boost/type_erasure/iterator.hpp
// Boost.TypeErasure library
//
// Copyright 2011 Steven Watanabe
//
// 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)
//
// $Id$
#ifndef BOOST_TYPE_ERASURE_ITERATOR_HPP_INCLUDED
#define BOOST_TYPE_ERASURE_ITERATOR_HPP_INCLUDED
#include <iterator>
#include <boost/mpl/vector.hpp>
#include <boost/mpl/if.hpp>
#include <boost/iterator/iterator_adaptor.hpp>
#include <boost/iterator/iterator_categories.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/type_erasure/operators.hpp>
#include <boost/type_erasure/builtin.hpp>
#include <boost/type_erasure/deduced.hpp>
#include <boost/type_erasure/is_placeholder.hpp>
namespace boost {
namespace type_erasure {
/** INTERNAL ONLY */
template<>
struct is_placeholder< ::boost::use_default> : ::boost::mpl::false_ {};
namespace detail {
template<class T>
struct iterator_value_type_impl
{
typedef typename ::std::iterator_traits<T>::value_type type;
};
}
/** INTERNAL ONLY */
template<class T>
struct iterator_value_type
{
typedef typename ::boost::mpl::eval_if<
::boost::type_erasure::is_placeholder<T>,
::boost::mpl::identity<void>,
::boost::type_erasure::detail::iterator_value_type_impl<T>
>::type type;
};
template<
class Traversal,
class T = _self,
class Reference = ::boost::use_default,
class DifferenceType = ::std::ptrdiff_t,
class ValueType = typename deduced<iterator_value_type<T> >::type
>
struct iterator;
#ifdef BOOST_TYPE_ERASURE_DOXYGEN
/**
* The @ref iterator concept can be used for any iterator category.
*
* \tparam Traversal must be one of @c boost::incrementable_traversal_tag,
* @c boost::single_pass_traversal_tag, @c boost::forward_traversal_tag,
* @c boost::bidirectional_traversal_tag, and @c boost::random_access_traversal_tag.
* \tparam T The placeholder representing the iterator.
* \tparam Reference The reference type. If it is boost::use_default, then
* reference will be value_type&.
* \tparam DifferenceType The iterator's difference type.
*
* The value_type of the iterator is deduced. To force it to be
* a specific type, use the @ref same_type concept.
*
* Example:
*
* \code
* mpl::vector<
* iterator<boost::forward_traversal_tag>,
* same_type<iterator<boost::forward_traversal_tag>::value_type, int> > int_it;
* \endcode
*/
template<
class Traversal,
class T = _self,
class Reference = boost::use_default,
class DifferenceType = std::ptrdiff_t
>
struct iterator
{
typedef detail::unspecified value_type;
typedef Reference reference;
typedef DifferenceType difference_type;
};
template<
class T = _self,
class Reference = boost::use_default,
class DifferenceType = std::ptrdiff_t
>
struct forward_iterator :
iterator<boost::forward_traversal_tag, T, Reference, DifferenceType>
{};
template<
class T = _self,
class Reference = boost::use_default,
class DifferenceType = std::ptrdiff_t
>
struct bidirectional_iterator :
iterator<boost::bidirectional_traversal_tag, T, Reference, DifferenceType>
{};
template<
class T = _self,
class Reference = boost::use_default,
class DifferenceType = std::ptrdiff_t
>
struct random_access_iterator :
iterator<boost::random_access_traversal_tag, T, Reference, DifferenceType>
{
};
#else
/** INTERNAL ONLY */
template<class Reference, class ValueType>
struct iterator_reference
{
typedef Reference type;
};
/** INTERNAL ONLY */
template<class ValueType>
struct iterator_reference< ::boost::use_default, ValueType>
{
typedef ValueType& type;
};
template<class T, class Reference, class DifferenceType, class ValueType>
struct iterator< ::boost::no_traversal_tag, T, Reference, DifferenceType, ValueType> :
boost::mpl::vector<
copy_constructible<T>,
constructible<T()>,
equality_comparable<T>,
dereferenceable<typename iterator_reference<Reference, ValueType>::type, T>,
assignable<T>
>
{
typedef ValueType value_type;
typedef typename iterator_reference<Reference, ValueType>::type reference;
typedef DifferenceType difference_type;
};
template<class T, class Reference, class DifferenceType, class ValueType>
struct iterator< ::boost::incrementable_traversal_tag, T, Reference, DifferenceType, ValueType> :
boost::mpl::vector<
iterator< ::boost::no_traversal_tag, T, Reference, DifferenceType>,
incrementable<T>
>
{
typedef ValueType value_type;
typedef typename iterator_reference<Reference, ValueType>::type reference;
typedef DifferenceType difference_type;
};
template<class T, class Reference, class DifferenceType, class ValueType>
struct iterator< ::boost::single_pass_traversal_tag, T, Reference, DifferenceType, ValueType> :
