contrib/cvs-1.12/src/stack.c

   1 /*
   2  * Copyright (C) 2004-2005 The Free Software Foundation, Inc.
   3  *
   4  * Portions Copyright (C) 2004-2005 Derek Price, Ximbiot <http://ximbiot.com>,
   5  *                                  and others.
   6  *
   7  * You may distribute under the terms of the GNU General Public License as
   8  * specified in the README file that comes with the CVS source distribution.
   9  *
  10  * This module uses the hash.c module to implement a stack.
  11  */
  12
  13 #include "cvs.h"
  14 #include <assert.h>
  15
  16
  17
  18 static void
  19 do_push (List *stack, void *elem, int isstring)
  20 {
  21     Node *p = getnode();
  22
  23     if (isstring)
  24         p->key = elem;
  25     else
  26         p->data = elem;
  27
  28     addnode(stack, p);
  29 }
  30
  31
  32
  33 void
  34 push (List *stack, void *elem)
  35 {
  36     do_push (stack, elem, 0);
  37 }
  38
  39
  40
  41 void
  42 push_string (List *stack, char *elem)
  43 {
  44     do_push (stack, elem, 1);
  45 }
  46
  47
  48
  49 static void *
  50 do_pop (List *stack, int isstring)
  51 {
  52     void *elem;
  53
  54     if (isempty (stack)) return NULL;
  55
  56     if (isstring)
  57     {
  58         elem = stack->list->prev->key;
  59         stack->list->prev->key = NULL;
  60     }
  61     else
  62     {
  63         elem = stack->list->prev->data;
  64         stack->list->prev->data = NULL;
  65     }
  66
  67     delnode (stack->list->prev);
  68     return elem;
  69 }
  70
  71
  72
  73 void *
  74 pop (List *stack)
  75 {
  76     return do_pop (stack, 0);
  77 }
  78
  79
  80
  81 char *
  82 pop_string (List *stack)
  83 {
  84     return do_pop (stack, 1);
  85 }
  86
  87
  88
  89 static void
  90 do_unshift (List *stack, void *elem, int isstring)
  91 {
  92     Node *p = getnode();
  93
  94     if (isstring)
  95         p->key = elem;
  96     else
  97         p->data = elem;
  98
  99     addnode_at_front(stack, p);
 100 }
 101
 102
 103
 104 void
 105 unshift (List *stack, void *elem)
 106 {
 107     do_unshift (stack, elem, 0);
 108 }
 109
 110
 111
 112 void
 113 unshift_string (List *stack, char *elem)
 114 {
 115     do_unshift (stack, elem, 1);
 116 }
 117
 118
 119
 120 static void *
 121 do_shift (List *stack, int isstring)
 122 {
 123     void *elem;
 124
 125     if (isempty (stack)) return NULL;
 126
 127     if (isstring)
 128     {
 129         elem = stack->list->next->key;
 130         stack->list->next->key = NULL;
 131     }
 132     else
 133     {
 134         elem = stack->list->next->data;
 135         stack->list->next->data = NULL;
 136     }
 137     delnode (stack->list->next);
 138     return elem;
 139 }
 140
 141
 142
 143 void *
 144 shift (List *stack)
 145 {
 146     return do_shift (stack, 0);
 147 }
 148
 149
 150
 151 char *
 152 shift_string (List *stack)
 153 {
 154     return do_shift (stack, 1);
 155 }
 156
 157
 158
 159 int
 160 isempty (List *stack)
 161 {
 162     if (stack->list == stack->list->next)
 163         return 1;
 164     return 0;
 165 }