1 #ifndef SQL_HSET_INCLUDED 2 #define SQL_HSET_INCLUDED 3 /* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; version 2 of the License. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software 16 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */ 17 18 #include "hash.h" 19 20 21 /** 22 A type-safe wrapper around mysys HASH. 23 */ 24 25 template <typename T> 26 class Hash_set 27 { 28 public: 29 enum { START_SIZE= 8 }; 30 /** 31 Constructs an empty hash. Does not allocate memory, it is done upon 32 the first insert. Thus does not cause or return errors. 33 */ 34 Hash_set(uchar *(*K)(const T *, size_t *, my_bool), 35 CHARSET_INFO *cs= &my_charset_bin) 36 { 37 my_hash_clear(&m_hash); 38 m_hash.get_key= (my_hash_get_key)K; 39 m_hash.charset= cs; 40 } 41 /** 42 Destroy the hash by freeing the buckets table. Does 43 not call destructors for the elements. 44 */ ~Hash_set()45 ~Hash_set() 46 { 47 my_hash_free(&m_hash); 48 } 49 /** 50 Insert a single value into a hash. Does not tell whether 51 the value was inserted -- if an identical value existed, 52 it is not replaced. 53 54 @retval TRUE Out of memory. 55 @retval FALSE OK. The value either was inserted or existed 56 in the hash. 57 */ insert(T * value)58 bool insert(T *value) 59 { 60 my_hash_init_opt(&m_hash, m_hash.charset, START_SIZE, 0, 0, 61 m_hash.get_key, 0, MYF(0)); 62 size_t key_len; 63 uchar *v= reinterpret_cast<uchar *>(value); 64 const uchar *key= m_hash.get_key(v, &key_len, FALSE); 65 if (find(key, key_len) == NULL) 66 return my_hash_insert(&m_hash, v); 67 return FALSE; 68 } remove(T * value)69 bool remove(T *value) 70 { 71 return my_hash_delete(&m_hash, reinterpret_cast<uchar*>(value)); 72 } find(const void * key,size_t klen)73 T *find(const void *key, size_t klen) const 74 { 75 return (T*)my_hash_search(&m_hash, reinterpret_cast<const uchar *>(key), klen); 76 } 77 /** Is this hash set empty? */ is_empty()78 bool is_empty() const { return m_hash.records == 0; } 79 /** Returns the number of unique elements. */ size()80 size_t size() const { return static_cast<size_t>(m_hash.records); } at(size_t i)81 const T* at(size_t i) const 82 { 83 return reinterpret_cast<T*>(my_hash_element(const_cast<HASH*>(&m_hash), i)); 84 } 85 /** An iterator over hash elements. Is not insert-stable. */ 86 class Iterator 87 { 88 public: Iterator(Hash_set & hash_set)89 Iterator(Hash_set &hash_set) 90 : m_hash(&hash_set.m_hash), 91 m_idx(0) 92 {} 93 /** 94 Return the current element and reposition the iterator to the next 95 element. 96 */ 97 inline T *operator++(int) 98 { 99 if (m_idx < m_hash->records) 100 return reinterpret_cast<T*>(my_hash_element(m_hash, m_idx++)); 101 return NULL; 102 } rewind()103 void rewind() { m_idx= 0; } 104 private: 105 HASH *m_hash; 106 uint m_idx; 107 }; 108 private: 109 HASH m_hash; 110 }; 111 112 #endif // SQL_HSET_INCLUDED 113