The MPL Reference Manual: push_back

push_back

Synopsis

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

Description

push_back performs an insertion at the end of the sequence with guaranteed O(1) complexity.

Header

#include <boost/mpl/push_back.hpp>

Model of

Tag Dispatched Metafunction

Parameters

Parameter	Requirement	Description
`Sequence`	Back Extensible Sequence	A sequence to insert into.
`T`	Any type	The element to be inserted.

Expression semantics

For any Back Extensible Sequence s and arbitrary type x:

typedef push_back<s,x>::type r;

Return type:

Return type:	Back Extensible Sequence.
Semantics:	Equivalent to typedef insert< s,end<s>::type,x >::type r;
Postcondition:	`back<r>::type` is identical to `x`; size<r>::value == size<s>::value + 1

Back Extensible Sequence.

Semantics:

Equivalent to

typedef insert< s,end<s>::type,x >::type r;

Postcondition:

back<r>::type is identical to x;

size<r>::value == size<s>::value + 1

Complexity

Amortized constant time.

Example

typedef vector_c<bool,false,false,false,
    true,true,true,false,false> bools;

typedef push_back<bools,false_>::type message;

BOOST_MPL_ASSERT_RELATION( back<message>::type::value, ==, false );
BOOST_MPL_ASSERT_RELATION(
      ( count_if<message, equal_to<_1,false_> >::value ), ==, 6
    );

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