summaryrefslogtreecommitdiff
path: root/mkfs.ubifs/hashtable/hashtable_itr.c
diff options
context:
space:
mode:
Diffstat (limited to 'mkfs.ubifs/hashtable/hashtable_itr.c')
-rw-r--r--mkfs.ubifs/hashtable/hashtable_itr.c188
1 files changed, 188 insertions, 0 deletions
diff --git a/mkfs.ubifs/hashtable/hashtable_itr.c b/mkfs.ubifs/hashtable/hashtable_itr.c
new file mode 100644
index 0000000..5dced84
--- /dev/null
+++ b/mkfs.ubifs/hashtable/hashtable_itr.c
@@ -0,0 +1,188 @@
+/* Copyright (C) 2002, 2004 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
+
+#include "hashtable.h"
+#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 */
+
+void *
+hashtable_iterator_key(struct hashtable_itr *i)
+{ return i->e->k; }
+
+void *
+hashtable_iterator_value(struct hashtable_itr *i)
+{ return i->e->v; }
+
+/*****************************************************************************/
+/* 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.
+*/