list.c

   1 /* list.c - Functions for manipulating linked lists of objects. */
   2
   3 /* Copyright (C) 1996
   4    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 #include "config.h"
  23
  24 #if defined (HAVE_UNISTD_H)
  25 #  ifdef _MINIX
  26 #    include <sys/types.h>
  27 #  endif
  28 #  include <unistd.h>
  29 #endif
  30
  31 #include "shell.h"
  32
  33 /* A global variable which acts as a sentinel for an `error' list return. */
  34 GENERIC_LIST global_error_list;
  35
  36 #ifdef INCLUDE_UNUSED
  37 /* Call FUNCTION on every member of LIST, a generic list. */
  38 void
  39 list_walk (list, function)
  40      GENERIC_LIST *list;
  41      sh_glist_func_t *function;
  42 {
  43   for ( ; list; list = list->next)
  44     if ((*function) (list) < 0)
  45       return;
  46 }
  47
  48 /* Call FUNCTION on every string in WORDS. */
  49 void
  50 wlist_walk (words, function)
  51      WORD_LIST *words;
  52      sh_icpfunc_t *function;
  53 {
  54   for ( ; words; words = words->next)
  55     if ((*function) (words->word->word) < 0)
  56       return;
  57 }
  58 #endif /* INCLUDE_UNUSED */
  59
  60 /* Reverse the chain of structures in LIST.  Output the new head
  61    of the chain.  You should always assign the output value of this
  62    function to something, or you will lose the chain. */
  63 GENERIC_LIST *
  64 list_reverse (list)
  65      GENERIC_LIST *list;
  66 {
  67   register GENERIC_LIST *next, *prev;
  68
  69   for (prev = (GENERIC_LIST *)NULL; list; )
  70     {
  71       next = list->next;
  72       list->next = prev;
  73       prev = list;
  74       list = next;
  75     }
  76   return (prev);
  77 }
  78
  79 /* Return the number of elements in LIST, a generic list. */
  80 int
  81 list_length (list)
  82      GENERIC_LIST *list;
  83 {
  84   register int i;
  85
  86   for (i = 0; list; list = list->next, i++);
  87   return (i);
  88 }
  89
  90 /* Append TAIL to HEAD.  Return the header of the list. */
  91 GENERIC_LIST *
  92 list_append (head, tail)
  93      GENERIC_LIST *head, *tail;
  94 {
  95   register GENERIC_LIST *t_head;
  96
  97   if (head == 0)
  98     return (tail);
  99
 100   for (t_head = head; t_head->next; t_head = t_head->next)
 101     ;
 102   t_head->next = tail;
 103   return (head);
 104 }
 105
 106 #ifdef INCLUDE_UNUSED
 107 /* Delete the element of LIST which satisfies the predicate function COMPARER.
 108    Returns the element that was deleted, so you can dispose of it, or -1 if
 109    the element wasn't found.  COMPARER is called with the list element and
 110    then ARG.  Note that LIST contains the address of a variable which points
 111    to the list.  You might call this function like this:
 112
 113    SHELL_VAR *elt = list_remove (&variable_list, check_var_has_name, "foo");
 114    dispose_variable (elt);
 115 */
 116 GENERIC_LIST *
 117 list_remove (list, comparer, arg)
 118      GENERIC_LIST **list;
 119      Function *comparer;
 120      char *arg;
 121 {
 122   register GENERIC_LIST *prev, *temp;
 123
 124   for (prev = (GENERIC_LIST *)NULL, temp = *list; temp; prev = temp, temp = temp->next)
 125     {
 126       if ((*comparer) (temp, arg))
 127         {
 128           if (prev)
 129             prev->next = temp->next;
 130           else
 131             *list = temp->next;
 132           return (temp);
 133         }
 134     }
 135   return ((GENERIC_LIST *)&global_error_list);
 136 }
 137 #endif