Add an Either<T,U> type to lldb_utility which represents a type-safe payload of either one type or another, à la Haskell

llvm-svn: 242867

Author: Enrico Granata

lldb/include/lldb/Utility/Either.h

@@ -0,0 +1,72 @@
+//===-- Either.h -----------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef liblldb_Either_h_
+#define liblldb_Either_h_
+
+#include "llvm/ADT/Optional.h"
+
+namespace lldb_utility {
+    template <typename T1, typename T2>
+    class Either {
+    private:
+        enum class Selected {
+            One, Two
+        };
+        
+        Selected m_selected;
+        union {
+            T1 m_t1;
+            T2 m_t2;
+        };
+        
+    public:
+        Either(const T1& t1)
+        {
+            m_t1 = t1;
+            m_selected = Selected::One;
+        }
+        
+        Either(const T2& t2)
+        {
+            m_t2 = t2;
+            m_selected = Selected::Two;
+        }
+        
+        template <class X, typename std::enable_if<std::is_same<T1,X>::value>::type * = nullptr >
+        llvm::Optional<T1>
+        GetAs()
+        {
+            switch (m_selected)
+            {
+                case Selected::One:
+                    return m_t1;
+                default:
+                    return llvm::Optional<T1>();
+            }
+        }
+        
+        template <class X, typename std::enable_if<std::is_same<T2,X>::value>::type * = nullptr >
+        llvm::Optional<T2>
+        GetAs()
+        {
+            switch (m_selected)
+            {
+                case Selected::Two:
+                    return m_t2;
+                default:
+                    return llvm::Optional<T2>();
+            }
+        }
+    };
+    
+} // namespace lldb_utility
+
+#endif // #ifndef liblldb_Either_h_
+

lldb/lldb.xcodeproj/project.pbxproj

@@ -2431,6 +2431,7 @@
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 		947A1D621616476A0017C8D1 /* CommandObjectPlugin.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = CommandObjectPlugin.cpp; path = source/Commands/CommandObjectPlugin.cpp; sourceTree = "<group>"; };
 		947A1D631616476A0017C8D1 /* CommandObjectPlugin.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = CommandObjectPlugin.h; path = source/Commands/CommandObjectPlugin.h; sourceTree = "<group>"; };
+		9481FE6B1B5F2D9200DED357 /* Either.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = Either.h; path = include/lldb/Utility/Either.h; sourceTree = "<group>"; };
 		9492E2A41A8AC11000295BBD /* CoreMedia.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = CoreMedia.cpp; path = source/DataFormatters/CoreMedia.cpp; sourceTree = "<group>"; };
 		949ADF001406F62E004833E1 /* ValueObjectConstResultImpl.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = ValueObjectConstResultImpl.h; path = include/lldb/Core/ValueObjectConstResultImpl.h; sourceTree = "<group>"; };
 		949ADF021406F648004833E1 /* ValueObjectConstResultImpl.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = ValueObjectConstResultImpl.cpp; path = source/Core/ValueObjectConstResultImpl.cpp; sourceTree = "<group>"; };
@@ -3532,6 +3533,7 @@
 				264723A511FA076E00DE380C /* CleanUp.h */,
 				3F81691B1ABA242B001DA9DF /* ConvertEnum.h */,
 				3F8169171ABA2419001DA9DF /* ConvertEnum.cpp */,
+				9481FE6B1B5F2D9200DED357 /* Either.h */,
 				4C73152119B7D71700F865A4 /* Iterable.h */,
 				942829541A89614000521B30 /* JSON.h */,
 				942829551A89614C00521B30 /* JSON.cpp */,