add any_terator

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Madzik 2018-01-26 19:22:40 +01:00
parent 9730da4805
commit 43c117e400
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// (C) Copyright Thomas Becker 2005. Permission to copy, use, modify, sell and
// distribute this software is granted provided this copyright notice appears
// in all copies. This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
// Revision History
// ================
//
// 27 Dec 2006 (Thomas Becker) Created
#ifndef ANY_ITERATOR_01102007TMB_HPP
#define ANY_ITERATOR_01102007TMB_HPP
// Includes
// ========
#include "detail/any_iterator_abstract_base.hpp"
#include "detail/any_iterator_wrapper.hpp"
#include "detail/any_iterator_metafunctions.hpp"
#include <boost/iterator/iterator_facade.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/and.hpp>
#include <boost/mpl/not.hpp>
#include <boost/static_assert.hpp>
namespace IteratorTypeErasure
{
///////////////////////////////////////////////////////////////////////
//
// The any_iterator is modeled after the "type erasure pattern" as set
// forth in boost::any. The class names correspond as follows:
//
// boost::any ==> any_iterator
// boost::any::placeholder ==> any_iterator_abstract_base
// boost::any::holder ==> any_iterator_wrapper
//
template<
class Value,
class CategoryOrTraversal,
class Reference = Value&,
class Difference = std::ptrdiff_t
>
class any_iterator :
public boost::iterator_facade<
any_iterator<
Value,
CategoryOrTraversal,
Reference,
Difference
>,
Value,
CategoryOrTraversal,
Reference,
Difference
>
{
// We make every other any_iterator our friend. This is needed only for
// the conversion from non-const to const, but there should be no harm
// in being overly friendly here.
template<
class OtherValue,
class OtherCategoryOrTraversal,
class OtherReference,
class OtherDifference
>
friend class any_iterator;
public:
typedef typename boost::iterator_category_to_traversal<CategoryOrTraversal>::type Traversal;
private:
struct enabler{}; // a private type avoids misuse
struct disabler{}; // a private type avoids misuse
// The type-erasing abstract base class, that is, the type that the
// impl-pointer points to.
typedef
detail::any_iterator_abstract_base<
Value,
Traversal,
Reference,
Difference
> abstract_base_type;
typedef
boost::iterator_facade<
any_iterator<
Value,
CategoryOrTraversal,
Reference,
Difference
>,
Value,
CategoryOrTraversal,
Reference,
Difference
> super_type;
// The two types that this any_iterator type recognizes as const versions of
// itself.
typedef any_iterator<
typename boost::add_const<Value>::type,
CategoryOrTraversal,
typename detail::make_iterator_reference_const<Reference>::type,
Difference
> const_type_with_const_value_type;
//
typedef any_iterator<
typename boost::remove_const<Value>::type,
CategoryOrTraversal,
typename detail::make_iterator_reference_const<Reference>::type,
Difference
> const_type_with_non_const_value_type;
public:
any_iterator() : m_pointer_to_impl(NULL)
{}
any_iterator(any_iterator const & rhs) : super_type(rhs)
{
if( rhs.m_pointer_to_impl )
{
m_pointer_to_impl = rhs.m_pointer_to_impl->clone();
}
else
{
m_pointer_to_impl = NULL;
}
}
any_iterator& operator=(any_iterator const & rhs)
{
if(this != &rhs)
{
any_iterator tmp(rhs);
swap(tmp);
}
return *this;
}
// Constructor from wrapped iterator. The static assert defines the
// granularity of the type erasure.
//
// NOTE 1: If you want to make the constructor non-explicit, then you
// really must replace the static assert with an enable_if, or else
// metafunctions such as is_convertible will say the wrong thing.
// However, if you use enable_if here, you'll descend into the ugly
// mess described in the last section of my article at
// http://www.artima.com/cppsource/type_erasure.html.
//
// NOTE 2: If you remove the restriction that the wrapped iterator
// cannot be an any_iterator, you must ensure that the conversions from
// non-const to const any_iterators still work correctly. If you don't
// do anything, you will end up with wrapping instead of conversion.
