grammar/detail/ci_string.hpp

0001 //
0002 // Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
0003 // Copyright (c) 2022 Alan de Freitas (alandefreitas@gmail.com)
0004 //
0005 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0006 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007 //
0008 // Official repository: https://github.com/boostorg/url
0009 //
0010
0011 #ifndef BOOST_URL_GRAMMAR_DETAIL_CI_STRING_HPP
0012 #define BOOST_URL_GRAMMAR_DETAIL_CI_STRING_HPP
0013
0014 #include <boost/core/detail/string_view.hpp>
0015 #include <boost/assert.hpp>
0016 #include <cstdint>
0017 #include <iterator>
0018 #include <type_traits>
0019
0020 namespace boost {
0021 namespace urls {
0022 namespace grammar {
0023 namespace detail {
0024
0025 template<class T, class = void>
0026 struct is_char_iter : std::false_type {};
0027
0028 template<class T>
0029 struct is_char_iter<T, void_t<
0030     decltype(std::declval<char&>() =
0031         *std::declval<T const&>()),
0032     decltype(std::declval<T&>() =
0033         ++std::declval<T&>()),
0034     decltype(std::declval<bool&>() =
0035         std::declval<T const&>() ==
0036         std::declval<T const&>())
0037     > > : std::integral_constant<bool,
0038         std::is_copy_constructible<T>::value>
0039 {
0040 };
0041
0042 template<class T, class = void>
0043 struct is_char_range : std::false_type {};
0044
0045 template<class T>
0046 struct is_char_range<T, void_t<
0047     decltype(std::declval<T const&>().begin()),
0048     decltype(std::declval<T const&>().end())
0049     > > : std::integral_constant<bool,
0050         is_char_iter<decltype(
0051             std::declval<T const&>(
0052                 ).begin())>::value &&
0053         is_char_iter<decltype(
0054             std::declval<T const&>(
0055                 ).end())>::value>
0056 {
0057 };
0058
0059 template<class T>
0060 struct type_id_impl
0061 {
0062     static
0063     constexpr
0064     char cid = 0;
0065 };
0066
0067 template<class T>
0068 constexpr
0069 char
0070 type_id_impl<T>::cid;
0071
0072 template<class T>
0073 constexpr
0074 std::uintptr_t
0075 type_id() noexcept
0076 {
0077     return std::uintptr_t(
0078         &type_id_impl<T>::cid);
0079 }
0080
0081 //------------------------------------------------
0082
0083 constexpr
0084 char
0085 to_lower(char c) noexcept
0086 {
0087     return
0088       (c >= 'A' &&
0089        c <= 'Z')
0090         ? c + 'a' - 'A'
0091         : c;
0092 }
0093
0094 constexpr
0095 char
0096 to_upper(char c) noexcept
0097 {
0098     return
0099       (c >= 'a' &&
0100        c <= 'z')
0101         ? c - ('a' - 'A')
0102         : c;
0103 }
0104
0105 //------------------------------------------------
0106
0107 template<class S0, class S1>
0108 auto
0109 ci_is_equal(
0110     S0 const& s0,
0111     S1 const& s1) ->
0112         typename std::enable_if<
0113             ! std::is_convertible<
0114                 S0, core::string_view>::value ||
0115             ! std::is_convertible<
0116                 S1, core::string_view>::value,
0117         bool>::type
0118 {
0119 /*  If you get a compile error here, it
0120     means that a range you passed does
0121     not meet the requirements stated
0122     in the documentation.
0123 */
0124     static_assert(
0125         is_char_range<S0>::value,
0126         "Type requirements not met");
0127     static_assert(
0128         is_char_range<S1>::value,
0129         "Type requirements not met");
0130
0131     // Arguments are sorted by type to
0132     // reduce the number of function
0133     // template instantiations. This
0134     // works because:
0135     //
0136     // ci_is_equal(s0,s1) == ci_is_equal(s1,s0)
0137     //
0138     BOOST_ASSERT(
0139         detail::type_id<S0>() <=
0140         detail::type_id<S1>());
0141
0142     auto it0 = s0.begin();
0143     auto it1 = s1.begin();
0144     auto const end0 = s0.end();
0145     auto const end1 = s1.end();
0146     for(;;)
0147     {
0148         if(it0 == end0)
0149             return it1 == end1;
0150         if(it1 == end1)
0151             return false;
0152         if( to_lower(*it0) !=
0153             to_lower(*it1))
0154             return false;
0155         ++it0;
0156         ++it1;
0157     }
0158 }
0159
0160 //------------------------------------------------
0161
0162 BOOST_URL_DECL
0163 bool
0164 ci_is_equal(
0165     core::string_view s0,
0166     core::string_view s1) noexcept;
0167
0168 BOOST_URL_DECL
0169 bool
0170 ci_is_less(
0171     core::string_view s0,
0172     core::string_view s1) noexcept;
0173
0174 } // detail
0175 } // grammar
0176 } // urls
0177 } // boost
0178
0179 #endif