Current File : //usr/include/mysql/server/private/sql_hset.h
#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 02110-1335 USA */
#include "hash.h"
/**
A type-safe wrapper around mysys HASH.
*/
template <typename T>
class Hash_set
{
public:
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(uchar *(*K)(const T *, size_t *, my_bool),
CHARSET_INFO *cs= &my_charset_bin)
{
my_hash_clear(&m_hash);
m_hash.get_key= (my_hash_get_key)K;
m_hash.charset= cs;
}
/**
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, m_hash.charset, START_SIZE, 0, 0,
m_hash.get_key, 0, MYF(0));
size_t key_len;
uchar *v= reinterpret_cast<uchar *>(value);
const uchar *key= m_hash.get_key(v, &key_len, FALSE);
if (find(key, key_len) == NULL)
return my_hash_insert(&m_hash, v);
return FALSE;
}
bool remove(T *value)
{
return my_hash_delete(&m_hash, reinterpret_cast<uchar*>(value));
}
T *find(const void *key, size_t klen) const
{
return (T*)my_hash_search(&m_hash, reinterpret_cast<const uchar *>(key), klen);
}
/** 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); }
const T* at(size_t i) const
{
return reinterpret_cast<T*>(my_hash_element(const_cast<HASH*>(&m_hash), i));
}
/** 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
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