//
template<class WrappedIterator>
explicit any_iterator(
WrappedIterator const & wrapped_iterator,
typename boost::disable_if<
detail::is_any_iterator<WrappedIterator>,
disabler
>::type = disabler()
)
{
//////////////////////////////////////////////////////////////////
//
// *** Message to Client ***
//
// If this static assert fires, you are trying to construct the any_iterator
// from a concrete iterator that is not suitable for the type erasure that
// the any_iterator provides.
//
BOOST_STATIC_ASSERT((detail::is_iterator_type_erasure_compatible<WrappedIterator, any_iterator>::type::value));
typedef
detail::any_iterator_wrapper<
WrappedIterator,
Value,
Traversal,
Reference,
Difference
> wrapper_type;
m_pointer_to_impl = wrapper_type::create(wrapped_iterator);
}
// Assignment from wrapped iterator. The enable_if condition defines
// the granularity of the type erasure.
//
// NOTE: If you remove the restriction that the wrapped iterator
// cannot be an any_iterator, you must ensure that the conversions from
// non-const to const any_iterators still work correctly. If you don't
// do anything, you will end up with wrapping instead of conversion.
template<class WrappedIterator>
typename boost::enable_if<
boost::mpl::and_<
detail::is_iterator_type_erasure_compatible<WrappedIterator, any_iterator>,
boost::mpl::not_<detail::is_any_iterator<WrappedIterator> >
>,
any_iterator
>::type &
operator=(WrappedIterator const & wrapped_iterator)
{
any_iterator tmp(wrapped_iterator);
swap(tmp);
return *this;
}
// Conversion from non-const to const any_iterator. There are two versions.
// This first one applies if the target has const value type.
operator const_type_with_const_value_type () const
{
const_type_with_const_value_type conversion_result;
if( m_pointer_to_impl )
{
conversion_result.m_pointer_to_impl = m_pointer_to_impl->make_const_clone_with_const_value_type();
}
return conversion_result;
}
// Conversion from non-const to const any_iterator. There are two versions.
// This second one applies if the target has non-const value type.
operator const_type_with_non_const_value_type () const
{
const_type_with_non_const_value_type conversion_result;
if( m_pointer_to_impl )
{
conversion_result.m_pointer_to_impl = m_pointer_to_impl->make_const_clone_with_non_const_value_type();
}
return conversion_result;
}
// Conversion to weaker traversal type
template<typename TargetTraversal>
operator any_iterator<
Value,
TargetTraversal,
Reference,
Difference
>
() const
{
//////////////////////////////////////////////////////////////////
//
// *** Message to Client ***
//
// If this static assert fires, you are trying to convert between two
// any_iterator types that are not suitable for conversion.
//
BOOST_STATIC_ASSERT((
boost::is_base_of<
typename boost::iterator_category_to_traversal<TargetTraversal>::type,
typename boost::iterator_category_to_traversal<CategoryOrTraversal>::type
>::type::value
));
any_iterator<
Value,
TargetTraversal,
Reference,
Difference
> conversion_result;
if( m_pointer_to_impl )
{
typename boost::iterator_category_to_traversal<TargetTraversal>::type* funcSelector = NULL;
conversion_result.m_pointer_to_impl = make_traversal_converted_version(funcSelector);
}
return conversion_result;
}
~any_iterator()
{
delete m_pointer_to_impl;
}
private:
friend class boost::iterator_core_access;
Reference dereference() const
{
return m_pointer_to_impl->dereference();
}
bool equal(any_iterator const & rhs) const
{
if( m_pointer_to_impl == rhs.m_pointer_to_impl )
{
return true;
}
if( m_pointer_to_impl == NULL || rhs.m_pointer_to_impl == NULL )
{
return false;
}
//////////////////////////////////////////////////////////////////
//
// *** Message to Client ***
//
// If the next line does not compile, you are trying to compare
// two iterators for equality whose categories do not allow that
// comparison.
return m_pointer_to_impl->equal(*(rhs.m_pointer_to_impl));
}
void increment()
{
m_pointer_to_impl->increment();
}
void decrement()
{
//////////////////////////////////////////////////////////////////
//
// *** Message to Client ***
//
// If the next line does not compile, you are trying to decrement
// an iterator whose category does not allow decrementing.
