123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125 |
- <?xml version="1.0" encoding="utf-8"?>
- <!--
- Copyright 2012 Eric Niebler
- Distributed under the Boost
- Software License, Version 1.0. (See accompanying
- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- -->
- <header name="boost/proto/transform/fold.hpp">
- <para>Contains definition of the
- <computeroutput>
- <classname alt="boost::proto::fold">proto::fold<></classname>
- </computeroutput> and
- <computeroutput>
- <classname alt="boost::proto::reverse_fold">proto::reverse_fold<></classname>
- </computeroutput>
- transforms.</para>
- <namespace name="boost">
- <namespace name="proto">
- <struct name="fold">
- <template>
- <template-type-parameter name="Sequence"/>
- <template-type-parameter name="State0"/>
- <template-type-parameter name="Fun"/>
- </template>
- <inherit>
- <classname>proto::transform</classname>< fold<Sequence, State0, Fun> ></inherit>
- <purpose>A <conceptname>PrimitiveTransform</conceptname> that invokes the
- <computeroutput>fusion::fold<></computeroutput> algorithm to accumulate a value.</purpose>
- <description>
- <para>
- For the complete description of the behavior of the <computeroutput>proto::fold<></computeroutput>
- transform, see the documentation for the nested <computeroutput>
- <classname>proto::fold::impl<></classname>
- </computeroutput> class template.
- </para>
- </description>
- <struct name="impl">
- <template>
- <template-type-parameter name="Expr"/>
- <template-type-parameter name="State"/>
- <template-type-parameter name="Data"/>
- </template>
- <inherit><classname>proto::transform_impl</classname>< Expr, State, Data ></inherit>
- <typedef name="X">
- <purpose>For exposition only</purpose>
- <type><classname>when</classname><<classname>_</classname>, Sequence></type>
- </typedef>
- <typedef name="Y">
- <purpose>For exposition only</purpose>
- <type><classname>when</classname><<classname>_</classname>, State0></type>
- </typedef>
- <typedef name="seq">
- <purpose>A Fusion sequence, for exposition only</purpose>
- <type>typename boost::result_of<X(Expr, State, Data)>::type</type>
- </typedef>
- <typedef name="state0">
- <purpose>An initial state for the fold, for exposition only</purpose>
- <type>typename boost::result_of<Y(Expr, State, Data)>::type</type>
- </typedef>
- <typedef name="fun">
- <purpose><computeroutput>fun(d)(s,e) == when<_,Fun>()(e,s,d)</computeroutput></purpose>
- <type><emphasis>unspecified</emphasis></type>
- </typedef>
- <typedef name="result_type">
- <type>typename fusion::result_of::fold<seq, state0, fun>::type</type>
- </typedef>
- <method-group name="public member functions">
- <method name="operator()" cv="const">
- <type>result_type</type>
- <parameter name="expr">
- <paramtype>typename impl::expr_param</paramtype>
- <description>
- <para>The current expression </para>
- </description>
- </parameter>
- <parameter name="state">
- <paramtype>typename impl::state_param</paramtype>
- <description>
- <para>The current state </para>
- </description>
- </parameter>
- <parameter name="data">
- <paramtype>typename impl::data_param</paramtype>
- <description>
- <para>An arbitrary data </para>
- </description>
- </parameter>
- <description>
- <para>
- Let <computeroutput>seq</computeroutput> be
- <computeroutput><classname>when</classname><<classname>_</classname>, Sequence>()(expr, state, data)</computeroutput>,
- let <computeroutput>state0</computeroutput> be
- <computeroutput><classname>when</classname><<classname>_</classname>, State0>()(expr, state, data)</computeroutput>,
- and let <computeroutput>fun(data)</computeroutput> be an object such that
- <computeroutput>fun(data)(state, expr)</computeroutput> is equivalent to
- <computeroutput><classname>when</classname><<classname>_</classname>, Fun>()(expr, state, data)</computeroutput>. Then,
- this function returns <computeroutput>fusion::fold(seq, state0, fun(data))</computeroutput>.
- </para>
- </description>
- </method>
- </method-group>
- </struct>
- </struct>
- <struct name="reverse_fold">
- <template>
- <template-type-parameter name="Sequence"/>
- <template-type-parameter name="State0"/>
- <template-type-parameter name="Fun"/>
- </template>
- <inherit><classname>proto::fold</classname>< <classname>proto::_reverse</classname>(Sequence), State0, Fun ></inherit>
- <purpose>
- A <conceptname>PrimitiveTransform</conceptname> that is the same as the <computeroutput><classname>proto::fold<></classname></computeroutput>
- transform, except that it folds back-to-front instead of front-to-back. It uses the
- <computeroutput>
- <classname>proto::_reverse</classname>
- </computeroutput> callable <conceptname>PolymorphicFunctionObject</conceptname> to create a
- <computeroutput>fusion::reverse_view<></computeroutput> of the sequence before invoking
- <computeroutput>fusion::fold<></computeroutput>.
- </purpose>
- </struct>
- </namespace>
- </namespace>
- </header>
|