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// (C) Copyright Jeremy Siek 2001.
// Distributed under 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)
// Revision History:
// 04 Oct 2001 David Abrahams
// Changed name of "bind" to "select" to avoid problems with MSVC.
#ifndef BOOST_DETAIL_NAMED_TEMPLATE_PARAMS_HPP
#define BOOST_DETAIL_NAMED_TEMPLATE_PARAMS_HPP
#include <boost/type_traits/conversion_traits.hpp>
#include <boost/type_traits/composite_traits.hpp> // for is_reference
#if defined(__BORLANDC__)
#include <boost/type_traits/ice.hpp>
#endif
namespace boost {
namespace detail {
struct default_argument { };
struct dummy_default_gen {
template <class Base, class Traits>
struct select {
typedef default_argument type;
};
};
// This class template is a workaround for MSVC.
template <class Gen> struct default_generator {
typedef detail::dummy_default_gen type;
};
template <class T> struct is_default {
enum { value = false };
typedef type_traits::no_type type;
};
template <> struct is_default<default_argument> {
enum { value = true };
typedef type_traits::yes_type type;
};
struct choose_default {
template <class Arg, class DefaultGen, class Base, class Traits>
struct select {
typedef typename default_generator<DefaultGen>::type Gen;
typedef typename Gen::template select<Base,Traits>::type type;
};
};
struct choose_arg {
template <class Arg, class DefaultGen, class Base, class Traits>
struct select {
typedef Arg type;
};
};
#if defined(__BORLANDC__)
template <class UseDefault>
struct choose_arg_or_default { typedef choose_arg type; };
template <>
struct choose_arg_or_default<type_traits::yes_type> {
typedef choose_default type;
};
#else
template <bool UseDefault>
struct choose_arg_or_default { typedef choose_arg type; };
template <>
struct choose_arg_or_default<true> {
typedef choose_default type;
};
#endif
template <class Arg, class DefaultGen, class Base, class Traits>
class resolve_default {
#if defined(__BORLANDC__)
typedef typename choose_arg_or_default<typename is_default<Arg>::type>::type Selector;
#else
// This usually works for Borland, but I'm seeing weird errors in
// iterator_adaptor_test.cpp when using this method.
enum { is_def = is_default<Arg>::value };
typedef typename choose_arg_or_default<is_def>::type Selector;
#endif
public:
typedef typename Selector
::template select<Arg, DefaultGen, Base, Traits>::type type;
};
// To differentiate an unnamed parameter from a traits generator
// we use is_convertible<X, iter_traits_gen_base>.
struct named_template_param_base { };
template <class X>
struct is_named_param_list {
enum { value = is_convertible<X, named_template_param_base>::value };
};
struct choose_named_params {
template <class Prev> struct select { typedef Prev type; };
};
struct choose_default_arg {
template <class Prev> struct select {
typedef detail::default_argument type;
};
};
template <bool Named> struct choose_default_dispatch_;
template <> struct choose_default_dispatch_<true> {
typedef choose_named_params type;
};
template <> struct choose_default_dispatch_<false> {
typedef choose_default_arg type;
};
// The use of inheritance here is a Solaris Forte 6 workaround.
template <bool Named> struct choose_default_dispatch
: public choose_default_dispatch_<Named> { };
template <class PreviousArg>
struct choose_default_argument {
enum { is_named = is_named_param_list<PreviousArg>::value };
typedef typename choose_default_dispatch<is_named>::type Selector;
typedef typename Selector::template select<PreviousArg>::type type;
};
// This macro assumes that there is a class named default_##TYPE
// defined before the application of the macro. This class should
// have a single member class template named "select" with two
// template parameters: the type of the class being created (e.g.,
// the iterator_adaptor type when creating iterator adaptors) and
// a traits class. The select class should have a single typedef
// named "type" that produces the default for TYPE. See
// boost/iterator_adaptors.hpp for an example usage. Also,
// applications of this macro must be placed in namespace
// boost::detail.
#define BOOST_NAMED_TEMPLATE_PARAM(TYPE) \
struct get_##TYPE##_from_named { \
template <class Base, class NamedParams, class Traits> \
struct select { \
typedef typename NamedParams::traits NamedTraits; \
typedef typename NamedTraits::TYPE TYPE; \
typedef typename resolve_default<TYPE, \
default_##TYPE, Base, NamedTraits>::type type; \
}; \
}; \
struct pass_thru_##TYPE { \
template <class Base, class Arg, class Traits> struct select { \
typedef typename resolve_default<Arg, \
default_##TYPE, Base, Traits>::type type; \
};\
}; \
template <int NamedParam> \
struct get_##TYPE##_dispatch { }; \
template <> struct get_##TYPE##_dispatch<1> { \
typedef get_##TYPE##_from_named type; \
}; \
template <> struct get_##TYPE##_dispatch<0> { \
typedef pass_thru_##TYPE type; \
}; \
template <class Base, class X, class Traits> \
class get_##TYPE { \
enum { is_named = is_named_param_list<X>::value }; \
typedef typename get_##TYPE##_dispatch<is_named>::type Selector; \
public: \
typedef typename Selector::template select<Base, X, Traits>::type type; \
}; \
template <> struct default_generator<default_##TYPE> { \
typedef default_##TYPE type; \
}
} // namespace detail
} // namespace boost
#endif // BOOST_DETAIL_NAMED_TEMPLATE_PARAMS_HPP
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