1 files changed, 117 insertions, 0 deletions
diff --git a/sql/sql_hset.h b/sql/sql_hset.h
new file mode 100644
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--- /dev/null
+++ b/sql/sql_hset.h
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+#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(PSI_memory_key psi_key, 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;
+    m_hash.array.m_psi_key= psi_key;
+  }
+  Hash_set(PSI_memory_key psi_key, CHARSET_INFO *charset, ulong default_array_elements,
+           size_t key_offset, size_t key_length, my_hash_get_key get_key,
+           void (*free_element)(void*), uint flags)
+  {
+    my_hash_init(psi_key, &m_hash, charset, default_array_elements, key_offset,
+                 key_length, get_key, free_element, flags);
+  }
+  /**
+    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.array.m_psi_key, &m_hash, m_hash.charset,
+                     START_SIZE, 0, 0, m_hash.get_key, 0, HASH_UNIQUE);
+    return my_hash_insert(&m_hash, reinterpret_cast<const uchar*>(value));
+  }
+  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); }
+  /** Erases all elements from the container */
+  void clear() { my_hash_reset(&m_hash); }
+  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