1 @comment %**start of header (This is for running Texinfo on a region.)
2 @setfilename rltech.info
3 @comment %**end of header (This is for running Texinfo on a region.)
7 This document describes the GNU Readline Library, a utility for aiding
8 in the consitency of user interface across discrete programs that need
9 to provide a command line interface.
11 Copyright (C) 1988, 1994, 1996 Free Software Foundation, Inc.
13 Permission is granted to make and distribute verbatim copies of
14 this manual provided the copyright notice and this permission notice
15 pare preserved on all copies.
18 Permission is granted to process this file through TeX and print the
19 results, provided the printed document carries copying permission
20 notice identical to this one except for the removal of this paragraph
21 (this paragraph not being relevant to the printed manual).
24 Permission is granted to copy and distribute modified versions of this
25 manual under the conditions for verbatim copying, provided that the entire
26 resulting derived work is distributed under the terms of a permission
27 notice identical to this one.
29 Permission is granted to copy and distribute translations of this manual
30 into another language, under the above conditions for modified versions,
31 except that this permission notice may be stated in a translation approved
35 @node Programming with GNU Readline
36 @chapter Programming with GNU Readline
38 This chapter describes the interface between the GNU Readline Library and
39 other programs. If you are a programmer, and you wish to include the
40 features found in GNU Readline
41 such as completion, line editing, and interactive history manipulation
42 in your own programs, this section is for you.
45 * Basic Behavior:: Using the default behavior of Readline.
46 * Custom Functions:: Adding your own functions to Readline.
47 * Readline Variables:: Variables accessible to custom
49 * Readline Convenience Functions:: Functions which Readline supplies to
50 aid in writing your own
51 * Custom Completers:: Supplanting or supplementing Readline's
56 @section Basic Behavior
58 Many programs provide a command line interface, such as @code{mail},
59 @code{ftp}, and @code{sh}. For such programs, the default behaviour of
60 Readline is sufficient. This section describes how to use Readline in
61 the simplest way possible, perhaps to replace calls in your code to
62 @code{gets()} or @code{fgets ()}.
65 @cindex readline, function
66 The function @code{readline ()} prints a prompt and then reads and returns
67 a single line of text from the user. The line @code{readline}
68 returns is allocated with @code{malloc ()}; you should @code{free ()}
69 the line when you are done with it. The declaration for @code{readline}
73 @code{char *readline (char *@var{prompt});}
79 @code{char *line = readline ("Enter a line: ");}
82 in order to read a line of text from the user.
83 The line returned has the final newline removed, so only the
86 If @code{readline} encounters an @code{EOF} while reading the line, and the
87 line is empty at that point, then @code{(char *)NULL} is returned.
88 Otherwise, the line is ended just as if a newline had been typed.
90 If you want the user to be able to get at the line later, (with
91 @key{C-p} for example), you must call @code{add_history ()} to save the
92 line away in a @dfn{history} list of such lines.
95 @code{add_history (line)};
99 For full details on the GNU History Library, see the associated manual.
101 It is preferable to avoid saving empty lines on the history list, since
102 users rarely have a burning need to reuse a blank line. Here is
103 a function which usefully replaces the standard @code{gets ()} library
104 function, and has the advantage of no static buffer to overflow:
107 /* A static variable for holding the line. */
108 static char *line_read = (char *)NULL;
110 /* Read a string, and return a pointer to it. Returns NULL on EOF. */
114 /* If the buffer has already been allocated, return the memory
119 line_read = (char *)NULL;
122 /* Get a line from the user. */
123 line_read = readline ("");
125 /* If the line has any text in it, save it on the history. */
126 if (line_read && *line_read)
127 add_history (line_read);
133 This function gives the user the default behaviour of @key{TAB}
134 completion: completion on file names. If you do not want Readline to
135 complete on filenames, you can change the binding of the @key{TAB} key
136 with @code{rl_bind_key ()}.
139 @code{int rl_bind_key (int @var{key}, int (*@var{function})());}
142 @code{rl_bind_key ()} takes two arguments: @var{key} is the character that
143 you want to bind, and @var{function} is the address of the function to
144 call when @var{key} is pressed. Binding @key{TAB} to @code{rl_insert ()}
145 makes @key{TAB} insert itself.
146 @code{rl_bind_key ()} returns non-zero if @var{key} is not a valid
147 ASCII character code (between 0 and 255).
149 Thus, to disable the default @key{TAB} behavior, the following suffices:
151 @code{rl_bind_key ('\t', rl_insert);}
154 This code should be executed once at the start of your program; you
155 might write a function called @code{initialize_readline ()} which
156 performs this and other desired initializations, such as installing
157 custom completers (@pxref{Custom Completers}).
159 @node Custom Functions
160 @section Custom Functions
162 Readline provides many functions for manipulating the text of
163 the line, but it isn't possible to anticipate the needs of all
164 programs. This section describes the various functions and variables
165 defined within the Readline library which allow a user program to add
166 customized functionality to Readline.
169 * The Function Type:: C declarations to make code readable.
170 * Function Writing:: Variables and calling conventions.
173 @node The Function Type
174 @subsection The Function Type
176 For readabilty, we declare a new type of object, called
177 @dfn{Function}. A @code{Function} is a C function which
178 returns an @code{int}. The type declaration for @code{Function} is:
181 @code{typedef int Function ();}
183 The reason for declaring this new type is to make it easier to write
184 code describing pointers to C functions. Let us say we had a variable
185 called @var{func} which was a pointer to a function. Instead of the
186 classic C declaration
188 @code{int (*)()func;}
193 @code{Function *func;}
199 typedef void VFunction ();
200 typedef char *CPFunction (); @r{and}
201 typedef char **CPPFunction ();
205 for functions returning no value, @code{pointer to char}, and
206 @code{pointer to pointer to char}, respectively.
