text: // Boost.Range library
  //
  //  Copyright Neil Groves 2007. 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_ADAPTOR_REPLACED_IF_IMPL_HPP_INCLUDED
  #define BOOST_RANGE_ADAPTOR_REPLACED_IF_IMPL_HPP_INCLUDED
  
  #include <boost/config.hpp>
  #include <boost/range/adaptor/argument_fwd.hpp>
  #include <boost/range/iterator_range.hpp>
  #include <boost/range/begin.hpp>
  #include <boost/range/end.hpp>
  #include <boost/range/value_type.hpp>
  #include <boost/iterator/iterator_adaptor.hpp>
  #include <boost/iterator/transform_iterator.hpp>
  
  namespace boost
  {
      namespace range_detail
      {
          template< class Pred, class Value >
          class replace_value_if
          {
          public:
              typedef const Value& result_type;
              typedef const Value& first_argument_type;
  
              replace_value_if(const Pred& pred, const Value& to)
                  :   m_pred(pred), m_to(to)
              {
              }
  
              const Value& operator()(const Value& x) const
              {
                  return m_pred(x) ? m_to : x;
              }
  
          private:
              Pred  m_pred;
              Value m_to;
          };
  
          template< class Pred, class R >
          class replace_if_range :
              public boost::iterator_range<
                  boost::transform_iterator<
                      replace_value_if< Pred, BOOST_DEDUCED_TYPENAME range_value<R>::type >,
                      BOOST_DEDUCED_TYPENAME range_iterator<R>::type > >
          {
          private:
              typedef replace_value_if< Pred, BOOST_DEDUCED_TYPENAME range_value<R>::type > Fn;
  
              typedef boost::iterator_range<
                  boost::transform_iterator<
                      replace_value_if< Pred, BOOST_DEDUCED_TYPENAME range_value<R>::type >,
                      BOOST_DEDUCED_TYPENAME range_iterator<R>::type > > base_t;
  
          public:
              typedef BOOST_DEDUCED_TYPENAME range_value<R>::type value_type;
  
              replace_if_range( R& r, const Pred& pred, value_type to )
                  : base_t( make_transform_iterator( boost::begin(r), Fn(pred, to) ),
                            make_transform_iterator( boost::end(r), Fn(pred, to) ) )
              { }
          };
  
          template< class Pred, class T >
          class replace_if_holder
          {
          public:
              replace_if_holder( const Pred& pred, const T& to )
                  : m_pred(pred), m_to(to)
              { }
  
              const Pred& pred() const { return m_pred; }
              const T& to() const { return m_to; }
  
          private:
              Pred m_pred;
              T m_to;
          };
  
          template< class Pred, class InputRng >
          inline replace_if_range<Pred, InputRng>
          operator|( InputRng& r,
                     const replace_if_holder<Pred, BOOST_DEDUCED_TYPENAME range_value<InputRng>::type>& f )
          {
              return replace_if_range<Pred, InputRng>(r, f.pred(), f.to());
          }
  
          template< class Pred, class InputRng >
          inline replace_if_range<Pred, const InputRng>
          operator|( const InputRng& r,
                     const replace_if_holder<Pred, BOOST_DEDUCED_TYPENAME range_value<InputRng>::type>& f )
          {
              return replace_if_range<Pred, const InputRng>(r, f.pred(), f.to());
          }
      } // 'range_detail'
  
      using range_detail::replace_if_range;
  
      namespace adaptors
      {
          namespace
          {
              const range_detail::forwarder2TU<range_detail::replace_if_holder>
                  replaced_if =
                      range_detail::forwarder2TU<range_detail::replace_if_holder>();
          }
          
          template<class Pred, class InputRange>
          inline replace_if_range<Pred, InputRange>
          replace_if(InputRange& rng, Pred pred,
                     BOOST_DEDUCED_TYPENAME range_value<InputRange>::type to)
          {
              return range_detail::replace_if_range<Pred, InputRange>(rng, pred, to);
          }
  
          template<class Pred, class InputRange>
          inline replace_if_range<Pred, const InputRange>
          replace_if(const InputRange& rng, Pred pred,
                     BOOST_DEDUCED_TYPENAME range_value<const InputRange>::type to)
          {
              return range_detail::replace_if_range<Pred, const InputRange>(rng, pred, to);
          }
      } // 'adaptors'
      
  } // 'boost'
  
  #endif // include guard
  