+++ /dev/null
-@ignore
-This file documents the user interface to the GNU History library.
-
-Copyright (C) 1988-2016 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}.
-If the maximum number of history entries has been set using
-@code{stifle_history()}, and the new number of history entries would exceed
-that maximum, the oldest history entry is removed.
-@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.
-The history list will contain only @var{max} entries at a time.
-@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}.
-The range of valid
-values of @var{offset} starts at @code{history_base} and ends at
-@var{history_length} - 1 (@pxref{History Variables}).
-If there is no entry there, or if @var{offset} is outside the valid
-range, 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}.
-If the timestamp is missing or invalid, return 0.
-@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)
-If the current history offset refers to a valid history entry,
-increment the current history offset.
-If the possibly-incremented history offset refers to a valid history
-entry, return a pointer to that entry;
-otherwise, return a @code{BNULL} 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 occurred 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 as described below.
-@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.
-
-The current timestamp format uses the value of @var{history_comment_char}
-to delimit timestamp entries in the history file. If that variable does
-not have a value (the default), timestamps will not be written.
-@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, the history expansion code implements shell-like quoting:
-single-quoted words are not scanned for the history expansion
-character or the history comment character, and double-quoted words may
-have history expansion performed, since single quotes are not special
-within double quotes.
-The default value is 0.
-@end deftypevar
-
-@deftypevar int history_quoting_state
-An application may set this variable to indicate that the current line
-being expanded is subject to existing quoting. If set to @samp{'}, the
-history expansion function will assume that the line is single-quoted and
-inhibit expansion until it reads an unquoted closing single quote; if set
-to @samp{"}, history expansion will assume the line is double quoted until
-it reads an unquoted closing double quote. If set to zero, the default,
-the history expansion function will assume the line is not quoted and
-treat quote characters within the line as described above.
-This is only effective if @var{history_quotes_inhibit_expansion} is set.
-@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
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