mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-21 04:42:53 +08:00
574 lines
20 KiB
Plaintext
574 lines
20 KiB
Plaintext
@ignore
|
|
This file documents the user interface to the GNU History library.
|
|
|
|
Copyright (C) 1988-2002 Free Software Foundation, Inc.
|
|
Authored by Brian Fox and Chet Ramey.
|
|
|
|
Permission is granted to make and distribute verbatim copies of this manual
|
|
provided the copyright notice and this permission notice are preserved on
|
|
all copies.
|
|
|
|
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).
|
|
|
|
Permission is granted to copy and distribute modified versions of this
|
|
manual under the conditions for verbatim copying, provided also that the
|
|
GNU Copyright statement is available to the distributee, and 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.
|
|
@end ignore
|
|
|
|
@node Programming with GNU History
|
|
@chapter Programming with GNU History
|
|
|
|
This chapter describes how to interface programs that you write
|
|
with the @sc{gnu} History Library.
|
|
It should be considered a technical guide.
|
|
For information on the interactive use of @sc{gnu} History, @pxref{Using
|
|
History Interactively}.
|
|
|
|
@menu
|
|
* Introduction to History:: What is the GNU History library for?
|
|
* History Storage:: How information is stored.
|
|
* History Functions:: Functions that you can use.
|
|
* History Variables:: Variables that control behaviour.
|
|
* History Programming Example:: Example of using the GNU History Library.
|
|
@end menu
|
|
|
|
@node Introduction to History
|
|
@section Introduction to History
|
|
|
|
Many programs read input from the user a line at a time. The @sc{gnu}
|
|
History library is able to keep track of those lines, associate arbitrary
|
|
data with each line, and utilize information from previous lines in
|
|
composing new ones.
|
|
|
|
The programmer using the History library has available functions
|
|
for remembering lines on a history list, associating arbitrary data
|
|
with a line, removing lines from the list, searching through the list
|
|
for a line containing an arbitrary text string, and referencing any line
|
|
in the list directly. In addition, a history @dfn{expansion} function
|
|
is available which provides for a consistent user interface across
|
|
different programs.
|
|
|
|
The user using programs written with the History library has the
|
|
benefit of a consistent user interface with a set of well-known
|
|
commands for manipulating the text of previous lines and using that text
|
|
in new commands. The basic history manipulation commands are similar to
|
|
the history substitution provided by @code{csh}.
|
|
|
|
If the programmer desires, he can use the Readline library, which
|
|
includes some history manipulation by default, and has the added
|
|
advantage of command line editing.
|
|
|
|
Before declaring any functions using any functionality the History
|
|
library provides in other code, an application writer should include
|
|
the file @code{<readline/history.h>} in any file that uses the
|
|
History library's features. It supplies extern declarations for all
|
|
of the library's public functions and variables, and declares all of
|
|
the public data structures.
|
|
|
|
@node History Storage
|
|
@section History Storage
|
|
|
|
The history list is an array of history entries. A history entry is
|
|
declared as follows:
|
|
|
|
@example
|
|
typedef void *histdata_t;
|
|
|
|
typedef struct _hist_entry @{
|
|
char *line;
|
|
char *timestamp;
|
|
histdata_t data;
|
|
@} HIST_ENTRY;
|
|
@end example
|
|
|
|
The history list itself might therefore be declared as
|
|
|
|
@example
|
|
HIST_ENTRY **the_history_list;
|
|
@end example
|
|
|
|
The state of the History library is encapsulated into a single structure:
|
|
|
|
@example
|
|
/*
|
|
* A structure used to pass around the current state of the history.
|
|
*/
|
|
typedef struct _hist_state @{
|
|
HIST_ENTRY **entries; /* Pointer to the entries themselves. */
|
|
int offset; /* The location pointer within this array. */
|
|
int length; /* Number of elements within this array. */
|
|
int size; /* Number of slots allocated to this array. */
|
|
int flags;
|
|
@} HISTORY_STATE;
|
|
@end example
|
|
|
|
If the flags member includes @code{HS_STIFLED}, the history has been
|
|
stifled.
|
|
|
|
@node History Functions
|
|
@section History Functions
|
|
|
|
This section describes the calling sequence for the various functions
|
|
exported by the @sc{gnu} History library.
|
|
|
|
@menu
|
|
* Initializing History and State Management:: Functions to call when you
|
|
want to use history in a
|
|
program.
|
|
* History List Management:: Functions used to manage the list
|
|
of history entries.
|
|
* Information About the History List:: Functions returning information about
|
|
the history list.