return m_pointer_to_impl->decrement();
}
void advance(Difference n)
{
//////////////////////////////////////////////////////////////////
//
// *** Message to Client ***
//
// If the next line does not compile, you are trying to use an
// operation that is defined only for random access iterators
// on an iterator that is not random access.
m_pointer_to_impl->advance(n);
}
Difference distance_to(any_iterator const & other) const
{
//////////////////////////////////////////////////////////////////
//
// *** Message to Client ***
//
// If the next line does not compile, you are trying to use an
// operation that is defined only for random access iterators
// on an iterator that is not random access.
return m_pointer_to_impl->distance_to(*(other.m_pointer_to_impl));
}
any_iterator& swap(any_iterator& other)
{
// NOTE: iterator_facade doesn't have a swap method, so no call
// to base class here.
std::swap(m_pointer_to_impl, other.m_pointer_to_impl);
return *this;
}
detail::any_iterator_abstract_base<
Value,
boost::incrementable_traversal_tag,
Reference,
Difference
>* make_traversal_converted_version(boost::incrementable_traversal_tag* funcSelector) const
{
return m_pointer_to_impl->make_incrementable_version();
}
detail::any_iterator_abstract_base<
Value,
boost::single_pass_traversal_tag,
Reference,
Difference
>* make_traversal_converted_version(boost::single_pass_traversal_tag* funcSelector) const
{
return m_pointer_to_impl->make_single_pass_version();
}
detail::any_iterator_abstract_base<
Value,
boost::forward_traversal_tag,
Reference,
Difference
>* make_traversal_converted_version(boost::forward_traversal_tag* funcSelector) const
{
return m_pointer_to_impl->make_forward_version();
}
detail::any_iterator_abstract_base<
Value,
boost::bidirectional_traversal_tag,
Reference,
Difference
>* make_traversal_converted_version(boost::bidirectional_traversal_tag* funcSelector) const
{
return m_pointer_to_impl->make_bidirectional_version();
}
abstract_base_type* m_pointer_to_impl;
};
// Metafunction that takes an iterator and returns an any_iterator with the same
// traits.
template<class iterator>
struct make_any_iterator_type
{
typedef
any_iterator<
typename boost::iterator_value<iterator>::type,
typename boost::iterator_category<iterator>::type,
typename boost::iterator_reference<iterator>::type,
typename boost::iterator_difference<iterator>::type
> type;
};
} // end namespace IteratorTypeErasure
#endif // ANY_ITERATOR_01102007TMB_HPP

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// (C) Copyright Thomas Becker 2005. Permission to copy, use, modify, sell and
// distribute this software is granted provided this copyright notice appears
// in all copies. This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
// Revision History
// ================
//
// 27 Dec 2006 (Thomas Becker) Created
#ifndef ANY_ITERATOR_ABSTRACT_BASE_01102007TMB_HPP
#define ANY_ITERATOR_ABSTRACT_BASE_01102007TMB_HPP
// Includes
// ========
#include "any_iterator_metafunctions.hpp"
#include <boost/iterator/iterator_categories.hpp>
#include <boost/type_traits/add_const.hpp>
#include <boost/type_traits/remove_const.hpp>
namespace IteratorTypeErasure
{
namespace detail
{
///////////////////////////////////////////////////////////////////////
//
// The partial specializations of any_iterator_abstract_base (which is
// the equivalent of boost::any::placeholder) mirror the hierarchy of
// boost's iterator traversal tags.
//
// The first four template arguments are as in boost::iterator_facade.
// The last template argument is the traversal tag of the most
// derived class of the current instantiation of the hierarchy. This
// is a slight variant of the CRTP where the derived class passes
// itself as a template argument to the base class(es). Here, it seemed
// more convenient to pass up just the traversal tag of the most
// derived class.
