void clear()
{
// Call the destructor for all objects and reinitialize the memory.
_Destroy( begin(), end() );
initialize_memory();
m_num_elements = 0;
}
value_type& find_or_insert( const key_type& key )
{
size_t buck = m_hasher( key ) & m_mask;
key_type& table_key = m_key_extract( m_table[ buck ] );
if ( ! m_key_equal( key, table_key ) )
{
// The bucket is either empty or it contains another item. In
// this case we have to mark it as discarded, because we cannot
// know how the reference will be used ( probably to overwrite
// the item with a new one that has a different key ).
if ( ! m_key_equal( table_key, m_empty_key ) )
{
// The bucket already contained an item. This item is
// discarded and replaced with an empty one. The destructor
// is called on it.
// The m_num_elements does not change because
m_discard( m_table[ buck ], m_empty_value );
_Destroy( m_table + buck );
reset_value( m_table + buck );
}
else
{
// The bucket was empty, so we have to increment the items
// counter
++m_num_elements;
}
// Set the key in the empty item
_Construct( &table_key, key );
}
// Returns the reference to the found or recently added item
return m_table[ buck ];
}
pair<iterator,bool> insert( const value_type& obj )
{
const key_type& obj_key = m_key_extract( obj );
const size_t buck = m_hasher( obj_key ) & m_mask;
const key_type& table_key = m_key_extract( m_table[ buck ] );
if ( ! m_key_equal( table_key, m_empty_key ) )
{
// There's already an item in the bucket and its key it different
// from the key of the inserted item. Element is discarded.
++m_num_collisions;
// Notify that the item will be discarded, to allow a policy to
// do something useful with it.
m_discard( m_table[ buck ], obj );
_Destroy( m_table + buck );
reset_value( m_table + buck );
}
else
++m_num_elements;
// Copy the object into the hash table.
_Construct( m_table + buck, obj );
return pair<iterator,bool>( iterator( this, m_table + buck ), true );
}
void erase( const iterator& it )
{
if ( it != m_end_it
&& ! m_key_equal( m_key_extract( *it ), m_empty_key ) )
{
_Destroy( &* it );
reset_value( it.m_pos );
--m_num_elements;
}
}
void resize( size_type size )
{
size_t new_size = round_to_power2( size );
size_t old_size = m_buckets;
if ( new_size == old_size )
{
// Do nothing
return;
}
else if ( new_size < old_size )
{
// The new table will be smaller, so there's no need to rehash
// all the items.
value_type* new_table;
new_table = m_allocator.allocate( new_size * ItemSize );
// Copy the elements that fit into the new table and destroy
// those that doesn't fit. Plain old memcpy seems to have much
// less problems with types than std::copy..
std::memcpy( new_table, m_table, new_size * ItemSize );
_Destroy( iterator( this, m_table + new_size, true ), m_end_it );
m_allocator.deallocate( m_table, old_size );
m_table = new_table;
m_end_marker = m_table + new_size;
m_end_it = iterator( this, m_end_marker );
m_buckets = new_size;
m_mask = m_buckets - 1;
// Re-count the number of elements.
m_num_elements = 0;
for ( const_iterator it = begin(); it != m_end_it; ++it )
++m_num_elements;
}
else // new_size > old_size
{
// Creates a new table and re-insert all the items, with
// new buckets.
cache_table other( new_size, m_hasher, m_key_equal );
other.set_empty_value( m_empty_value );
swap( other );
insert( other.begin(), other.end() );
}
}
void erase( iterator first, iterator last )
{
m_num_elements -= mm::distance( first, last );
_Destroy( first, last );
std::uninitialized_fill( first, last, m_empty_value );
}