|
|
* Moving Around the History List:: Functions used to change the position
|
|
in the history list.
|
|
* Searching the History List:: Functions to search the history list
|
|
for entries containing a string.
|
|
* Managing the History File:: Functions that read and write a file
|
|
containing the history list.
|
|
* History Expansion:: Functions to perform csh-like history
|
|
expansion.
|
|
@end menu
|
|
|
|
@node Initializing History and State Management
|
|
@subsection Initializing History and State Management
|
|
|
|
This section describes functions used to initialize and manage
|
|
the state of the History library when you want to use the history
|
|
functions in your program.
|
|
|
|
@deftypefun void using_history (void)
|
|
Begin a session in which the history functions might be used. This
|
|
initializes the interactive variables.
|
|
@end deftypefun
|
|
|
|
@deftypefun {HISTORY_STATE *} history_get_history_state (void)
|
|
Return a structure describing the current state of the input history.
|
|
@end deftypefun
|
|
|
|
@deftypefun void history_set_history_state (HISTORY_STATE *state)
|
|
Set the state of the history list according to @var{state}.
|
|
@end deftypefun
|
|
|
|
@node History List Management
|
|
@subsection History List Management
|
|
|
|
These functions manage individual entries on the history list, or set
|
|
parameters managing the list itself.
|
|
|
|
@deftypefun void add_history (const char *string)
|
|
Place @var{string} at the end of the history list. The associated data
|
|
field (if any) is set to @code{NULL}.
|
|
@end deftypefun
|
|
|
|
@deftypefun void add_history_time (const char *string)
|
|
Change the time stamp associated with the most recent history entry to
|
|
@var{string}.
|
|
@end deftypefun
|
|
|
|
@deftypefun {HIST_ENTRY *} remove_history (int which)
|
|
Remove history entry at offset @var{which} from the history. The
|
|
removed element is returned so you can free the line, data,
|
|
and containing structure.
|
|
@end deftypefun
|
|
|
|
@deftypefun {histdata_t} free_history_entry (HIST_ENTRY *histent)
|
|
Free the history entry @var{histent} and any history library private
|
|
data associated with it. Returns the application-specific data
|
|
so the caller can dispose of it.
|
|
@end deftypefun
|
|
|
|
@deftypefun {HIST_ENTRY *} replace_history_entry (int which, const char *line, histdata_t data)
|
|
Make the history entry at offset @var{which} have @var{line} and @var{data}.
|
|
This returns the old entry so the caller can dispose of any
|
|
application-specific data. In the case
|
|
of an invalid @var{which}, a @code{NULL} pointer is returned.
|
|
@end deftypefun
|
|
|
|
@deftypefun void clear_history (void)
|
|
Clear the history list by deleting all the entries.
|
|
@end deftypefun
|
|
|
|
@deftypefun void stifle_history (int max)
|
|
Stifle the history list, remembering only the last @var{max} entries.
|
|
@end deftypefun
|
|
|
|
@deftypefun int unstifle_history (void)
|
|
Stop stifling the history. This returns the previously-set
|
|
maximum number of history entries (as set by @code{stifle_history()}).
|
|
The value is positive if the history was
|
|
stifled, negative if it wasn't.
|
|
@end deftypefun
|
|
|
|
@deftypefun int history_is_stifled (void)
|
|
Returns non-zero if the history is stifled, zero if it is not.
|
|
@end deftypefun
|
|
|
|
@node Information About the History List
|
|
@subsection Information About the History List
|
|
|
|
These functions return information about the entire history list or
|
|
individual list entries.
|
|
|
|
@deftypefun {HIST_ENTRY **} history_list (void)
|
|
Return a @code{NULL} terminated array of @code{HIST_ENTRY *} which is the
|
|
current input history. Element 0 of this list is the beginning of time.
|
|
If there is no history, return @code{NULL}.
|
|
@end deftypefun
|
|
|
|
@deftypefun int where_history (void)
|
|
Returns the offset of the current history element.
|
|
@end deftypefun
|
|
|
|
@deftypefun {HIST_ENTRY *} current_history (void)
|
|
Return the history entry at the current position, as determined by
|
|
@code{where_history()}. If there is no entry there, return a @code{NULL}
|
|
pointer.
|
|
@end deftypefun
|
|
|
|
@deftypefun {HIST_ENTRY *} history_get (int offset)
|
|
Return the history entry at position @var{offset}, starting from
|
|
@code{history_base} (@pxref{History Variables}).
