Chris@16: // Boost.Range library
Chris@16: //
Chris@16: //  Copyright Neil Groves 2010. Use, modification and
Chris@16: //  distribution is subject to the Boost Software License, Version
Chris@16: //  1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: //  http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: // For more information, see http://www.boost.org/libs/range/
Chris@16: //
Chris@16: #ifndef BOOST_RANGE_DETAIL_ANY_ITERATOR_HPP_INCLUDED
Chris@16: #define BOOST_RANGE_DETAIL_ANY_ITERATOR_HPP_INCLUDED
Chris@16: 
Chris@16: #include <boost/mpl/and.hpp>
Chris@16: #include <boost/mpl/or.hpp>
Chris@16: #include <boost/mpl/not.hpp>
Chris@16: #include <boost/iterator/iterator_facade.hpp>
Chris@16: #include <boost/type_traits/is_const.hpp>
Chris@16: #include <boost/type_traits/is_reference.hpp>
Chris@16: #include <boost/type_traits/remove_reference.hpp>
Chris@16: #include <boost/range/detail/any_iterator_buffer.hpp>
Chris@16: #include <boost/range/detail/any_iterator_interface.hpp>
Chris@16: #include <boost/range/detail/any_iterator_wrapper.hpp>
Chris@16: #include <boost/utility/enable_if.hpp>
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16:     namespace range_detail
Chris@16:     {
Chris@16:         // metafunction to determine if T is a const reference
Chris@16:         template<class T>
Chris@16:         struct is_const_reference
Chris@16:         {
Chris@16:             typedef typename mpl::and_<
Chris@16:                 typename is_reference<T>::type,
Chris@16:                 typename is_const<
Chris@16:                     typename remove_reference<T>::type
Chris@16:                 >::type
Chris@16:             >::type type;
Chris@16:         };
Chris@16: 
Chris@16:         // metafunction to determine if T is a mutable reference
Chris@16:         template<class T>
Chris@16:         struct is_mutable_reference
Chris@16:         {
Chris@16:             typedef typename mpl::and_<
Chris@16:                 typename is_reference<T>::type,
Chris@16:                 typename mpl::not_<
Chris@16:                     typename is_const<
Chris@16:                         typename remove_reference<T>::type
Chris@16:                     >::type
Chris@16:                 >::type
Chris@16:             >::type type;
Chris@16:         };
Chris@16: 
Chris@16:         // metafunction to evaluate if a source 'reference' can be
Chris@16:         // converted to a target 'reference' as a value.
Chris@16:         //
Chris@16:         // This is true, when the target reference type is actually
Chris@16:         // not a reference, and the source reference is convertible
Chris@16:         // to the target type.
Chris@16:         template<class SourceReference, class TargetReference>
Chris@16:         struct is_convertible_to_value_as_reference
Chris@16:         {
Chris@16:             typedef typename mpl::and_<
Chris@16:                 typename mpl::not_<
Chris@16:                     typename is_reference<TargetReference>::type
Chris@16:                 >::type
Chris@16:               , typename is_convertible<
Chris@16:                     SourceReference
Chris@16:                   , TargetReference
Chris@16:                 >::type
Chris@16:             >::type type;
Chris@16:         };
Chris@16: 
Chris@16:         template<
Chris@16:             class Value
Chris@16:           , class Traversal
Chris@16:           , class Reference
Chris@16:           , class Difference
Chris@16:           , class Buffer = any_iterator_default_buffer
Chris@16:         >
Chris@16:         class any_iterator;
Chris@16: 
Chris@16:         // metafunction to determine if SomeIterator is an
Chris@16:         // any_iterator.
Chris@16:         //
Chris@16:         // This is the general implementation which evaluates to false.
Chris@16:         template<class SomeIterator>
Chris@16:         struct is_any_iterator
Chris@16:             : mpl::bool_<false>
Chris@16:         {
Chris@16:         };
Chris@16: 
Chris@16:         // specialization of is_any_iterator to return true for
Chris@16:         // any_iterator classes regardless of template parameters.
Chris@16:         template<
Chris@16:             class Value
Chris@16:           , class Traversal
Chris@16:           , class Reference
Chris@16:           , class Difference
Chris@16:           , class Buffer
Chris@16:         >
Chris@16:         struct is_any_iterator<
Chris@16:             any_iterator<
Chris@16:                 Value
Chris@16:               , Traversal
Chris@16:               , Reference
Chris@16:               , Difference
Chris@16:               , Buffer
Chris@16:             >
Chris@16:         >
Chris@16:             : mpl::bool_<true>
Chris@16:         {
Chris@16:         };
Chris@16:     } // namespace range_detail
Chris@16: 
Chris@101:     namespace iterators
Chris@101:     {
Chris@16:     namespace detail
Chris@16:     {
Chris@16:         // Rationale:
Chris@16:         // These are specialized since the iterator_facade versions lack
Chris@16:         // the requisite typedefs to allow wrapping to determine the types
Chris@16:         // if a user copy constructs from a postfix increment.