208 @node Function Writing
209 @subsection Writing a New Function
211 In order to write new functions for Readline, you need to know the
212 calling conventions for keyboard-invoked functions, and the names of the
213 variables that describe the current state of the line read so far.
215 The calling sequence for a command @code{foo} looks like
218 @code{foo (int count, int key)}
222 where @var{count} is the numeric argument (or 1 if defaulted) and
223 @var{key} is the key that invoked this function.
225 It is completely up to the function as to what should be done with the
226 numeric argument. Some functions use it as a repeat count, some
227 as a flag, and others to choose alternate behavior (refreshing the current
228 line as opposed to refreshing the screen, for example). Some choose to
229 ignore it. In general, if a
230 function uses the numeric argument as a repeat count, it should be able
231 to do something useful with both negative and positive arguments.
232 At the very least, it should be aware that it can be passed a
235 @node Readline Variables
236 @section Readline Variables
238 These variables are available to function writers.
240 @deftypevar {char *} rl_line_buffer
241 This is the line gathered so far. You are welcome to modify the
242 contents of the line, but see @ref{Allowing Undoing}.
245 @deftypevar int rl_point
246 The offset of the current cursor position in @code{rl_line_buffer}
250 @deftypevar int rl_end
251 The number of characters present in @code{rl_line_buffer}. When
252 @code{rl_point} is at the end of the line, @code{rl_point} and
253 @code{rl_end} are equal.
256 @deftypevar int rl_mark
257 The mark (saved position) in the current line. If set, the mark
258 and point define a @emph{region}.
261 @deftypevar int rl_done
262 Setting this to a non-zero value causes Readline to return the current
266 @deftypevar int rl_pending_input
267 Setting this to a value makes it the next keystroke read. This is a
268 way to stuff a single character into the input stream.
271 @deftypevar {char *} rl_prompt
272 The prompt Readline uses. This is set from the argument to
273 @code{readline ()}, and should not be assigned to directly.
276 @deftypevar {char *} rl_library_version
277 The version number of this revision of the library.
280 @deftypevar {char *} rl_terminal_name
281 The terminal type, used for initialization.
284 @deftypevar {char *} rl_readline_name
285 This variable is set to a unique name by each application using Readline.
286 The value allows conditional parsing of the inputrc file
287 (@pxref{Conditional Init Constructs}).
290 @deftypevar {FILE *} rl_instream
291 The stdio stream from which Readline reads input.
294 @deftypevar {FILE *} rl_outstream
295 The stdio stream to which Readline performs output.
298 @deftypevar {Function *} rl_startup_hook
299 If non-zero, this is the address of a function to call just
300 before @code{readline} prints the first prompt.
303 @deftypevar {Function *} rl_event_hook
304 If non-zero, this is the address of a function to call periodically
305 when readline is waiting for terminal input.
308 @deftypevar {Function *} rl_getc_function
309 If non-zero, @code{readline} will call indirectly through this pointer
310 to get a character from the input stream. By default, it is set to
311 @code{rl_getc}, the default @code{readline} character input function
312 (@pxref{Utility Functions}).
315 @deftypevar {VFunction *} rl_redisplay_function
316 If non-zero, @code{readline} will call indirectly through this pointer
317 to update the display with the current contents of the editing buffer.
318 By default, it is set to @code{rl_redisplay}, the default @code{readline}
319 redisplay function (@pxref{Redisplay}).
322 @deftypevar {Keymap} rl_executing_keymap
323 This variable is set to the keymap (@pxref{Keymaps}) in which the
324 currently executing readline function was found.
327 @deftypevar {Keymap} rl_binding_keymap
328 This variable is set to the keymap (@pxref{Keymaps}) in which the
329 last key binding occurred.
332 @node Readline Convenience Functions
333 @section Readline Convenience Functions
336 * Function Naming:: How to give a function you write a name.
337 * Keymaps:: Making keymaps.
338 * Binding Keys:: Changing Keymaps.
339 * Associating Function Names and Bindings:: Translate function names to
341 * Allowing Undoing:: How to make your functions undoable.
342 * Redisplay:: Functions to control line display.
343 * Modifying Text:: Functions to modify @code{rl_line_buffer}.
344 * Utility Functions:: Generally useful functions and hooks.
345 * Alternate Interface:: Using Readline in a `callback' fashion.
348 @node Function Naming
349 @subsection Naming a Function
351 The user can dynamically change the bindings of keys while using
352 Readline. This is done by representing the function with a descriptive
353 name. The user is able to type the descriptive name when referring to
354 the function. Thus, in an init file, one might find
357 Meta-Rubout: backward-kill-word
360 This binds the keystroke @key{Meta-Rubout} to the function
361 @emph{descriptively} named @code{backward-kill-word}. You, as the
362 programmer, should bind the functions you write to descriptive names as
363 well. Readline provides a function for doing that:
365 @deftypefun int rl_add_defun (char *name, Function *function, int key)
366 Add @var{name} to the list of named functions. Make @var{function} be
367 the function that gets called. If @var{key} is not -1, then bind it to
368 @var{function} using @code{rl_bind_key ()}.
371 Using this function alone is sufficient for most applications. It is
372 the recommended way to add a few functions to the default functions that
373 Readline has built in. If you need to do something other
374 than adding a function to Readline, you may need to use the
375 underlying functions described below.
