Add Flags<T> class as a type-safe way of storing OR-combinations of enums.

test/base-unittests/flags-unittest.cc

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/base/flags.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace v8 {
+namespace base {
+
+namespace {
+
+enum Flag1 {
+  kFlag1None = 0,
+  kFlag1First = 1u << 1,
+  kFlag1Second = 1u << 2,
+  kFlag1All = kFlag1None | kFlag1First | kFlag1Second
+};
+DEFINE_FLAGS(Flags1, Flag1);
+
+
+DEFINE_OPERATORS_FOR_FLAGS(Flags1)
+
+
+Flags1 bar(Flags1 flags1) { return flags1; }
+
+}  // namespace
+
+
+TEST(FlagsTest, BasicOperations) {
+  Flags1 a;
+  EXPECT_EQ(kFlag1None, static_cast<int>(a));
+  a |= kFlag1First;
+  EXPECT_EQ(kFlag1First, static_cast<int>(a));
+  a = a | kFlag1Second;
+  EXPECT_EQ(kFlag1All, static_cast<int>(a));
+  a &= kFlag1Second;
+  EXPECT_EQ(kFlag1Second, static_cast<int>(a));
+  a = kFlag1None & a;
+  EXPECT_EQ(kFlag1None, static_cast<int>(a));
+  a ^= (kFlag1All | kFlag1None);
+  EXPECT_EQ(kFlag1All, static_cast<int>(a));
+  Flags1 b = ~a;
+  EXPECT_EQ(kFlag1All, static_cast<int>(a));
+  EXPECT_EQ(~static_cast<int>(a), static_cast<int>(b));
+  Flags1 c = a;
+  EXPECT_EQ(a, c);
+  EXPECT_NE(a, b);
+  EXPECT_EQ(a, bar(a));
+  EXPECT_EQ(a, bar(kFlag1All));
+}
+
+
+namespace {
+namespace foo {
+
+enum Option {
+  kNoOptions = 0,
+  kOption1 = 1,
+  kOption2 = 2,
+  kAllOptions = kNoOptions | kOption1 | kOption2
+};
+DEFINE_FLAGS(Options, Option);
+
+}  // namespace foo
+
+
+DEFINE_OPERATORS_FOR_FLAGS(foo::Options)
+
+}  // namespace
+
+
+TEST(FlagsTest, NamespaceScope) {
+  foo::Options options;
+  options ^= foo::kNoOptions;
+  options |= foo::kOption1 | foo::kOption2;
+  EXPECT_EQ(foo::kAllOptions, static_cast<int>(options));
+}
+
+
+namespace {
+
+struct Foo {
+  enum Enum { kEnum1 = 1, kEnum2 = 2 };
+  DEFINE_FLAGS(Enums, Enum);
+};
+
+
+DEFINE_OPERATORS_FOR_FLAGS(Foo::Enums)
+
+}  // namespace
+
+
+TEST(FlagsTest, ClassScope) {
+  Foo::Enums enums;
+  enums |= Foo::kEnum1;
+  enums |= Foo::kEnum2;
+  EXPECT_TRUE(enums & Foo::kEnum1);
+  EXPECT_TRUE(enums & Foo::kEnum2);
+}
+
+}  // namespace base
+}  // namespace v8