lib/readline/callback.c

   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
  55 rl_vcpfunc_t *rl_linefunc;              /* user callback function */
  56 static int in_handler;          /* terminal_prepped and signals set? */
  57
  58 /* Make sure the terminal is set up, initialize readline, and prompt. */
  59 static 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. */
  79 void
  80 rl_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. */
  90 void
  91 rl_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. */
 135 void
 136 rl_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