iterator< ::boost::incrementable_traversal_tag, T, Reference, DifferenceType, ValueType>
{};
template<class T, class Reference, class DifferenceType, class ValueType>
struct iterator< ::boost::forward_traversal_tag, T, Reference, DifferenceType, ValueType> :
iterator< ::boost::incrementable_traversal_tag, T, Reference, DifferenceType, ValueType>
{};
template<class T, class Reference, class DifferenceType, class ValueType>
struct iterator< ::boost::bidirectional_traversal_tag, T, Reference, DifferenceType, ValueType> :
boost::mpl::vector<
iterator< ::boost::incrementable_traversal_tag, T, Reference, DifferenceType, ValueType>,
decrementable<T>
>
{
typedef ValueType value_type;
typedef typename iterator_reference<Reference, ValueType>::type reference;
typedef DifferenceType difference_type;
};
template<class T, class Reference, class DifferenceType, class ValueType>
struct iterator< ::boost::random_access_traversal_tag, T, Reference, DifferenceType, ValueType> :
boost::mpl::vector<
iterator< ::boost::bidirectional_traversal_tag, T, Reference, DifferenceType, ValueType>,
addable<T, DifferenceType, T>,
addable<DifferenceType, T, T>,
subtractable<T, DifferenceType, T>,
subtractable<T, T, DifferenceType>,
subscriptable<typename iterator_reference<Reference, ValueType>::type, T, DifferenceType>
>
{
typedef ValueType value_type;
typedef typename iterator_reference<Reference, ValueType>::type reference;
typedef DifferenceType difference_type;
};
template<
class T = _self,
class Reference = ::boost::use_default,
class DifferenceType = ::std::ptrdiff_t,
class ValueType = typename deduced<iterator_value_type<T> >::type
>
struct forward_iterator :
iterator< ::boost::forward_traversal_tag, T, Reference, DifferenceType, ValueType>
{};
template<
class T = _self,
class Reference = ::boost::use_default,
class DifferenceType = ::std::ptrdiff_t,
class ValueType = typename deduced<iterator_value_type<T> >::type
>
struct bidirectional_iterator :
iterator< ::boost::bidirectional_traversal_tag, T, Reference, DifferenceType, ValueType>
{};
template<
class T = _self,
class Reference = ::boost::use_default,
class DifferenceType = ::std::ptrdiff_t,
class ValueType = typename deduced<iterator_value_type<T> >::type
>
struct random_access_iterator :
iterator< ::boost::random_access_traversal_tag, T, Reference, DifferenceType, ValueType>
{
};
#endif
/// \cond show_operators
template<class T, class Reference, class DifferenceType, class ValueType, class Base>
struct concept_interface<iterator< ::boost::no_traversal_tag, T, Reference, DifferenceType, ValueType>, Base, T>
: Base
{
typedef typename rebind_any<Base, ValueType>::type value_type;
typedef typename rebind_any<
Base,
typename iterator_reference<Reference, ValueType>::type
>::type reference;
typedef DifferenceType difference_type;
typedef typename ::boost::mpl::if_< ::boost::is_reference<reference>,
typename ::boost::remove_reference<reference>::type*,
value_type*
>::type pointer;
};
template<class T, class Reference, class DifferenceType, class ValueType, class Base>
struct concept_interface<iterator< ::boost::forward_traversal_tag, T, Reference, DifferenceType, ValueType>, Base, T>
: Base
{
typedef std::forward_iterator_tag iterator_category;
};
template<class T, class Reference, class DifferenceType, class ValueType, class Base>
struct concept_interface<forward_iterator<T, Reference, DifferenceType, ValueType>, Base, T>
: Base
{
typedef std::forward_iterator_tag iterator_category;
};
template<class T, class Reference, class DifferenceType, class ValueType, class Base>
struct concept_interface<iterator< ::boost::bidirectional_traversal_tag, T, Reference, DifferenceType, ValueType>, Base, T>
: Base
{
typedef std::bidirectional_iterator_tag iterator_category;
};
template<class T, class Reference, class DifferenceType, class ValueType, class Base>
struct concept_interface<bidirectional_iterator<T, Reference, DifferenceType, ValueType>, Base, T>
: Base
{
typedef std::bidirectional_iterator_tag iterator_category;
};
template<class T, class Reference, class DifferenceType, class ValueType, class Base>
struct concept_interface<iterator< ::boost::random_access_traversal_tag, T, Reference, DifferenceType, ValueType>, Base, T>
: Base
{
typedef std::random_access_iterator_tag iterator_category;
};
template<class T, class Reference, class DifferenceType, class ValueType, class Base>
struct concept_interface<random_access_iterator<T, Reference, DifferenceType, ValueType>, Base, T>
: Base
{
typedef std::random_access_iterator_tag iterator_category;
};
/// \endcond
}
}
#endif