callback.c revision 75406 
1/* callback.c -- functions to use readline as an X `callback' mechanism. */
2
3/* Copyright (C) 1987, 1989, 1992 Free Software Foundation, Inc.
4
5   This file is part of the GNU Readline Library, a library for
6   reading lines of text with interactive input and history editing.
7
8   The GNU Readline Library is free software; you can redistribute it
9   and/or modify it under the terms of the GNU General Public License
10   as published by the Free Software Foundation; either version 2, or
11   (at your option) any later version.
12
13   The GNU Readline Library is distributed in the hope that it will be
14   useful, but WITHOUT ANY WARRANTY; without even the implied warranty
15   of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   GNU General Public License for more details.
17
18   The GNU General Public License is often shipped with GNU software, and
19   is generally kept in a file called COPYING or LICENSE.  If you do not
20   have a copy of the license, write to the Free Software Foundation,
21   59 Temple Place, Suite 330, Boston, MA 02111 USA. */
22#define READLINE_LIBRARY
23
24#if defined (HAVE_CONFIG_H)
25#  include <config.h>
26#endif
27
28#include "rlconf.h"
29
30#if defined (READLINE_CALLBACKS)
31
32#include <sys/types.h>
33#include <stdio.h>
34
35/* System-specific feature definitions and include files. */
36#include "rldefs.h"
37#include "readline.h"
38#include "rlprivate.h"
39
40/* **************************************************************** */
41/*								    */
42/*			Callback Readline Functions                 */
43/*								    */
44/* **************************************************************** */
45
46/* Allow using readline in situations where a program may have multiple
47   things to handle at once, and dispatches them via select().  Call
48   rl_callback_handler_install() with the prompt and a function to call
49   whenever a complete line of input is ready.  The user must then
50   call rl_callback_read_char() every time some input is available, and
51   rl_callback_read_char() will call the user's function with the complete
52   text read in at each end of line.  The terminal is kept prepped and
53   signals handled all the time, except during calls to the user's function. */
54
55rl_vcpfunc_t *rl_linefunc;		/* user callback function */
56static int in_handler;		/* terminal_prepped and signals set? */
57
58/* Make sure the terminal is set up, initialize readline, and prompt. */
59static void
60_rl_callback_newline ()
61{
62  rl_initialize ();
63
64  if (in_handler == 0)
65    {
66      in_handler = 1;
67
68      (*rl_prep_term_function) (_rl_meta_flag);
69
70#if defined (HANDLE_SIGNALS)
71      rl_set_signals ();
72#endif
73    }
74
75  readline_internal_setup ();
76}
77
78/* Install a readline handler, set up the terminal, and issue the prompt. */
79void
80rl_callback_handler_install (prompt, linefunc)
81     const char *prompt;
82     rl_vcpfunc_t *linefunc;
83{
84  rl_set_prompt (prompt);
85  rl_linefunc = linefunc;
86  _rl_callback_newline ();
87}
88
89/* Read one character, and dispatch to the handler if it ends the line. */
90void
91rl_callback_read_char ()
92{
93  char *line;
94  int eof;
95
96  if (rl_linefunc == NULL)
97    {
98      fprintf (stderr, "readline: readline_callback_read_char() called with no handler!\r\n");
99      abort ();
100    }
101
102  eof = readline_internal_char ();
103
104  /* We loop in case some function has pushed input back with rl_execute_next. */
105  for (;;)
106    {
107      if (rl_done)
108	{
109	  line = readline_internal_teardown (eof);
110
111	  (*rl_deprep_term_function) ();
112#if defined (HANDLE_SIGNALS)
113	  rl_clear_signals ();
114#endif
115	  in_handler = 0;
116	  (*rl_linefunc) (line);
117
118	  /* If the user did not clear out the line, do it for him. */
119	  if (rl_line_buffer[0])
120	    _rl_init_line_state ();
121
122	  /* Redisplay the prompt if readline_handler_{install,remove}
123	     not called. */
124	  if (in_handler == 0 && rl_linefunc)
125	    _rl_callback_newline ();
126	}
127      if (rl_pending_input)
128	eof = readline_internal_char ();
129      else
130        break;
131    }
132}
133
134/* Remove the handler, and make sure the terminal is in its normal state. */
135void
136rl_callback_handler_remove ()
137{
138  rl_linefunc = NULL;
139  if (in_handler)
140    {
141      in_handler = 0;
142      (*rl_deprep_term_function) ();
143#if defined (HANDLE_SIGNALS)
144      rl_clear_signals ();
145#endif
146    }
147}
148
149#endif
150