// Copyright 2009 (C) Dean Michael Berris <me@deanberris.com>
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// Copyright 2012 (C) Google, Inc.
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// Copyright 2012 (C) Jeffrey Lee Hellrung, Jr.
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef BOOST_FUNCTION_INPUT_ITERATOR
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#define BOOST_FUNCTION_INPUT_ITERATOR
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#include <boost/config.hpp>
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#include <boost/assert.hpp>
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#include <boost/core/addressof.hpp>
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#include <boost/mpl/if.hpp>
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#include <boost/function_types/is_function_pointer.hpp>
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#include <boost/function_types/result_type.hpp>
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#include <boost/iterator/iterator_facade.hpp>
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#include <boost/none.hpp>
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#include <boost/optional/optional.hpp>
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#include <boost/utility/result_of.hpp>
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#ifdef BOOST_RESULT_OF_USE_TR1
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#include <boost/type_traits/is_function.hpp>
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#endif
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namespace boost {
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namespace iterators {
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namespace impl {
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// Computes the return type of an lvalue-call with an empty argument,
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// i.e. decltype(declval<F&>()()). F should be a nullary lvalue-callable
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// or function.
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template <class F>
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struct result_of_nullary_lvalue_call
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{
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typedef typename result_of<
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#ifdef BOOST_RESULT_OF_USE_TR1
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typename mpl::if_<is_function<F>, F&, F>::type()
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#else
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F&()
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#endif
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>::type type;
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};
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template <class Function, class Input>
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class function_input_iterator
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: public iterator_facade<
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function_input_iterator<Function, Input>,
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typename result_of_nullary_lvalue_call<Function>::type,
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single_pass_traversal_tag,
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typename result_of_nullary_lvalue_call<Function>::type const &
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>
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{
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public:
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function_input_iterator() {}
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function_input_iterator(Function & f_, Input state_ = Input())
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: f(boost::addressof(f_)), state(state_) {}
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void increment() {
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if(value)
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value = none;
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else
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(*f)();
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++state;
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}
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typename result_of_nullary_lvalue_call<Function>::type const &
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dereference() const {
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return (value ? value : value = (*f)()).get();
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}
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bool equal(function_input_iterator const & other) const {
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return f == other.f && state == other.state;
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}
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private:
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Function * f;
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Input state;
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mutable optional<typename result_of_nullary_lvalue_call<Function>::type> value;
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};
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template <class Function, class Input>
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class function_pointer_input_iterator
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: public iterator_facade<
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function_pointer_input_iterator<Function, Input>,
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typename function_types::result_type<Function>::type,
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single_pass_traversal_tag,
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typename function_types::result_type<Function>::type const &
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>
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{
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public:
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function_pointer_input_iterator() {}
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function_pointer_input_iterator(Function &f_, Input state_ = Input())
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: f(f_), state(state_) {}
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void increment() {
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if(value)
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value = none;
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else
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(*f)();
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++state;
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}
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typename function_types::result_type<Function>::type const &
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dereference() const {
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return (value ? value : value = (*f)()).get();
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}
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bool equal(function_pointer_input_iterator const & other) const {
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return f == other.f && state == other.state;
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}
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private:
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Function f;
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Input state;
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mutable optional<typename function_types::result_type<Function>::type> value;
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};
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} // namespace impl
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template <class Function, class Input>
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class function_input_iterator
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: public mpl::if_<
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function_types::is_function_pointer<Function>,
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impl::function_pointer_input_iterator<Function,Input>,
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impl::function_input_iterator<Function,Input>
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>::type
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{
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typedef typename mpl::if_<
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function_types::is_function_pointer<Function>,
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impl::function_pointer_input_iterator<Function,Input>,
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impl::function_input_iterator<Function,Input>
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>::type base_type;
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public:
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function_input_iterator(Function & f, Input i)
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: base_type(f, i) {}
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};
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template <class Function, class Input>
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inline function_input_iterator<Function, Input>
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make_function_input_iterator(Function & f, Input state) {
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typedef function_input_iterator<Function, Input> result_t;
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return result_t(f, state);
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}
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template <class Function, class Input>
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inline function_input_iterator<Function*, Input>
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make_function_input_iterator(Function * f, Input state) {
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typedef function_input_iterator<Function*, Input> result_t;
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return result_t(f, state);
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}
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struct infinite {
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infinite & operator++() { return *this; }
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infinite & operator++(int) { return *this; }
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bool operator==(infinite &) const { return false; };
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bool operator==(infinite const &) const { return false; };
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};
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} // namespace iterators
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using iterators::function_input_iterator;
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using iterators::make_function_input_iterator;
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using iterators::infinite;
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} // namespace boost
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#endif
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