[Sync] Rework SharedValue<T> into Immutable<T>

chrome/browser/sync/util/immutable_unittest.cc

+// Copyright (c) 2011 The Chromium 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 "chrome/browser/sync/util/immutable.h"
+
+#include <algorithm>
+#include <cstddef>
+#include <deque>
+#include <list>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace browser_sync {
+
+// Helper class that keeps track of the token passed in at
+// construction and how many times that token is copied.
+class TokenCore : public base::RefCounted<TokenCore> {
+ public:
+  explicit TokenCore(const char* token) : token_(token), copy_count_(0) {}
+
+  const char* GetToken() const { return token_; }
+
+  void RecordCopy() { ++copy_count_; }
+
+  int GetCopyCount() const { return copy_count_; }
+
+ private:
+  friend class base::RefCounted<TokenCore>;
+
+  ~TokenCore() {}
+
+  const char* const token_;
+  int copy_count_;
+};
+
+enum SwapBehavior {
+  USE_DEFAULT_SWAP,
+  USE_FAST_SWAP_VIA_ADL,
+  USE_FAST_SWAP_VIA_SPECIALIZATION
+};
+
+const char kEmptyToken[] = "<empty token>";
+
+// Base class for various token classes, differing in swap behavior.
+template <SwapBehavior>
+class TokenBase {
+ public:
+  TokenBase() : core_(new TokenCore(kEmptyToken)) {}
+
+  explicit TokenBase(const char* token) : core_(new TokenCore(token)) {}
+
+  TokenBase(const TokenBase& other) : core_(other.core_) {
+    core_->RecordCopy();
+  }
+
+  TokenBase& operator=(const TokenBase& other) {
+    core_ = other.core_;
+    core_->RecordCopy();
+    return *this;
+  }
+
+  const char* GetToken() const {
+    return core_->GetToken();
+  }
+
+  int GetCopyCount() const {
+    return core_->GetCopyCount();
+  }
+
+  // For associative containers.
+  bool operator<(const TokenBase& other) const {
+    return std::string(GetToken()) < std::string(other.GetToken());
+  }
+
+  // STL-style swap.
+  void swap(TokenBase& other) {
+    using std::swap;
+    swap(other.core_, core_);
+  }
+
+  // Google-style swap.
+  void Swap(TokenBase* other) {
+    using std::swap;
+    swap(other->core_, core_);
+  }
+
+ private:
+  scoped_refptr<TokenCore> core_;
+};
+
+typedef TokenBase<USE_DEFAULT_SWAP> Token;
+typedef TokenBase<USE_FAST_SWAP_VIA_ADL> ADLToken;
+typedef TokenBase<USE_FAST_SWAP_VIA_SPECIALIZATION> SpecializationToken;
+
+void swap(ADLToken& t1, ADLToken& t2) {
+  t1.Swap(&t2);
+}
+
+}  // namespace browser_sync
+
+// Allowed by the standard (17.4.3.1/1).
+namespace std {
+
+template <>
+void swap(browser_sync::SpecializationToken& t1,
+          browser_sync::SpecializationToken& t2) {
+  t1.Swap(&t2);
+}
+
+}  // namespace
+
+namespace browser_sync {
+namespace {
+
+class ImmutableTest : public ::testing::Test {};
+
+TEST_F(ImmutableTest, Int) {
+  int x = 5;
+  Immutable<int> ix(&x);
+  EXPECT_EQ(5, ix.Get());
+  EXPECT_EQ(0, x);
+}
+
+TEST_F(ImmutableTest, IntCopy) {
+  int x = 5;
+  Immutable<int> ix = Immutable<int>(&x);
+  EXPECT_EQ(5, ix.Get());
+  EXPECT_EQ(0, x);
+}
+
+TEST_F(ImmutableTest, IntAssign) {
+  int x = 5;
+  Immutable<int> ix;
+  EXPECT_EQ(0, ix.Get());
+  ix = Immutable<int>(&x);
+  EXPECT_EQ(5, ix.Get());
+  EXPECT_EQ(0, x);
+}
+
+TEST_F(ImmutableTest, IntMakeImmutable) {
+  int x = 5;
+  Immutable<int> ix = MakeImmutable(&x);
+  EXPECT_EQ(5, ix.Get());
+  EXPECT_EQ(0, x);
+}
+
+template <typename T, typename ImmutableT>
+void RunTokenTest(const char* token, bool expect_copies) {
+  SCOPED_TRACE(token);
+  T t(token);
+  EXPECT_EQ(token, t.GetToken());
+  EXPECT_EQ(0, t.GetCopyCount());
+
+  ImmutableT immutable_t(&t);
+  EXPECT_EQ(token, immutable_t.Get().GetToken());
+  EXPECT_EQ(kEmptyToken, t.GetToken());
+  EXPECT_EQ(expect_copies, immutable_t.Get().GetCopyCount() > 0);
+  EXPECT_EQ(expect_copies, t.GetCopyCount() > 0);
+}
+
+TEST_F(ImmutableTest, Token) {
+  RunTokenTest<Token, Immutable<Token> >("Token", true /* expect_copies */);
+}
+
+TEST_F(ImmutableTest, TokenSwapMemFnByRef) {
+  RunTokenTest<Token, Immutable<Token, HasSwapMemFnByRef<Token> > >(
+      "TokenSwapMemFnByRef", false /* expect_copies */);
+}
+
+TEST_F(ImmutableTest, TokenSwapMemFnByPtr) {
+  RunTokenTest<Token, Immutable<Token, HasSwapMemFnByPtr<Token> > >(
+      "TokenSwapMemFnByPtr", false /* expect_copies */);
+}
+
+TEST_F(ImmutableTest, ADLToken) {
+  RunTokenTest<ADLToken, Immutable<ADLToken> >(
+      "ADLToken", false /* expect_copies */);
+}
+
+TEST_F(ImmutableTest, SpecializationToken) {
+  RunTokenTest<SpecializationToken, Immutable<SpecializationToken> >(
+      "SpecializationToken", false /* expect_copies */);
+}
+
+template <typename C, typename ImmutableC>
+void RunTokenContainerTest(const char* token) {
+  SCOPED_TRACE(token);
+  const Token tokens[] = { Token(), Token(token) };
+  const size_t token_count = arraysize(tokens);
+  C c(tokens, tokens + token_count);
+  const int copy_count = c.begin()->GetCopyCount();
+  EXPECT_GT(copy_count, 0);
+  for (typename C::const_iterator it = c.begin(); it != c.end(); ++it) {
+    EXPECT_EQ(copy_count, it->GetCopyCount());
+  }
+
+  // Make sure making the container immutable doesn't incur any copies

