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