list.c

   1 /* list.c - Functions for manipulating linked lists of objects. */
   2
   3 /* Copyright (C) 1996-2009 Free Software Foundation, Inc.
   4
   5    This file is part of GNU Bash, the Bourne Again SHell.
   6
   7    Bash is free software: you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation, either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    Bash is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "config.h"
  22
  23 #if defined (HAVE_UNISTD_H)
  24 #  ifdef _MINIX
  25 #    include <sys/types.h>
  26 #  endif
  27 #  include <unistd.h>
  28 #endif
  29
  30 #include "shell.h"
  31
  32 /* A global variable which acts as a sentinel for an `error' list return. */
  33 GENERIC_LIST global_error_list;
  34
  35 #ifdef INCLUDE_UNUSED
  36 /* Call FUNCTION on every member of LIST, a generic list. */
  37 void
  38 list_walk (list, function)
  39      GENERIC_LIST *list;
  40      sh_glist_func_t *function;
  41 {
  42   for ( ; list; list = list->next)
  43     if ((*function) (list) < 0)
  44       return;
  45 }
  46
  47 /* Call FUNCTION on every string in WORDS. */
  48 void
  49 wlist_walk (words, function)
  50      WORD_LIST *words;
  51      sh_icpfunc_t *function;
  52 {
  53   for ( ; words; words = words->next)
  54     if ((*function) (words->word->word) < 0)
  55       return;
  56 }
  57 #endif /* INCLUDE_UNUSED */
  58
  59 /* Reverse the chain of structures in LIST.  Output the new head
  60    of the chain.  You should always assign the output value of this
  61    function to something, or you will lose the chain. */
  62 GENERIC_LIST *
  63 list_reverse (list)
  64      GENERIC_LIST *list;
  65 {
  66   register GENERIC_LIST *next, *prev;
  67
  68   for (prev = (GENERIC_LIST *)NULL; list; )
  69     {
  70       next = list->next;
  71       list->next = prev;
  72       prev = list;
  73       list = next;
  74     }
  75   return (prev);
  76 }
  77
  78 /* Return the number of elements in LIST, a generic list. */
  79 int
  80 list_length (list)
  81      GENERIC_LIST *list;
  82 {
  83   register int i;
  84
  85   for (i = 0; list; list = list->next, i++);
  86   return (i);
  87 }
  88
  89 /* Append TAIL to HEAD.  Return the header of the list. */
  90 GENERIC_LIST *
  91 list_append (head, tail)
  92      GENERIC_LIST *head, *tail;
  93 {
  94   register GENERIC_LIST *t_head;
  95
  96   if (head == 0)
  97     return (tail);
  98
  99   for (t_head = head; t_head->next; t_head = t_head->next)
 100     ;
 101   t_head->next = tail;
 102   return (head);
 103 }
 104
 105 #ifdef INCLUDE_UNUSED
 106 /* Delete the element of LIST which satisfies the predicate function COMPARER.
 107    Returns the element that was deleted, so you can dispose of it, or -1 if
 108    the element wasn't found.  COMPARER is called with the list element and
 109    then ARG.  Note that LIST contains the address of a variable which points
 110    to the list.  You might call this function like this:
 111
 112    SHELL_VAR *elt = list_remove (&variable_list, check_var_has_name, "foo");
 113    dispose_variable (elt);
 114 */
 115 GENERIC_LIST *
 116 list_remove (list, comparer, arg)
 117      GENERIC_LIST **list;
 118      Function *comparer;
 119      char *arg;
 120 {
 121   register GENERIC_LIST *prev, *temp;
 122
 123   for (prev = (GENERIC_LIST *)NULL, temp = *list; temp; prev = temp, temp = temp->next)
 124     {
 125       if ((*comparer) (temp, arg))
 126         {
 127           if (prev)
 128             prev->next = temp->next;
 129           else
 130             *list = temp->next;
 131           return (temp);
 132         }
 133     }
 134   return ((GENERIC_LIST *)&global_error_list);
 135 }
 136 #endif