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Front Page / Algorithms / Iteration Algorithms / fold |
template< typename Sequence , typename State , typename ForwardOp > struct fold { 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.
#include <boost/mpl/fold.hpp>
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. |
For any Forward Sequence s, binary Lambda Expression op, and arbitrary type state:
typedef fold<s,state,op>::type t;
Return type: | A type. |
---|---|
Semantics: | Equivalent to typedef iter_fold< s,state,apply<op,_1,deref<_2> > >::type t; |
Linear. Exactly size<s>::value applications of op.