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boost/range/iterator_range_core.hpp

// Boost.Range library
//
//  Copyright Neil Groves & Thorsten Ottosen & Pavol Droba 2003-2004.
//  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_ITERATOR_RANGE_CORE_HPP_INCLUDED
#define BOOST_RANGE_ITERATOR_RANGE_CORE_HPP_INCLUDED

#include <boost/config.hpp> // Define __STL_CONFIG_H, if appropriate.
#include <boost/detail/workaround.hpp>

#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1500))
    #pragma warning( push )
    #pragma warning( disable : 4996 )
#endif

#include <boost/assert.hpp>
#include <boost/iterator/iterator_traits.hpp>
#include <boost/iterator/iterator_facade.hpp>
#include <boost/type_traits/is_abstract.hpp>
#include <boost/type_traits/is_pointer.hpp>
#include <boost/range/functions.hpp>
#include <boost/range/iterator.hpp>
#include <boost/range/difference_type.hpp>
#include <boost/range/algorithm/equal.hpp>
#include <boost/range/detail/safe_bool.hpp>
#include <boost/utility/enable_if.hpp>
#include <iterator>
#include <algorithm>
#include <cstddef>

/*! \file
    Defines the \c iterator_class and related functions.
    \c iterator_range is a simple wrapper of iterator pair idiom. It provides
    a rich subset of Container interface.
*/


namespace boost
{
    namespace iterator_range_detail
    {
        //
        // The functions adl_begin and adl_end are implemented in a separate
        // class for gcc-2.9x
        //
        template<class IteratorT>
        struct iterator_range_impl {
            template< class ForwardRange >
            static IteratorT adl_begin( ForwardRange& r )
            {
                return static_cast<IteratorT>( boost::begin( r ) );
            }

            template< class ForwardRange >
            static IteratorT adl_end( ForwardRange& r )
            {
                return static_cast<IteratorT>( boost::end( r ) );
            }
        };

        template< class Left, class Right >
        inline bool less_than( const Left& l, const Right& r )
        {
            return std::lexicographical_compare( boost::begin(l),
                                                 boost::end(l),
                                                 boost::begin(r),
                                                 boost::end(r) );
        }
        
        template< class Left, class Right >
        inline bool greater_than( const Left& l, const Right& r )
        {
            return less_than(r,l);
        }
        
        template< class Left, class Right >
        inline bool less_or_equal_than( const Left& l, const Right& r )
        {
            return !iterator_range_detail::less_than(r,l);
        }
        
        template< class Left, class Right >
        inline bool greater_or_equal_than( const Left& l, const Right& r )
        {
            return !iterator_range_detail::less_than(l,r);
        }

        // This version is maintained since it is used in other boost libraries
        // such as Boost.Assign
        template< class Left, class Right >
        inline bool equal(const Left& l, const Right& r)
        {
            return boost::equal(l, r);
        }

        struct range_tag { };
        struct const_range_tag { };
    }

//  iterator range template class -----------------------------------------//

        //! iterator_range class
        /*!
            An \c iterator_range delimits a range in a sequence by beginning and ending iterators.
            An iterator_range can be passed to an algorithm which requires a sequence as an input.
            For example, the \c toupper() function may be used most frequently on strings,
            but can also be used on iterator_ranges:

            \code
                boost::tolower( find( s, "UPPERCASE STRING" ) );
            \endcode

            Many algorithms working with sequences take a pair of iterators,
            delimiting a working range, as an arguments. The \c iterator_range class is an
            encapsulation of a range identified by a pair of iterators.
            It provides a collection interface,
            so it is possible to pass an instance to an algorithm requiring a collection as an input.
        */
        template<class IteratorT>
        class iterator_range
        {
            typedef range_detail::safe_bool< IteratorT iterator_range<IteratorT>::* > safe_bool_t;
        protected: // Used by sub_range
            //! implementation class
            typedef iterator_range_detail::iterator_range_impl<IteratorT> impl;
        public:
            //! this type
            typedef iterator_range<IteratorT> type;
            typedef BOOST_DEDUCED_TYPENAME safe_bool_t::unspecified_bool_type unspecified_bool_type;
            //BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION(value_type);

            //! Encapsulated value type
            typedef BOOST_DEDUCED_TYPENAME
                iterator_value<IteratorT>::type value_type;

            //! Difference type
            typedef BOOST_DEDUCED_TYPENAME
                iterator_difference<IteratorT>::type difference_type;

            //! Size type
            typedef std::size_t size_type; // note: must be unsigned

            //! This type
            typedef iterator_range<IteratorT> this_type;

