78 lines
1.6 KiB
Plaintext
78 lines
1.6 KiB
Plaintext
[#token]
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[section token]
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[h1 Synopsis]
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template <class P>
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struct token;
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This is a [link parser_combinator parser combinator].
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[table Arguments
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[[Name] [Type]]
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[[`P`] [[link parser parser]]]
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]
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[h1 Description]
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`token` parses the input using `P` when it succeeds, `token` consumes all
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whitespaces afterwards. The result of parsing is the result of `P`.
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[h1 Header]
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#include <boost/metaparse/token.hpp>
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[h1 Expression semantics]
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For any `p` parser the following are equivalent:
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token<p>
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first_of<p, spaces>
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[h1 Example]
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#include <boost/metaparse/token.hpp>
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#include <boost/metaparse/int_.hpp>
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#include <boost/metaparse/start.hpp>
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#include <boost/metaparse/get_result.hpp>
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#include <boost/metaparse/get_remaining.hpp>
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#include <boost/metaparse/is_error.hpp>
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#include <boost/metaparse/string.hpp>
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#include <type_traits>
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using namespace boost::metaparse;
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using int_token = token<int_>;
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static_assert(
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get_result<
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int_token::apply<BOOST_METAPARSE_STRING("13 "), start>
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>::type::value,
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"the result of int_token is the number"
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);
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static_assert(
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std::is_same<
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BOOST_METAPARSE_STRING(""),
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get_remaining<int_token::apply<BOOST_METAPARSE_STRING("13 "), start>>::type
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>::type::value,
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"token consumes whitespaces after the number"
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);
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static_assert(
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get_result<
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int_token::apply<BOOST_METAPARSE_STRING("13"), start>
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>::type::value,
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"whitespaces after the number are optional"
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);
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static_assert(
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is_error<int_token::apply<BOOST_METAPARSE_STRING("foo"), start>>::type::value,
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"when there is no number, token fails"
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);
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[endsect]
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