//
template<
class Value,
class Traversal,
class Reference,
class Difference,
class UsedAsBaseForTraversal = Traversal
>
class any_iterator_abstract_base;
///////////////////////////////////////////////////////////////////////
//
template<
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_abstract_base<
Value,
boost::incrementable_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
>
{
protected:
typedef any_iterator_abstract_base<
Value,
UsedAsBaseForTraversal,
Reference,
Difference
> most_derived_type;
typedef most_derived_type clone_result_type;
typedef any_iterator_abstract_base<
typename boost::add_const<Value>::type,
UsedAsBaseForTraversal,
typename make_iterator_reference_const<Reference>::type,
Difference
> const_clone_with_const_value_type_result_type;
typedef any_iterator_abstract_base<
typename boost::remove_const<Value>::type,
UsedAsBaseForTraversal,
typename make_iterator_reference_const<Reference>::type,
Difference
> const_clone_with_non_const_value_type_result_type;
public:
// Plain clone function for copy construction and assignment.
virtual clone_result_type * clone() const=0;
// Clone functions for conversion to a const iterator
virtual const_clone_with_const_value_type_result_type * make_const_clone_with_const_value_type() const=0;
virtual const_clone_with_non_const_value_type_result_type * make_const_clone_with_non_const_value_type() const=0;
// gcc 3.4.2 does not like pure virtual declaration with inline definition,
// so I make the destructor non-pure just to spite them.
virtual ~any_iterator_abstract_base()
{}
virtual Reference dereference() const=0;
virtual void increment() = 0;
};
///////////////////////////////////////////////////////////////////////
//
template<
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_abstract_base<
Value,
boost::single_pass_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> : public any_iterator_abstract_base<
Value,
boost::incrementable_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
>
{
public:
// gcc 3.4.2 insists on qualification of most_derived_type.
virtual bool equal(typename any_iterator_abstract_base::most_derived_type const &) const = 0;
virtual any_iterator_abstract_base<
Value,
boost::incrementable_traversal_tag,
Reference,
Difference
>* make_incrementable_version() const=0;
};
///////////////////////////////////////////////////////////////////////
//
template<
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_abstract_base<
Value,
boost::forward_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> : public any_iterator_abstract_base<
Value,
boost::single_pass_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
>
{
public:
virtual any_iterator_abstract_base<
Value,
boost::single_pass_traversal_tag,
Reference,
Difference
>* make_single_pass_version() const=0;
};
///////////////////////////////////////////////////////////////////////
//
template<
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_abstract_base<
Value,
boost::bidirectional_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> : public any_iterator_abstract_base<
Value,
boost::forward_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
>
{
public:
virtual void decrement() = 0;
virtual any_iterator_abstract_base<
Value,
boost::forward_traversal_tag,
Reference,
Difference
>* make_forward_version() const=0;
};
///////////////////////////////////////////////////////////////////////
//
template<
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_abstract_base<
Value,
boost::random_access_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> : public any_iterator_abstract_base<
Value,
boost::bidirectional_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
>
{
public:
virtual void advance(Difference) = 0;
// gcc 3.4.2 insists on qualification of most_derived_type.
