ceph/src/boost/libs/metaparse/include/boost/metaparse/v1/impl/string_at.hpp

   1 #ifndef BOOST_METAPARSE_V1_IMPL_STRING_AT_HPP
   2 #define BOOST_METAPARSE_V1_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/config.hpp>
  10 #include <boost/static_assert.hpp>
  11 #include <boost/metaparse/v1/impl/no_char.hpp>
  12
  13 namespace boost
  14 {
  15   namespace metaparse
  16   {
  17     namespace v1
  18     {
  19       namespace impl
  20       {
  21         template <int MaxLen, int Len, class T>
  22         BOOST_CONSTEXPR int string_at(const T (&s)[Len], int n)
  23         {
  24           // "MaxLen + 1" adds the \0 character of the string literal to the
  25           // limit
  26           BOOST_STATIC_ASSERT((Len <= MaxLen + 1));
  27           return n >= Len - 1 ? BOOST_NO_CHAR : s[n];
  28         }
  29       }
  30     }
  31   }
  32 }
  33
  34 #ifdef BOOST_METAPARSE_V1_STRING_AT
  35 #  error BOOST_METAPARSE_V1_STRING_AT already defined
  36 #endif
  37 #define BOOST_METAPARSE_V1_STRING_AT \
  38   ::boost::metaparse::v1::impl::string_at<BOOST_METAPARSE_LIMIT_STRING_SIZE>
  39
  40 #endif
  41