ceph/src/boost/boost/metaparse/v1/cpp11/impl/string_at.hpp

   1 #ifndef BOOST_METAPARSE_V1_CPP11_IMPL_STRING_AT_HPP
   2 #define BOOST_METAPARSE_V1_CPP11_IMPL_STRING_AT_HPP
   3
   4 // Copyright Abel Sinkovics (abel@sinkovics.hu)  2016.
   5 // Distributed under the Boost Software License, Version 1.0.
   6 //    (See accompanying file LICENSE_1_0.txt or copy at
   7 //          http://www.boost.org/LICENSE_1_0.txt)
   8
   9 #include <boost/metaparse/limit_string_size.hpp>
  10
  11 namespace boost
  12 {
  13   namespace metaparse
  14   {
  15     namespace v1
  16     {
  17       namespace impl
  18       {
  19         template <int MaxLen, int Len, class T>
  20         constexpr T string_at(const T (&s)[Len], int n)
  21         {
  22           // "MaxLen + 1" adds the \0 character of the string literal to the
  23           // limit
  24           static_assert(Len <= MaxLen + 1, "String literal is too long.");
  25           return n >= Len - 1 ? T() : s[n];
  26         }
  27       }
  28     }
  29   }
  30 }
  31
  32 #ifdef BOOST_METAPARSE_V1_STRING_AT
  33 #  error BOOST_METAPARSE_V1_STRING_AT already defined
  34 #endif
  35 #define BOOST_METAPARSE_V1_STRING_AT \
  36   ::boost::metaparse::v1::impl::string_at<BOOST_METAPARSE_LIMIT_STRING_SIZE>
  37
  38 #endif
  39