|
|
If there is no entry there, or if @var{offset}
|
|
is greater than the history length, return a @code{NULL} pointer.
|
|
@end deftypefun
|
|
|
|
@deftypefun time_t history_get_time (HIST_ENTRY *entry)
|
|
Return the time stamp associated with the history entry @var{entry}.
|
|
@end deftypefun
|
|
|
|
@deftypefun int history_total_bytes (void)
|
|
Return the number of bytes that the primary history entries are using.
|
|
This function returns the sum of the lengths of all the lines in the
|
|
history.
|
|
@end deftypefun
|
|
|
|
@node Moving Around the History List
|
|
@subsection Moving Around the History List
|
|
|
|
These functions allow the current index into the history list to be
|
|
set or changed.
|
|
|
|
@deftypefun int history_set_pos (int pos)
|
|
Set the current history offset to @var{pos}, an absolute index
|
|
into the list.
|
|
Returns 1 on success, 0 if @var{pos} is less than zero or greater
|
|
than the number of history entries.
|
|
@end deftypefun
|
|
|
|
@deftypefun {HIST_ENTRY *} previous_history (void)
|
|
Back up the current history offset to the previous history entry, and
|
|
return a pointer to that entry. If there is no previous entry, return
|
|
a @code{NULL} pointer.
|
|
@end deftypefun
|
|
|
|
@deftypefun {HIST_ENTRY *} next_history (void)
|
|
Move the current history offset forward to the next history entry, and
|
|
return the a pointer to that entry. If there is no next entry, return
|
|
a @code{NULL} pointer.
|
|
@end deftypefun
|
|
|
|
@node Searching the History List
|
|
@subsection Searching the History List
|
|
@cindex History Searching
|
|
|
|
These functions allow searching of the history list for entries containing
|
|
a specific string. Searching may be performed both forward and backward
|
|
from the current history position. The search may be @dfn{anchored},
|
|
meaning that the string must match at the beginning of the history entry.
|
|
@cindex anchored search
|
|
|
|
@deftypefun int history_search (const char *string, int direction)
|
|
Search the history for @var{string}, starting at the current history offset.
|
|
If @var{direction} is less than 0, then the search is through
|
|
previous entries, otherwise through subsequent entries.
|
|
If @var{string} is found, then
|
|
the current history index is set to that history entry, and the value
|
|
returned is the offset in the line of the entry where
|
|
@var{string} was found. Otherwise, nothing is changed, and a -1 is
|
|
returned.
|
|
@end deftypefun
|
|
|
|
@deftypefun int history_search_prefix (const char *string, int direction)
|
|
Search the history for @var{string}, starting at the current history
|
|
offset. The search is anchored: matching lines must begin with
|
|
@var{string}. If @var{direction} is less than 0, then the search is
|
|
through previous entries, otherwise through subsequent entries.
|
|
If @var{string} is found, then the
|
|
current history index is set to that entry, and the return value is 0.
|
|
Otherwise, nothing is changed, and a -1 is returned.
|
|
@end deftypefun
|
|
|
|
@deftypefun int history_search_pos (const char *string, int direction, int pos)
|
|
Search for @var{string} in the history list, starting at @var{pos}, an
|
|
absolute index into the list. If @var{direction} is negative, the search
|
|
proceeds backward from @var{pos}, otherwise forward. Returns the absolute
|
|
index of the history element where @var{string} was found, or -1 otherwise.
|
|
@end deftypefun
|
|
|
|
@node Managing the History File
|
|
@subsection Managing the History File
|
|
|
|
The History library can read the history from and write it to a file.
|
|
This section documents the functions for managing a history file.
|
|
|
|
@deftypefun int read_history (const char *filename)
|
|
Add the contents of @var{filename} to the history list, a line at a time.
|
|
If @var{filename} is @code{NULL}, then read from @file{~/.history}.
|
|
Returns 0 if successful, or @code{errno} if not.
|
|
@end deftypefun
|
|
|
|
@deftypefun int read_history_range (const char *filename, int from, int to)
|
|
Read a range of lines from @var{filename}, adding them to the history list.
|
|
Start reading at line @var{from} and end at @var{to}.
|
|
If @var{from} is zero, start at the beginning. If @var{to} is less than
|
|
@var{from}, then read until the end of the file. If @var{filename} is
|
|
@code{NULL}, then read from @file{~/.history}. Returns 0 if successful,
|
|
or @code{errno} if not.
|
|
@end deftypefun
|
|
|
|
@deftypefun int write_history (const char *filename)
|
|
Write the current history to @var{filename}, overwriting @var{filename}
|
|
if necessary.
