etl::select1st< TPair > Struct Template Reference

Functor to select pair::first. More...

#include <utility.h>

Public Types
typedef TPair::first_type	type
	type of member pair::first.

Public Member Functions
type &	operator() (TPair &p) const
	Function call that return p.first.
const type &	operator() (const TPair &p) const
	Function call that return p.first.

Detailed Description

template<typename TPair>
struct etl::select1st< TPair >

Functor to select pair::first.

select1st is a functor object that takes a single argument, a pair, and returns the pair::first element. Example

      using Map    = std::map<int, double>;
      using Vector = std::vector<int>;
 
      const Map map = {{1, 0.3},
                       {47, 0.8},
                       {33, 0.1}};
      Vector    result{};
 
      // Extract the map keys into a vector
      std::transform(map.begin(), map.end(), std::back_inserter(result), etl::select1st<Map::value_type>());

Template Parameters

TPair

The function object's argument type.

See also

select2nd

Member Function Documentation

operator()() [1/2]

template<typename TPair>

const type & etl::select1st< TPair >::operator() ( const TPair & p ) const

inline

Function call that return p.first.

Returns

a reference to member pair::first of the pair p

operator()() [2/2]

template<typename TPair>

type & etl::select1st< TPair >::operator() ( TPair & p ) const

inline

Function call that return p.first.

Returns

a reference to member pair::first of the pair p

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The documentation for this struct was generated from the following file:

• include/etl/utility.h