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// unordered_fast_key_table.h
/* Copyright 2012 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <boost/smart_ptr/scoped_array.hpp>
#include "mongo/base/disallow_copying.h"
namespace mongo {
template<typename K_L, typename K_S>
struct UnorderedFastKeyTable_LS_C {
K_S operator()( const K_L& a ) const {
return K_S(a);
}
};
template< typename K_L, // key lookup
typename K_S, // key storage
typename V, // value
typename H , // hash of K_L
typename E, // equal of K_L
typename C, // convertor from K_S -> K_L
typename C_LS=UnorderedFastKeyTable_LS_C<K_L,K_S> // convertor from K_L -> K_S
>
class UnorderedFastKeyTable {
public:
typedef std::pair<K_S, V> value_type;
typedef K_L key_type;
typedef V mapped_type;
private:
struct Entry {
Entry()
: used( false ), everUsed( false ) {
}
bool used;
bool everUsed;
size_t curHash;
value_type data;
};
struct Area {
Area( unsigned capacity, double maxProbeRatio );
Area( const Area& other );
int find( const K_L& key, size_t hash, int* firstEmpty, const UnorderedFastKeyTable& sm ) const;
bool transfer( Area* newArea, const UnorderedFastKeyTable& sm ) const;
void swap( Area* other ) {
using std::swap;
swap( _capacity, other->_capacity );
swap( _maxProbe, other->_maxProbe );
swap( _entries, other->_entries );
}
unsigned _capacity;
unsigned _maxProbe;
boost::scoped_array<Entry> _entries;
};
public:
static const unsigned DEFAULT_STARTING_CAPACITY = 20;
/**
* @param startingCapacity how many buckets should exist on initial creation
* DEFAULT_STARTING_CAPACITY
* @param maxProbeRatio the percentage of buckets we're willing to probe
* no defined default as you can't have a static const double on windows
*/
UnorderedFastKeyTable( unsigned startingCapacity = DEFAULT_STARTING_CAPACITY,
double maxProbeRatio = 0.05 );
UnorderedFastKeyTable( const UnorderedFastKeyTable& other );
UnorderedFastKeyTable& operator=( const UnorderedFastKeyTable& other ) {
other.copyTo( this );
return *this;
}
void copyTo( UnorderedFastKeyTable* out ) const;
/**
* @return number of elements in map
*/
size_t size() const { return _size; }
bool empty() const { return _size == 0; }
/*
* @return storage space
*/
size_t capacity() const { return _area._capacity; }
V& operator[]( const K_L& key ) { return get( key ); }
V& get( const K_L& key );
/**
* @return number of elements removed
*/
size_t erase( const K_L& key );
class const_iterator {
public:
const_iterator() { _position = -1; }
const_iterator( const Area* area ) {
_area = area;
_position = 0;
_max = _area->_capacity - 1;
_skip();
}
const_iterator( const Area* area, int pos ) {
_area = area;
_position = pos;
_max = pos;
}
const value_type* operator->() const { return &_area->_entries[_position].data; }
const_iterator operator++() {
if ( _position < 0 )
return *this;
_position++;
if ( _position > _max )
_position = -1;
else
_skip();
return *this;
}
bool operator==( const const_iterator& other ) const {
return _position == other._position;
}
bool operator!=( const const_iterator& other ) const {
return _position != other._position;
}
private:
void _skip() {
while ( true ) {
if ( _area->_entries[_position].used )
break;
if ( _position >= _max ) {
_position = -1;
break;
}
++_position;
}
}
const Area* _area;
int _position;
int _max; // inclusive
};
/**
* @return either a one-shot iterator with the key, or end()
*/
const_iterator find( const K_L& key ) const;
const_iterator begin() const;
const_iterator end() const;
private:
/*
* @param firstEmpty, if we return -1, and firstEmpty != NULL,
* this will be set to the first empty bucket we found
* @retrun offset into _entries or -1 if not there
*/
int _find( const K_L& key, int hash, int* firstEmpty ) const;
void _grow();
// ----
size_t _size;
double _maxProbeRatio;
Area _area;
H _hash;
E _equals;
C _convertor;
C_LS _convertorOther;
};
}
#include "mongo/util/unordered_fast_key_table_internal.h"
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