40 lines
1.0 KiB
C++
40 lines
1.0 KiB
C++
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#ifndef BOOST_METAPARSE_V1_CPP11_IMPL_STRING_AT_HPP
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#define BOOST_METAPARSE_V1_CPP11_IMPL_STRING_AT_HPP
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// Copyright Abel Sinkovics (abel@sinkovics.hu) 2016.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#include <boost/metaparse/limit_string_size.hpp>
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namespace boost
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{
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namespace metaparse
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{
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namespace v1
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{
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namespace impl
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{
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template <int MaxLen, int Len, class T>
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constexpr T string_at(const T (&s)[Len], int n)
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{
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// "MaxLen + 1" adds the \0 character of the string literal to the
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// limit
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static_assert(Len <= MaxLen + 1, "String literal is too long.");
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return n >= Len - 1 ? T() : s[n];
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}
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}
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}
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}
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}
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#ifdef BOOST_METAPARSE_V1_STRING_AT
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# error BOOST_METAPARSE_V1_STRING_AT already defined
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#endif
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#define BOOST_METAPARSE_V1_STRING_AT \
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::boost::metaparse::v1::impl::string_at<BOOST_METAPARSE_LIMIT_STRING_SIZE>
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#endif
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