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// Copyright 2009 (C) Dean Michael Berris <me@deanberris.com>
// Copyright 2012 (C) Google, Inc.
// Copyright 2012 (C) Jeffrey Lee Hellrung, Jr.
// 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)
//
#ifndef BOOST_FUNCTION_INPUT_ITERATOR
#define BOOST_FUNCTION_INPUT_ITERATOR
#include <boost/assert.hpp>
#include <boost/mpl/if.hpp>
#include <boost/function_types/is_function_pointer.hpp>
#include <boost/function_types/is_function_reference.hpp>
#include <boost/function_types/result_type.hpp>
#include <boost/iterator/iterator_facade.hpp>
#include <boost/none.hpp>
#include <boost/optional/optional.hpp>
namespace boost {
namespace iterators {
namespace impl {
template <class Function, class Input>
class function_input_iterator
: public iterator_facade<
function_input_iterator<Function, Input>,
typename Function::result_type,
single_pass_traversal_tag,
typename Function::result_type const &
>
{
public:
function_input_iterator() {}
function_input_iterator(Function & f_, Input state_ = Input())
: f(&f_), state(state_) {}
void increment() {
if(value)
value = none;
else
(*f)();
++state;
}
typename Function::result_type const &
dereference() const {
return (value ? value : value = (*f)()).get();
}
bool equal(function_input_iterator const & other) const {
return f == other.f && state == other.state;
}
private:
Function * f;
Input state;
mutable optional<typename Function::result_type> value;
};
template <class Function, class Input>
class function_pointer_input_iterator
: public iterator_facade<
function_pointer_input_iterator<Function, Input>,
typename function_types::result_type<Function>::type,
single_pass_traversal_tag,
typename function_types::result_type<Function>::type const &
>
{
public:
function_pointer_input_iterator() {}
function_pointer_input_iterator(Function &f_, Input state_ = Input())
: f(f_), state(state_) {}
void increment() {
if(value)
value = none;
else
(*f)();
++state;
}
typename function_types::result_type<Function>::type const &
dereference() const {
return (value ? value : value = (*f)()).get();
}
bool equal(function_pointer_input_iterator const & other) const {
return f == other.f && state == other.state;
}
private:
Function f;
Input state;
mutable optional<typename function_types::result_type<Function>::type> value;
};
template <class Function, class Input>
class function_reference_input_iterator
: public function_pointer_input_iterator<Function*,Input>
{
public:
function_reference_input_iterator(Function & f_, Input state_ = Input())
: function_pointer_input_iterator<Function*,Input>(&f_, state_)
{}
};
} // namespace impl
template <class Function, class Input>
class function_input_iterator
: public mpl::if_<
function_types::is_function_pointer<Function>,
impl::function_pointer_input_iterator<Function,Input>,
typename mpl::if_<
function_types::is_function_reference<Function>,
impl::function_reference_input_iterator<Function,Input>,
impl::function_input_iterator<Function,Input>
>::type
>::type
{
typedef typename mpl::if_<
function_types::is_function_pointer<Function>,
impl::function_pointer_input_iterator<Function,Input>,
typename mpl::if_<
function_types::is_function_reference<Function>,
impl::function_reference_input_iterator<Function,Input>,
impl::function_input_iterator<Function,Input>
>::type
>::type base_type;
public:
function_input_iterator(Function & f, Input i)
: base_type(f, i) {}
};
template <class Function, class Input>
inline function_input_iterator<Function, Input>
make_function_input_iterator(Function & f, Input state) {
typedef function_input_iterator<Function, Input> result_t;
return result_t(f, state);
}
template <class Function, class Input>
inline function_input_iterator<Function*, Input>
make_function_input_iterator(Function * f, Input state) {
typedef function_input_iterator<Function*, Input> result_t;
return result_t(f, state);
}
struct infinite {
infinite & operator++() { return *this; }
infinite & operator++(int) { return *this; }
bool operator==(infinite &) const { return false; };
bool operator==(infinite const &) const { return false; };
};
} // namespace iterators
using iterators::function_input_iterator;
using iterators::make_function_input_iterator;
using iterators::infinite;
} // namespace boost
#endif
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