378 @subsection Selecting a Keymap
380 Key bindings take place on a @dfn{keymap}. The keymap is the
381 association between the keys that the user types and the functions that
382 get run. You can make your own keymaps, copy existing keymaps, and tell
383 Readline which keymap to use.
385 @deftypefun Keymap rl_make_bare_keymap ()
386 Returns a new, empty keymap. The space for the keymap is allocated with
387 @code{malloc ()}; you should @code{free ()} it when you are done.
390 @deftypefun Keymap rl_copy_keymap (Keymap map)
391 Return a new keymap which is a copy of @var{map}.
394 @deftypefun Keymap rl_make_keymap ()
395 Return a new keymap with the printing characters bound to rl_insert,
396 the lowercase Meta characters bound to run their equivalents, and
397 the Meta digits bound to produce numeric arguments.
400 @deftypefun void rl_discard_keymap (Keymap keymap)
401 Free the storage associated with @var{keymap}.
404 Readline has several internal keymaps. These functions allow you to
405 change which keymap is active.
407 @deftypefun Keymap rl_get_keymap ()
408 Returns the currently active keymap.
411 @deftypefun void rl_set_keymap (Keymap keymap)
412 Makes @var{keymap} the currently active keymap.
415 @deftypefun Keymap rl_get_keymap_by_name (char *name)
416 Return the keymap matching @var{name}. @var{name} is one which would
417 be supplied in a @code{set keymap} inputrc line (@pxref{Readline Init File}).
420 @deftypefun {char *} rl_get_keymap_name (Keymap keymap)
421 Return the name matching @var{keymap}. @var{name} is one which would
422 be supplied in a @code{set keymap} inputrc line (@pxref{Readline Init File}).
426 @subsection Binding Keys
428 You associate keys with functions through the keymap. Readline has
429 several internal keymaps: @code{emacs_standard_keymap},
430 @code{emacs_meta_keymap}, @code{emacs_ctlx_keymap},
431 @code{vi_movement_keymap}, and @code{vi_insertion_keymap}.
432 @code{emacs_standard_keymap} is the default, and the examples in
433 this manual assume that.
435 These functions manage key bindings.
437 @deftypefun int rl_bind_key (int key, Function *function)
438 Binds @var{key} to @var{function} in the currently active keymap.
439 Returns non-zero in the case of an invalid @var{key}.
442 @deftypefun int rl_bind_key_in_map (int key, Function *function, Keymap map)
443 Bind @var{key} to @var{function} in @var{map}. Returns non-zero in the case
444 of an invalid @var{key}.
447 @deftypefun int rl_unbind_key (int key)
448 Bind @var{key} to the null function in the currently active keymap.
449 Returns non-zero in case of error.
452 @deftypefun int rl_unbind_key_in_map (int key, Keymap map)
453 Bind @var{key} to the null function in @var{map}.
454 Returns non-zero in case of error.
457 @deftypefun int rl_generic_bind (int type, char *keyseq, char *data, Keymap map)
458 Bind the key sequence represented by the string @var{keyseq} to the arbitrary
459 pointer @var{data}. @var{type} says what kind of data is pointed to by
460 @var{data}; this can be a function (@code{ISFUNC}), a macro
461 (@code{ISMACR}), or a keymap (@code{ISKMAP}). This makes new keymaps as
462 necessary. The initial keymap in which to do bindings is @var{map}.
465 @deftypefun int rl_parse_and_bind (char *line)
466 Parse @var{line} as if it had been read from the @code{inputrc} file and
467 perform any key bindings and variable assignments found
468 (@pxref{Readline Init File}).
471 @deftypefun int rl_read_init_file (char *filename)
472 Read keybindings and variable assignments from @var{filename}
473 (@pxref{Readline Init File}).
476 @node Associating Function Names and Bindings
477 @subsection Associating Function Names and Bindings
479 These functions allow you to find out what keys invoke named functions
480 and the functions invoked by a particular key sequence.
482 @deftypefun {Function *} rl_named_function (char *name)
483 Return the function with name @var{name}.
486 @deftypefun {Function *} rl_function_of_keyseq (char *keyseq, Keymap map, int *type)
487 Return the function invoked by @var{keyseq} in keymap @var{map}.
488 If @var{map} is NULL, the current keymap is used. If @var{type} is
489 not NULL, the type of the object is returned in it (one of @code{ISFUNC},
490 @code{ISKMAP}, or @code{ISMACR}).
493 @deftypefun {char **} rl_invoking_keyseqs (Function *function)
494 Return an array of strings representing the key sequences used to
495 invoke @var{function} in the current keymap.
498 @deftypefun {char **} rl_invoking_keyseqs_in_map (Function *function, Keymap map)
499 Return an array of strings representing the key sequences used to
500 invoke @var{function} in the keymap @var{map}.
503 @deftypefun void rl_function_dumper (int readable)
504 Print the readline function names and the key sequences currently
505 bound to them to @code{rl_outstream}. If @var{readable} is non-zero,
506 the list is formatted in such a way that it can be made part of an
507 @code{inputrc} file and re-read.
510 @deftypefun void rl_list_funmap_names ()
511 Print the names of all bindable Readline functions to @code{rl_outstream}.
514 @node Allowing Undoing
515 @subsection Allowing Undoing
517 Supporting the undo command is a painless thing, and makes your
518 functions much more useful. It is certainly easy to try
519 something if you know you can undo it. I could use an undo function for
522 If your function simply inserts text once, or deletes text once, and
523 uses @code{rl_insert_text ()} or @code{rl_delete_text ()} to do it, then
524 undoing is already done for you automatically.
