings returned will be used. +@end deftypevar + +@deftypevar {CPFunction *} rl_filename_quoting_function +A pointer to a function that will quote a filename in an application- +specific fashion. This is called if filename completion is being +attempted and one of the characters in @code{rl_filename_quote_characters} +appears in a completed filename. The function is called with +@var{text}, @var{match_type}, and @var{quote_pointer}. The @var{text} +is the filename to be quoted. The @var{match_type} is either +@code{SINGLE_MATCH}, if there is only one completion match, or +@code{MULT_MATCH}. Some functions use this to decide whether or not to +insert a closing quote character. The @var{quote_pointer} is a pointer +to any opening quote character the user typed. Some functions choose +to reset this character. +@end deftypevar + +@deftypevar {CPFunction *} rl_filename_dequoting_function +A pointer to a function that will remove application-specific quoting +characters from a filename before completion is attempted, so those +characters do not interfere with matching the text against names in +the filesystem. It is called with @var{text}, the text of the word +to be dequoted, and @var{quote_char}, which is the quoting character +that delimits the filename (usually @samp{'} or @samp{"}). If +@var{quote_char} is zero, the filename was not in an embedded string. +@end deftypevar + +@deftypevar {Function *} rl_char_is_quoted_p +A pointer to a function to call that determines whether or not a specific +character in the line buffer is quoted, according to whatever quoting +mechanism the program calling readline uses. The function is called with +two arguments: @var{text}, the text of the line, and @var{index}, the +index of the character in the line. It is used to decide whether a +character found in @code{rl_completer_word_break_characters} should be +used to break words for the completer. +@end deftypevar + +@deftypevar int rl_completion_query_items +Up to this many items will be displayed in response to a +possible-completions call. After that, we ask the user if she is sure +she wants to see them all. The default value is 100. +@end deftypevar + +@deftypevar {char *} rl_basic_word_break_characters +The basic list of characters that signal a break between words for the +completer routine. The default value of this variable is the characters +which break words for completion in Bash, i.e., +@code{" \t\n\"\\'`@@$><=;|&@{("}. +@end deftypevar + +@deftypevar {char *} rl_basic_quote_characters +List of quote characters which can cause a word break. +@end deftypevar + +@deftypevar {char *} rl_completer_word_break_characters +The list of characters that signal a break between words for +@code{rl_complete_internal ()}. The default list is the value of +@code{rl_basic_word_break_characters}. +@end deftypevar + +@deftypevar {char *} rl_completer_quote_characters +List of characters which can be used to quote a substring of the line. +Completion occurs on the entire substring, and within the substring +@code{rl_completer_word_break_characters} are treated as any other character, +unless they also appear within this list. +@end deftypevar + +@deftypevar {char *} rl_filename_quote_characters +A list of characters that cause a filename to be quoted by the completer +when they appear in a completed filename. The default is the null string. +@end deftypevar + +@deftypevar {char *} rl_special_prefixes +The list of characters that are word break characters, but should be +left in @var{text} when it is passed to the completion function. +Programs can use this to help determine what kind of completing to do. +For instance, Bash sets this variable to "$@@" so that it can complete +shell variables and hostnames. +@end deftypevar + +@deftypevar {int} rl_completion_append_character +When a single completion alternative matches at the end of the command +line, this character is appended to the inserted completion text. The +default is a space character (@samp{ }). Setting this to the null +character (@samp{\0}) prevents anything being appended automatically. +This can be changed in custom completion functions to +provide the ``most sensible word separator character'' according to +an application-specific command line syntax specification. +@end deftypevar + +@deftypevar int rl_ignore_completion_duplicates +If non-zero, then disallow duplicates in the matches. Default is 1. +@end deftypevar + +@deftypevar int rl_filename_completion_desired +Non-zero means that the results of the matches are to be treated as +filenames. This is @emph{always} zero on entry, and can only be changed +within a completion entry generator function. If it is set to a non-zero +value, directory names have a slash appended and Readline attempts to +quote completed filenames if they contain any embedded word break +characters. +@end deftypevar + +@deftypevar int rl_filename_quoting_desired +Non-zero means that the results of the matches are to be quoted using +double quotes (or an application-specific quoting mechanism) if the +completed filename contains any characters in +@code{rl_filename_quote_chars}. This is @emph{always} non-zero +on entry, and can only be changed within a completion entry generator +function. The quoting is effected via a call to the function pointed to +by @code{rl_filename_quoting_function}. +@end deftypevar + +@deftypevar int rl_inhibit_completion +If this variable is non-zero, completion is inhibit<ed. The completion +character will be inserted as any other bound to @code{self-insert}. +@end deftypevar + +@deftypevar {Function *} rl_ignore_some_completions_function +This function, if defined, is called by the completer when real filename +completion is done, after all the matching names have been generated. +It is passed a @code{NULL} terminated array of matches. +The first element (@code{matches[0]}) is the +maximal substring common to all matches. This function can +re-arrange the list of matches as required, but each element deleted +from the array must be freed. +@end deftypevar + +@deftypevar {Function *} rl_directory_completion_hook +This function, if defined, is allowed to modify the directory portion +of filenames Readline completes. It is called with the address of a +string (the current directory name) as an argument. It could be used +to expand symbolic links or shell variables in pathnames. +@end deftypevar + +@node A Short Completion Example +@subsection A Short Completion Example + +Here is a small application demonstrating the use of the GNU Readline +library. It is called @code{fileman}, and the source code resides in +@file{examples/fileman.c}. This sample application provides +completion of command names, line editing features, and access to the +history list. + +@page +@smallexample +/* fileman.c -- A tiny application which demonstrates how to use the + GNU Readline library. This application interactively allows users + to manipulate files and their modes. */ + +#include <stdio.h> +#include <sys/types.h> +#include <sys/file.h> +#include <sys/stat.h> +#include <sys/errno.h> + +#include <readline/readline.h> +#include <readline/history.h> + +extern char *getwd (); +extern char *xmalloc (); + +/* The names of functions that actually do the manipulation. */ +int com_list (), com_view (), com_rename (), com_stat (), com_pwd (); +int com_delete (), com_help (), com_cd (), com_quit (); + +/* A structure which contains information on the commands this program + can understand. */ + +typedef struct @{ + char *name; /* User printable name of the function. */ + Function *func; /* Function to call to do the job. */ + char *doc; /* Documentation for this function. */ +@} COMMAND; + +COMMAND commands[] = @{ + @{ "cd", com_cd, "Change to directory DIR" @}, + @{ "delete", com_delete, "Delete FILE" @}, + @{ "help", com_help, "Display this text" @}, + @{ "?", com_help, "Synonym for `help'" @}, + @{ "list", com_list, "List files in DIR" @}, + @{ "ls", com_list, "Synonym for `list'" @}, + @{ "pwd", com_pwd, "Print the current working directory" @}, + @{ "quit", com_quit, "Quit using Fileman" @}, + @{ "rename", com_rename, "Rename FILE to NEWNAME" @}, + @{ "stat", com_stat, "Print out statistics on FILE" @}, + @{ "view", com_view, "View the contents of FILE" @}, + @{ (char *)NULL, (Function *)NULL, (char *)NULL @} +@}; + +/* Forward declarations. */ +char *stripwhite (); +COMMAND *find_command (); + +/* The name of this program, as taken from argv[0]. */ +char *progname; + +/* When non-zero, this global means the user is done using this program. */ +int done; + +char * +dupstr (s) + int s; +@{ + char *r; + + r = xmalloc (strlen (s) + 1); + strcpy (r, s); + return (r); +@} + +main (argc, argv) + int argc; + char **argv; +@{ + char *line, *s; + + progname = argv[0]; + + initialize_readline (); /* Bind our completer. */ + + /* Loop reading and executing lines until the user quits. */ + for ( ; done == 0; ) + @{ + line = readline ("FileMan: "); + + if (!line) + break; + + /* Remove leading and trailing whitespace from the line. + Then, if there is anything left, add it to the history list + and execute it. */ + s = stripwhite (line); + + if (*s) + @{ + add_history (s); + execute_line (s); + @} + + free (line); + @} + exit (0); +@} + +/* Execute a command line. */ +int +execute_line (line) + char *line; +@{ + register int i; + COMMAND *command; + char *word; + + /* Isolate the command word. */ + i = 0; + while (line[i] && whitespace (line[i])) + i++; + word = line + i; + + while (line[i] && !whitespace (line[i])) + i++; + + if (line[i]) + line[i++] = '\0'; + + command = find_command (word); + + if (!command) + @{ + fprintf (stderr, "%s: No such command for FileMan.\n", word); + return (-1); + @} + + /* Get argument to command, if any. */ + while (whitespace (line[i])) + i++; + + word = line + i; + + /* Call the function. */ + return ((*(command->func)) (word)); +@} + +/* Look up NAME as the name of a command, and return a pointer to that + command. Return a NULL pointer if NAME isn't a command name. */ +COMMAND * +find_command (name) + char *name; +@{ + register int i; + + for (i = 0; commands[i].name; i++) + if (strcmp (name, commands[i].name) == 0) + return (&commands[i]); + + return ((COMMAND *)NULL); +@} + +/* Strip whitespace from the start and end of STRING. Return a pointer + into STRING. */ +char * +stripwhite (string) + char *string; +@{ + register char *s, *t; + + for (s = string; whitespace (*s); s++) + ; + + if (*s == 0) + return (s); + + t = s + strlen (s) - 1; + while (t > s && whitespace (*t)) + t--; + *++t = '\0'; + + return s; +@} + +/* **************************************************************** */ +/* */ +/* Interface to Readline Completion */ +/* */ +/* **************************************************************** */ + +char *command_generator (); +char **fileman_completion (); + +/* Tell the GNU Readline library how to complete. We want to try to complete + on command names if this is the first word in the line, or on filenames + if not. */ +initialize_readline () +@{ + /* Allow conditional parsing of the ~/.inputrc file. */ + rl_readline_name = "FileMan"; + + /* Tell the completer that we want a crack first. */ + rl_attempted_completion_function = (CPPFunction *)fileman_completion; +@} + +/* Attempt to complete on the contents of TEXT. START and END bound the + region of rl_line_buffer that contains the word to complete. TEXT is + the word to complete. We can use the entire contents of rl_line_buffer + in case we want to do some simple parsing. Return the array of matches, + or NULL if there aren't any. */ +char ** +fileman_completion (text, start, end) + char *text; + int start, end; +@{ + char **matches; + + matches = (char **)NULL; + + /* If this word is at the start of the line, then it is a command + to complete. Otherwise it is the name of a file in the current + directory. */ + if (start == 0) + matches = completion_matches (text, command_generator); + + return (matches); +@} + +/* Generator function for command completion. STATE lets us know whether + to start from scratch; without any state (i.e. STATE == 0), then we + start at the top of the list. */ +char * +command_generator (text, state) + char *text; + int state; +@{ + static int list_index, len; + char *name; + + /* If this is a new word to complete, initialize now. This includes + saving the length of TEXT for efficiency, and initializing the index + variable to 0. */ + if (!state) + @{ + list_index = 0; + len = strlen (text); + @} + + /* Return the next name which partially matches from the command list. */ + while (name = commands[list_index].name) + @{ + list_index++; + + if (strncmp (name, text, len) == 0) + return (dupstr(name)); + @} + + /* If no names matched, then return NULL. */ + return ((char *)NULL); +@} + +/* **************************************************************** */ +/* */ +/* FileMan Commands */ +/* */ +/* **************************************************************** */ + +/* String to pass to system (). This is for the LIST, VIEW and RENAME + commands. */ +static char syscom[1024]; + +/* List the file(s) named in arg. */ +com_list (arg) + char *arg; +@{ + if (!arg) + arg = ""; + + sprintf (syscom, "ls -FClg %s", arg); + return (system (syscom)); +@} + +com_view (arg) + char *arg; +@{ + if (!valid_argument ("view", arg)) + return 1; + + sprintf (syscom, "more %s", arg); + return (system (syscom)); +@} + +com_rename (arg) + char *arg; +@{ + too_dangerous ("rename"); + return (1); +@} + +com_stat (arg) + char *arg; +@{ + struct stat finfo; + + if (!valid_argument ("stat", arg)) + return (1); + + if (stat (arg, &finfo) == -1) + @{ + perror (arg); + return (1); + @} + + printf ("Statistics for `%s':\n", arg); + + printf ("%s has %d link%s, and is %d byte%s in length.\n", arg, + finfo.st_nlink, + (finfo.st_nlink == 1) ? "" : "s", + finfo.st_size, + (finfo.st_size == 1) ? "" : "s"); + printf ("Inode Last Change at: %s", ctime (&finfo.st_ctime)); + printf (" Last access at: %s", ctime (&finfo.st_atime)); + printf (" Last modified at: %s", ctime (&finfo.st_mtime)); + return (0); +@} + +com_delete (arg) + char *arg; +@{ + too_dangerous ("delete"); + return (1); +@} + +/* Print out help for ARG, or for all of the commands if ARG is + not present. */ +com_help (arg) + char *arg; +@{ + register int i; + int printed = 0; + + for (i = 0; commands[i].name; i++) + @{ + if (!*arg || (strcmp (arg, commands[i].name) == 0)) + @{ + printf ("%s\t\t%s.\n", commands[i].name, commands[i].doc); + printed++; + @} + @} + + if (!printed) + @{ + printf ("No commands match `%s'. Possibilties are:\n", arg); + + for (i = 0; commands[i].name; i++) + @{ + /* Print in six columns. */ + if (printed == 6) + @{ + printed = 0; + printf ("\n"); + @} + + printf ("%s\t", commands[i].name); + printed++; + @} + + if (printed) + printf ("\n"); + @} + return (0); +@} + +/* Change to the directory ARG. */ +com_cd (arg) + char *arg; +@{ + if (chdir (arg) == -1) + @{ + perror (arg); + return 1; + @} + + com_pwd (""); + return (0); +@} + +/* Print out the current working directory. */ +com_pwd (ignore) + char *ignore; +@{ + char dir[1024], *s; + + s = getwd (dir); + if (s == 0) + @{ + printf ("Error getting pwd: %s\n", dir); + return 1; + @} + + printf ("Current directory is %s\n", dir); + return 0; +@} + +/* The user wishes to quit using this program. Just set DONE non-zero. */ +com_quit (arg) + char *arg; +@{ + done = 1; + return (0); +@} + +/* Function which tells you that you can't do this. */ +too_dangerous (caller) + char *caller; +@{ + fprintf (stderr, + "%s: Too dangerous for me to distribute. Write it yourself.\n", + caller); +@} + +/* Return non-zero if ARG is a valid argument for CALLER, else print + an error message and return zero. */ +int +valid_argument (caller, arg) + char *caller, *arg; +@{ + if (!arg || !*arg) + @{ + fprintf (stderr, "%s: Argument required.\n", caller); + return (0); + @} + + return (1); +@} +@end smallexample |