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- [#one_char_except]
- [section one_char_except]
- [h1 Synopsis]
- template <class... Cs>
- struct one_char_except;
- This is a [link parser parser].
- [table Arguments
- [[Name] [Type]]
- [[`Cs`] [[link boxed_value boxed] character values]]
- ]
- [h1 Description]
- `one_char_except` accepts one character except any of `Cs`. When the input is
- empty or begins with one of the non-accepted characters, `one_char_except`
- rejects the input. Otherwise it accepts the input and the result of parsing is
- the character value.
- On compilers, which are not C++11-compliant, the maximum number of characters
- this class can have is the value the macro
- `BOOST_METAPARSE_LIMIT_ONE_CHAR_EXCEPT_SIZE` expands to. Its default value is
- 10.
- [h1 Header]
- #include <boost/metaparse/one_char_except.hpp>
- [h1 Expression semantics]
- For any `c1`, ..., `cn` boxed characters the following are equivalent
- one_char_except<c1, ..., cn>
-
- one_char_except_c<c1::type::value, ..., cn::type::value>
- [h1 Example]
- #include <boost/metaparse/one_char_except.hpp>
- #include <boost/metaparse/lit_c.hpp>
- #include <boost/metaparse/middle_of.hpp>
- #include <boost/metaparse/repeated.hpp>
- #include <boost/metaparse/start.hpp>
- #include <boost/metaparse/string.hpp>
- #include <boost/metaparse/get_result.hpp>
-
- #include <boost/mpl/vector.hpp>
- #include <boost/mpl/char.hpp>
- #include <boost/mpl/equal.hpp>
-
- #include <type_traits>
-
- using namespace boost::metaparse;
-
- using string_literal_parser =
- middle_of<
- lit_c<'"'>,
- repeated<one_char_except<std::integral_constant<char, '"'>>>,
- lit_c<'"'>
- >;
-
- static_assert(
- boost::mpl::equal<
- boost::mpl::vector<
- boost::mpl::char_<'h'>,
- boost::mpl::char_<'e'>,
- boost::mpl::char_<'l'>,
- boost::mpl::char_<'l'>,
- boost::mpl::char_<'o'>
- >,
- get_result<
- string_literal_parser::apply<BOOST_METAPARSE_STRING("\"hello\""), start>
- >::type
- >::type::value,
- "it should return the content of the string literal"
- );
- [endsect]
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