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|
// Boost.Range library
//
// Copyright Neil Groves 2010. Use, modification and
// distribution is subject to 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)
//
// For more information, see http://www.boost.org/libs/range/
//
#ifndef BOOST_RANGE_DETAIL_ANY_ITERATOR_HPP_INCLUDED
#define BOOST_RANGE_DETAIL_ANY_ITERATOR_HPP_INCLUDED
#include <boost/mpl/and.hpp>
#include <boost/mpl/or.hpp>
#include <boost/mpl/not.hpp>
#include <boost/iterator/iterator_facade.hpp>
#include <boost/type_traits/is_const.hpp>
#include <boost/type_traits/is_reference.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/range/detail/any_iterator_buffer.hpp>
#include <boost/range/detail/any_iterator_interface.hpp>
#include <boost/range/detail/any_iterator_wrapper.hpp>
#include <boost/utility/enable_if.hpp>
namespace boost
{
namespace range_detail
{
// metafunction to determine if T is a const reference
template<class T>
struct is_const_reference
{
typedef typename mpl::and_<
typename is_reference<T>::type,
typename is_const<
typename remove_reference<T>::type
>::type
>::type type;
};
// metafunction to determine if T is a mutable reference
template<class T>
struct is_mutable_reference
{
typedef typename mpl::and_<
typename is_reference<T>::type,
typename mpl::not_<
typename is_const<
typename remove_reference<T>::type
>::type
>::type
>::type type;
};
// metafunction to evaluate if a source 'reference' can be
// converted to a target 'reference' as a value.
//
// This is true, when the target reference type is actually
// not a reference, and the source reference is convertible
// to the target type.
template<class SourceReference, class TargetReference>
struct is_convertible_to_value_as_reference
{
typedef typename mpl::and_<
typename mpl::not_<
typename is_reference<TargetReference>::type
>::type
, typename is_convertible<
SourceReference
, TargetReference
>::type
>::type type;
};
template<
class Value
, class Traversal
, class Reference
, class Difference
, class Buffer = any_iterator_default_buffer
>
class any_iterator;
// metafunction to determine if SomeIterator is an
// any_iterator.
//
// This is the general implementation which evaluates to false.
template<class SomeIterator>
struct is_any_iterator
: mpl::bool_<false>
{
};
// specialization of is_any_iterator to return true for
// any_iterator classes regardless of template parameters.
template<
class Value
, class Traversal
, class Reference
, class Difference
, class Buffer
>
struct is_any_iterator<
any_iterator<
Value
, Traversal
, Reference
, Difference
, Buffer
>
>
: mpl::bool_<true>
{
};
} // namespace range_detail
namespace iterators
{
namespace detail
{
// Rationale:
// These are specialized since the iterator_facade versions lack
// the requisite typedefs to allow wrapping to determine the types
// if a user copy constructs from a postfix increment.
template<
class Value
, class Traversal
, class Reference
, class Difference
, class Buffer
>
class postfix_increment_proxy<
range_detail::any_iterator<
Value
, Traversal
, Reference
, Difference
, Buffer
>
>
{
typedef range_detail::any_iterator<
Value
, Traversal
, Reference
, Difference
, Buffer
> any_iterator_type;
public:
typedef Value value_type;
typedef typename std::iterator_traits<any_iterator_type>::iterator_category iterator_category;
typedef Difference difference_type;
typedef typename iterator_pointer<any_iterator_type>::type pointer;
typedef Reference reference;
explicit postfix_increment_proxy(any_iterator_type const& x)
: stored_value(*x)
{}
value_type&
operator*() const
{
return this->stored_value;
}
private:
mutable value_type stored_value;
};
template<
class Value
, class Traversal
, class Reference
, class Difference
, class Buffer
>
class writable_postfix_increment_proxy<
range_detail::any_iterator<
Value
, Traversal
, Reference
, Difference
, Buffer
>
>
{
typedef range_detail::any_iterator<
Value
, Traversal
, Reference
, Difference
, Buffer
> any_iterator_type;
public:
typedef Value value_type;
typedef typename std::iterator_traits<any_iterator_type>::iterator_category iterator_category;
typedef Difference difference_type;
typedef typename iterator_pointer<any_iterator_type>::type pointer;
typedef Reference reference;
explicit writable_postfix_increment_proxy(any_iterator_type const& x)
: stored_value(*x)
, stored_iterator(x)
{}
// Dereferencing must return a proxy so that both *r++ = o and
// value_type(*r++) can work. In this case, *r is the same as
// *r++, and the conversion operator below is used to ensure
// readability.