Chris@16: 
Chris@16:         template<
Chris@16:             class Value
Chris@16:           , class Traversal
Chris@16:           , class Reference
Chris@16:           , class Difference
Chris@16:           , class Buffer
Chris@16:         >
Chris@16:         class postfix_increment_proxy<
Chris@16:                     range_detail::any_iterator<
Chris@16:                         Value
Chris@16:                       , Traversal
Chris@16:                       , Reference
Chris@16:                       , Difference
Chris@16:                       , Buffer
Chris@16:                     >
Chris@16:                 >
Chris@16:         {
Chris@16:             typedef range_detail::any_iterator<
Chris@16:                 Value
Chris@16:               , Traversal
Chris@16:               , Reference
Chris@16:               , Difference
Chris@16:               , Buffer
Chris@16:             > any_iterator_type;
Chris@16: 
Chris@16:         public:
Chris@16:             typedef Value value_type;
Chris@16:             typedef typename std::iterator_traits<any_iterator_type>::iterator_category iterator_category;
Chris@16:             typedef Difference difference_type;
Chris@16:             typedef typename iterator_pointer<any_iterator_type>::type pointer;
Chris@16:             typedef Reference reference;
Chris@16: 
Chris@16:             explicit postfix_increment_proxy(any_iterator_type const& x)
Chris@16:                 : stored_value(*x)
Chris@16:             {}
Chris@16: 
Chris@16:             value_type&
Chris@16:             operator*() const
Chris@16:             {
Chris@16:                 return this->stored_value;
Chris@16:             }
Chris@16:         private:
Chris@16:             mutable value_type stored_value;
Chris@16:         };
Chris@16: 
Chris@16:         template<
Chris@16:             class Value
Chris@16:           , class Traversal
Chris@16:           , class Reference
Chris@16:           , class Difference
Chris@16:           , class Buffer
Chris@16:         >
Chris@16:         class writable_postfix_increment_proxy<
Chris@16:                     range_detail::any_iterator<
Chris@16:                         Value
Chris@16:                       , Traversal
Chris@16:                       , Reference
Chris@16:                       , Difference
Chris@16:                       , Buffer
Chris@16:                     >
Chris@16:                 >
Chris@16:         {
Chris@16:             typedef range_detail::any_iterator<
Chris@16:                         Value
Chris@16:                       , Traversal
Chris@16:                       , Reference
Chris@16:                       , Difference
Chris@16:                       , Buffer
Chris@16:                     > any_iterator_type;
Chris@16:          public:
Chris@16:             typedef Value value_type;
Chris@16:             typedef typename std::iterator_traits<any_iterator_type>::iterator_category iterator_category;
Chris@16:             typedef Difference difference_type;
Chris@16:             typedef typename iterator_pointer<any_iterator_type>::type pointer;
Chris@16:             typedef Reference reference;
Chris@16: 
Chris@16:             explicit writable_postfix_increment_proxy(any_iterator_type const& x)
Chris@16:               : stored_value(*x)
Chris@16:               , stored_iterator(x)
Chris@16:             {}
Chris@16: 
Chris@16:             // Dereferencing must return a proxy so that both *r++ = o and
Chris@16:             // value_type(*r++) can work.  In this case, *r is the same as
Chris@16:             // *r++, and the conversion operator below is used to ensure
Chris@16:             // readability.
