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) 1987-2009 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
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation, either version 3 of the License, or
  11 (at your option) any later version.
  12
  13 Bash is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 $PRODUCES break.c
  22
  23 $BUILTIN break
  24 $FUNCTION break_builtin
  25 $SHORT_DOC break [n]
  26 Exit for, while, or until loops.
  27
  28 Exit a FOR, WHILE or UNTIL loop.  If N is specified, break N enclosing
  29 loops.
  30
  31 Exit Status:
  32 The exit status is 0 unless N is not greater than or equal to 1.
  33 $END
  34 #include <config.h>
  35
  36 #if defined (HAVE_UNISTD_H)
  37 #  ifdef _MINIX
  38 #    include <sys/types.h>
  39 #  endif
  40 #  include <unistd.h>
  41 #endif
  42
  43 #include "../bashintl.h"
  44
  45 #include "../shell.h"
  46 #include "common.h"
  47
  48 extern char *this_command_name;
  49 extern int posixly_correct;
  50
  51 static int check_loop_level __P((void));
  52
  53 /* The depth of while's and until's. */
  54 int loop_level = 0;
  55
  56 /* Non-zero when a "break" instruction is encountered. */
  57 int breaking = 0;
  58
  59 /* Non-zero when we have encountered a continue instruction. */
  60 int continuing = 0;
  61
  62 /* Set up to break x levels, where x defaults to 1, but can be specified
  63    as the first argument. */
  64 int
  65 break_builtin (list)
  66      WORD_LIST *list;
  67 {
  68   intmax_t newbreak;
  69
  70   if (check_loop_level () == 0)
  71     return (EXECUTION_SUCCESS);
  72
  73   (void)get_numeric_arg (list, 1, &newbreak);
  74
  75   if (newbreak <= 0)
  76     {
  77       sh_erange (list->word->word, _("loop count"));
  78       breaking = loop_level;
  79       return (EXECUTION_FAILURE);
  80     }
  81
  82   if (newbreak > loop_level)
  83     newbreak = loop_level;
  84
  85   breaking = newbreak;
  86
  87   return (EXECUTION_SUCCESS);
  88 }
  89
  90 $BUILTIN continue
  91 $FUNCTION continue_builtin
  92 $SHORT_DOC continue [n]
  93 Resume for, while, or until loops.
  94
  95 Resumes the next iteration of the enclosing FOR, WHILE or UNTIL loop.
  96 If N is specified, resumes the Nth enclosing loop.
  97
  98 Exit Status:
  99 The exit status is 0 unless N is not greater than or equal to 1.
 100 $END
 101
 102 /* Set up to continue x levels, where x defaults to 1, but can be specified
 103    as the first argument. */
 104 int
 105 continue_builtin (list)
 106      WORD_LIST *list;
 107 {
 108   intmax_t newcont;
 109
 110   if (check_loop_level () == 0)
 111     return (EXECUTION_SUCCESS);
 112
 113   (void)get_numeric_arg (list, 1, &newcont);
 114
 115   if (newcont <= 0)
 116     {
 117       sh_erange (list->word->word, _("loop count"));
 118       breaking = loop_level;
 119       return (EXECUTION_FAILURE);
 120     }
 121
 122   if (newcont > loop_level)
 123     newcont = loop_level;
 124
 125   continuing = newcont;
 126
 127   return (EXECUTION_SUCCESS);
 128 }
 129
 130 /* Return non-zero if a break or continue command would be okay.
 131    Print an error message if break or continue is meaningless here. */
 132 static int
 133 check_loop_level ()
 134 {
 135 #if defined (BREAK_COMPLAINS)
 136   if (loop_level == 0 && posixly_correct == 0)
 137     builtin_error (_("only meaningful in a `for', `while', or `until' loop"));
 138 #endif /* BREAK_COMPLAINS */
 139
 140   return (loop_level);
 141 }