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/*
* Copyright (c) 2009-2011 Petri Lehtinen <petri@digip.org>
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See LICENSE for details.
*/

#ifndef HASHTABLE_H
#define HASHTABLE_H

typedef size_t (*key_hash_fn)(const void *key);
typedef int (*key_cmp_fn)(const void *key1, const void *key2);
typedef void (*free_fn)(void *key);

struct hashtable_list {
    struct hashtable_list *prev;
    struct hashtable_list *next;
};

/* "pair" may be a bit confusing a name, but think of it as a
key-value pair. In this case, it just encodes some extra data,
too */
struct hashtable_pair {
    size_t hash;
    struct hashtable_list list;
    json_t *value;
    size_t serial;
    char key[1];
};

struct hashtable_bucket {
    struct hashtable_list *first;
    struct hashtable_list *last;
};

typedef struct hashtable {
    size_t size;
    struct hashtable_bucket *buckets;
    size_t num_buckets; /* index to primes[] */
    struct hashtable_list list;
} hashtable_t;


#define hashtable_key_to_iter(key_) \
(&(container_of(key_, struct hashtable_pair, key)->list))

/**
* hashtable_init - Initialize a hashtable object
*
* @hashtable: The (statically allocated) hashtable object
*
* Initializes a statically allocated hashtable object. The object
* should be cleared with hashtable_close when it's no longer used.
*
* Returns 0 on success, -1 on error (out of memory).
*/
int hashtable_init(hashtable_t *hashtable);

/**
* hashtable_close - Release all resources used by a hashtable object
*
* @hashtable: The hashtable
*
* Destroys a statically allocated hashtable object.
*/
void hashtable_close(hashtable_t *hashtable);

/**
* hashtable_set - Add/modify value in hashtable
*
* @hashtable: The hashtable object
* @key: The key
* @serial: For addition order of keys
* @value: The value
*
* If a value with the given key already exists, its value is replaced
* with the new value. Value is "stealed" in the sense that hashtable
* doesn't increment its refcount but decreases the refcount when the
* value is no longer needed.
*
* Returns 0 on success, -1 on failure (out of memory).
*/
int hashtable_set(hashtable_t *hashtable,
                  const char *key, size_t serial,
                  json_t *value);

/**
* hashtable_get - Get a value associated with a key
*
* @hashtable: The hashtable object
* @key: The key
*
* Returns value if it is found, or NULL otherwise.
*/
void *hashtable_get(hashtable_t *hashtable, const char *key);

/**
* hashtable_del - Remove a value from the hashtable
*
* @hashtable: The hashtable object
* @key: The key
*
* Returns 0 on success, or -1 if the key was not found.
*/
int hashtable_del(hashtable_t *hashtable, const char *key);

/**
* hashtable_clear - Clear hashtable
*
* @hashtable: The hashtable object
*
* Removes all items from the hashtable.
*/
void hashtable_clear(hashtable_t *hashtable);

/**
* hashtable_iter - Iterate over hashtable
*
* @hashtable: The hashtable object
*
* Returns an opaque iterator to the first element in the hashtable.
* The iterator should be passed to hashtable_iter_* functions.
* The hashtable items are not iterated over in any particular order.
*
* There's no need to free the iterator in any way. The iterator is
* valid as long as the item that is referenced by the iterator is not
* deleted. Other values may be added or deleted. In particular,
* hashtable_iter_next() may be called on an iterator, and after that
* the key/value pair pointed by the old iterator may be deleted.
*/
void *hashtable_iter(hashtable_t *hashtable);

/**
* hashtable_iter_at - Return an iterator at a specific key
*
* @hashtable: The hashtable object
* @key: The key that the iterator should point to
*
* Like hashtable_iter() but returns an iterator pointing to a
* specific key.
*/
void *hashtable_iter_at(hashtable_t *hashtable, const char *key);

/**
* hashtable_iter_next - Advance an iterator
*
* @hashtable: The hashtable object
* @iter: The iterator
*
* Returns a new iterator pointing to the next element in the
* hashtable or NULL if the whole hastable has been iterated over.
*/
void *hashtable_iter_next(hashtable_t *hashtable, void *iter);

/**
* hashtable_iter_key - Retrieve the key pointed by an iterator
*
* @iter: The iterator
*/
void *hashtable_iter_key(void *iter);

/**
* hashtable_iter_serial - Retrieve the serial number pointed to by an iterator
*
* @iter: The iterator
*/
size_t hashtable_iter_serial(void *iter);

/**
* hashtable_iter_value - Retrieve the value pointed by an iterator
*
* @iter: The iterator
*/
void *hashtable_iter_value(void *iter);

/**
* hashtable_iter_set - Set the value pointed by an iterator
*
* @iter: The iterator
* @value: The value to set
*/
void hashtable_iter_set(void *iter, json_t *value);

#endif
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