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- [#digit_val]
- [section digit_val]
- [h1 Synopsis]
- struct digit_val;
- This is a [link parser parser].
- [h1 Description]
- It accepts one character in the range `0-9`. The result of the parser is the
- value represented by the accepted character.
- [h1 Header]
- #include <boost/metaparse/digit_val.hpp>
- [h1 Expression semantics]
- The following are equivalent:
- digit_val
-
- transform<digit, util::digit_to_int<>>
- [h1 Example]
- #include <boost/metaparse/digit_val.hpp>
- #include <boost/metaparse/start.hpp>
- #include <boost/metaparse/string.hpp>
- #include <boost/metaparse/is_error.hpp>
- #include <boost/metaparse/get_result.hpp>
-
- using namespace boost::metaparse;
-
- static_assert(
- !is_error<digit_val::apply<BOOST_METAPARSE_STRING("0"), start>>::type::value,
- "digit_val should accept a digit"
- );
-
- static_assert(
- is_error<digit_val::apply<BOOST_METAPARSE_STRING("x"), start>>::type::value,
- "digit_val should reject a character"
- );
-
- static_assert(
- get_result<
- digit_val::apply<BOOST_METAPARSE_STRING("0"), start>
- >::type::value == 0,
- "the result of parsing should be the int value"
- );
- [endsect]
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