80 lines
1.7 KiB
Markdown
80 lines
1.7 KiB
Markdown
# t00034 - Template metaprogramming type function test case
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## Config
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```yaml
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compilation_database_dir: ..
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output_directory: puml
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diagrams:
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t00034_class:
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type: class
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glob:
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- ../../tests/t00034/t00034.cc
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using_namespace:
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- clanguml::t00034
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include:
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namespaces:
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- clanguml::t00034
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plantuml:
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after:
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- "@A(R) --> @A(A) : +la"
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```
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## Source code
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File t00034.cc
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```cpp
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#include <type_traits>
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namespace clanguml {
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//
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// Based on https://github.com/facebook/folly/blob/master/folly/Unit.h
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//
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namespace t00034 {
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struct Void {
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constexpr bool operator==(const Void & /* unused */) const { return true; }
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constexpr bool operator!=(const Void & /* unused */) const { return false; }
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};
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constexpr Void void_t{};
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template <typename T> struct lift_void {
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using type = T;
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};
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template <> struct lift_void<void> {
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using type = Void;
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};
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//
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// TODO: This is a shortcoming of libclang which parses the type of lift_void_t
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// alias as unexposed, i.e. no actual reference to T can be inferred without
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// manually parsing the string 'typename lift_void<T>::type'
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// For now, this test validates that the visitor does not crash, the reference
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// between R and A has to be provided in the configuration file
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//
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template <typename T> using lift_void_t = typename lift_void<T>::type;
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template <typename T> struct drop_void {
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using type = T;
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};
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template <> struct drop_void<Void> {
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using type = void;
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};
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template <typename T> using drop_void_t = typename drop_void<T>::type;
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struct A {
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};
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struct R {
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lift_void_t<A> *la;
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lift_void_t<void> *lv;
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};
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} // namespace t00034
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} // namespace clanguml
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```
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## Generated UML diagrams
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