williamr@2: // (C) Copyright David Abrahams 2002.
williamr@2: // (C) Copyright Jeremy Siek    2002.
williamr@2: // (C) Copyright Thomas Witt    2002.
williamr@2: // Distributed under the Boost Software License, Version 1.0. (See
williamr@2: // accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: #ifndef BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
williamr@2: #define BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
williamr@2: 
williamr@2: #include <boost/function.hpp>
williamr@2: #include <boost/iterator.hpp>
williamr@2: #include <boost/iterator/detail/enable_if.hpp>
williamr@2: #include <boost/iterator/iterator_adaptor.hpp>
williamr@2: #include <boost/iterator/iterator_categories.hpp>
williamr@2: #include <boost/mpl/not.hpp>
williamr@2: #include <boost/mpl/bool.hpp>
williamr@2: #include <boost/type_traits/function_traits.hpp>
williamr@2: #include <boost/type_traits/is_const.hpp>
williamr@2: #include <boost/type_traits/is_class.hpp>
williamr@2: #include <boost/type_traits/is_function.hpp>
williamr@2: #include <boost/type_traits/is_reference.hpp>
williamr@2: #include <boost/type_traits/remove_const.hpp>
williamr@2: #include <boost/type_traits/remove_reference.hpp>
williamr@2: 
williamr@2: #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))
williamr@2: # include <boost/type_traits/is_base_and_derived.hpp>
williamr@2: 
williamr@2: #endif 
williamr@2: #include <boost/iterator/detail/config_def.hpp>
williamr@2: 
williamr@2: 
williamr@2: namespace boost
williamr@2: {
williamr@2:   template <class UnaryFunction, class Iterator, class Reference = use_default, class Value = use_default>
williamr@2:   class transform_iterator;
williamr@2: 
williamr@2:   namespace detail 
williamr@2:   {
williamr@2: 
williamr@2:     template <class UnaryFunction>
williamr@2:     struct function_object_result
williamr@2:     {
williamr@2:       typedef typename UnaryFunction::result_type type;
williamr@2:     };
williamr@2: 
williamr@2: #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
williamr@2:     template <class Return, class Argument>
williamr@2:     struct function_object_result<Return(*)(Argument)>
williamr@2:     {
williamr@2:       typedef Return type;
williamr@2:     };
williamr@2: #endif
williamr@2: 
williamr@2:     // Compute the iterator_adaptor instantiation to be used for transform_iterator
williamr@2:     template <class UnaryFunction, class Iterator, class Reference, class Value>
williamr@2:     struct transform_iterator_base
williamr@2:     {
williamr@2:      private:
williamr@2:         // By default, dereferencing the iterator yields the same as
williamr@2:         // the function.  Do we need to adjust the way
williamr@2:         // function_object_result is computed for the standard
williamr@2:         // proposal (e.g. using Doug's result_of)?
williamr@2:         typedef typename ia_dflt_help<
williamr@2:             Reference
williamr@2:           , function_object_result<UnaryFunction>
williamr@2:         >::type reference;
williamr@2: 
williamr@2:         // To get the default for Value: remove any reference on the
williamr@2:         // result type, but retain any constness to signal
williamr@2:         // non-writability.  Note that if we adopt Thomas' suggestion
williamr@2:         // to key non-writability *only* on the Reference argument,
williamr@2:         // we'd need to strip constness here as well.
williamr@2:         typedef typename ia_dflt_help<
williamr@2:             Value
williamr@2:           , remove_reference<reference>
williamr@2:         >::type cv_value_type;
williamr@2: 
williamr@2:      public:
williamr@2:         typedef iterator_adaptor<
williamr@2:             transform_iterator<UnaryFunction, Iterator, Reference, Value>
williamr@2:           , Iterator
williamr@2:           , cv_value_type
williamr@2:           , use_default    // Leave the traversal category alone
williamr@2:           , reference
williamr@2:         > type;
williamr@2:     };
williamr@2:   }
williamr@2: 
williamr@2:   template <class UnaryFunction, class Iterator, class Reference, class Value>
williamr@2:   class transform_iterator
williamr@2:     : public detail::transform_iterator_base<UnaryFunction, Iterator, Reference, Value>::type
williamr@2:   {
williamr@2:     typedef typename
williamr@2:     detail::transform_iterator_base<UnaryFunction, Iterator, Reference, Value>::type
williamr@2:     super_t;
williamr@2: 
williamr@2:     friend class iterator_core_access;
williamr@2: 
williamr@2:   public:
williamr@2:     transform_iterator() { }
williamr@2: 
williamr@2:     transform_iterator(Iterator const& x, UnaryFunction f)
williamr@2:       : super_t(x), m_f(f) { }
williamr@2: 
williamr@2:     explicit transform_iterator(Iterator const& x)
williamr@2:       : super_t(x)
williamr@2:     {
williamr@2:         // Pro8 is a little too aggressive about instantiating the
williamr@2:         // body of this function.
