add

TinySTL/Test/TypeTraitsTest.cpp

+#include "TypeTraitsTest.h"
+#include <cassert>
+
+namespace TinySTL{
+	namespace TypeTraitsTest{
+		void testCase1(){
+		}
+
+		void testAllCases(){
+			testCase1();
+		}
+	}
+}
\ No newline at end of file

TinySTL/Test/TypeTraitsTest.h

+#ifndef _TYPE_TRAITS_TEST_H_
+#define _TYPE_TRAITS_TEST_H_
+
+#include "../TypeTraits.h"
+
+namespace TinySTL{
+	namespace TypeTraitsTest{
+		void testAllCases();
+	}
+}
+
+#endif
\ No newline at end of file

TinySTL/TinySTL.vcxproj

@@ -103,6 +103,7 @@
     <ClCompile Include="Test\StringTest.cpp" />
     <ClCompile Include="Test\SuffixArrayTest.cpp" />
     <ClCompile Include="Test\TrieTreeTest.cpp" />
+    <ClCompile Include="Test\TypeTraitsTest.cpp" />
     <ClCompile Include="Test\UFSetTest.cpp" />
     <ClCompile Include="Test\UniquePtrTest.cpp" />
     <ClCompile Include="Test\Unordered_setTest.cpp" />
@@ -160,6 +161,7 @@
     <ClInclude Include="Test\SuffixArrayTest.h" />
     <ClInclude Include="Test\TestUtil.h" />
     <ClInclude Include="Test\TrieTreeTest.h" />
+    <ClInclude Include="Test\TypeTraitsTest.h" />
     <ClInclude Include="Test\UFSetTest.h" />
     <ClInclude Include="Test\UniquePtrTest.h" />
     <ClInclude Include="Test\Unordered_setTest.h" />

TinySTL/TinySTL.vcxproj.filters

@@ -111,6 +111,9 @@
     <ClCompile Include="Test\UFSetTest.cpp">
       <Filter>Test</Filter>
     </ClCompile>
+    <ClCompile Include="Test\TypeTraitsTest.cpp">
+      <Filter>Test</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="TypeTraits.h">
@@ -299,6 +302,9 @@
     <ClInclude Include="UFSet.h">
       <Filter>头文件</Filter>
     </ClInclude>
+    <ClInclude Include="Test\TypeTraitsTest.h">
+      <Filter>Test</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <None Include="..\README.md" />

TinySTL/TypeTraits.h

@@ -3,6 +3,19 @@
 
 namespace TinySTL{
 
+	namespace{
+		template<bool, class Ta, class Tb>
+		struct IfThenElse;
+		template<class Ta, class Tb>
+		struct IfThenElse < true, Ta, Tb > {
+			using result = Ta;
+		};
+		template<class Ta, class Tb>
+		struct IfThenElse < false, Ta, Tb > {
+			using result = Tb;
+		};
+	}
+
 	struct _true_type { };
 	struct _false_type { };
 
@@ -236,6 +249,6 @@ namespace TinySTL{
 		typedef _true_type		has_trivial_destructor;
 		typedef _true_type		is_POD_type;
 	};
-}
 
+}
 #endif
\ No newline at end of file

TinySTL/main.cpp

@@ -21,6 +21,7 @@
 #include "Test\StringTest.h"
 #include "Test\SuffixArrayTest.h"
 #include "Test\TrieTreeTest.h"
+#include "Test\TypeTraitsTest.h"
 #include "Test\UFSetTest.h"
 #include "Test\UniquePtrTest.h"
 #include "Test\Unordered_setTest.h"
@@ -47,6 +48,7 @@ int main(){
 	TinySTL::StringTest::testAllCases();
 	TinySTL::SuffixArrayTest::testAllCases();
 	TinySTL::TrieTreeTest::testAllCases();
+	TinySTL::TypeTraitsTest::testAllCases();
 	TinySTL::UFSetTest::testAllCases();
 	TinySTL::UniquePtrTest::testAllCases();
 	TinySTL::Unordered_setTest::testAllCases();