Chris@16:             writable_postfix_increment_proxy const&
Chris@16:             operator*() const
Chris@16:             {
Chris@16:                 return *this;
Chris@16:             }
Chris@16: 
Chris@16:             // Provides readability of *r++
Chris@16:             operator value_type&() const
Chris@16:             {
Chris@16:                 return stored_value;
Chris@16:             }
Chris@16: 
Chris@16:             // Provides writability of *r++
Chris@16:             template <class T>
Chris@16:             T const& operator=(T const& x) const
Chris@16:             {
Chris@16:                 *this->stored_iterator = x;
Chris@16:                 return x;
Chris@16:             }
Chris@16: 
Chris@16:             // This overload just in case only non-const objects are writable
Chris@16:             template <class T>
Chris@16:             T& operator=(T& x) const
Chris@16:             {
Chris@16:                 *this->stored_iterator = x;
Chris@16:                 return x;
Chris@16:             }
Chris@16: 
Chris@16:             // Provides X(r++)
Chris@16:             operator any_iterator_type const&() const
Chris@16:             {
Chris@16:                 return stored_iterator;
Chris@16:             }
Chris@16: 
Chris@16:          private:
Chris@16:             mutable value_type stored_value;
Chris@16:             any_iterator_type stored_iterator;
Chris@16:         };
Chris@16: 
Chris@101:     } //namespace detail
Chris@101:     } //namespace iterators
Chris@16: 
Chris@16:     namespace range_detail
Chris@16:     {
Chris@16:         template<
Chris@16:             class Value
Chris@16:           , class Traversal
Chris@16:           , class Reference
Chris@16:           , class Difference
Chris@16:           , class Buffer
Chris@16:         >
Chris@16:         class any_iterator
Chris@16:             : public iterator_facade<
Chris@16:                         any_iterator<
Chris@16:                             Value
Chris@16:                           , Traversal
Chris@16:                           , Reference
Chris@16:                           , Difference
Chris@16:                           , Buffer
Chris@16:                         >
Chris@16:                     , Value
Chris@16:                     , Traversal
Chris@16:                     , Reference
Chris@16:                     , Difference
Chris@16:                 >
Chris@16:         {
Chris@16:             template<
Chris@16:                 class OtherValue
Chris@16:               , class OtherTraversal
Chris@16:               , class OtherReference
Chris@16:               , class OtherDifference
Chris@16:               , class OtherBuffer
Chris@16:             >
Chris@16:             friend class any_iterator;
Chris@16: 
Chris@16:             struct enabler {};
Chris@16:             struct disabler {};
Chris@16: 
Chris@16:             typedef typename any_iterator_interface_type_generator<
Chris@16:                 Traversal
Chris@16:               , Reference
Chris@16:               , Difference
Chris@16:               , Buffer
Chris@16:             >::type abstract_base_type;
Chris@16: 
Chris@16:             typedef iterator_facade<
Chris@16:                         any_iterator<
Chris@16:                             Value
Chris@16:                           , Traversal
Chris@16:                           , Reference
Chris@16:                           , Difference
Chris@16:                           , Buffer
Chris@16:                         >
Chris@16:                       , Value
Chris@16:                       , Traversal
Chris@16:                       , Reference
Chris@16:                       , Difference
Chris@16:                   > base_type;
Chris@16: 
Chris@16:             typedef Buffer buffer_type;
Chris@16: 
Chris@16:         public:
Chris@16:             typedef typename base_type::value_type value_type;
Chris@16:             typedef typename base_type::reference reference;
Chris@16:             typedef typename base_type::difference_type difference_type;
Chris@16: 
Chris@16:             // Default constructor
Chris@16:             any_iterator()
Chris@16:                 : m_impl(0) {}
Chris@16: 
Chris@16:             // Simple copy construction without conversion
Chris@16:             any_iterator(const any_iterator& other)
Chris@16:                 : base_type(other)
Chris@16:                 , m_impl(other.m_impl
Chris@16:                             ? other.m_impl->clone(m_buffer)
Chris@16:                             : 0)
Chris@16:             {
Chris@16:             }
Chris@16: 
Chris@16:             // Simple assignment operator without conversion
Chris@16:             any_iterator& operator=(const any_iterator& other)
Chris@16:             {
Chris@16:                 if (this != &other)
Chris@16:                 {
Chris@16:                     if (m_impl)
Chris@16:                         m_impl->~abstract_base_type();
Chris@16:                     m_buffer.deallocate();
Chris@16:                     m_impl = 0;
Chris@16:                     if (other.m_impl)
Chris@16:                         m_impl = other.m_impl->clone(m_buffer);
Chris@16:                 }
Chris@16:                 return *this;
Chris@16:             }
Chris@16: 
Chris@16:             // Implicit conversion from another any_iterator where the
Chris@16:             // conversion is from a non-const reference to a const reference
Chris@16:             template<
Chris@16:                 class OtherValue
Chris@16:               , class OtherTraversal
Chris@16:               , class OtherReference
Chris@16:               , class OtherDifference
Chris@16:             >
Chris@16:             any_iterator(const any_iterator<
Chris@16:                                 OtherValue,
Chris@16:                                 OtherTraversal,
Chris@16:                                 OtherReference,
Chris@16:                                 OtherDifference,
Chris@16:                                 Buffer
Chris@16:                             >& other,
Chris@101:                          typename ::boost::enable_if<
Chris@16:                             typename mpl::and_<
Chris@16:                                 typename is_mutable_reference<OtherReference>::type,
Chris@16:                                 typename is_const_reference<Reference>::type
Chris@16:                             >::type,
Chris@16:                             enabler
Chris@16:                         >::type* = 0
Chris@16:                     )
Chris@16:                 : m_impl(other.m_impl
Chris@16:                             ? other.m_impl->clone_const_ref(m_buffer)
Chris@16:                          : 0
Chris@16:                         )
Chris@16:             {
Chris@16:             }
Chris@16: 
Chris@16:             // Implicit conversion from another any_iterator where the
Chris@16:             // reference types of the source and the target are references
Chris@16:             // that are either both const, or both non-const.
