/* Copyright (C) 2002 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */

#ifndef __HASHTABLE_CWC22_H__
#define __HASHTABLE_CWC22_H__

/*****************************************************************************/

typedef struct entry
{
	void *k, *v;
	unsigned int h;
	struct entry *next;
} entry;

typedef struct hashtable
{
	unsigned int tablelength;
	entry **table;
	unsigned int entrycount;
	unsigned int loadlimit;
	unsigned int primeindex;
	unsigned int (*hashfn) (const void *k);
	int (*eqfn) (const void *k1, const void *k2);
} hashtable;

/*****************************************************************************/
unsigned int
hash(hashtable *h, const void *k);

/* Example of use:
*
*      hashtable  *h;
*      struct some_key   *k;
*      struct some_value *v;
*
*      static unsigned int         hash_from_key_fn( void *k );
*      static int                  keys_equal_fn ( void *key1, void *key2 );
*
*      h = create_hashtable(16, hash_from_key_fn, keys_equal_fn);
*      k = (struct some_key *)     malloc(sizeof(struct some_key));
*      v = (struct some_value *)   malloc(sizeof(struct some_value));
*
*      (initialise k and v to suitable values)
*
*      if (! hashtable_insert(h,k,v) )
*      {     exit(-1);               }
*
*      if (NULL == (found = hashtable_search(h,k) ))
*      {    printf("not found!");                  }
*
*      if (NULL == (found = hashtable_remove(h,k) ))
*      {    printf("Not found\n");                 }
*
*/

/*
* Macros may be used to define type-safe(r) hashtable access functions, with
* methods specialized to take known key and value types as parameters.
*
* Example:
*
* Insert this at the start of your file:
*
* DEFINE_HASHTABLE_INSERT(insert_some, struct some_key, struct some_value);
* DEFINE_HASHTABLE_SEARCH(search_some, struct some_key, struct some_value);
* DEFINE_HASHTABLE_REMOVE(remove_some, struct some_key, struct some_value);
*
* This defines the functions 'insert_some', 'search_some' and 'remove_some'.
* These operate just like hashtable_insert etc., with the same parameters,
* but their function signatures have 'struct some_key *' rather than
* 'void *', and hence can generate compile time errors if your program is
* supplying incorrect data as a key (and similarly for value).
*
* Note that the hash and key equality functions passed to create_hashtable
* still take 'void *' parameters instead of 'some key *'. This shouldn't be
* a difficult issue as they're only defined and passed once, and the other
* functions will ensure that only valid keys are supplied to them.
*
* The cost for this checking is increased code size and runtime overhead
* - if performance is important, it may be worth switching back to the
* unsafe methods once your program has been debugged with the safe methods.
* This just requires switching to some simple alternative defines - eg:
* #define insert_some hashtable_insert
*
*/

/*****************************************************************************
* create_hashtable

* @name                    create_hashtable
* @param   minsize         minimum initial size of hashtable
* @param   hashfunction    function for hashing keys
* @param   key_eq_fn       function for determining key equality
* @return                  newly created hashtable or NULL on failure
*/

hashtable *
create_hashtable(unsigned int minsize,
				 unsigned int (*hashfunction) (const void*),
				 int (*key_eq_fn) (const void*,const void*));


/*****************************************************************************
* create_string_hashtable
* @name create_string_hashtable
* @return hashtable for string keys, with start size of 16
*/
hashtable *
create_string_hashtable(void);


/*****************************************************************************
* hashtable_insert

* @name        hashtable_insert
* @param   h   the hashtable to insert into
* @param   k   the key - hashtable claims ownership and will free on removal
* @param   v   the value - does not claim ownership
* @return      non-zero for successful insertion
*
* This function will cause the table to expand if the insertion would take
* the ratio of entries to table size over the maximum load factor.
*
* This function does not check for repeated insertions with a duplicate key.
* The value returned when using a duplicate key is undefined -- when
* the hashtable changes size, the order of retrieval of duplicate key
* entries is reversed.
* If in doubt, remove before insert.
*/

int
hashtable_insert(hashtable *h, void *k, void *v);

#define DEFINE_HASHTABLE_INSERT(fnname, keytype, valuetype) \
int fnname (hashtable *h, keytype *k, valuetype *v) \
{ \
	return hashtable_insert(h,k,v); \
}

/*****************************************************************************
* hashtable_search

* @name        hashtable_search
* @param   h   the hashtable to search
* @param   k   the key to search for  - does not claim ownership
* @return      the value associated with the key, or NULL if none found
*/

void *
hashtable_search(hashtable *h, const void *k);

#define DEFINE_HASHTABLE_SEARCH(fnname, keytype, valuetype) \
valuetype * fnname (hashtable *h, keytype *k) \
{ \
	return (valuetype *) (hashtable_search(h,k)); \
}

/*****************************************************************************
* hashtable_remove

* @name        hashtable_remove
* @param   h   the hashtable to remove the item from
* @param   k   the key to search for  - does not claim ownership
* @return      the value associated with the key, or NULL if none found
*/

void * /* returns value */
hashtable_remove(hashtable *h, void *k);

#define DEFINE_HASHTABLE_REMOVE(fnname, keytype, valuetype) \
valuetype * fnname (hashtable *h, keytype *k) \
{ \
	return (valuetype *) (hashtable_remove(h,k)); \
}


/**
* @name hash_str
* @param str the string to hash
* @return the hash value
*/
unsigned int
hash_str(const void *str);

/**
* @name str_eq
* @param str1 the string to compare
* @param str2 the string to compare
* @return 1 if equal 0 if not
*/
int
str_eq(const void *str1, const void *str2);


/*****************************************************************************
* hashtable_count

* @name        hashtable_count
* @param   h   the hashtable
* @return      the number of items stored in the hashtable
*/
unsigned int
hashtable_count(hashtable *h);


/*****************************************************************************
* hashtable_destroy

* @name        hashtable_destroy
* @param   h   the hashtable
* @param       free_values     whether to call 'free' on the remaining values
*/

void
hashtable_destroy(hashtable *h, int free_values);



/*****************************************************************************/
/* indexFor */
static inline unsigned int
indexFor(unsigned int tablelength, unsigned int hashvalue)
{
	return (hashvalue % tablelength);
};


#endif /* __HASHTABLE_CWC22_H__ */

/*
* Copyright (c) 2002, 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.
*/