            //! Reference type
            //
            // Needed because value-type is the same for
            // const and non-const iterators
            //
            typedef BOOST_DEDUCED_TYPENAME
                iterator_reference<IteratorT>::type reference;

            //! const_iterator type
            /*!
                There is no distinction between const_iterator and iterator.
                These typedefs are provides to fulfill container interface
            */
            typedef IteratorT const_iterator;
            //! iterator type
            typedef IteratorT iterator;

        private: // for return value of operator()()
            typedef BOOST_DEDUCED_TYPENAME
                boost::mpl::if_< boost::is_abstract<value_type>,
                                 reference, value_type >::type abstract_value_type;

        public:
            iterator_range() : m_Begin( iterator() ), m_End( iterator() )
            { }

            //! Constructor from a pair of iterators
            template< class Iterator >
            iterator_range( Iterator Begin, Iterator End ) :
                m_Begin(Begin), m_End(End)
            {}

            //! Constructor from a Range
            template< class Range >
            iterator_range( const Range& r ) :
                m_Begin( impl::adl_begin( r ) ), m_End( impl::adl_end( r ) )
            {}

            //! Constructor from a Range
            template< class Range >
            iterator_range( Range& r ) :
                m_Begin( impl::adl_begin( r ) ), m_End( impl::adl_end( r ) )
            {}

            //! Constructor from a Range
            template< class Range >
            iterator_range( const Range& r, iterator_range_detail::const_range_tag ) :
                m_Begin( impl::adl_begin( r ) ), m_End( impl::adl_end( r ) )
            {}

            //! Constructor from a Range
            template< class Range >
            iterator_range( Range& r, iterator_range_detail::range_tag ) :
                m_Begin( impl::adl_begin( r ) ), m_End( impl::adl_end( r ) )
            {}

            #if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)
            this_type& operator=( const this_type& r )
            {
                m_Begin  = r.begin();
                m_End    = r.end();
                return *this;
            }
            #endif

            template< class Iterator >
            iterator_range& operator=( const iterator_range<Iterator>& r )
            {
                m_Begin  = r.begin();
                m_End    = r.end();
                return *this;
            }

            template< class ForwardRange >
            iterator_range& operator=( ForwardRange& r )
            {
                m_Begin  = impl::adl_begin( r );
                m_End    = impl::adl_end( r );
                return *this;
            }

            template< class ForwardRange >
            iterator_range& operator=( const ForwardRange& r )
            {
                m_Begin  = impl::adl_begin( r );
                m_End    = impl::adl_end( r );
                return *this;
            }

            IteratorT begin() const
            {
                return m_Begin;
            }

            IteratorT end() const
            {
                return m_End;
            }

            difference_type size() const
            {
                return m_End - m_Begin;
            }

            bool empty() const
            {
                return m_Begin == m_End;
            }

            operator unspecified_bool_type() const
            {
                return safe_bool_t::to_unspecified_bool(m_Begin != m_End, &iterator_range::m_Begin);
            }

            bool operator!() const
            {
                return empty();
            }

            bool equal( const iterator_range& r ) const
            {
                return m_Begin == r.m_Begin && m_End == r.m_End;
            }


#ifdef BOOST_NO_FUNCTION_TEMPLATE_ORDERING

            bool operator==( const iterator_range& r ) const
            {
                return boost::equal( *this, r );
            }

            bool operator!=( const iterator_range& r ) const
            {
                return !operator==(r);
            }

           bool operator<( const iterator_range& r ) const
           {
               return iterator_range_detail::less_than( *this, r );
           }
           
           bool operator>( const iterator_range& r ) const
           {
               return iterator_range_detail::greater_than( *this, r );
           }
           
           bool operator<=( const iterator_range& r ) const
           {
               return iterator_range_detail::less_or_equal_than( *this, r );
           }
           
           bool operator>=( const iterator_range& r ) const
           {
               return iterator_range_detail::greater_or_equal_than( *this, r );
           }

#endif

        public: // convenience
           reference front() const
           {
               BOOST_ASSERT( !empty() );
               return *m_Begin;
           }

           reference back() const
           {
               BOOST_ASSERT( !empty() );
               IteratorT last( m_End );
               return *--last;
           }

           // pop_front() - added to model the SinglePassRangePrimitiveConcept
           void pop_front()
           {
               BOOST_ASSERT( !empty() );
               ++m_Begin;
           }

           // pop_back() - added to model the BidirectionalRangePrimitiveConcept
           void pop_back()
           {
               BOOST_ASSERT( !empty() );
               --m_End;
           }

           reference operator[]( difference_type at ) const
           {
               BOOST_ASSERT( at >= 0 && at < size() );
               return m_Begin[at];
           }

