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