boost/regex/v4/iterator_category.hpp

   1 /*
   2  *
   3  * Copyright (c) 2002
   4  * John Maddock
   5  *
   6  * Use, modification and distribution are subject to the
   7  * Boost Software License, Version 1.0. (See accompanying file
   8  * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9  *
  10  */
  11
  12  /*
  13   *   LOCATION:    see http://www.boost.org for most recent version.
  14   *   FILE         regex_match.hpp
  15   *   VERSION      see <boost/version.hpp>
  16   *   DESCRIPTION: Iterator traits for selecting an iterator type as
  17   *                an integral constant expression.
  18   */
  19
  20
  21 #ifndef BOOST_REGEX_ITERATOR_CATEGORY_HPP
  22 #define BOOST_REGEX_ITERATOR_CATEGORY_HPP
  23
  24 #include <iterator>
  25 #include <boost/type_traits/is_convertible.hpp>
  26 #include <boost/type_traits/is_pointer.hpp>
  27
  28 namespace boost{
  29 namespace detail{
  30
  31 template <class I>
  32 struct is_random_imp
  33 {
  34 #ifndef BOOST_NO_STD_ITERATOR_TRAITS
  35 private:
  36    typedef typename std::iterator_traits<I>::iterator_category cat;
  37 public:
  38    BOOST_STATIC_CONSTANT(bool, value = (::boost::is_convertible<cat*, std::random_access_iterator_tag*>::value));
  39 #else
  40    BOOST_STATIC_CONSTANT(bool, value = false);
  41 #endif
  42 };
  43
  44 template <class I>
  45 struct is_random_pointer_imp
  46 {
  47    BOOST_STATIC_CONSTANT(bool, value = true);
  48 };
  49
  50 template <bool is_pointer_type>
  51 struct is_random_imp_selector
  52 {
  53    template <class I>
  54    struct rebind
  55    {
  56       typedef is_random_imp<I> type;
  57    };
  58 };
  59
  60 template <>
  61 struct is_random_imp_selector<true>
  62 {
  63    template <class I>
  64    struct rebind
  65    {
  66       typedef is_random_pointer_imp<I> type;
  67    };
  68 };
  69
  70 }
  71
  72 template <class I>
  73 struct is_random_access_iterator
  74 {
  75 private:
  76    typedef detail::is_random_imp_selector< ::boost::is_pointer<I>::value> selector;
  77    typedef typename selector::template rebind<I> bound_type;
  78    typedef typename bound_type::type answer;
  79 public:
  80    BOOST_STATIC_CONSTANT(bool, value = answer::value);
  81 };
  82
  83 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
  84 template <class I>
  85 const bool is_random_access_iterator<I>::value;
  86 #endif
  87
  88 }
  89
  90 #endif
  91