virtual Difference distance_to(typename any_iterator_abstract_base::most_derived_type const &) const= 0;
virtual any_iterator_abstract_base<
Value,
boost::bidirectional_traversal_tag,
Reference,
Difference
>* make_bidirectional_version() const=0;
};
} // end namespace detail
} // end namespace IteratorTypeErasure
#endif // ANY_ITERATOR_ABSTRACT_BASE_01102007TMB_HPP

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// (C) Copyright Thomas Becker 2005. Permission to copy, use, modify, sell and
// distribute this software is granted provided this copyright notice appears
// in all copies. This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
// File Name
// =========
//
// metafunctions.h
// Description
// ===========
//
// Metafunctions for any_iterator
#ifndef ANY_ITERATOR_METAFUNCTIONS_01102007TMB_HPP
#define ANY_ITERATOR_METAFUNCTIONS_01102007TMB_HPP
// Revision History
// ================
//
// 27 Dec 2006 (Thomas Becker) Created
// Includes
// ========
#include <boost/iterator/iterator_categories.hpp>
#include <boost/iterator/iterator_traits.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/type_traits/is_base_of.hpp>
#include <boost/type_traits/is_convertible.hpp>
#include <boost/type_traits/is_reference.hpp>
#include <boost/type_traits/is_pointer.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/and.hpp>
#include <boost/mpl/or.hpp>
#include <boost/mpl/not.hpp>
namespace IteratorTypeErasure
{
template<
class Value,
class Traversal,
class Reference,
class Difference
>
class any_iterator;
namespace detail
{
///////////////////////////////////////////////////////////////////////
//
template<typename T>
struct remove_reference_and_const
{
typedef typename boost::remove_const<
typename boost::remove_reference<
typename boost::remove_const<
T
>::type
>::type
>::type type;
};
///////////////////////////////////////////////////////////////////////
//
template<typename IteratorReference>
struct make_iterator_reference_const
{
typedef typename boost::mpl::if_<
typename boost::is_reference<IteratorReference>::type,
typename boost::remove_const<
typename boost::remove_reference<
typename boost::remove_const<
IteratorReference
>::type
>::type
>::type const &,
typename boost::remove_const<
typename boost::remove_reference<
typename boost::remove_const<
IteratorReference
>::type
>::type
>::type const
>::type type;
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class AnyIterator
>
struct value_types_erasure_compatible
{
// Really, we just want WrappedIterator's value_type to convert to
// AnyIterator's value_type. But many real world output iterators
// define their value_type as void. Therefore, we simply ignore
// the value type for output iterators. That's fine because for
// output iterators, the relevant type erasure information is all
// in the reference type.
typedef typename boost::mpl::or_<
boost::is_same<
typename boost::iterator_category<WrappedIterator>::type,
std::output_iterator_tag
>,
// Really, we just want WrappedIterator's value_type to convert to
// AnyIterator's value_type. But we need to work around a flaw in
// boost::is_convertible. boost::is_convertible<X, Y>::value is
// false whenever X and Y are abstract base classes (even when X
// and Y are the same). This will be fixed in C++ concepts.
boost::mpl::or_<
boost::is_same<
typename boost::iterator_value<WrappedIterator>::type,
typename boost::iterator_value<AnyIterator>::type
>,
boost::is_base_of<
typename boost::iterator_value<AnyIterator>::type,
typename boost::iterator_value<WrappedIterator>::type
>,
boost::is_convertible<
typename boost::iterator_value<WrappedIterator>::type,
typename boost::iterator_value<AnyIterator>::type
>
>
> type;
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class AnyIterator
>
struct reference_types_erasure_compatible_1
{
typedef typename boost::is_convertible<
typename boost::iterator_reference<WrappedIterator>::type,
typename boost::iterator_reference<AnyIterator>::type
>::type type;
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class AnyIterator
>
struct reference_types_erasure_compatible_2
{
typedef typename boost::mpl::if_<
boost::is_reference<
typename boost::iterator_reference<AnyIterator>::type
>,
boost::is_reference<
typename boost::iterator_reference<WrappedIterator>::type
>,
boost::mpl::bool_<true>
>::type type;
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class AnyIterator
>
struct reference_types_erasure_compatible_3
{
typedef typename boost::mpl::if_<
boost::mpl::and_<
boost::is_reference<
typename boost::iterator_reference<AnyIterator>::type
>,
boost::is_reference<
typename boost::iterator_reference<WrappedIterator>::type
>
>,
boost::mpl::or_<
boost::is_same<
typename remove_reference_and_const<
typename boost::iterator_reference<AnyIterator>::type
>::type,
typename remove_reference_and_const<
typename boost::iterator_reference<WrappedIterator>::type
>::type
>,
boost::is_base_of<
typename remove_reference_and_const<
typename boost::iterator_reference<AnyIterator>::type
>::type,
typename remove_reference_and_const<
typename boost::iterator_reference<WrappedIterator>::type
>::type
>
>,
boost::mpl::bool_<true>
>::type type;
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class AnyIterator
>
struct reference_types_erasure_compatible
{
// Output iterators are weird. Many real world output iterators
// define their reference type as void. In the world of boost
// iterators, that's terribly wrong, because in that world, an
// iterator's reference type is always the result type of
// operator* (and that makes very good sense, too). Therefore,
// when WrappedIterator is an output iterator, we use
// WrappedIterator& for WrappedIterator's reference type,
// because that's the real, true reference type. Moreover,
// we just require that WrappedIterator& convert to AnyIterator's
// reference type. The other subtleties are not relevant.