writable_postfix_increment_proxy const&
operator*() const
{
return *this;
}
// Provides readability of *r++
operator value_type&() const
{
return stored_value;
}
// Provides writability of *r++
template <class T>
T const& operator=(T const& x) const
{
*this->stored_iterator = x;
return x;
}
// This overload just in case only non-const objects are writable
template <class T>
T& operator=(T& x) const
{
*this->stored_iterator = x;
return x;
}
// Provides X(r++)
operator any_iterator_type const&() const
{
return stored_iterator;
}
private:
mutable value_type stored_value;
any_iterator_type stored_iterator;
};
} //namespace detail
} //namespace iterators
namespace range_detail
{
template<
class Value
, class Traversal
, class Reference
, class Difference
, class Buffer
>
class any_iterator
: public iterator_facade<
any_iterator<
Value
, Traversal
, Reference
, Difference
, Buffer
>
, Value
, Traversal
, Reference
, Difference
>
{
template<
class OtherValue
, class OtherTraversal
, class OtherReference
, class OtherDifference
, class OtherBuffer
>
friend class any_iterator;
struct enabler {};
struct disabler {};
typedef typename any_iterator_interface_type_generator<
Traversal
, Reference
, Difference
, Buffer
>::type abstract_base_type;
typedef iterator_facade<
any_iterator<
Value
, Traversal
, Reference
, Difference
, Buffer
>
, Value
, Traversal
, Reference
, Difference
> base_type;
typedef Buffer buffer_type;
public:
typedef typename base_type::value_type value_type;
typedef typename base_type::reference reference;
typedef typename base_type::difference_type difference_type;
// Default constructor
any_iterator()
: m_impl(0) {}
// Simple copy construction without conversion
any_iterator(const any_iterator& other)
: base_type(other)
, m_impl(other.m_impl
? other.m_impl->clone(m_buffer)
: 0)
{
}
// Simple assignment operator without conversion
any_iterator& operator=(const any_iterator& other)
{
if (this != &other)
{
if (m_impl)
m_impl->~abstract_base_type();
m_buffer.deallocate();
m_impl = 0;
if (other.m_impl)
m_impl = other.m_impl->clone(m_buffer);
}
return *this;
}
// Implicit conversion from another any_iterator where the
// conversion is from a non-const reference to a const reference
template<
class OtherValue
, class OtherTraversal
, class OtherReference
, class OtherDifference
>
any_iterator(const any_iterator<
OtherValue,
OtherTraversal,
OtherReference,
OtherDifference,
Buffer
>& other,
typename ::boost::enable_if<
typename mpl::and_<
typename is_mutable_reference<OtherReference>::type,
typename is_const_reference<Reference>::type
>::type,
enabler
>::type* = 0
)
: m_impl(other.m_impl
? other.m_impl->clone_const_ref(m_buffer)
: 0
)
{
}
// Implicit conversion from another any_iterator where the
// reference types of the source and the target are references
// that are either both const, or both non-const.
template<
class OtherValue
, class OtherTraversal
, class OtherReference
, class OtherDifference
>
any_iterator(const any_iterator<
OtherValue
, OtherTraversal
, OtherReference
, OtherDifference
, Buffer
>& other,
typename ::boost::enable_if<
typename mpl::or_<
typename mpl::and_<
typename is_mutable_reference<OtherReference>::type,
typename is_mutable_reference<Reference>::type
>::type,
typename mpl::and_<
typename is_const_reference<OtherReference>::type,
typename is_const_reference<Reference>::type
>::type
>::type,
enabler
>::type* = 0
)
: m_impl(other.m_impl
? other.m_impl->clone(m_buffer)
: 0
)
{
}
// Implicit conversion to an any_iterator that uses a value for
// the reference type.
