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 02110-1301, USA */
17
18#include "hash.h"
19
20
21/**
22 A type-safe wrapper around mysys HASH.
23*/
24
25template <typename T>
26class Hash_set
27{
28public:
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 */
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 */
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 }
69 bool remove(T *value)
70 {
71 return my_hash_delete(&m_hash, reinterpret_cast<uchar*>(value));
72 }
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? */
78 bool is_empty() const { return m_hash.records == 0; }
79 /** Returns the number of unique elements. */
80 size_t size() const { return static_cast<size_t>(m_hash.records); }
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:
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 }
103 void rewind() { m_idx= 0; }
104 private:
105 HASH *m_hash;
106 uint m_idx;
107 };
108private:
109 HASH m_hash;
110};
111
112#endif // SQL_HSET_INCLUDED
113