Traits for std::map key and value iterators. More...

#include <base/Iterator.h>

Public Types
typedef TMap	MapType
	The map type.

typedef TMap::key_type	KeyType
	The maps key type.

typedef transform_iterator< GetPairFirst< typename MapType::value_type >, typename MapType::const_iterator >	Key_const_iterator
	The key iterator type.

typedef TMap::mapped_type	ValueType
	The maps value (mapped) type.

typedef transform_iterator< GetPairSecond< typename MapType::value_type >, typename MapType::const_iterator >	Value_const_iterator
	The value iterator type.

Detailed Description

template<class TMap>
struct zypp::MapKVIteratorTraits< TMap >

Traits for std::map key and value iterators.

GetPairFirst and GetPairSecond help building a transform_iterator that iterates over keys or values of a std::map. Class MapKVIteratorTraits provides some typedefs, you usg. do not want to write explicitly.

// typedefs
typedef std::map<K,V> MapType;
 
// transform_iterator<GetPairFirst<MapType::value_type>,  MapType::const_iterator>
typedef MapKVIteratorTraits<MapType>::Key_const_iterator MapTypeKey_iterator;
// transform_iterator<GetPairSecond<MapType::value_type>, MapType::const_iterator>
typedef MapKVIteratorTraits<MapType>::Value_const_iterator  MapTypeValue_iterator;
 
// usage
MapType mymap;
 
MapTypeKey_const_iterator keyBegin( make_map_key_begin( mymap ) );
MapTypeKey_const_iterator keyEnd  ( make_map_key_end( mymap ) );
 
MapTypeValue_const_iterator valBegin( make_map_value_begin( mymap ) );
MapTypeValue_const_iterator valEnd  ( make_map_value_end( mymap ) );
 
std::for_each( keyBegin, keyEnd, DoSomething() );
std::for_each( valBegin, valEnd, DoSomething() );

Or short:

typedef std::map<K,V> MapType;
MapType mymap;
 
std::for_each( make_map_key_begin( mymap ),   make_map_key_end( mymap ),   DoSomething() );
std::for_each( make_map_value_begin( mymap ), make_map_value_end( mymap ), DoSomething() );