template<
class OtherValue
, class OtherTraversal
, class OtherReference
, class OtherDifference
>
any_iterator(const any_iterator<
OtherValue
, OtherTraversal
, OtherReference
, OtherDifference
, Buffer
>& other,
typename ::boost::enable_if<
typename is_convertible_to_value_as_reference<
OtherReference
, Reference
>::type,
enabler
>::type* = 0
)
: m_impl(other.m_impl
? other.m_impl->clone_reference_as_value(m_buffer)
: 0
)
{
}
any_iterator clone() const
{
any_iterator result;
if (m_impl)
result.m_impl = m_impl->clone(result.m_buffer);
return result;
}
any_iterator<
Value
, Traversal
, typename abstract_base_type::const_reference
, Difference
, Buffer
>
clone_const_ref() const
{
typedef any_iterator<
Value
, Traversal
, typename abstract_base_type::const_reference
, Difference
, Buffer
> result_type;
result_type result;
if (m_impl)
result.m_impl = m_impl->clone_const_ref(result.m_buffer);
return result;
}
// implicit conversion and construction from type-erasure-compatible
// iterators
template<class WrappedIterator>
explicit any_iterator(
const WrappedIterator& wrapped_iterator,
typename disable_if<
typename is_any_iterator<WrappedIterator>::type
, disabler
>::type* = 0
)
{
typedef typename any_iterator_wrapper_type_generator<
WrappedIterator
, Traversal
, Reference
, Difference
, Buffer
>::type wrapper_type;
void* ptr = m_buffer.allocate(sizeof(wrapper_type));
m_impl = new(ptr) wrapper_type(wrapped_iterator);
}
~any_iterator()
{
// manually run the destructor, the deallocation is automatically
// handled by the any_iterator_small_buffer base class.
if (m_impl)
m_impl->~abstract_base_type();
}
private:
friend class ::boost::iterator_core_access;
Reference dereference() const
{
BOOST_ASSERT( m_impl );
return m_impl->dereference();
}
bool equal(const any_iterator& other) const
{
return (m_impl == other.m_impl)
|| (m_impl && other.m_impl && m_impl->equal(*other.m_impl));
}
void increment()
{
BOOST_ASSERT( m_impl );
m_impl->increment();
}
void decrement()
{
BOOST_ASSERT( m_impl );
m_impl->decrement();
}
Difference distance_to(const any_iterator& other) const
{
return m_impl && other.m_impl
? m_impl->distance_to(*other.m_impl)
: 0;
}
void advance(Difference offset)
{
BOOST_ASSERT( m_impl );
m_impl->advance(offset);
}
any_iterator& swap(any_iterator& other)
{
BOOST_ASSERT( this != &other );
// grab a temporary copy of the other iterator
any_iterator tmp(other);
// deallocate the other iterator, taking care to obey the
// class-invariants in-case of exceptions later
if (other.m_impl)
{
other.m_impl->~abstract_base_type();
other.m_buffer.deallocate();
other.m_impl = 0;
}
// If this is a non-null iterator then we need to put
// a clone of this iterators implementation into the other
// iterator.
// We can't just swap because of the small buffer optimization.
if (m_impl)
{
other.m_impl = m_impl->clone(other.m_buffer);
m_impl->~abstract_base_type();
m_buffer.deallocate();
m_impl = 0;
}
// assign to this instance a clone of the temporarily held
// tmp which represents the input other parameter at the
// start of execution of this function.
if (tmp.m_impl)
m_impl = tmp.m_impl->clone(m_buffer);
return *this;
}
buffer_type m_buffer;
abstract_base_type* m_impl;
};
} // namespace range_detail
} // namespace boost
#endif // include guard
|
