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
  44 static int check_loop_level ();
  45
  46 /* The depth of while's and until's. */
  47 int loop_level = 0;
  48
  49 /* Non-zero when a "break" instruction is encountered. */
  50 int breaking = 0;
  51
  52 /* Non-zero when we have encountered a continue instruction. */
  53 int continuing = 0;
  54
  55 /* Set up to break x levels, where x defaults to 1, but can be specified
  56    as the first argument. */
  57 int
  58 break_builtin (list)
  59      WORD_LIST *list;
  60 {
  61   int newbreak;
  62
  63   if (check_loop_level () == 0)
  64     return (EXECUTION_FAILURE);
  65
  66   newbreak = get_numeric_arg (list, 1);
  67
  68   if (newbreak <= 0)
  69     {
  70       builtin_error ("loop count must be > 0");
  71       breaking = loop_level;
  72       return (EXECUTION_FAILURE);
  73     }
  74
  75   if (newbreak > loop_level)
  76     newbreak = loop_level;
  77
  78   breaking = newbreak;
  79
  80   return (EXECUTION_SUCCESS);
  81 }
  82
  83 $BUILTIN continue
  84 $FUNCTION continue_builtin
  85 $SHORT_DOC continue [n]
  86 Resume the next iteration of the enclosing FOR, WHILE or UNTIL loop.
  87 If N is specified, resume at the N-th enclosing loop.
  88 $END
  89
  90 /* Set up to continue x levels, where x defaults to 1, but can be specified
  91    as the first argument. */
  92 int
  93 continue_builtin (list)
  94      WORD_LIST *list;
  95 {
  96   int newcont;
  97
  98   if (check_loop_level () == 0)
  99     return (EXECUTION_FAILURE);
 100
 101   newcont = get_numeric_arg (list, 1);
 102
 103   if (newcont <= 0)
 104     {
 105       builtin_error ("loop count must be > 0");
 106       breaking = loop_level;
 107       return (EXECUTION_FAILURE);
 108     }
 109
 110   if (newcont > loop_level)
 111     newcont = loop_level;
 112
 113   continuing = newcont;
 114
 115   return (EXECUTION_SUCCESS);
 116 }
 117
 118 /* Return non-zero if a break or continue command would be okay.
 119    Print an error message if break or continue is meaningless here. */
 120 static int
 121 check_loop_level ()
 122 {
 123 #if defined (BREAK_COMPLAINS)
 124   if (loop_level == 0)
 125     builtin_error ("only meaningful in a `for', `while', or `until' loop");
 126 #endif /* BREAK_COMPLAINS */
 127
 128   return (loop_level);
 129 }