|
|
If @var{filename} is @code{NULL}, then write the history list to
|
|
@file{~/.history}.
|
|
Returns 0 on success, or @code{errno} on a read or write error.
|
|
@end deftypefun
|
|
|
|
@deftypefun int append_history (int nelements, const char *filename)
|
|
Append the last @var{nelements} of the history list to @var{filename}.
|
|
If @var{filename} is @code{NULL}, then append to @file{~/.history}.
|
|
Returns 0 on success, or @code{errno} on a read or write error.
|
|
@end deftypefun
|
|
|
|
@deftypefun int history_truncate_file (const char *filename, int nlines)
|
|
Truncate the history file @var{filename}, leaving only the last
|
|
@var{nlines} lines.
|
|
If @var{filename} is @code{NULL}, then @file{~/.history} is truncated.
|
|
Returns 0 on success, or @code{errno} on failure.
|
|
@end deftypefun
|
|
|
|
@node History Expansion
|
|
@subsection History Expansion
|
|
|
|
These functions implement history expansion.
|
|
|
|
@deftypefun int history_expand (char *string, char **output)
|
|
Expand @var{string}, placing the result into @var{output}, a pointer
|
|
to a string (@pxref{History Interaction}). Returns:
|
|
@table @code
|
|
@item 0
|
|
If no expansions took place (or, if the only change in
|
|
the text was the removal of escape characters preceding the history expansion
|
|
character);
|
|
@item 1
|
|
if expansions did take place;
|
|
@item -1
|
|
if there was an error in expansion;
|
|
@item 2
|
|
if the returned line should be displayed, but not executed,
|
|
as with the @code{:p} modifier (@pxref{Modifiers}).
|
|
@end table
|
|
|
|
If an error ocurred in expansion, then @var{output} contains a descriptive
|
|
error message.
|
|
@end deftypefun
|
|
|
|
@deftypefun {char *} get_history_event (const char *string, int *cindex, int qchar)
|
|
Returns the text of the history event beginning at @var{string} +
|
|
@var{*cindex}. @var{*cindex} is modified to point to after the event
|
|
specifier. At function entry, @var{cindex} points to the index into
|
|
@var{string} where the history event specification begins. @var{qchar}
|
|
is a character that is allowed to end the event specification in addition
|
|
to the ``normal'' terminating characters.
|
|
@end deftypefun
|
|
|
|
@deftypefun {char **} history_tokenize (const char *string)
|
|
Return an array of tokens parsed out of @var{string}, much as the
|
|
shell might. The tokens are split on the characters in the
|
|
@var{history_word_delimiters} variable,
|
|
and shell quoting conventions are obeyed.
|
|
@end deftypefun
|
|
|
|
@deftypefun {char *} history_arg_extract (int first, int last, const char *string)
|
|
Extract a string segment consisting of the @var{first} through @var{last}
|
|
arguments present in @var{string}. Arguments are split using
|
|
@code{history_tokenize}.
|
|
@end deftypefun
|
|
|
|
@node History Variables
|
|
@section History Variables
|
|
|
|
This section describes the externally-visible variables exported by
|
|
the @sc{gnu} History Library.
|
|
|
|
@deftypevar int history_base
|
|
The logical offset of the first entry in the history list.
|
|
@end deftypevar
|
|
|
|
@deftypevar int history_length
|
|
The number of entries currently stored in the history list.
|
|
@end deftypevar
|
|
|
|
@deftypevar int history_max_entries
|
|
The maximum number of history entries. This must be changed using
|
|
@code{stifle_history()}.
|
|
@end deftypevar
|
|
|
|
@deftypevar int history_write_timestamps
|
|
If non-zero, timestamps are written to the history file, so they can be
|
|
preserved between sessions. The default value is 0, meaning that
|
|
timestamps are not saved.
|
|
@end deftypevar
|
|
|
|
@deftypevar char history_expansion_char
|
|
The character that introduces a history event. The default is @samp{!}.
|
|
Setting this to 0 inhibits history expansion.
|
|
@end deftypevar
|
|
|
|
@deftypevar char history_subst_char
|
|
The character that invokes word substitution if found at the start of
|
|
a line. The default is @samp{^}.
|
|
@end deftypevar
|
|
|
|
@deftypevar char history_comment_char
|
|
During tokenization, if this character is seen as the first character
|
|
of a word, then it and all subsequent characters up to a newline are
|
|
ignored, suppressing history expansion for the remainder of the line.
