regex/v4/iterator_category.hpp

0001 /*
0002  *
0003  * Copyright (c) 2002
0004  * John Maddock
0005  *
0006  * Use, modification and distribution are subject to the
0007  * Boost Software License, Version 1.0. (See accompanying file
0008  * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0009  *
0010  */
0011
0012  /*
0013   *   LOCATION:    see http://www.boost.org for most recent version.
0014   *   FILE         regex_match.hpp
0015   *   VERSION      see <boost/version.hpp>
0016   *   DESCRIPTION: Iterator traits for selecting an iterator type as
0017   *                an integral constant expression.
0018   */
0019
0020
0021 #ifndef BOOST_REGEX_ITERATOR_CATEGORY_HPP
0022 #define BOOST_REGEX_ITERATOR_CATEGORY_HPP
0023
0024 #include <iterator>
0025 #include <boost/type_traits/is_convertible.hpp>
0026 #include <boost/type_traits/is_pointer.hpp>
0027
0028 namespace boost{
0029 namespace detail{
0030
0031 template <class I>
0032 struct is_random_imp
0033 {
0034 #ifndef BOOST_NO_STD_ITERATOR_TRAITS
0035 private:
0036    typedef typename std::iterator_traits<I>::iterator_category cat;
0037 public:
0038    BOOST_STATIC_CONSTANT(bool, value = (::boost::is_convertible<cat*, std::random_access_iterator_tag*>::value));
0039 #else
0040    BOOST_STATIC_CONSTANT(bool, value = false);
0041 #endif
0042 };
0043
0044 template <class I>
0045 struct is_random_pointer_imp
0046 {
0047    BOOST_STATIC_CONSTANT(bool, value = true);
0048 };
0049
0050 template <bool is_pointer_type>
0051 struct is_random_imp_selector
0052 {
0053    template <class I>
0054    struct rebind
0055    {
0056       typedef is_random_imp<I> type;
0057    };
0058 };
0059
0060 template <>
0061 struct is_random_imp_selector<true>
0062 {
0063    template <class I>
0064    struct rebind
0065    {
0066       typedef is_random_pointer_imp<I> type;
0067    };
0068 };
0069
0070 }
0071
0072 template <class I>
0073 struct is_random_access_iterator
0074 {
0075 private:
0076    typedef detail::is_random_imp_selector< ::boost::is_pointer<I>::value> selector;
0077    typedef typename selector::template rebind<I> bound_type;
0078    typedef typename bound_type::type answer;
0079 public:
0080    BOOST_STATIC_CONSTANT(bool, value = answer::value);
0081 };
0082
0083 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
0084 template <class I>
0085 const bool is_random_access_iterator<I>::value;
0086 #endif
0087
0088 }
0089
0090 #endif
0091