builtins/break.def

   1 This file is break.def, from which is created break.c.
   2 It implements the builtins "break" and "continue" in Bash.
   3
   4 Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc.
   5
   6 This file is part of GNU Bash, the Bourne Again SHell.
   7
   8 Bash is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 Bash is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License along
  19 with Bash; see the file COPYING.  If not, write to the Free Software
  20 Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.
  21
  22 $PRODUCES break.c
  23
  24 $BUILTIN break
  25 $FUNCTION break_builtin
  26 $SHORT_DOC break [n]
  27 Exit from within a FOR, WHILE or UNTIL loop.  If N is specified,
  28 break N levels.
  29 $END
  30 #include <config.h>
  31
  32 #if defined (HAVE_UNISTD_H)
  33 #  ifdef _MINIX
  34 #    include <sys/types.h>
  35 #  endif
  36 #  include <unistd.h>
  37 #endif
  38
  39 #include "../shell.h"
  40 #include "common.h"
  41
  42 extern char *this_command_name;
  43 extern int posixly_correct;
  44
  45 static int check_loop_level ();
  46
  47 /* The depth of while's and until's. */
  48 int loop_level = 0;
  49
  50 /* Non-zero when a "break" instruction is encountered. */
  51 int breaking = 0;
  52
  53 /* Non-zero when we have encountered a continue instruction. */
  54 int continuing = 0;
  55
  56 /* Set up to break x levels, where x defaults to 1, but can be specified
  57    as the first argument. */
  58 int
  59 break_builtin (list)
  60      WORD_LIST *list;
  61 {
  62   int newbreak;
  63
  64   if (check_loop_level () == 0)
  65     return (EXECUTION_SUCCESS);
  66
  67   newbreak = get_numeric_arg (list, 1);
  68
  69   if (newbreak <= 0)
  70     {
  71       builtin_error ("loop count must be > 0");
  72       breaking = loop_level;
  73       return (EXECUTION_FAILURE);
  74     }
  75
  76   if (newbreak > loop_level)
  77     newbreak = loop_level;
  78
  79   breaking = newbreak;
  80
  81   return (EXECUTION_SUCCESS);
  82 }
  83
  84 $BUILTIN continue
  85 $FUNCTION continue_builtin
  86 $SHORT_DOC continue [n]
  87 Resume the next iteration of the enclosing FOR, WHILE or UNTIL loop.
  88 If N is specified, resume at the N-th enclosing loop.
  89 $END
  90
  91 /* Set up to continue x levels, where x defaults to 1, but can be specified
  92    as the first argument. */
  93 int
  94 continue_builtin (list)
  95      WORD_LIST *list;
  96 {
  97   int newcont;
  98
  99   if (check_loop_level () == 0)
 100     return (EXECUTION_SUCCESS);
 101
 102   newcont = get_numeric_arg (list, 1);
 103
 104   if (newcont <= 0)
 105     {
 106       builtin_error ("loop count must be > 0");
 107       breaking = loop_level;
 108       return (EXECUTION_FAILURE);
 109     }
 110
 111   if (newcont > loop_level)
 112     newcont = loop_level;
 113
 114   continuing = newcont;
 115
 116   return (EXECUTION_SUCCESS);
 117 }
 118
 119 /* Return non-zero if a break or continue command would be okay.
 120    Print an error message if break or continue is meaningless here. */
 121 static int
 122 check_loop_level ()
 123 {
 124 #if defined (BREAK_COMPLAINS)
 125   if (loop_level == 0 && posixly_correct == 0)
 126     builtin_error ("only meaningful in a `for', `while', or `until' loop");
 127 #endif /* BREAK_COMPLAINS */
 128
 129   return (loop_level);
 130 }