williamr@2: #if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
williamr@2:         // don't provide this constructor if UnaryFunction is a
williamr@2:         // function pointer type, since it will be 0.  Too dangerous.
williamr@2:         BOOST_STATIC_ASSERT(is_class<UnaryFunction>::value);
williamr@2: #endif 
williamr@2:     }
williamr@2: 
williamr@2:     template<
williamr@2:         class OtherUnaryFunction
williamr@2:       , class OtherIterator
williamr@2:       , class OtherReference
williamr@2:       , class OtherValue>
williamr@2:     transform_iterator(
williamr@2:          transform_iterator<OtherUnaryFunction, OtherIterator, OtherReference, OtherValue> const& t
williamr@2:        , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
williamr@2: #if !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
williamr@2:        , typename enable_if_convertible<OtherUnaryFunction, UnaryFunction>::type* = 0
williamr@2: #endif 
williamr@2:     )
williamr@2:       : super_t(t.base()), m_f(t.functor())
williamr@2:    {}
williamr@2: 
williamr@2:     UnaryFunction functor() const
williamr@2:       { return m_f; }
williamr@2: 
williamr@2:   private:
williamr@2:     typename super_t::reference dereference() const
williamr@2:     { return m_f(*this->base()); }
williamr@2: 
williamr@2:     // Probably should be the initial base class so it can be
williamr@2:     // optimized away via EBO if it is an empty class.
williamr@2:     UnaryFunction m_f;
williamr@2:   };
williamr@2: 
williamr@2:   template <class UnaryFunction, class Iterator>
williamr@2:   transform_iterator<UnaryFunction, Iterator>
williamr@2:   make_transform_iterator(Iterator it, UnaryFunction fun)
williamr@2:   {
williamr@2:       return transform_iterator<UnaryFunction, Iterator>(it, fun);
williamr@2:   }
williamr@2: 
williamr@2:   // Version which allows explicit specification of the UnaryFunction
williamr@2:   // type.
williamr@2:   //
williamr@2:   // This generator is not provided if UnaryFunction is a function
williamr@2:   // pointer type, because it's too dangerous: the default-constructed
williamr@2:   // function pointer in the iterator be 0, leading to a runtime
williamr@2:   // crash.
williamr@2:   template <class UnaryFunction, class Iterator>
williamr@2: #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
williamr@2:   typename mpl::if_<
williamr@2: #else 
williamr@2:   typename iterators::enable_if<
williamr@2: #endif 
williamr@2:       is_class<UnaryFunction>   // We should probably find a cheaper test than is_class<>
williamr@2:     , transform_iterator<UnaryFunction, Iterator>
williamr@2: #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
williamr@2:     , int[3]
williamr@2: #endif 
williamr@2:   >::type
williamr@2:   make_transform_iterator(Iterator it)
williamr@2:   {
williamr@2:       return transform_iterator<UnaryFunction, Iterator>(it, UnaryFunction());
williamr@2:   }
williamr@2: 
williamr@2: #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION ) && !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
williamr@2:   template <class Return, class Argument, class Iterator>
williamr@2:   transform_iterator< Return (*)(Argument), Iterator, Return>
williamr@2:   make_transform_iterator(Iterator it, Return (*fun)(Argument))
williamr@2:   {
williamr@2:     return transform_iterator<Return (*)(Argument), Iterator, Return>(it, fun);
williamr@2:   }
williamr@2: #endif
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #include <boost/iterator/detail/config_undef.hpp>
williamr@2: 
williamr@2: #endif // BOOST_TRANSFORM_ITERATOR_23022003THW_HPP