526 If you do multiple insertions or multiple deletions, or any combination
527 of these operations, you should group them together into one operation.
528 This is done with @code{rl_begin_undo_group ()} and
529 @code{rl_end_undo_group ()}.
531 The types of events that can be undone are:
534 enum undo_code @{ UNDO_DELETE, UNDO_INSERT, UNDO_BEGIN, UNDO_END @};
537 Notice that @code{UNDO_DELETE} means to insert some text, and
538 @code{UNDO_INSERT} means to delete some text. That is, the undo code
539 tells undo what to undo, not how to undo it. @code{UNDO_BEGIN} and
540 @code{UNDO_END} are tags added by @code{rl_begin_undo_group ()} and
541 @code{rl_end_undo_group ()}.
543 @deftypefun int rl_begin_undo_group ()
544 Begins saving undo information in a group construct. The undo
545 information usually comes from calls to @code{rl_insert_text ()} and
546 @code{rl_delete_text ()}, but could be the result of calls to
547 @code{rl_add_undo ()}.
550 @deftypefun int rl_end_undo_group ()
551 Closes the current undo group started with @code{rl_begin_undo_group
552 ()}. There should be one call to @code{rl_end_undo_group ()}
553 for each call to @code{rl_begin_undo_group ()}.
556 @deftypefun void rl_add_undo (enum undo_code what, int start, int end, char *text)
557 Remember how to undo an event (according to @var{what}). The affected
558 text runs from @var{start} to @var{end}, and encompasses @var{text}.
561 @deftypefun void free_undo_list ()
562 Free the existing undo list.
565 @deftypefun int rl_do_undo ()
566 Undo the first thing on the undo list. Returns @code{0} if there was
567 nothing to undo, non-zero if something was undone.
570 Finally, if you neither insert nor delete text, but directly modify the
571 existing text (e.g., change its case), call @code{rl_modifying ()}
572 once, just before you modify the text. You must supply the indices of
573 the text range that you are going to modify.
575 @deftypefun int rl_modifying (int start, int end)
576 Tell Readline to save the text between @var{start} and @var{end} as a
577 single undo unit. It is assumed that you will subsequently modify
582 @subsection Redisplay
584 @deftypefun void rl_redisplay ()
585 Change what's displayed on the screen to reflect the current contents
586 of @code{rl_line_buffer}.
589 @deftypefun int rl_forced_update_display ()
590 Force the line to be updated and redisplayed, whether or not
591 Readline thinks the screen display is correct.
594 @deftypefun int rl_on_new_line ()
595 Tell the update routines that we have moved onto a new (empty) line,
596 usually after ouputting a newline.
599 @deftypefun int rl_reset_line_state ()
600 Reset the display state to a clean state and redisplay the current line
601 starting on a new line.
604 @deftypefun int rl_message (va_alist)
605 The arguments are a string as would be supplied to @code{printf}. The
606 resulting string is displayed in the @dfn{echo area}. The echo area
607 is also used to display numeric arguments and search strings.
610 @deftypefun int rl_clear_message ()
611 Clear the message in the echo area.
615 @subsection Modifying Text
617 @deftypefun int rl_insert_text (char *text)
618 Insert @var{text} into the line at the current cursor position.
621 @deftypefun int rl_delete_text (int start, int end)
622 Delete the text between @var{start} and @var{end} in the current line.
625 @deftypefun {char *} rl_copy_text (int start, int end)
626 Return a copy of the text between @var{start} and @var{end} in
630 @deftypefun int rl_kill_text (int start, int end)
631 Copy the text between @var{start} and @var{end} in the current line
632 to the kill ring, appending or prepending to the last kill if the
633 last command was a kill command. The text is deleted.
634 If @var{start} is less than @var{end},
635 the text is appended, otherwise prepended. If the last command was
636 not a kill, a new kill ring slot is used.
639 @node Utility Functions
640 @subsection Utility Functions
642 @deftypefun int rl_read_key ()
643 Return the next character available. This handles input inserted into
644 the input stream via @var{pending input} (@pxref{Readline Variables})
645 and @code{rl_stuff_char ()}, macros, and characters read from the keyboard.
648 @deftypefun int rl_getc (FILE *)
649 Return the next character available from the keyboard.
652 @deftypefun int rl_stuff_char (int c)
653 Insert @var{c} into the Readline input stream. It will be "read"
654 before Readline attempts to read characters from the terminal with
655 @code{rl_read_key ()}.
658 @deftypefun rl_extend_line_buffer (int len)
659 Ensure that @code{rl_line_buffer} has enough space to hold @var{len}
660 characters, possibly reallocating it if necessary.
663 @deftypefun int rl_initialize ()
664 Initialize or re-initialize Readline's internal state.
667 @deftypefun int rl_reset_terminal (char *terminal_name)
668 Reinitialize Readline's idea of the terminal settings using
669 @var{terminal_name} as the terminal type (e.g., @code{vt100}).
