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