[Nicolas Zea, 2011/09/15 23:39:46]

immutable container?

[akalin, 2011/09/16 00:59:59]

"making the container immutable" sounds fine to me...

+  // of the tokens.
+  ImmutableC immutable_c(&c);
+  EXPECT_TRUE(c.empty());
+  ASSERT_EQ(token_count, immutable_c.Get().size());
+  int i = 0;
+  for (typename C::const_iterator it = c.begin(); it != c.end(); ++it) {
+    EXPECT_EQ(tokens[i].GetToken(), it->GetToken());
+    EXPECT_EQ(copy_count, it->GetCopyCount());
+    ++i;
+  }
+}
+
+TEST_F(ImmutableTest, Vector) {
+  RunTokenContainerTest<std::vector<Token>, Immutable<std::vector<Token> > >(
+      "Vector");
+}
+
+TEST_F(ImmutableTest, VectorSwapMemFnByRef) {
+  RunTokenContainerTest<
+    std::vector<Token>,
+    Immutable<std::vector<Token>, HasSwapMemFnByRef<std::vector<Token> > > >(
+        "VectorSwapMemFnByRef");
+}
+
+TEST_F(ImmutableTest, Deque) {
+  RunTokenContainerTest<std::deque<Token>, Immutable<std::deque<Token> > >(
+      "Deque");
+}
+
+TEST_F(ImmutableTest, List) {
+  RunTokenContainerTest<std::list<Token>, Immutable<std::list<Token> > >(
+      "List");
+}
+
+TEST_F(ImmutableTest, Set) {
+  RunTokenContainerTest<std::set<Token>, Immutable<std::set<Token> > >(
+      "Set");
+}
+
+}  // namespace
+}  // namespace browser_sync