1 /* Copyright (C) 2002, 2004 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
2
3 #include "hashtable.h"
4 #define HASHTABLE_INDEXFOR
5 #include "hashtable_private.h"
6 #include "hashtable_itr.h"
7 #include <stdlib.h> /* defines NULL */
8
9 /*****************************************************************************/
10 /* hashtable_iterator - iterator constructor */
11
12 struct hashtable_itr *
hashtable_iterator(struct hashtable * h)13 hashtable_iterator(struct hashtable *h)
14 {
15 unsigned int i, tablelength;
16 struct hashtable_itr *itr = (struct hashtable_itr *)
17 malloc(sizeof(struct hashtable_itr));
18 if (NULL == itr) return NULL;
19 itr->h = h;
20 itr->e = NULL;
21 itr->parent = NULL;
22 tablelength = h->tablelength;
23 itr->index = tablelength;
24 if (0 == h->entrycount) return itr;
25
26 for (i = 0; i < tablelength; i++)
27 {
28 if (NULL != h->table[i])
29 {
30 itr->e = h->table[i];
31 itr->index = i;
32 break;
33 }
34 }
35 return itr;
36 }
37
38 /*****************************************************************************/
39 /* key - return the key of the (key,value) pair at the current position */
40 /* value - return the value of the (key,value) pair at the current position */
41
42 void *
hashtable_iterator_key(struct hashtable_itr * i)43 hashtable_iterator_key(struct hashtable_itr *i)
44 { return i->e->k; }
45
46 void *
hashtable_iterator_value(struct hashtable_itr * i)47 hashtable_iterator_value(struct hashtable_itr *i)
48 { return i->e->v; }
49
50 /*****************************************************************************/
51 /* advance - advance the iterator to the next element
52 * returns zero if advanced to end of table */
53
54 int
hashtable_iterator_advance(struct hashtable_itr * itr)55 hashtable_iterator_advance(struct hashtable_itr *itr)
56 {
57 unsigned int j,tablelength;
58 struct entry **table;
59 struct entry *next;
60 if (NULL == itr->e) return 0; /* stupidity check */
61
62 next = itr->e->next;
63 if (NULL != next)
64 {
65 itr->parent = itr->e;
66 itr->e = next;
67 return -1;
68 }
69 tablelength = itr->h->tablelength;
70 itr->parent = NULL;
71 if (tablelength <= (j = ++(itr->index)))
72 {
73 itr->e = NULL;
74 return 0;
75 }
76 table = itr->h->table;
77 while (NULL == (next = table[j]))
78 {
79 if (++j >= tablelength)
80 {
81 itr->index = tablelength;
82 itr->e = NULL;
83 return 0;
84 }
85 }
86 itr->index = j;
87 itr->e = next;
88 return -1;
89 }
90
91 /*****************************************************************************/
92 /* remove - remove the entry at the current iterator position
93 * and advance the iterator, if there is a successive
94 * element.
95 * If you want the value, read it before you remove:
96 * beware memory leaks if you don't.
97 * Returns zero if end of iteration. */
98
99 int
hashtable_iterator_remove(struct hashtable_itr * itr)100 hashtable_iterator_remove(struct hashtable_itr *itr)
101 {
102 struct entry *remember_e, *remember_parent;
103 int ret;
104
105 /* Do the removal */
106 if (NULL == (itr->parent))
107 {
108 /* element is head of a chain */
109 itr->h->table[itr->index] = itr->e->next;
110 } else {
111 /* element is mid-chain */
112 itr->parent->next = itr->e->next;
113 }
114 /* itr->e is now outside the hashtable */
115 remember_e = itr->e;
116 itr->h->entrycount--;
117 freekey(remember_e->k);
118
119 /* Advance the iterator, correcting the parent */
120 remember_parent = itr->parent;
121 ret = hashtable_iterator_advance(itr);
122 if (itr->parent == remember_e) { itr->parent = remember_parent; }
123 free(remember_e);
124 return ret;
125 }
126
127 /*****************************************************************************/
128 int /* returns zero if not found */
hashtable_iterator_search(struct hashtable_itr * itr,struct hashtable * h,void * k)129 hashtable_iterator_search(struct hashtable_itr *itr,
130 struct hashtable *h, void *k)
131 {
132 struct entry *e, *parent;
133 unsigned int hashvalue, index;
134
135 hashvalue = hash(h,k);
136 index = indexFor(h->tablelength,hashvalue);
137
138 e = h->table[index];
139 parent = NULL;
140 while (NULL != e)
141 {
142 /* Check hash value to short circuit heavier comparison */
143 if ((hashvalue == e->h) && (h->eqfn(k, e->k)))
144 {
145 itr->index = index;
146 itr->e = e;
147 itr->parent = parent;
148 itr->h = h;
149 return -1;
150 }
151 parent = e;
152 e = e->next;
153 }
154 return 0;
155 }
156
157
158 /*
159 * Copyright (c) 2002, 2004, Christopher Clark
160 * All rights reserved.
161 *
162 * Redistribution and use in source and binary forms, with or without
163 * modification, are permitted provided that the following conditions
164 * are met:
165 *
166 * * Redistributions of source code must retain the above copyright
167 * notice, this list of conditions and the following disclaimer.
168 *
169 * * Redistributions in binary form must reproduce the above copyright
170 * notice, this list of conditions and the following disclaimer in the
171 * documentation and/or other materials provided with the distribution.
172 *
173 * * Neither the name of the original author; nor the names of any contributors
174 * may be used to endorse or promote products derived from this software
175 * without specific prior written permission.
176 *
177 *
178 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
179 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
180 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
181 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
182 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
183 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
184 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
185 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
186 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
187 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
188 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
189 */
190