672 @deftypefun int alphabetic (int c)
673 Return 1 if @var{c} is an alphabetic character.
676 @deftypefun int numeric (int c)
677 Return 1 if @var{c} is a numeric character.
680 @deftypefun int ding ()
681 Ring the terminal bell, obeying the setting of @code{bell-style}.
684 The following are implemented as macros, defined in @code{chartypes.h}.
686 @deftypefun int uppercase_p (int c)
687 Return 1 if @var{c} is an uppercase alphabetic character.
690 @deftypefun int lowercase_p (int c)
691 Return 1 if @var{c} is a lowercase alphabetic character.
694 @deftypefun int digit_p (int c)
695 Return 1 if @var{c} is a numeric character.
698 @deftypefun int to_upper (int c)
699 If @var{c} is a lowercase alphabetic character, return the corresponding
703 @deftypefun int to_lower (int c)
704 If @var{c} is an uppercase alphabetic character, return the corresponding
708 @deftypefun int digit_value (int c)
709 If @var{c} is a number, return the value it represents.
712 @node Alternate Interface
713 @subsection Alternate Interface
715 An alternate interface is available to plain @code{readline()}. Some
716 applications need to interleave keyboard I/O with file, device, or
717 window system I/O, typically by using a main loop to @code{select()}
718 on various file descriptors. To accomodate this need, readline can
719 also be invoked as a `callback' function from an event loop. There
720 are functions available to make this easy.
722 @deftypefun void rl_callback_handler_install (char *prompt, Vfunction *lhandler)
723 Set up the terminal for readline I/O and display the initial
724 expanded value of @var{prompt}. Save the value of @var{lhandler} to
725 use as a callback when a complete line of input has been entered.
728 @deftypefun void rl_callback_read_char ()
729 Whenever an application determines that keyboard input is available, it
730 should call @code{rl_callback_read_char()}, which will read the next
731 character from the current input source. If that character completes the
732 line, @code{rl_callback_read_char} will invoke the @var{lhandler}
733 function saved by @code{rl_callback_handler_install} to process the
734 line. @code{EOF} is indicated by calling @var{lhandler} with a
738 @deftypefun void rl_callback_handler_remove ()
739 Restore the terminal to its initial state and remove the line handler.
740 This may be called from within a callback as well as independently.
743 @subsection An Example
745 Here is a function which changes lowercase characters to their uppercase
746 equivalents, and uppercase characters to lowercase. If
747 this function was bound to @samp{M-c}, then typing @samp{M-c} would
748 change the case of the character under point. Typing @samp{M-1 0 M-c}
749 would change the case of the following 10 characters, leaving the cursor on
750 the last character changed.
753 /* Invert the case of the COUNT following characters. */
755 invert_case_line (count, key)
758 register int start, end, i;
762 if (rl_point >= rl_end)
773 /* Find the end of the range to modify. */
774 end = start + (count * direction);
776 /* Force it to be within range. */
792 /* Tell readline that we are modifying the line, so it will save
793 the undo information. */
794 rl_modifying (start, end);
796 for (i = start; i != end; i++)
798 if (uppercase_p (rl_line_buffer[i]))
799 rl_line_buffer[i] = to_lower (rl_line_buffer[i]);
800 else if (lowercase_p (rl_line_buffer[i]))
801 rl_line_buffer[i] = to_upper (rl_line_buffer[i]);
803 /* Move point to on top of the last character changed. */
804 rl_point = (direction == 1) ? end - 1 : start;
809 @node Custom Completers
810 @section Custom Completers
812 Typically, a program that reads commands from the user has a way of
813 disambiguating commands and data. If your program is one of these, then
814 it can provide completion for commands, data, or both.
815 The following sections describe how your program and Readline
816 cooperate to provide this service.
819 * How Completing Works:: The logic used to do completion.
820 * Completion Functions:: Functions provided by Readline.
821 * Completion Variables:: Variables which control completion.
822 * A Short Completion Example:: An example of writing completer subroutines.
825 @node How Completing Works
826 @subsection How Completing Works
828 In order to complete some text, the full list of possible completions
829 must be available. That is, it is not possible to accurately
830 expand a partial word without knowing all of the possible words
831 which make sense in that context. The Readline library provides
832 the user interface to completion, and two of the most common
833 completion functions: filename and username. For completing other types
834 of text, you must write your own completion function. This section
835 describes exactly what such functions must do, and provides an example.
837 There are three major functions used to perform completion:
841 The user-interface function @code{rl_complete ()}. This function is
842 called with the same arguments as other Readline
843 functions intended for interactive use: @var{count} and
844 @var{invoking_key}. It isolates the word to be completed and calls
845 @code{completion_matches ()} to generate a list of possible completions.
846 It then either lists the possible completions, inserts the possible
847 completions, or actually performs the
848 completion, depending on which behavior is desired.
851 The internal function @code{completion_matches ()} uses your
852 @dfn{generator} function to generate the list of possible matches, and
853 then returns the array of these matches. You should place the address
854 of your generator function in @code{rl_completion_entry_function}.
857 The generator function is called repeatedly from
858 @code{completion_matches ()}, returning a string each time. The
859 arguments to the generator function are @var{text} and @var{state}.
860 @var{text} is the partial word to be completed. @var{state} is zero the
861 first time the function is called, allowing the generator to perform
862 any necessary initialization, and a positive non-zero integer for
863 each subsequent call. When the generator function returns
864 @code{(char *)NULL} this signals @code{completion_matches ()} that there are
865 no more possibilities left. Usually the generator function computes the
866 list of possible completions when @var{state} is zero, and returns them
867 one at a time on subsequent calls. Each string the generator function
868 returns as a match must be allocated with @code{malloc()}; Readline
869 frees the strings when it has finished with them.
873 @deftypefun int rl_complete (int ignore, int invoking_key)
874 Complete the word at or before point. You have supplied the function
875 that does the initial simple matching selection algorithm (see
876 @code{completion_matches ()}). The default is to do filename completion.
879 @deftypevar {Function *} rl_completion_entry_function
880 This is a pointer to the generator function for @code{completion_matches
881 ()}. If the value of @code{rl_completion_entry_function} is
882 @code{(Function *)NULL} then the default filename generator function,
883 @code{filename_completion_function ()}, is used.
