#ifndef SQL_HSET_INCLUDED
#define SQL_HSET_INCLUDED
/* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; version 2 of the License.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */

#include "my_global.h"
#include "hash.h"


/**
 A type-safe wrapper around mysys HASH.
*/

template <typename T, my_hash_get_key K>
class Hash_set
{
public:
 typedef T Value_type;
 enum { START_SIZE= 8 };
 /**
 Constructs an empty hash. Does not allocate memory, it is done upon
 the first insert. Thus does not cause or return errors.
 */
 Hash_set()
 {
 my_hash_clear(&m_hash);
 }
 /**
 Destroy the hash by freeing the buckets table. Does
 not call destructors for the elements.
 */
 ~Hash_set()
 {
 my_hash_free(&m_hash);
 }
 /**
 Insert a single value into a hash. Does not tell whether
 the value was inserted -- if an identical value existed,
 it is not replaced.

 @retval TRUE Out of memory.
 @retval FALSE OK. The value either was inserted or existed
 in the hash.
 */
 bool insert(T *value)
 {
 my_hash_init_opt(&m_hash, &my_charset_bin, START_SIZE, 0, 0, K, 0, MYF(0));
 size_t key_len;
 const uchar *key= K(reinterpret_cast<uchar*>(value), &key_len, FALSE);
 if (my_hash_search(&m_hash, key, key_len) == NULL)
 return my_hash_insert(&m_hash, reinterpret_cast<uchar *>(value));
 return FALSE;
 }
 /** Is this hash set empty? */
 bool is_empty() const { return m_hash.records == 0; }
 /** Returns the number of unique elements. */
 size_t size() const { return static_cast<size_t>(m_hash.records); }
 /** An iterator over hash elements. Is not insert-stable. */
 class Iterator
 {
 public:
 Iterator(Hash_set &hash_set)
 : m_hash(&hash_set.m_hash),
 m_idx(0)
 {}
 /**
 Return the current element and reposition the iterator to the next
 element.
 */
 inline T *operator++(int)
 {
 if (m_idx < m_hash->records)
 return reinterpret_cast<T*>(my_hash_element(m_hash, m_idx++));
 return NULL;
 }
 void rewind() { m_idx= 0; }
 private:
 HASH *m_hash;
 uint m_idx;
 };
private:
 HASH m_hash;
};

#endif // SQL_HSET_INCLUDED