           //
           // When storing transform iterators, operator[]()
           // fails because it returns by reference. Therefore
           // operator()() is provided for these cases.
           //
           abstract_value_type operator()( difference_type at ) const
           {
               BOOST_ASSERT( at >= 0 && at < size() );
               return m_Begin[at];
           }

           iterator_range& advance_begin( difference_type n )
           {
               std::advance( m_Begin, n );
               return *this;
           }

           iterator_range& advance_end( difference_type n )
           {
               std::advance( m_End, n );
               return *this;
           }

        private:
            // begin and end iterators
            IteratorT m_Begin;
            IteratorT m_End;

        protected:
            //
            // Allow subclasses an easy way to access the
            // base type
            //
            typedef iterator_range iterator_range_;
        };

//  iterator range free-standing operators ---------------------------//

        /////////////////////////////////////////////////////////////////////
        // comparison operators
        /////////////////////////////////////////////////////////////////////

        template< class IteratorT, class ForwardRange >
        inline bool operator==( const ForwardRange& l,
                                const iterator_range<IteratorT>& r )
        {
            return boost::equal( l, r );
        }

        template< class IteratorT, class ForwardRange >
        inline bool operator!=( const ForwardRange& l,
                                const iterator_range<IteratorT>& r )
        {
            return !boost::equal( l, r );
        }

        template< class IteratorT, class ForwardRange >
        inline bool operator<( const ForwardRange& l,
                               const iterator_range<IteratorT>& r )
        {
            return iterator_range_detail::less_than( l, r );
        }
        
        template< class IteratorT, class ForwardRange >
        inline bool operator<=( const ForwardRange& l,
                                const iterator_range<IteratorT>& r )
        {
            return iterator_range_detail::less_or_equal_than( l, r );
        }
        
        template< class IteratorT, class ForwardRange >
        inline bool operator>( const ForwardRange& l,
                               const iterator_range<IteratorT>& r )
        {
            return iterator_range_detail::greater_than( l, r );
        }
        
        template< class IteratorT, class ForwardRange >
        inline bool operator>=( const ForwardRange& l,
                                const iterator_range<IteratorT>& r )
        {
            return iterator_range_detail::greater_or_equal_than( l, r );
        }

#ifdef BOOST_NO_FUNCTION_TEMPLATE_ORDERING
#else
        template< class Iterator1T, class Iterator2T >
        inline bool operator==( const iterator_range<Iterator1T>& l,
                                const iterator_range<Iterator2T>& r )
        {
            return boost::equal( l, r );
        }

        template< class IteratorT, class ForwardRange >
        inline bool operator==( const iterator_range<IteratorT>& l,
                                const ForwardRange& r )
        {
            return boost::equal( l, r );
        }


        template< class Iterator1T, class Iterator2T >
        inline bool operator!=( const iterator_range<Iterator1T>& l,
                                const iterator_range<Iterator2T>& r )
        {
            return !boost::equal( l, r );
        }

        template< class IteratorT, class ForwardRange >
        inline bool operator!=( const iterator_range<IteratorT>& l,
                                const ForwardRange& r )
        {
            return !boost::equal( l, r );
        }


        template< class Iterator1T, class Iterator2T >
        inline bool operator<( const iterator_range<Iterator1T>& l,
                               const iterator_range<Iterator2T>& r )
        {
            return iterator_range_detail::less_than( l, r );
        }

        template< class IteratorT, class ForwardRange >
        inline bool operator<( const iterator_range<IteratorT>& l,
                               const ForwardRange& r )
        {
            return iterator_range_detail::less_than( l, r );
        }
        
        template< class Iterator1T, class Iterator2T >
        inline bool operator<=( const iterator_range<Iterator1T>& l,
                                const iterator_range<Iterator2T>& r )
        {
            return iterator_range_detail::less_or_equal_than( l, r );
        }
        
        template< class IteratorT, class ForwardRange >
        inline bool operator<=( const iterator_range<IteratorT>& l,
                                const ForwardRange& r )
        {
            return iterator_range_detail::less_or_equal_than( l, r );
        }
        
        template< class Iterator1T, class Iterator2T >
        inline bool operator>( const iterator_range<Iterator1T>& l,
                               const iterator_range<Iterator2T>& r )
        {
            return iterator_range_detail::greater_than( l, r );
        }
        
        template< class IteratorT, class ForwardRange >
        inline bool operator>( const iterator_range<IteratorT>& l,
                               const ForwardRange& r )
        {
            return iterator_range_detail::greater_than( l, r );
        }
        
        template< class Iterator1T, class Iterator2T >
        inline bool operator>=( const iterator_range<Iterator1T>& l,
                                const iterator_range<Iterator2T>& r )
        {
            return iterator_range_detail::greater_or_equal_than( l, r );
        }
        
        template< class IteratorT, class ForwardRange >
        inline bool operator>=( const iterator_range<IteratorT>& l,
                                const ForwardRange& r )
        {
            return iterator_range_detail::greater_or_equal_than( l, r );
        }

