Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for a snapshot of the master branch, built from commit 41c88d7887.

filter

Description

Returns the result type of filter given the sequence type and type to retain.

Synopsis

template<
    typename Sequence,
    typename T
    >
struct filter
{
    typedef unspecified type;
};

Table 1.87. Parameter

Parameter	Requirement	Description
`Sequence`	A model of Forward Sequence	Operation's argument
`T`	Any type	Type to retain

Expression Semantics

result_of::filter<Sequence, T>::type

Return type:

A model of Forward Sequence.
A model of Associative Sequence if Sequence implements the Associative Sequence model.

Semantics: Returns a sequence containing the elements of Sequence that are of type T. Equivalent to result_of::filter_if<Sequence, boost::is_same<mpl::_, T> >::type.

Complexity

Constant.

Header

#include <boost/fusion/algorithm/transformation/filter.hpp>
#include <boost/fusion/include/filter.hpp>