71 lines
1.5 KiB
Plaintext
71 lines
1.5 KiB
Plaintext
[#get_prev_char]
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[section get_prev_char]
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[h1 Synopsis]
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template <class SourcePosition>
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struct get_prev_char;
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This is a [link lazy_metafunction lazy template metafunction].
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[table Arguments
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[[Name] [Type]]
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[[`SourcePosition`] [[link source_position source position]]]
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]
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[h1 Description]
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Returns the last character the source position was updated with. The value it
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returns for [link start `start`] is unspecified.
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[h1 Header]
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#include <boost/metaparse/get_prev_char.hpp>
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[h1 Expression semantics]
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For any `l`, `c` compile-time wrapped integral values and `ch` compile-time
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wrapped character the following are equivalent
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get_prev_char<source_position<l, c, ch>>::type
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ch::type
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[h1 Example]
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#include <boost/metaparse/get_prev_char.hpp>
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#include <boost/metaparse/source_position.hpp>
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#include <type_traits>
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using namespace boost::metaparse;
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struct returns_source_position
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{
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using type =
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source_position<
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std::integral_constant<int, 11>,
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std::integral_constant<int, 13>,
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std::integral_constant<char, 'x'>
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>;
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};
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static_assert(
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get_prev_char<
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source_position<
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std::integral_constant<int, 11>,
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std::integral_constant<int, 13>,
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std::integral_constant<char, 'x'>
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>
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>::type::value == 'x',
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"It should return the prev. char of a source position"
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);
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static_assert(
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get_prev_char<returns_source_position>::type::value == 'x',
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"It should support lazy evaluation"
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);
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[endsect]
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