886 @node Completion Functions
887 @subsection Completion Functions
889 Here is the complete list of callable completion functions present in
892 @deftypefun int rl_complete_internal (int what_to_do)
893 Complete the word at or before point. @var{what_to_do} says what to do
894 with the completion. A value of @samp{?} means list the possible
895 completions. @samp{TAB} means do standard completion. @samp{*} means
896 insert all of the possible completions. @samp{!} means to display
897 all of the possible completions, if there is more than one, as well as
898 performing partial completion.
901 @deftypefun int rl_complete (int ignore, int invoking_key)
902 Complete the word at or before point. You have supplied the function
903 that does the initial simple matching selection algorithm (see
904 @code{completion_matches ()} and @code{rl_completion_entry_function}).
905 The default is to do filename
906 completion. This calls @code{rl_complete_internal ()} with an
907 argument depending on @var{invoking_key}.
910 @deftypefun int rl_possible_completions (int count, int invoking_key))
911 List the possible completions. See description of @code{rl_complete
912 ()}. This calls @code{rl_complete_internal ()} with an argument of
916 @deftypefun int rl_insert_completions (int count, int invoking_key))
917 Insert the list of possible completions into the line, deleting the
918 partially-completed word. See description of @code{rl_complete ()}.
919 This calls @code{rl_complete_internal ()} with an argument of @samp{*}.
922 @deftypefun {char **} completion_matches (char *text, CPFunction *entry_func)
923 Returns an array of @code{(char *)} which is a list of completions for
924 @var{text}. If there are no completions, returns @code{(char **)NULL}.
925 The first entry in the returned array is the substitution for @var{text}.
926 The remaining entries are the possible completions. The array is
927 terminated with a @code{NULL} pointer.
929 @var{entry_func} is a function of two args, and returns a
930 @code{(char *)}. The first argument is @var{text}. The second is a
931 state argument; it is zero on the first call, and non-zero on subsequent
932 calls. @var{entry_func} returns a @code{NULL} pointer to the caller
933 when there are no more matches.
936 @deftypefun {char *} filename_completion_function (char *text, int state)
937 A generator function for filename completion in the general case. Note
938 that completion in Bash is a little different because of all
939 the pathnames that must be followed when looking up completions for a
940 command. The Bash source is a useful reference for writing custom
941 completion functions.
944 @deftypefun {char *} username_completion_function (char *text, int state)
945 A completion generator for usernames. @var{text} contains a partial
946 username preceded by a random character (usually @samp{~}). As with all
947 completion generators, @var{state} is zero on the first call and non-zero
948 for subsequent calls.
951 @node Completion Variables
952 @subsection Completion Variables
954 @deftypevar {Function *} rl_completion_entry_function
955 A pointer to the generator function for @code{completion_matches ()}.
956 @code{NULL} means to use @code{filename_entry_function ()}, the default
960 @deftypevar {CPPFunction *} rl_attempted_completion_function
961 A pointer to an alternative function to create matches.
962 The function is called with @var{text}, @var{start}, and @var{end}.
963 @var{start} and @var{end} are indices in @code{rl_line_buffer} saying
964 what the boundaries of @var{text} are. If this function exists and
965 returns @code{NULL}, or if this variable is set to @code{NULL}, then
966 @code{rl_complete ()} will call the value of
967 @code{rl_completion_entry_function} to generate matches, otherwise the
968 array of strings returned will be used.
971 @deftypevar {CPFunction *} rl_filename_quoting_function
972 A pointer to a function that will quote a filename in an application-
973 specific fashion. This is called if filename completion is being
974 attempted and one of the characters in @code{rl_filename_quote_characters}
975 appears in a completed filename. The function is called with
976 @var{text}, @var{match_type}, and @var{quote_pointer}. The @var{text}
977 is the filename to be quoted. The @var{match_type} is either
978 @code{SINGLE_MATCH}, if there is only one completion match, or
979 @code{MULT_MATCH}. Some functions use this to decide whether or not to
980 insert a closing quote character. The @var{quote_pointer} is a pointer
981 to any opening quote character the user typed. Some functions choose
982 to reset this character.
985 @deftypevar {CPFunction *} rl_filename_dequoting_function
986 A pointer to a function that will remove application-specific quoting
987 characters from a filename before completion is attempted, so those
988 characters do not interfere with matching the text against names in
989 the filesystem. It is called with @var{text}, the text of the word
990 to be dequoted, and @var{quote_char}, which is the quoting character
991 that delimits the filename (usually @samp{'} or @samp{"}). If
992 @var{quote_char} is zero, the filename was not in an embedded string.
995 @deftypevar {Function *} rl_char_is_quoted_p
996 A pointer to a function to call that determines whether or not a specific
997 character in the line buffer is quoted, according to whatever quoting
998 mechanism the program calling readline uses. The function is called with
999 two arguments: @var{text}, the text of the line, and @var{index}, the
1000 index of the character in the line. It is used to decide whether a
1001 character found in @code{rl_completer_word_break_characters} should be
1002 used to break words for the completer.
1005 @deftypevar int rl_completion_query_items
1006 Up to this many items will be displayed in response to a
1007 possible-completions call. After that, we ask the user if she is sure
1008 she wants to see them all. The default value is 100.
1011 @deftypevar {char *} rl_basic_word_break_characters
1012 The basic list of characters that signal a break between words for the
1013 completer routine. The default value of this variable is the characters
1014 which break words for completion in Bash, i.e.,
1015 @code{" \t\n\"\\'`@@$><=;|&@{("}.
