Add unittests for DiverseStack.

unittests/Basic/CMakeLists.txt

@@ -9,6 +9,7 @@ add_swift_unittest(SwiftBasicTests
   BlotMapVectorTest.cpp
   ClusteredBitVectorTest.cpp
   DemangleTest.cpp
+  DiverseStackTest.cpp
   EditorPlaceholderTest.cpp
   EncodedSequenceTest.cpp
   FileSystemTest.cpp

unittests/Basic/DiverseStackTest.cpp

@@ -0,0 +1,84 @@
+//===--- DiverseStackTest.cpp ---------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+#include "swift/Basic/DiverseStack.h"
+#include "gtest/gtest.h"
+
+using namespace swift;
+
+namespace {
+
+struct ParentType {
+  uint8_t allocatedSize;
+
+public:
+  ParentType(uint8_t allocatedSize) : allocatedSize(allocatedSize) {}
+
+  unsigned allocated_size() const { return allocatedSize; }
+};
+
+struct TwoByteType : ParentType {
+  uint8_t Value;
+
+  TwoByteType(uint8_t Value) : ParentType(sizeof(*this)), Value(Value) {}
+};
+
+struct ThreeByteType : ParentType {
+  uint16_t Value;
+
+  ThreeByteType(uint16_t Value) : ParentType(sizeof(*this)), Value(Value) {}
+};
+
+} // end anonymous namespace
+
+TEST(DiverseStack, MonomorphicPushPop) {
+  DiverseStack<ParentType, 128> Stack;
+
+  EXPECT_TRUE(Stack.empty());
+
+  constexpr size_t TwoByteDataSize = 5;
+  uint8_t InputData[TwoByteDataSize] = {5, 9, 1, 2, 10};
+  for (unsigned i = 0; i < TwoByteDataSize; ++i) {
+    Stack.push<TwoByteType>(TwoByteType(InputData[i]));
+  }
+
+  EXPECT_FALSE(Stack.empty());
+
+  for (int i = TwoByteDataSize - 1; i >= 0; --i) {
+    TwoByteType T = reinterpret_cast<TwoByteType &>(Stack.top());
+    Stack.pop();
+    EXPECT_EQ(T.Value, InputData[i]);
+  }
+
+  EXPECT_TRUE(Stack.empty());
+}
+
+// We test the property here that iterating forward through the stack iterates
+// in stack order. This is a bit counter-intuitive for people used to vector
+// stacks.
+TEST(DiverseStack, Iterate) {
+  DiverseStack<ParentType, 128> Stack;
+
+  constexpr size_t TwoByteDataSize = 5;
+  uint8_t InputData[TwoByteDataSize] = {5, 9, 1, 2, 10};
+  for (unsigned i = 0; i < TwoByteDataSize; ++i) {
+    Stack.push<TwoByteType>(TwoByteType(InputData[i]));
+  }
+
+  const uint8_t *Ptr = &InputData[TwoByteDataSize - 1];
+  for (auto II = Stack.begin(), IE = Stack.end(); II != IE;) {
+    TwoByteType T = reinterpret_cast<TwoByteType &>(*II);
+    EXPECT_EQ(T.Value, *Ptr);
+    --Ptr;
+    ++II;
+  }
+}