63 lines
1.3 KiB
Plaintext
63 lines
1.3 KiB
Plaintext
[#fail]
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[section fail]
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[h1 Synopsis]
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template <class Msg>
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struct fail;
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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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[[`Msg`] [[link parsing_error_message parsing error message]]]
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]
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[h1 Description]
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Parser rejecting every input.
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[h1 Header]
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#include <boost/metaparse/fail.hpp>
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[h1 Expression semantics]
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For any `msg` parsing error message, `s` compile-time string and `pos` source
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position
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fail<msg>::apply<s, pos>::type
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returns an error with `msg` as the error message.
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[h1 Example]
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#include <boost/metaparse/fail.hpp>
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#include <boost/metaparse/string.hpp>
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#include <boost/metaparse/start.hpp>
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#include <boost/metaparse/is_error.hpp>
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#include <boost/metaparse/get_message.hpp>
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#include <boost/metaparse/define_error.hpp>
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using namespace boost::metaparse;
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BOOST_METAPARSE_DEFINE_ERROR(sample_error, "This is an example parsing error");
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using fail_p = fail<sample_error>;
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static_assert(
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is_error<fail_p::apply<BOOST_METAPARSE_STRING("foo"), start>>::type::value,
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"it should reject every input"
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);
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static_assert(
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std::is_same<
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get_message<fail_p::apply<BOOST_METAPARSE_STRING("foo"), start>>::type,
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sample_error
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>::type::value,
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"the error message should be the type specified"
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);
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[endsect]
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