1018 @deftypevar {char *} rl_basic_quote_characters
1019 List of quote characters which can cause a word break.
1022 @deftypevar {char *} rl_completer_word_break_characters
1023 The list of characters that signal a break between words for
1024 @code{rl_complete_internal ()}. The default list is the value of
1025 @code{rl_basic_word_break_characters}.
1028 @deftypevar {char *} rl_completer_quote_characters
1029 List of characters which can be used to quote a substring of the line.
1030 Completion occurs on the entire substring, and within the substring
1031 @code{rl_completer_word_break_characters} are treated as any other character,
1032 unless they also appear within this list.
1035 @deftypevar {char *} rl_filename_quote_characters
1036 A list of characters that cause a filename to be quoted by the completer
1037 when they appear in a completed filename. The default is empty.
1040 @deftypevar {char *} rl_special_prefixes
1041 The list of characters that are word break characters, but should be
1042 left in @var{text} when it is passed to the completion function.
1043 Programs can use this to help determine what kind of completing to do.
1044 For instance, Bash sets this variable to "$@@" so that it can complete
1045 shell variables and hostnames.
1048 @deftypevar {int} rl_completion_append_character
1049 When a single completion alternative matches at the end of the command
1050 line, this character is appended to the inserted completion text. The
1051 default is a space character (@samp{ }). Setting this to the null
1052 character (@samp{\0}) prevents anything being appended automatically.
1053 This can be changed in custom completion functions to
1054 provide the ``most sensible word separator character'' according to
1055 an application-specific command line syntax specification.
1058 @deftypevar int rl_ignore_completion_duplicates
1059 If non-zero, then disallow duplicates in the matches. Default is 1.
1062 @deftypevar int rl_filename_completion_desired
1063 Non-zero means that the results of the matches are to be treated as
1064 filenames. This is @emph{always} zero on entry, and can only be changed
1065 within a completion entry generator function. If it is set to a non-zero
1066 value, directory names have a slash appended and Readline attempts to
1067 quote completed filenames if they contain any embedded word break
1071 @deftypevar int rl_filename_quoting_desired
1072 Non-zero means that the results of the matches are to be quoted using
1073 double quotes (or an application-specific quoting mechanism) if the
1074 completed filename contains any characters in
1075 @code{rl_filename_quote_chars}. This is @emph{always} non-zero
1076 on entry, and can only be changed within a completion entry generator
1077 function. The quoting is effected via a call to the function pointed to
1078 by @code{rl_filename_quoting_function}.
1081 @deftypevar int rl_inhibit_completion
1082 If this variable is non-zero, completion is inhibit<ed. The completion
1083 character will be inserted as any other bound to @code{self-insert}.
1086 @deftypevar {Function *} rl_ignore_some_completions_function
1087 This function, if defined, is called by the completer when real filename
1088 completion is done, after all the matching names have been generated.
1089 It is passed a @code{NULL} terminated array of matches.
1090 The first element (@code{matches[0]}) is the
1091 maximal substring common to all matches. This function can
1092 re-arrange the list of matches as required, but each element deleted
1093 from the array must be freed.
1096 @deftypevar {Function *} rl_directory_completion_hook
1097 This function, if defined, is allowed to modify the directory portion
1098 of filenames Readline completes. It is called with the address of a
1099 string (the current directory name) as an argument. It could be used
1100 to expand symbolic links or shell variables in pathnames.
1103 @node A Short Completion Example
1104 @subsection A Short Completion Example
1106 Here is a small application demonstrating the use of the GNU Readline
1107 library. It is called @code{fileman}, and the source code resides in
1108 @file{examples/fileman.c}. This sample application provides
1109 completion of command names, line editing features, and access to the
1114 /* fileman.c -- A tiny application which demonstrates how to use the
1115 GNU Readline library. This application interactively allows users
1116 to manipulate files and their modes. */
1119 #include <sys/types.h>
1120 #include <sys/file.h>
1121 #include <sys/stat.h>
1122 #include <sys/errno.h>
1124 #include <readline/readline.h>
1125 #include <readline/history.h>
1127 extern char *getwd ();
1128 extern char *xmalloc ();
1130 /* The names of functions that actually do the manipulation. */
1131 int com_list (), com_view (), com_rename (), com_stat (), com_pwd ();
1132 int com_delete (), com_help (), com_cd (), com_quit ();
1134 /* A structure which contains information on the commands this program
1138 char *name; /* User printable name of the function. */
1139 Function *func; /* Function to call to do the job. */
1140 char *doc; /* Documentation for this function. */
1143 COMMAND commands[] = @{
1144 @{ "cd", com_cd, "Change to directory DIR" @},
1145 @{ "delete", com_delete, "Delete FILE" @},
1146 @{ "help", com_help, "Display this text" @},
1147 @{ "?", com_help, "Synonym for `help'" @},
1148 @{ "list", com_list, "List files in DIR" @},
1149 @{ "ls", com_list, "Synonym for `list'" @},
1150 @{ "pwd", com_pwd, "Print the current working directory" @},
1151 @{ "quit", com_quit, "Quit using Fileman" @},
1152 @{ "rename", com_rename, "Rename FILE to NEWNAME" @},
1153 @{ "stat", com_stat, "Print out statistics on FILE" @},
1154 @{ "view", com_view, "View the contents of FILE" @},
1155 @{ (char *)NULL, (Function *)NULL, (char *)NULL @}
1158 /* Forward declarations. */
1159 char *stripwhite ();
1160 COMMAND *find_command ();
1162 /* The name of this program, as taken from argv[0]. */
1165 /* When non-zero, this global means the user is done using this program. */
1174 r = xmalloc (strlen (s) + 1);
1187 initialize_readline (); /* Bind our completer. */
1189 /* Loop reading and executing lines until the user quits. */
1190 for ( ; done == 0; )
1192 line = readline ("FileMan: ");
1197 /* Remove leading and trailing whitespace from the line.