typedef typename boost::mpl::if_<
boost::is_same<
typename boost::iterator_category<WrappedIterator>::type,
std::output_iterator_tag
>,
boost::is_convertible<
WrappedIterator&,
typename boost::iterator_reference<AnyIterator>::type
>,
boost::mpl::and_<
// WrappedIterator's reference type must convert to AnyIterator's reference type.
typename reference_types_erasure_compatible_1<WrappedIterator, AnyIterator>::type,
// If AnyIterator's reference type is a reference, then the
// same must be true for WrappedIterator's reference type.
typename reference_types_erasure_compatible_2<WrappedIterator, AnyIterator>::type,
// If AnyIterator's reference type and WrappedIterator's
// reference type are both references, then one of the
// following must hold:
//
// 1) AnyIterator's reference type and WrappedIterator's
// reference type are the same.
//
// 2) AnyIterator's reference type is a base class of WrappedIterator's
// reference type.
//
typename reference_types_erasure_compatible_3<WrappedIterator, AnyIterator>::type
>
>::type type;
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class AnyIterator
>
struct difference_types_erasure_compatible
{
// Difference type matters only for random access iterators.
typedef typename boost::mpl::or_<
boost::mpl::not_<
boost::is_same<
// Do not use boost::iterator_traversal<AnyIterator>::type here,
// as it does not equal the traversal tag.
typename AnyIterator::Traversal,
boost::random_access_traversal_tag
>
>,
boost::mpl::and_<
boost::is_convertible<
typename boost::iterator_difference<WrappedIterator>::type,
typename boost::iterator_difference<AnyIterator>::type
>,
boost::is_convertible<
typename boost::iterator_difference<AnyIterator>::type,
typename boost::iterator_difference<WrappedIterator>::type
>
>
> type;
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class AnyIterator
>
struct traversal_types_erasure_compatible
{
typedef typename boost::mpl::or_<
boost::is_same<
// Do not use boost::iterator_traversal<AnyIterator>::type here,
// as it does not equal the traversal tag.
typename AnyIterator::Traversal,
typename boost::iterator_traversal<WrappedIterator>::type
>,
boost::is_base_of<
// Do not use boost::iterator_traversal<AnyIterator>::type here,
// as it does not equal the traversal tag.
typename AnyIterator::Traversal,
typename boost::iterator_traversal<WrappedIterator>::type
>
> type;
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class AnyIterator
>
struct is_iterator_type_erasure_compatible :
public boost::mpl::bool_<
boost::mpl::and_<
value_types_erasure_compatible<WrappedIterator, AnyIterator>,
reference_types_erasure_compatible<WrappedIterator, AnyIterator>,
difference_types_erasure_compatible<WrappedIterator, AnyIterator>,
traversal_types_erasure_compatible<WrappedIterator, AnyIterator>
>::value
>
{
};
///////////////////////////////////////////////////////////////////////
//
template<class SomeIterator>
struct is_any_iterator : public boost::mpl::bool_<false>
{
};
//
template<
class Value,
class Traversal,
class Reference,
class Difference
>
struct is_any_iterator<
any_iterator<
Value,
Traversal,
Reference,
Difference
>
> : public boost::mpl::bool_<true>
{
};
} // end namespace detail
} // end namespace IteratorTypeErasure
#endif // ANY_ITERATOR_METAFUNCTIONS_01102007TMB_HPP

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// (C) Copyright Thomas Becker 2005. Permission to copy, use, modify, sell and
// distribute this software is granted provided this copyright notice appears
// in all copies. This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
// Revision History
// ================
//
// 27 Dec 2006 (Thomas Becker) Created
// 12 Jul 2010 (Thomas Becker acting on bug report by Edgar Binder)
// Bug fix: Constructors and create function of <code>any_iterator_wrapper</code>
// from wrapped iterator must take their argument by const reference (performance!).