#endif // BOOST_NO_FUNCTION_TEMPLATE_ORDERING

//  iterator range utilities -----------------------------------------//

        //! iterator_range construct helper
        /*!
            Construct an \c iterator_range from a pair of iterators

            \param Begin A begin iterator
            \param End An end iterator
            \return iterator_range object
        */
        template< typename IteratorT >
        inline iterator_range< IteratorT >
        make_iterator_range( IteratorT Begin, IteratorT End )
        {
            return iterator_range<IteratorT>( Begin, End );
        }

#ifdef BOOST_NO_FUNCTION_TEMPLATE_ORDERING

        template< typename Range >
        inline iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<Range>::type >
        make_iterator_range( Range& r )
        {
            return iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<Range>::type >
                ( boost::begin( r ), boost::end( r ) );
        }

#else
        //! iterator_range construct helper
        /*!
            Construct an \c iterator_range from a \c Range containing the begin
            and end iterators.
        */
        template< class ForwardRange >
        inline iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type >
        make_iterator_range( ForwardRange& r )
        {
           return iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type >
                ( r, iterator_range_detail::range_tag() );
        }

        template< class ForwardRange >
        inline iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<const ForwardRange>::type >
        make_iterator_range( const ForwardRange& r )
        {
           return iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<const ForwardRange>::type >
                ( r, iterator_range_detail::const_range_tag() );
        }

#endif // BOOST_NO_FUNCTION_TEMPLATE_ORDERING

        namespace iterator_range_detail
        {
            template< class Range >
            inline iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<Range>::type >
            make_range_impl( Range& r,
                             BOOST_DEDUCED_TYPENAME range_difference<Range>::type advance_begin,
                             BOOST_DEDUCED_TYPENAME range_difference<Range>::type advance_end )
            {
                //
                // Not worth the effort
                //
                //if( advance_begin == 0 && advance_end == 0 )
                //    return make_iterator_range( r );
                //

                BOOST_DEDUCED_TYPENAME range_iterator<Range>::type
                    new_begin = boost::begin( r ),
                    new_end   = boost::end( r );
                std::advance( new_begin, advance_begin );
                std::advance( new_end, advance_end );
                return make_iterator_range( new_begin, new_end );
            }
        }

#ifdef BOOST_NO_FUNCTION_TEMPLATE_ORDERING

        template< class Range >
        inline iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<Range>::type >
        make_iterator_range( Range& r,
                    BOOST_DEDUCED_TYPENAME range_difference<Range>::type advance_begin,
                    BOOST_DEDUCED_TYPENAME range_difference<Range>::type advance_end )
        {
            //BOOST_ASSERT( advance_begin - advance_end <= size(r) && "creating invalid range" );
            return iterator_range_detail::make_range_impl( r, advance_begin, advance_end );
        }

#else

        template< class Range >
        inline iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<Range>::type >
        make_iterator_range( Range& r,
                    BOOST_DEDUCED_TYPENAME range_difference<Range>::type advance_begin,
                    BOOST_DEDUCED_TYPENAME range_difference<Range>::type advance_end )
        {
            //BOOST_ASSERT( advance_begin - advance_end <= size(r) && "creating invalid range" );
            return iterator_range_detail::make_range_impl( r, advance_begin, advance_end );
        }

        template< class Range >
        inline iterator_range< BOOST_DEDUCED_TYPENAME range_iterator<const Range>::type >
        make_iterator_range( const Range& r,
                    BOOST_DEDUCED_TYPENAME range_difference<Range>::type advance_begin,
                    BOOST_DEDUCED_TYPENAME range_difference<Range>::type advance_end )
        {
            //BOOST_ASSERT( advance_begin - advance_end <= size(r) && "creating invalid range" );
            return iterator_range_detail::make_range_impl( r, advance_begin, advance_end );
        }

#endif // BOOST_NO_FUNCTION_TEMPLATE_ORDERING

        //! copy a range into a sequence
        /*!
            Construct a new sequence of the specified type from the elements
            in the given range

            \param Range An input range
            \return New sequence
        */
        template< typename SeqT, typename Range >
        inline SeqT copy_range( const Range& r )
        {
            return SeqT( boost::begin( r ), boost::end( r ) );
        }

} // namespace 'boost'

#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1500))
    #pragma warning( pop )
#endif

#endif