ceph/src/boost/boost/beast/core/string.hpp

   1 //
   2 // Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // Official repository: https://github.com/boostorg/beast
   8 //
   9
  10 #ifndef BOOST_BEAST_STRING_HPP
  11 #define BOOST_BEAST_STRING_HPP
  12
  13 #include <boost/beast/core/detail/config.hpp>
  14 #include <boost/version.hpp>
  15 #ifndef BOOST_BEAST_NO_BOOST_STRING_VIEW
  16 # if BOOST_VERSION >= 106400
  17 #  define BOOST_BEAST_NO_BOOST_STRING_VIEW 0
  18 # else
  19 #  define BOOST_BEAST_NO_BOOST_STRING_VIEW 1
  20 # endif
  21 #endif
  22
  23 #if BOOST_BEAST_NO_BOOST_STRING_VIEW
  24 #include <boost/utility/string_ref.hpp>
  25 #else
  26 #include <boost/utility/string_view.hpp>
  27 #endif
  28
  29 #include <algorithm>
  30
  31 namespace boost {
  32 namespace beast {
  33
  34 #if BOOST_BEAST_NO_BOOST_STRING_VIEW
  35 /// The type of string view used by the library
  36 using string_view = boost::string_ref;
  37
  38 /// The type of basic string view used by the library
  39 template<class CharT, class Traits>
  40 using basic_string_view =
  41     boost::basic_string_ref<CharT, Traits>;
  42 #else
  43 /// The type of string view used by the library
  44 using string_view = boost::string_view;
  45
  46 /// The type of basic string view used by the library
  47 template<class CharT, class Traits>
  48 using basic_string_view =
  49     boost::basic_string_view<CharT, Traits>;
  50 #endif
  51
  52 namespace detail {
  53
  54 inline
  55 char
  56 ascii_tolower(char c)
  57 {
  58     if(c >= 'A' && c <= 'Z')
  59         c += 'a' - 'A';
  60     return c;
  61 }
  62
  63 template<class = void>
  64 bool
  65 iequals(
  66     beast::string_view lhs,
  67     beast::string_view rhs)
  68 {
  69     auto n = lhs.size();
  70     if(rhs.size() != n)
  71         return false;
  72     auto p1 = lhs.data();
  73     auto p2 = rhs.data();
  74     char a, b;
  75     while(n--)
  76     {
  77         a = *p1++;
  78         b = *p2++;
  79         if(a != b)
  80             goto slow;
  81     }
  82     return true;
  83
  84     while(n--)
  85     {
  86     slow:
  87         if(ascii_tolower(a) != ascii_tolower(b))
  88             return false;
  89         a = *p1++;
  90         b = *p2++;
  91     }
  92     return true;
  93 }
  94
  95 } // detail
  96
  97 /** Returns `true` if two strings are equal, using a case-insensitive comparison.
  98
  99     The case-comparison operation is defined only for low-ASCII characters.
 100
 101     @param lhs The string on the left side of the equality
 102
 103     @param rhs The string on the right side of the equality
 104 */
 105 inline
 106 bool
 107 iequals(
 108     beast::string_view lhs,
 109     beast::string_view rhs)
 110 {
 111     return detail::iequals(lhs, rhs);
 112 }
 113
 114 /** A case-insensitive less predicate for strings.
 115
 116     The case-comparison operation is defined only for low-ASCII characters.
 117 */
 118 struct iless
 119 {
 120     bool
 121     operator()(
 122         string_view lhs,
 123         string_view rhs) const
 124     {
 125         using std::begin;
 126         using std::end;
 127         return std::lexicographical_compare(
 128             begin(lhs), end(lhs), begin(rhs), end(rhs),
 129             [](char c1, char c2)
 130             {
 131                 return detail::ascii_tolower(c1) < detail::ascii_tolower(c2);
 132             }
 133         );
 134     }
 135 };
 136
 137 /** A case-insensitive equality predicate for strings.
 138
 139     The case-comparison operation is defined only for low-ASCII characters.
 140 */
 141 struct iequal
 142 {
 143     bool
 144     operator()(
 145         string_view lhs,
 146         string_view rhs) const
 147     {
 148         return iequals(lhs, rhs);
 149     }
 150 };
 151
 152 } // beast
 153 } // boost
 154
 155 #endif