|
|
This is disabled by default.
|
|
@end deftypevar
|
|
|
|
@deftypevar {char *} history_word_delimiters
|
|
The characters that separate tokens for @code{history_tokenize()}.
|
|
The default value is @code{" \t\n()<>;&|"}.
|
|
@end deftypevar
|
|
|
|
@deftypevar {char *} history_search_delimiter_chars
|
|
The list of additional characters which can delimit a history search
|
|
string, in addition to space, TAB, @samp{:} and @samp{?} in the case of
|
|
a substring search. The default is empty.
|
|
@end deftypevar
|
|
|
|
@deftypevar {char *} history_no_expand_chars
|
|
The list of characters which inhibit history expansion if found immediately
|
|
following @var{history_expansion_char}. The default is space, tab, newline,
|
|
carriage return, and @samp{=}.
|
|
@end deftypevar
|
|
|
|
@deftypevar int history_quotes_inhibit_expansion
|
|
If non-zero, single-quoted words are not scanned for the history expansion
|
|
character. The default value is 0.
|
|
@end deftypevar
|
|
|
|
@deftypevar {rl_linebuf_func_t *} history_inhibit_expansion_function
|
|
This should be set to the address of a function that takes two arguments:
|
|
a @code{char *} (@var{string})
|
|
and an @code{int} index into that string (@var{i}).
|
|
It should return a non-zero value if the history expansion starting at
|
|
@var{string[i]} should not be performed; zero if the expansion should
|
|
be done.
|
|
It is intended for use by applications like Bash that use the history
|
|
expansion character for additional purposes.
|
|
By default, this variable is set to @code{NULL}.
|
|
@end deftypevar
|
|
|
|
@node History Programming Example
|
|
@section History Programming Example
|
|
|
|
The following program demonstrates simple use of the @sc{gnu} History Library.
|
|
|
|
@smallexample
|
|
#include <stdio.h>
|
|
#include <readline/history.h>
|
|
|
|
main (argc, argv)
|
|
int argc;
|
|
char **argv;
|
|
@{
|
|
char line[1024], *t;
|
|
int len, done = 0;
|
|
|
|
line[0] = 0;
|
|
|
|
using_history ();
|
|
while (!done)
|
|
@{
|
|
printf ("history$ ");
|
|
fflush (stdout);
|
|
t = fgets (line, sizeof (line) - 1, stdin);
|
|
if (t && *t)
|
|
@{
|
|
len = strlen (t);
|
|
if (t[len - 1] == '\n')
|
|
t[len - 1] = '\0';
|
|
@}
|
|
|
|
if (!t)
|
|
strcpy (line, "quit");
|
|
|
|
if (line[0])
|
|
@{
|
|
char *expansion;
|
|
int result;
|
|
|
|
result = history_expand (line, &expansion);
|
|
if (result)
|
|
fprintf (stderr, "%s\n", expansion);
|
|
|
|
if (result < 0 || result == 2)
|
|
@{
|
|
free (expansion);
|
|
continue;
|
|
@}
|
|
|
|
add_history (expansion);
|
|
strncpy (line, expansion, sizeof (line) - 1);
|
|
free (expansion);
|
|
@}
|
|
|
|
if (strcmp (line, "quit") == 0)
|
|
done = 1;
|
|
else if (strcmp (line, "save") == 0)
|
|
write_history ("history_file");
|
|
else if (strcmp (line, "read") == 0)
|
|
read_history ("history_file");
|
|
else if (strcmp (line, "list") == 0)
|
|
@{
|
|
register HIST_ENTRY **the_list;
|
|
register int i;
|
|
|
|
the_list = history_list ();
|
|
if (the_list)
|
|
for (i = 0; the_list[i]; i++)
|
|
printf ("%d: %s\n", i + history_base, the_list[i]->line);
|
|
@}
|
|
else if (strncmp (line, "delete", 6) == 0)
|
|
@{
|
|
int which;
|
|
if ((sscanf (line + 6, "%d", &which)) == 1)
|
|
@{
|
|
HIST_ENTRY *entry = remove_history (which);
|
|
if (!entry)
|
|
fprintf (stderr, "No such entry %d\n", which);
|
|
else
|
|
@{
|
|
free (entry->line);
|
|
free (entry);
|
|
@}
|
|
@}
|
|
else
|
|
@{
|
|
fprintf (stderr, "non-numeric arg given to `delete'\n");
|
|
@}
|
|
@}
|
|
@}
|
|
@}
|
|
@end smallexample
|