Chris@16:             template<
Chris@16:                 class OtherValue
Chris@16:               , class OtherTraversal
Chris@16:               , class OtherReference
Chris@16:               , class OtherDifference
Chris@16:             >
Chris@16:             any_iterator(const any_iterator<
Chris@16:                                 OtherValue
Chris@16:                               , OtherTraversal
Chris@16:                               , OtherReference
Chris@16:                               , OtherDifference
Chris@16:                               , Buffer
Chris@16:                             >& other,
Chris@101:                          typename ::boost::enable_if<
Chris@16:                             typename mpl::or_<
Chris@16:                                 typename mpl::and_<
Chris@16:                                     typename is_mutable_reference<OtherReference>::type,
Chris@16:                                     typename is_mutable_reference<Reference>::type
Chris@16:                                 >::type,
Chris@16:                                 typename mpl::and_<
Chris@16:                                     typename is_const_reference<OtherReference>::type,
Chris@16:                                     typename is_const_reference<Reference>::type
Chris@16:                                 >::type
Chris@16:                             >::type,
Chris@16:                             enabler
Chris@16:                         >::type* = 0
Chris@16:                         )
Chris@16:                 : m_impl(other.m_impl
Chris@16:                             ? other.m_impl->clone(m_buffer)
Chris@16:                          : 0
Chris@16:                         )
Chris@16:             {
Chris@16:             }
Chris@16: 
Chris@16:             // Implicit conversion to an any_iterator that uses a value for
Chris@16:             // the reference type.
Chris@16:             template<
Chris@16:                 class OtherValue
Chris@16:               , class OtherTraversal
Chris@16:               , class OtherReference
Chris@16:               , class OtherDifference
Chris@16:             >
Chris@16:             any_iterator(const any_iterator<
Chris@16:                                 OtherValue
Chris@16:                               , OtherTraversal
Chris@16:                               , OtherReference
Chris@16:                               , OtherDifference
Chris@16:                               , Buffer
Chris@16:                             >& other,
Chris@101:                         typename ::boost::enable_if<
Chris@16:                             typename is_convertible_to_value_as_reference<
Chris@16:                                         OtherReference
Chris@16:                                       , Reference
Chris@16:                                     >::type,
Chris@16:                             enabler
Chris@16:                         >::type* = 0
Chris@16:                         )
Chris@16:                 : m_impl(other.m_impl
Chris@16:                             ? other.m_impl->clone_reference_as_value(m_buffer)
Chris@16:                             : 0
Chris@16:                             )
Chris@16:             {
Chris@16:             }
Chris@16: 
Chris@16:             any_iterator clone() const
Chris@16:             {
Chris@16:                 any_iterator result;
Chris@16:                 if (m_impl)
Chris@16:                     result.m_impl = m_impl->clone(result.m_buffer);
Chris@16:                 return result;
Chris@16:             }
Chris@16: 
Chris@16:             any_iterator<
Chris@16:                 Value
Chris@16:               , Traversal
Chris@16:               , typename abstract_base_type::const_reference
Chris@16:               , Difference
Chris@16:               , Buffer
Chris@16:             >
Chris@16:             clone_const_ref() const
Chris@16:             {
Chris@16:                 typedef any_iterator<
Chris@16:                     Value
Chris@16:                   , Traversal
Chris@16:                   , typename abstract_base_type::const_reference
Chris@16:                   , Difference
Chris@16:                   , Buffer
Chris@16:                 > result_type;
Chris@16: 
Chris@16:                 result_type result;
Chris@16: 
Chris@16:                 if (m_impl)
Chris@16:                     result.m_impl = m_impl->clone_const_ref(result.m_buffer);
Chris@16: 
Chris@16:                 return result;
Chris@16:             }
Chris@16: 
Chris@16:             // implicit conversion and construction from type-erasure-compatible
Chris@16:             // iterators
Chris@16:             template<class WrappedIterator>
Chris@16:             explicit any_iterator(
Chris@16:                 const WrappedIterator& wrapped_iterator,
Chris@16:                 typename disable_if<
Chris@16:                     typename is_any_iterator<WrappedIterator>::type
Chris@16:                   , disabler
Chris@16:                 >::type* = 0
Chris@16:                 )
Chris@16:             {
Chris@16:                 typedef typename any_iterator_wrapper_type_generator<
Chris@16:                             WrappedIterator
Chris@16:                           , Traversal
Chris@16:                           , Reference
Chris@16:                           , Difference
Chris@16:                           , Buffer
Chris@16:                         >::type wrapper_type;
Chris@16: 
Chris@16:                 void* ptr = m_buffer.allocate(sizeof(wrapper_type));
Chris@16:                 m_impl = new(ptr) wrapper_type(wrapped_iterator);
Chris@16:             }
Chris@16: 
Chris@16:             ~any_iterator()
Chris@16:             {
Chris@16:                 // manually run the destructor, the deallocation is automatically
Chris@16:                 // handled by the any_iterator_small_buffer base class.
