accumulate

Synopsis

template<
      typename Sequence
    , typename State
    , typename ForwardOp
    >
struct accumulate
{
    typedef unspecified type;
};

Returns the result of the successive application of binary ForwardOp to the result of the previous ForwardOp invocation (State if it's the first call) and every element of the sequence in the range [begin<Sequence>::type, end<Sequence>::type) in order. [Note: accumulate is a synonym for fold — end note]

Header

#include <boost/mpl/accumulate.hpp>

Parameters

Parameter	Requirement	Description
`Sequence`	Forward Sequence	A sequence to iterate.
`State`	Any type	The initial state for the first `ForwardOp` application.
`ForwardOp`	Binary Lambda Expression	The operation to be executed on forward traversal.

Expression semantics

For any Forward Sequence s, binary Lambda Expression op, and arbitrary type state:

typedef accumulate<s,state,op>::type t;

Return type:

Return type:	A type.
Semantics:	Equivalent to typedef fold<s,state,op>::type t;

A type.

Semantics:

Equivalent to

typedef fold<s,state,op>::type t;

Complexity

Linear. Exactly size<s>::value applications of op.

Example

typedef vector<long,float,short,double,float,long,long double> types;
typedef accumulate<
      types
    , int_<0>
    , if_< is_float<_2>,next<_1>,_1 >
    >::type number_of_floats;

BOOST_MPL_ASSERT_RELATION( number_of_floats::value, ==, 4 );