75 lines
1.8 KiB
Plaintext
75 lines
1.8 KiB
Plaintext
[#BOOST_METAPARSE_DEFINE_ERROR]
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[section BOOST_METAPARSE_DEFINE_ERROR]
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[h1 Synopsis]
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#define BOOST_METAPARSE_DEFINE_ERROR(name, msg) \
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// unspecified
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This is a macro.
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[table Arguments
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[[Name] [Type]]
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[[`name`] [identifier token]]
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[[`msg`] [string literal]]
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]
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[h1 Description]
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Macro for defining a [link parsing_error_message parsing error message] class.
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`name` is the name of the class representing the error message and `msg` is a
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string literal containing the description of the error.
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[h1 Header]
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#include <boost/metaparse/define_error.hpp>
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[h1 Expression semantics]
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For any `n` name and `m` string literal, given the following is defined:
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BOOST_METAPARSE_DEFINE_ERROR(n, m);
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the following pairs of expressions are equivalent:
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n::get_value()
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std::string(m)
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n::type
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n
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[h1 Example]
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#include <boost/metaparse/define_error.hpp>
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#include <boost/metaparse/repeated1.hpp>
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#include <boost/metaparse/letter.hpp>
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#include <boost/metaparse/int_.hpp>
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#include <boost/metaparse/token.hpp>
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#include <boost/metaparse/sequence.hpp>
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#include <boost/metaparse/change_error_message.hpp>
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#include <boost/metaparse/start.hpp>
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#include <boost/metaparse/get_message.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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BOOST_METAPARSE_DEFINE_ERROR(age_expected, "Age expected");
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using name_token = token<repeated1<letter>>;
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using age_token = token<change_error_message<int_, age_expected>>;
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using name_age = sequence<name_token, age_token>;
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static_assert(
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std::is_same<
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age_expected,
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get_message<name_age::apply<BOOST_METAPARSE_STRING("Joe "), start>>::type
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>::type::value,
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"the error message should be age_expected when the age is missing"
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);
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[endsect]
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