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97 lines
2.7 KiB
C++
97 lines
2.7 KiB
C++
#ifndef SQL_HSET_INCLUDED
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#define SQL_HSET_INCLUDED
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/* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */
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#include "my_global.h"
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#include "hash.h"
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/**
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A type-safe wrapper around mysys HASH.
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*/
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template <typename T, my_hash_get_key K>
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class Hash_set
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{
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public:
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typedef T Value_type;
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enum { START_SIZE= 8 };
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/**
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Constructs an empty hash. Does not allocate memory, it is done upon
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the first insert. Thus does not cause or return errors.
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*/
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Hash_set()
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{
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my_hash_clear(&m_hash);
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}
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/**
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Destroy the hash by freeing the buckets table. Does
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not call destructors for the elements.
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*/
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~Hash_set()
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{
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my_hash_free(&m_hash);
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}
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/**
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Insert a single value into a hash. Does not tell whether
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the value was inserted -- if an identical value existed,
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it is not replaced.
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@retval TRUE Out of memory.
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@retval FALSE OK. The value either was inserted or existed
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in the hash.
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*/
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bool insert(T *value)
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{
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my_hash_init_opt(&m_hash, &my_charset_bin, START_SIZE, 0, 0, K, 0, MYF(0));
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size_t key_len;
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const uchar *key= K(reinterpret_cast<uchar*>(value), &key_len, FALSE);
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if (my_hash_search(&m_hash, key, key_len) == NULL)
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return my_hash_insert(&m_hash, reinterpret_cast<uchar *>(value));
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return FALSE;
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}
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/** Is this hash set empty? */
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bool is_empty() const { return m_hash.records == 0; }
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/** Returns the number of unique elements. */
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size_t size() const { return static_cast<size_t>(m_hash.records); }
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/** An iterator over hash elements. Is not insert-stable. */
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class Iterator
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{
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public:
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Iterator(Hash_set &hash_set)
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: m_hash(&hash_set.m_hash),
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m_idx(0)
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{}
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/**
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Return the current element and reposition the iterator to the next
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element.
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*/
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inline T *operator++(int)
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{
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if (m_idx < m_hash->records)
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return reinterpret_cast<T*>(my_hash_element(m_hash, m_idx++));
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return NULL;
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}
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void rewind() { m_idx= 0; }
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private:
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HASH *m_hash;
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uint m_idx;
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};
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private:
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HASH m_hash;
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};
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#endif // SQL_HSET_INCLUDED
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