Chris@16:                 if (m_impl)
Chris@16:                     m_impl->~abstract_base_type();
Chris@16:             }
Chris@16: 
Chris@16:         private:
Chris@16:             friend class ::boost::iterator_core_access;
Chris@16: 
Chris@16:             Reference dereference() const
Chris@16:             {
Chris@16:                 BOOST_ASSERT( m_impl );
Chris@16:                 return m_impl->dereference();
Chris@16:             }
Chris@16: 
Chris@16:             bool equal(const any_iterator& other) const
Chris@16:             {
Chris@16:                 return (m_impl == other.m_impl)
Chris@16:                     || (m_impl && other.m_impl && m_impl->equal(*other.m_impl));
Chris@16:             }
Chris@16: 
Chris@16:             void increment()
Chris@16:             {
Chris@16:                 BOOST_ASSERT( m_impl );
Chris@16:                 m_impl->increment();
Chris@16:             }
Chris@16: 
Chris@16:             void decrement()
Chris@16:             {
Chris@16:                 BOOST_ASSERT( m_impl );
Chris@16:                 m_impl->decrement();
Chris@16:             }
Chris@16: 
Chris@16:             Difference distance_to(const any_iterator& other) const
Chris@16:             {
Chris@16:                 return m_impl && other.m_impl
Chris@16:                     ? m_impl->distance_to(*other.m_impl)
Chris@16:                     : 0;
Chris@16:             }
Chris@16: 
Chris@16:             void advance(Difference offset)
Chris@16:             {
Chris@16:                 BOOST_ASSERT( m_impl );
Chris@16:                 m_impl->advance(offset);
Chris@16:             }
Chris@16: 
Chris@16:             any_iterator& swap(any_iterator& other)
Chris@16:             {
Chris@16:                 BOOST_ASSERT( this != &other );
Chris@16:                 // grab a temporary copy of the other iterator
Chris@16:                 any_iterator tmp(other);
Chris@16: 
Chris@16:                 // deallocate the other iterator, taking care to obey the
Chris@16:                 // class-invariants in-case of exceptions later
Chris@16:                 if (other.m_impl)
Chris@16:                 {
Chris@16:                     other.m_impl->~abstract_base_type();
Chris@16:                     other.m_buffer.deallocate();
Chris@16:                     other.m_impl = 0;
Chris@16:                 }
Chris@16: 
Chris@16:                 // If this is a non-null iterator then we need to put
Chris@16:                 // a clone of this iterators implementation into the other
Chris@16:                 // iterator.
Chris@16:                 // We can't just swap because of the small buffer optimization.
Chris@16:                 if (m_impl)
Chris@16:                 {
Chris@16:                     other.m_impl = m_impl->clone(other.m_buffer);
Chris@16:                     m_impl->~abstract_base_type();
Chris@16:                     m_buffer.deallocate();
Chris@16:                     m_impl = 0;
Chris@16:                 }
Chris@16: 
Chris@16:                 // assign to this instance a clone of the temporarily held
Chris@16:                 // tmp which represents the input other parameter at the
Chris@16:                 // start of execution of this function.
Chris@16:                 if (tmp.m_impl)
Chris@16:                     m_impl = tmp.m_impl->clone(m_buffer);
Chris@16: 
Chris@16:                 return *this;
Chris@16:             }
Chris@16: 
Chris@16:             buffer_type m_buffer;
Chris@16:             abstract_base_type* m_impl;
Chris@16:         };
Chris@16: 
Chris@16:     } // namespace range_detail
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // include guard