1198 Then, if there is anything left, add it to the history list
1200 s = stripwhite (line);
1213 /* Execute a command line. */
1222 /* Isolate the command word. */
1224 while (line[i] && whitespace (line[i]))
1228 while (line[i] && !whitespace (line[i]))
1234 command = find_command (word);
1238 fprintf (stderr, "%s: No such command for FileMan.\n", word);
1242 /* Get argument to command, if any. */
1243 while (whitespace (line[i]))
1248 /* Call the function. */
1249 return ((*(command->func)) (word));
1252 /* Look up NAME as the name of a command, and return a pointer to that
1253 command. Return a NULL pointer if NAME isn't a command name. */
1260 for (i = 0; commands[i].name; i++)
1261 if (strcmp (name, commands[i].name) == 0)
1262 return (&commands[i]);
1264 return ((COMMAND *)NULL);
1267 /* Strip whitespace from the start and end of STRING. Return a pointer
1273 register char *s, *t;
1275 for (s = string; whitespace (*s); s++)
1281 t = s + strlen (s) - 1;
1282 while (t > s && whitespace (*t))
1289 /* **************************************************************** */
1291 /* Interface to Readline Completion */
1293 /* **************************************************************** */
1295 char *command_generator ();
1296 char **fileman_completion ();
1298 /* Tell the GNU Readline library how to complete. We want to try to complete
1299 on command names if this is the first word in the line, or on filenames
1301 initialize_readline ()
1303 /* Allow conditional parsing of the ~/.inputrc file. */
1304 rl_readline_name = "FileMan";
1306 /* Tell the completer that we want a crack first. */
1307 rl_attempted_completion_function = (CPPFunction *)fileman_completion;
1310 /* Attempt to complete on the contents of TEXT. START and END bound the
1311 region of rl_line_buffer that contains the word to complete. TEXT is
1312 the word to complete. We can use the entire contents of rl_line_buffer
1313 in case we want to do some simple parsing. Return the array of matches,
1314 or NULL if there aren't any. */
1316 fileman_completion (text, start, end)
1322 matches = (char **)NULL;
1324 /* If this word is at the start of the line, then it is a command
1325 to complete. Otherwise it is the name of a file in the current
1328 matches = completion_matches (text, command_generator);
1333 /* Generator function for command completion. STATE lets us know whether
1334 to start from scratch; without any state (i.e. STATE == 0), then we
1335 start at the top of the list. */
1337 command_generator (text, state)
1341 static int list_index, len;
1344 /* If this is a new word to complete, initialize now. This includes
1345 saving the length of TEXT for efficiency, and initializing the index
1350 len = strlen (text);
1353 /* Return the next name which partially matches from the command list. */
1354 while (name = commands[list_index].name)
1358 if (strncmp (name, text, len) == 0)
1359 return (dupstr(name));
1362 /* If no names matched, then return NULL. */
1363 return ((char *)NULL);
1366 /* **************************************************************** */
1368 /* FileMan Commands */
1370 /* **************************************************************** */
1372 /* String to pass to system (). This is for the LIST, VIEW and RENAME
1374 static char syscom[1024];
1376 /* List the file(s) named in arg. */
1383 sprintf (syscom, "ls -FClg %s", arg);
1384 return (system (syscom));
1390 if (!valid_argument ("view", arg))
1393 sprintf (syscom, "more %s", arg);
1394 return (system (syscom));
1400 too_dangerous ("rename");
1409 if (!valid_argument ("stat", arg))
1412 if (stat (arg, &finfo) == -1)
1418 printf ("Statistics for `%s':\n", arg);
1420 printf ("%s has %d link%s, and is %d byte%s in length.\n", arg,
1422 (finfo.st_nlink == 1) ? "" : "s",
1424 (finfo.st_size == 1) ? "" : "s");
1425 printf ("Inode Last Change at: %s", ctime (&finfo.st_ctime));
1426 printf (" Last access at: %s", ctime (&finfo.st_atime));
1427 printf (" Last modified at: %s", ctime (&finfo.st_mtime));
1434 too_dangerous ("delete");
1438 /* Print out help for ARG, or for all of the commands if ARG is
1446 for (i = 0; commands[i].name; i++)
1448 if (!*arg || (strcmp (arg, commands[i].name) == 0))
1450 printf ("%s\t\t%s.\n", commands[i].name, commands[i].doc);
1457 printf ("No commands match `%s'. Possibilties are:\n", arg);
1459 for (i = 0; commands[i].name; i++)
1461 /* Print in six columns. */
1468 printf ("%s\t", commands[i].name);
1478 /* Change to the directory ARG. */
1482 if (chdir (arg) == -1)
1492 /* Print out the current working directory. */
1501 printf ("Error getting pwd: %s\n", dir);
1505 printf ("Current directory is %s\n", dir);
1509 /* The user wishes to quit using this program. Just set DONE non-zero. */
1517 /* Function which tells you that you can't do this. */
1518 too_dangerous (caller)
1522 "%s: Too dangerous for me to distribute. Write it yourself.\n",
1526 /* Return non-zero if ARG is a valid argument for CALLER, else print
1527 an error message and return zero. */
1529 valid_argument (caller, arg)
1534 fprintf (stderr, "%s: Argument required.\n", caller);