/* 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 */

struct hashtable_itr {
	struct hashtable *h;
	struct entry *e;
	struct entry *parent;
	unsigned int index;
};

/*****************************************************************************/
/* 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.
 */
