...one of the most highly
regarded and expertly designed C++ library projects in the
world.

— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards

template< typename Sequence , typename State , typename ForwardOp > struct iter_fold { typedefunspecifiedtype; };

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 each iterator in the range `[begin<Sequence>::type,end<Sequence>::type)`

in the linear order.

#include "boost/mpl/iter_fold.hpp"

Parameter | Requirement | Description |
---|---|---|

`Sequence` | A model of Sequence | A sequence to iterate. |

`State` | A type | The initial state for the first `ForwardOp` application. |

`ForwardOp` | A model of [Lambda Function] | The operation to be executed on forward traversal. |

Expression | Expression type | Precondition | Semantics | Postcondition |
---|---|---|---|---|

`typedef iter_fold<Sequence,T,Op>::type t;` | A type | Equivalent to `typedef lambda<Op>::type op; typedef begin<Sequence>::type i1; typedef apply<op,T,i1>::type t1; typedef i1::next i2; typedef apply<op,t1,i2>::type t2; ...; typedef apply<op,T,in>::type tn; typedef in::next last; typedef tn t` , where `n == size<Sequence>::type::value` and `last` is identical to `end<Sequence>::type` ; Equivalent to `typedef T t;` if the sequence is empty. |

Linear. Exactly `size<Sequence>::type::value`

applications of `ForwardOp`

.

typedef list_c<int,5,-1,0,7,2,0,-5,4> numbers; typedef iter_fold< numbers , begin<numbers>::type , if_< less< deref<_1>, deref<_2> >,_2,_1 > >::type max_element_iter;BOOST_STATIC_ASSERT(max_element_iter::type::value == 7);

Algorithms, `iter_fold_backward`

, `fold`

, `fold_backward`

, `copy`

, `copy_backward`

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Last edited July 19, 2002 1:16 am