#ifndef ANY_ITERATOR_WRAPPER_01102007TMB_HPP
#define ANY_ITERATOR_WRAPPER_01102007TMB_HPP
// Includes
// ========
#include "any_iterator_abstract_base.hpp"
#include "any_iterator_metafunctions.hpp"
#include <boost/type_traits/add_const.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/cast.hpp>
namespace IteratorTypeErasure
{
namespace detail
{
///////////////////////////////////////////////////////////////////////
//
// The partial specializations of any_iterator_wrapper (which is the
// the equivalent of boost::any::holder) mirror the hierarchy of
// boost's iterator traversal tags.
//
// The first four template arguments are as in boost::iterator_facade.
// The last template argument is the traversal tag of the most
// derived class of the current instantiation of the hierarchy. This
// is a slight variant of the CRTP where the derived class passes
// itself as a template argument to the base class(es). Here, it seemed
// more convenient to pass up just the traversal tag of the most
// derived class.
//
template<
class WrappedIterator,
class Value,
class Traversal,
class Reference,
class Difference,
class UsedAsBaseForTraversal = Traversal
>
class any_iterator_wrapper;
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_wrapper<
WrappedIterator,
Value,
boost::incrementable_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> : public any_iterator_abstract_base<
Value,
UsedAsBaseForTraversal,
Reference,
Difference
>
{
protected:
typedef any_iterator_abstract_base<Value, UsedAsBaseForTraversal, Reference, Difference> abstract_base_type;
private:
typedef typename abstract_base_type::clone_result_type clone_result_type;
typedef typename abstract_base_type::const_clone_with_const_value_type_result_type const_clone_with_const_value_type_result_type;
typedef typename abstract_base_type::const_clone_with_non_const_value_type_result_type const_clone_with_non_const_value_type_result_type;
typedef any_iterator_wrapper<
WrappedIterator,
Value,
UsedAsBaseForTraversal,
Reference,
Difference
> clone_type;
typedef any_iterator_wrapper<
WrappedIterator,
typename boost::add_const<Value>::type,
UsedAsBaseForTraversal,
typename make_iterator_reference_const<Reference>::type,
Difference
> const_clone_type_with_const_value_type;
typedef any_iterator_wrapper<
WrappedIterator,
typename boost::remove_const<Value>::type,
UsedAsBaseForTraversal,
typename make_iterator_reference_const<Reference>::type,
Difference
> const_clone_type_with_non_const_value_type;
public:
any_iterator_wrapper()
{}
any_iterator_wrapper(WrappedIterator const& wrapped_iterator) :
m_wrapped_iterator(wrapped_iterator)
{}
static abstract_base_type* create(WrappedIterator const& wrapped_iterator)
{
return new clone_type(wrapped_iterator);
}
// Plain clone function for copy construction and assignment.
virtual clone_result_type * clone() const
{
return new clone_type(m_wrapped_iterator);
}
// Clone functions for conversion to a const iterator
virtual const_clone_with_const_value_type_result_type* make_const_clone_with_const_value_type() const
{
return new const_clone_type_with_const_value_type(m_wrapped_iterator);
}
//
virtual const_clone_with_non_const_value_type_result_type* make_const_clone_with_non_const_value_type() const
{
return new const_clone_type_with_non_const_value_type(m_wrapped_iterator);
}
virtual Reference dereference() const
{
// This const cast is needed for output iterators. Is this perhaps an oversight
// in iterator_facade?
return *const_cast<any_iterator_wrapper*>(this)->m_wrapped_iterator;
}
virtual void increment()
{
++m_wrapped_iterator;
}
protected:
WrappedIterator& get_wrapped_iterator()
{
return m_wrapped_iterator;
}
WrappedIterator const & get_wrapped_iterator() const
{
return m_wrapped_iterator;
}
private:
WrappedIterator m_wrapped_iterator;
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_wrapper<
WrappedIterator,
Value,
boost::single_pass_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> : public any_iterator_wrapper<
WrappedIterator,
Value,
boost::incrementable_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
>
{
public:
typedef
any_iterator_wrapper<
WrappedIterator,
Value,
boost::incrementable_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> super_type;
any_iterator_wrapper()
{}
any_iterator_wrapper(WrappedIterator const& wrapped_iterator) : super_type(wrapped_iterator)
{}
// gcc 3.4.2 insists on qualification of abstract_base_type.
