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authorAdrian Kummerlaender2015-02-12 10:16:54 +0100
committerAdrian Kummerlaender2015-02-12 10:16:54 +0100
commitad27a79a2e6bc380e68ec77ae961917a9fb402d3 (patch)
tree7b6f43b9973d9ccae40adeb16f1184d8ea8d8e5b /src/function/detail
parentf1268ca3bf10ab136bafbd63894ce12353fa8690 (diff)
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Revamped partial function application
* moved internals into separate header i.e. the `detail` namespace relating to `Apply` * implemented automatic alias selection by implementing aliae of the basic variadic `type` template alias in different base classes ** variadic partial application is implemented in `detail::apply_variadic` *** `detail::apply_single` and `detail::apply_pair` define aliae to `detail::apply_variadic`'s `type` template alias *** both restricted aliae derive from `detail::apply_variadic` ** `Apply` derives from any of the aliae defining base classes depending on the count of placeholders as determined by `detail::count_placeholders` *** `Apply` is guaranteed to always be derived from `detail::apply_variadic` one way or the other * changed functions, test cases and examples depending on `Apply` accordingly ** `Length` had to be reimplemented without `Apply` as it doesn't allow usage of aliae expecting a different count of arguments anymore *** this is a advantage in the sense that core functionality of _TypeAsValue_ now doesn't depend on this complex partial application implementation anymore *** such functionality may be reimplemented separately from `Apply` * removed unnecessary `tav` namespace prefixes
Diffstat (limited to 'src/function/detail')
-rw-r--r--src/function/detail/apply.h86
1 files changed, 86 insertions, 0 deletions
diff --git a/src/function/detail/apply.h b/src/function/detail/apply.h
new file mode 100644
index 0000000..bf60be1
--- /dev/null
+++ b/src/function/detail/apply.h
@@ -0,0 +1,86 @@
+#ifndef TYPEASVALUE_SRC_FUNCTION_DETAIL_APPLY_H_
+#define TYPEASVALUE_SRC_FUNCTION_DETAIL_APPLY_H_
+
+#include <type_traits>
+
+#include "list/list.h"
+#include "list/operation/nth.h"
+#include "list/operation/higher/query.h"
+
+namespace tav {
+namespace detail {
+
+struct placeholder_tag { };
+
+template <typename Type>
+using is_placeholder = tav::Boolean<
+ std::is_base_of<placeholder_tag, Type>::value
+>;
+
+template <int Index>
+struct placeholder : placeholder_tag { };
+
+template <
+ typename Partials,
+ typename Argument
+>
+struct resolve_placeholder {
+ typedef Argument type;
+};
+
+template <
+ typename Partials,
+ int Index
+>
+struct resolve_placeholder<Partials, placeholder<Index>> {
+ typedef typename Nth<Size<Index>, Partials>::type type;
+};
+
+template <typename... Arguments>
+using count_placeholders = Count<
+ is_placeholder,
+ typename List<Arguments...>::type
+>;
+
+template <
+ template<typename...> class Function,
+ typename... Arguments
+>
+struct apply_variadic {
+ template <typename... Partials>
+ using type = Function<
+ typename resolve_placeholder<
+ typename tav::List<Partials...>::type,
+ Arguments
+ >::type...
+ >;
+};
+
+template <
+ template<typename...> class Function,
+ typename... Arguments
+>
+struct apply_single : apply_variadic<Function, Arguments...> {
+ template <typename Partial0>
+ using type = typename apply_variadic<
+ Function,
+ Arguments...
+ >::template type<Partial0>;
+};
+
+template <
+ template<typename...> class Function,
+ typename... Arguments
+>
+struct apply_pair : apply_variadic<Function, Arguments...> {
+ template <typename Partial0, typename Partial1>
+ using type = typename apply_variadic<
+ Function,
+ Arguments...
+ >::template type<Partial0, Partial1>;
+};
+
+}
+}
+
+#endif // TYPEASVALUE_SRC_FUNCTION_DETAIL_APPLY_H_