rltech.texinfo

linux下bash源码

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 bindable Readline functions:
@var{count} and @var{invoking_key}.
It isolates the word to be completed and calls
@code{rl_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{rl_completion_matches()} uses an
application-supplied @dfn{generator} function to generate the list of
possible matches, and then returns the array of these matches.
The caller should place the address of its generator function in
@code{rl_completion_entry_function}.

@item
The generator function is called repeatedly from
@code{rl_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.  The generator function returns
@code{(char *)NULL} to inform @code{rl_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{rl_completion_matches()}).  The default is to do filename completion.
@end deftypefun

@deftypevar {rl_compentry_func_t *} rl_completion_entry_function
This is a pointer to the generator function for
@code{rl_completion_matches()}.
If the value of @code{rl_completion_entry_function} is
@code{NULL} then the default filename generator
function, @code{rl_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{rl_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 **} rl_completion_matches (const char *text, rl_compentry_func_t *entry_func)
Returns an array of strings which is a list of completions for
@var{text}.  If there are no completions, returns @code{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 *} rl_filename_completion_function (const char *text, int state)
A generator function for filename completion in the general case.
@var{text} is a partial filename.
The Bash source is a useful reference for writing custom
completion functions (the Bash completion functions call this and other
Readline functions).
@end deftypefun

@deftypefun {char *} rl_username_completion_function (const 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 {rl_compentry_func_t *} rl_completion_entry_function
A pointer to the generator function for @code{rl_completion_matches()}.
@code{NULL} means to use @code{rl_filename_completion_function()}, the default
filename completer.
@end deftypevar

@deftypevar {rl_completion_func_t *} 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} defining
the boundaries of @var{text}, which is a character string.
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.
If this function sets the @code{rl_attempted_completion_over}
variable to a non-zero value, Readline will not perform its default
completion even if this function returns no matches.
@end deftypevar

@deftypevar {rl_quote_func_t *} 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 {rl_dequote_func_t *} 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 {rl_linebuf_func_t *} 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 {const 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:
@code{" \t\n\"\\'`@@$><=;|&@{("}.
@end deftypevar

@deftypevar {const char *} rl_basic_quote_characters
A list of quote characters which can cause a word break.
@end deftypevar

@deftypevar {const 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 {const char *} rl_completer_quote_characters
A 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 {const 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 {const 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 duplicates in the matches are removed.
The 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 characters in
@code{rl_filename_quote_characters} and @code{rl_filename_quoting_desired}
is set to a non-zero value.
@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_attempted_completion_over
If an application-specific completion function assigned to
@code{rl_attempted_completion_function} sets this variable to a non-zero
value, Readline will not perform its default filename completion even
if the application's completion function returns no matches.
It should be set only by an application's completion function.
@end deftypevar

@deftypevar int rl_completion_type
Set to a character describing the type of completion Readline is currently
attempting; see the description of @code{rl_complete_internal()}
(@pxref{Completion Functions}) for the list of characters.
@end deftypevar

@deftypevar int rl_inhibit_completion
If this variable is non-zero, completion is inhibited.  The completion
character will be inserted as any other bound to @code{self-insert}.
@end deftypevar

@deftypevar {rl_compignore_func_t *} 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 {rl_icppfunc_t *} 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, and may modify that string.
If the string is replaced with a new string, the old value should be freed.
Any modified directory name should have a trailing slash.
The modified value will be displayed as part of the completion, replacing
the directory portion of the pathname the user typed.
It returns an integer that should be non-zero if the function modifies
its directory argument.
It could be used to expand symbolic links or shell variables in pathnames.
@end deftypevar

@deftypevar {rl_compdisp_func_t *} rl_completion_display_matches_hook
If non-zero, then this is the address of a function to call when
completing a word would normally display the list of possible matches.
This function is called in lieu of Readline displaying the list.
It takes three arguments:
(@code{char **}@var{matches}, @code{int} @var{num_matches}, @code{int} @var{max_length})
where @var{matches} is the array of matching strings,
@var{num_matches} is the number of strings in that array, and
@var{max_length} is the length of the longest string in that array.
Readline provides a convenience function, @code{rl_display_match_list},
that takes care of doing the display to Readline's output stream.  That
function may be called from this hook.
@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 <re