summaryrefslogtreecommitdiffstats
path: root/runtime/hashtable_itr.c
blob: a065f12b6d8555f6470b2a611e56d90451001607 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
/* Copyright (C) 2002, 2004 Christopher Clark  <firstname.lastname@cl.cam.ac.uk> */

#include "hashtable_private.h"
#include "hashtable_itr.h"
#include <stdlib.h> /* defines NULL */

/*****************************************************************************/
/* hashtable_iterator    - iterator constructor */

struct hashtable_itr *
hashtable_iterator(struct hashtable *h)
{
	unsigned int i, tablelength;
	struct hashtable_itr *itr = (struct hashtable_itr *)
	malloc(sizeof(struct hashtable_itr));
	if (NULL == itr) return NULL;
	itr->h = h;
	itr->e = NULL;
	itr->parent = NULL;
	tablelength = h->tablelength;
	itr->index = tablelength;
	if (0 == h->entrycount) return itr;

	for (i = 0; i < tablelength; i++)
	{
		if (NULL != h->table[i])
		{
			itr->e = h->table[i];
			itr->index = i;
			break;
		}
	}
	return itr;
}

/*****************************************************************************/
/* key      - return the key of the (key,value) pair at the current position */
/* value    - return the value of the (key,value) pair at the current position */

#if 0 /* these are now inline functions! */
void *
hashtable_iterator_key(struct hashtable_itr *i)
{ return i->e->k; }

void *
hashtable_iterator_value(struct hashtable_itr *i)
{ return i->e->v; }
#endif

/*****************************************************************************/
/* advance - advance the iterator to the next element
 *           returns zero if advanced to end of table */

int
hashtable_iterator_advance(struct hashtable_itr *itr)
{
	unsigned int j,tablelength;
	struct entry **table;
	struct entry *next;
	if (NULL == itr->e) return 0; /* stupidity check */

	next = itr->e->next;
	if (NULL != next)
	{
		itr->parent = itr->e;
		itr->e = next;
		return -1;
	}
	tablelength = itr->h->tablelength;
	itr->parent = NULL;
	if (tablelength <= (j = ++(itr->index)))
	{
		itr->e = NULL;
		return 0;
	}
	table = itr->h->table;
	while (NULL == (next = table[j]))
	{
		if (++j >= tablelength)
		{
			itr->index = tablelength;
			itr->e = NULL;
			return 0;
		}
	}
	itr->index = j;
	itr->e = next;
	return -1;
}

/*****************************************************************************/
/* remove - remove the entry at the current iterator position
 *          and advance the iterator, if there is a successive
 *          element.
 *          If you want the value, read it before you remove:
 *          beware memory leaks if you don't.
 *          Returns zero if end of iteration. */

int
hashtable_iterator_remove(struct hashtable_itr *itr)
{
	struct entry *remember_e, *remember_parent;
	int ret;

	/* Do the removal */
	if (NULL == (itr->parent))
	{
		/* element is head of a chain */
		itr->h->table[itr->index] = itr->e->next;
	} else {
		/* element is mid-chain */
		itr->parent->next = itr->e->next;
	}
	/* itr->e is now outside the hashtable */
	remember_e = itr->e;
	itr->h->entrycount--;
	freekey(remember_e->k);

	/* Advance the iterator, correcting the parent */
	remember_parent = itr->parent;
	ret = hashtable_iterator_advance(itr);
	if (itr->parent == remember_e) { itr->parent = remember_parent; }
	free(remember_e);
	return ret;
}

/*****************************************************************************/
int /* returns zero if not found */
hashtable_iterator_search(struct hashtable_itr *itr,
			struct hashtable *h, void *k)
{
	struct entry *e, *parent;
	unsigned int hashvalue, index;

	hashvalue = hash(h,k);
	index = indexFor(h->tablelength,hashvalue);

	e = h->table[index];
	parent = NULL;
	while (NULL != e)
	{
		/* Check hash value to short circuit heavier comparison */
		if ((hashvalue == e->h) && (h->eqfn(k, e->k)))
		{
			itr->index = index;
			itr->e = e;
			itr->parent = parent;
			itr->h = h;
			return -1;
		}
		parent = e;
		e = e->next;
	}
	return 0;
}


/*
 * Copyright (c) 2002, 2004, Christopher Clark
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of the original author; nor the names of any contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/