virtual bool equal(typename any_iterator_wrapper::abstract_base_type const & rhs) const
{
return this->get_wrapped_iterator() == boost::polymorphic_downcast<any_iterator_wrapper const *>(&rhs)->get_wrapped_iterator();
}
any_iterator_abstract_base<
Value,
boost::incrementable_traversal_tag,
Reference,
Difference
>* make_incrementable_version() const
{
return new any_iterator_wrapper<
WrappedIterator,
Value,
boost::incrementable_traversal_tag,
Reference,
Difference
>(this->get_wrapped_iterator());
}
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_wrapper<
WrappedIterator,
Value,
boost::forward_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> : public any_iterator_wrapper<
WrappedIterator,
Value,
boost::single_pass_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
>
{
public:
typedef
any_iterator_wrapper<
WrappedIterator,
Value,
boost::single_pass_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> super_type;
any_iterator_wrapper()
{}
any_iterator_wrapper(WrappedIterator const& wrapped_iterator) : super_type(wrapped_iterator)
{}
any_iterator_abstract_base<
Value,
boost::single_pass_traversal_tag,
Reference,
Difference
>* make_single_pass_version() const
{
return new any_iterator_wrapper<
WrappedIterator,
Value,
boost::single_pass_traversal_tag,
Reference,
Difference
>(this->get_wrapped_iterator());
}
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_wrapper<
WrappedIterator,
Value,
boost::bidirectional_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> : public any_iterator_wrapper<
WrappedIterator,
Value,
boost::forward_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
>
{
public:
typedef
any_iterator_wrapper<
WrappedIterator,
Value,
boost::forward_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> super_type;
any_iterator_wrapper()
{}
any_iterator_wrapper(WrappedIterator const& wrapped_iterator) : super_type(wrapped_iterator)
{}
virtual void decrement()
{
--(this->get_wrapped_iterator());
}
any_iterator_abstract_base<
Value,
boost::forward_traversal_tag,
Reference,
Difference
>* make_forward_version() const
{
return new any_iterator_wrapper<
WrappedIterator,
Value,
boost::forward_traversal_tag,
Reference,
Difference
>(this->get_wrapped_iterator());
}
};
///////////////////////////////////////////////////////////////////////
//
template<
class WrappedIterator,
class Value,
class Reference,
class Difference,
class UsedAsBaseForTraversal
>
class any_iterator_wrapper<
WrappedIterator,
Value,
boost::random_access_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> : public any_iterator_wrapper<
WrappedIterator,
Value,
boost::bidirectional_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
>
{
public:
typedef
any_iterator_wrapper<
WrappedIterator,
Value,
boost::bidirectional_traversal_tag,
Reference,
Difference,
UsedAsBaseForTraversal
> super_type;
any_iterator_wrapper()
{}
any_iterator_wrapper(WrappedIterator const& wrapped_iterator) : super_type(wrapped_iterator)
{}
virtual void advance(Difference n)
{
this->get_wrapped_iterator() += n;
}
// gcc 3.4.2 insists on qualification of abstract_base_type.
virtual Difference distance_to(typename any_iterator_wrapper::abstract_base_type const & other) const
{
return boost::polymorphic_downcast<any_iterator_wrapper const *>(&other)->get_wrapped_iterator() - this->get_wrapped_iterator();
}
any_iterator_abstract_base<
Value,
boost::bidirectional_traversal_tag,
Reference,
Difference
>* make_bidirectional_version() const
{
return new any_iterator_wrapper<
WrappedIterator,
Value,
boost::bidirectional_traversal_tag,
Reference,
Difference
>(this->get_wrapped_iterator());
}
};
} // end namespace detail
} // end namespace IteratorTypeErasure
#endif // ANY_ITERATOR_WRAPPER_01102007TMB_HPP