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- [#letter]
- [section letter]
- [h1 Synopsis]
- struct letter;
- This is a [link parser parser].
- [h1 Description]
- Parser accepting one character in the range `a-z` or `A-Z`. The result of the
- parser is the accepted character.
- [h1 Header]
- #include <boost/metaparse/letter.hpp>
- [h1 Expression semantics]
- The following are equivalent:
- letter
-
- accept_when<one_char, util::is_letter<>, error::letter_expected>
- [h1 Example]
- #include <boost/metaparse/letter.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<letter::apply<BOOST_METAPARSE_STRING("a"), start>>::type::value,
- "letter should accept a letter"
- );
-
- static_assert(
- is_error<letter::apply<BOOST_METAPARSE_STRING("0"), start>>::type::value,
- "letter should reject a digit"
- );
-
- static_assert(
- get_result<
- letter::apply<BOOST_METAPARSE_STRING("z"), start>
- >::type::value == 'z',
- "the result of parsing should be the character value"
- );
- [endsect]
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