replace_if

Description

Replaces each element of a given sequence for which an unary function object evaluates to true replaced with a new value.

Synopsis

template<
    typename Sequence,
    typename F,
    typename T>
typename result_of::replace_if<Sequence const, F, T>::type replace_if(
    Sequence const& seq, F f, T const& new_value);

Table 1.58. Parameters

Parameter	Requirement	Description
`seq`	A model of Forward Sequence	Operation's argument
`f`	A function object for which `f(e)` is a valid expression, convertible to `bool`, for each element `e` in `seq`	Operation's argument
`new_value`	Any type	Replacement value

Expression Semantics

replace_if(seq, f, new_value);

Return type: A model of Forward Sequence.

Semantics: Returns a new sequence with all the elements of seq, with new_value assigned to each element for which f evaluates to true.

Complexity

Constant. Returns a view which is lazily evaluated.

Header

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

Example

struct odd
{
    template<typename T>
    bool operator()(T t) const
    {
        return t % 2;
    }
};
...
assert(replace_if(make_vector(1,2), odd(), 3) == make_vector(3,2));