From e1800140dbfcdf44ef74e3bf1c5c78ff18c8f951 Mon Sep 17 00:00:00 2001
From: Jan Travnicek <Jan.Travnicek@fit.cvut.cz>
Date: Fri, 14 Jun 2019 08:41:52 +0200
Subject: [PATCH] add and use constexpr_switch
---
.../src/common/AbstractionHelpers.hpp | 23 +++++-------
alib2std/src/extensions/utility.hpp | 16 ++++++++
alib2std/test-src/extensions/UtilityTest.cpp | 37 +++++++++++++++++++
3 files changed, 62 insertions(+), 14 deletions(-)
diff --git a/alib2abstraction/src/common/AbstractionHelpers.hpp b/alib2abstraction/src/common/AbstractionHelpers.hpp
index 15a7660123..4a86d5dec0 100644
--- a/alib2abstraction/src/common/AbstractionHelpers.hpp
+++ b/alib2abstraction/src/common/AbstractionHelpers.hpp
@@ -35,22 +35,17 @@ constexpr decltype ( auto ) apply ( F && f, Tuple && t ) {
}
template < class ... Params >
-struct CheckInput;
+struct CheckInput {
+ static bool checkInput ( const std::shared_ptr < OperationAbstraction > & operation, unsigned index ) {
+ bool res = false;
-template < >
-struct CheckInput < > {
- static bool checkInput ( const std::shared_ptr < OperationAbstraction > &, unsigned ) {
- throw std::logic_error ( "Out of types to check" );
- }
-};
+ auto lambda = [ & ] ( auto I ) {
+ res = ( bool ) std::dynamic_pointer_cast < std::decay_t < std::tuple_element_t < decltype ( I )::value, std::tuple < Params ... > > > > ( operation->getProxyAbstraction ( ) );
+ };
-template < class Param, class ... Params >
-struct CheckInput < Param, Params ... > {
- static bool checkInput ( const std::shared_ptr < OperationAbstraction > & operation, unsigned index ) {
- if ( index == 0 )
- return ( bool ) std::dynamic_pointer_cast < typename std::decay < Param >::type > ( operation->getProxyAbstraction ( ) );
- else
- return CheckInput < Params ... >::checkInput ( operation, index - 1 );
+ ext::constexpr_switch < sizeof ... ( Params ) > ( index, lambda );
+
+ return res;
}
};
diff --git a/alib2std/src/extensions/utility.hpp b/alib2std/src/extensions/utility.hpp
index 8782eef5fe..689eb23a2b 100644
--- a/alib2std/src/extensions/utility.hpp
+++ b/alib2std/src/extensions/utility.hpp
@@ -51,6 +51,22 @@ inline auto move_copy ( const T & param ) {
}
}
+namespace detail {
+
+template < class F, std::size_t ... Is >
+void constexpr_switch ( const std::size_t i, F && f, std::index_sequence < Is ... > ) {
+ [ ] ( ... ) { } (
+ ( i == Is && ( ( void ) std::forward < F > ( f ) . operator ( ) ( std::integral_constant < size_t, Is > ( ) ), false ) ) ...
+ );
+}
+
+} // namespace detail
+
+template < std::size_t N, class F >
+void constexpr_switch ( const std::size_t i, F && f ) {
+ detail::constexpr_switch ( i, std::forward < F > ( f ), std::make_index_sequence < N > { } );
+}
+
} /* namespace ext */
#endif /* __UTILITY_HPP_ */
diff --git a/alib2std/test-src/extensions/UtilityTest.cpp b/alib2std/test-src/extensions/UtilityTest.cpp
index 866d111496..6a77be3d31 100644
--- a/alib2std/test-src/extensions/UtilityTest.cpp
+++ b/alib2std/test-src/extensions/UtilityTest.cpp
@@ -16,4 +16,41 @@ TEST_CASE ( "Utility", "[unit][std][bits]" ) {
ext::ptr_value < Foo > val ( Foo { } );
CHECK ( val->bar ( ) == 1 );
}
+
+ SECTION ( "Constexp switch" ) {
+ {
+ auto const t = std::make_tuple(42, 'z', 3.14, 13, 0, "Hello, World!");
+
+ auto lambda = [ & ] ( auto I ) {
+ if constexpr ( I == 0 )
+ CHECK ( std::get < decltype ( I )::value > ( t ) == 42 );
+ else if constexpr ( I == 1 )
+ CHECK ( std::get < decltype ( I )::value > ( t ) == 'z' );
+ else if constexpr ( I == 2 )
+ CHECK ( std::get < decltype ( I )::value > ( t ) == 3.14 );
+ else if constexpr ( I == 3 )
+ CHECK ( std::get < decltype ( I )::value > ( t ) == 13 );
+ else if constexpr ( I == 4 )
+ CHECK ( std::get < decltype ( I )::value > ( t ) == 0 );
+ else // constexpr ( I == 5 )
+ CHECK ( std::get < decltype ( I )::value > ( t ) == std::string ( "Hello, World!" ) );
+ };
+
+ for (std::size_t i = 0; i < std::tuple_size<decltype(t)>::value; ++i) {
+ ext::constexpr_switch < std::tuple_size<decltype(t)>::value > ( i, lambda );
+ }
+ }
+
+ {
+ auto const t = std::array<int, 4>{{0,1,2,3}};
+
+ auto lambda = [ & ] ( auto I ) {
+ CHECK ( std::get < decltype ( I )::value > ( t ) == I );
+ };
+
+ for (std::size_t i = 0; i < t.size(); ++i) {
+ ext::constexpr_switch < std::tuple_size<decltype(t)>::value > ( i, lambda );
+ }
+ }
+ }
}
--
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