Add C++11 compatible base::hash function object.

test/unittests/base/functional-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/functional.h"
+
+#include <limits>
+#include <set>
+
+#include "test/unittests/test-utils.h"
+
+namespace v8 {
+namespace base {
+
+TEST(FunctionalTest, HashBool) {
+  hash<bool> h, h1, h2;
+  EXPECT_EQ(h1(true), h2(true));
+  EXPECT_EQ(h1(false), h2(false));
+  EXPECT_NE(h(true), h(false));
+}
+
+
+TEST(FunctionalTest, HashFloatZero) {
+  hash<float> h;
+  EXPECT_EQ(h(0.0f), h(-0.0f));
+}
+
+
+TEST(FunctionalTest, HashDoubleZero) {
+  hash<double> h;
+  EXPECT_EQ(h(0.0), h(-0.0));
+}
+
+
+template <typename T>
+class FunctionalTest : public TestWithRandomNumberGenerator {};
+
+typedef ::testing::Types<signed char, unsigned char,
+                         short,                    // NOLINT(runtime/int)
+                         unsigned short,           // NOLINT(runtime/int)
+                         int, unsigned int, long,  // NOLINT(runtime/int)
+                         unsigned long,            // NOLINT(runtime/int)
+                         long long,                // NOLINT(runtime/int)
+                         unsigned long long,       // NOLINT(runtime/int)
+                         int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t,
+                         int64_t, uint64_t, float, double> FunctionalTypes;
+
+TYPED_TEST_CASE(FunctionalTest, FunctionalTypes);
+
+
+TYPED_TEST(FunctionalTest, EqualToImpliesSameHashCode) {
+  hash<TypeParam> h;
+  std::equal_to<TypeParam> e;
+  TypeParam values[32];
+  this->rng()->NextBytes(values, sizeof(values));
+  TRACED_FOREACH(TypeParam, v1, values) {
+    TRACED_FOREACH(TypeParam, v2, values) {
+      if (e(v1, v2)) EXPECT_EQ(h(v1), h(v2));
+    }
+  }
+}
+
+
+TYPED_TEST(FunctionalTest, HashEqualsHashValue) {
+  for (int i = 0; i < 128; ++i) {
+    TypeParam v;
+    this->rng()->NextBytes(&v, sizeof(v));
+    hash<TypeParam> h;
+    EXPECT_EQ(h(v), hash_value(v));
+  }
+}
+
+
+TYPED_TEST(FunctionalTest, HashIsStateless) {
+  hash<TypeParam> h1, h2;
+  for (int i = 0; i < 128; ++i) {
+    TypeParam v;
+    this->rng()->NextBytes(&v, sizeof(v));
+    EXPECT_EQ(h1(v), h2(v));
+  }
+}
+
+
+TYPED_TEST(FunctionalTest, HashIsOkish) {
+  const size_t kValues = 128;
+  const size_t kMinHashes = kValues / (sizeof(uint64_t) / sizeof(size_t));
+  std::set<TypeParam> vs;
+  while (vs.size() != kValues) {
+    TypeParam v;
+    this->rng()->NextBytes(&v, sizeof(v));
+    vs.insert(v);
+  }
+  std::set<size_t> hs;
+  for (const auto& v : vs) {
+    hash<TypeParam> h;
+    hs.insert(h(v));
+  }
+  EXPECT_LE(kMinHashes, hs.size());
+}
+
+
+namespace {
+
+struct Foo {
+  int x;
+  double y;
+};
+
+
+size_t hash_value(Foo const& v) { return hash_combine(v.x, v.y); }
+
+}  // namespace
+
+
+TEST(FunctionalTest, HashUsesArgumentDependentLookup) {
+  const int kIntValues[] = {std::numeric_limits<int>::min(), -1, 0, 1, 42,
+                            std::numeric_limits<int>::max()};
+  const double kDoubleValues[] = {
+      std::numeric_limits<double>::min(), -1, -0, 0, 1,
+      std::numeric_limits<double>::max()};
+  TRACED_FOREACH(int, x, kIntValues) {
+    TRACED_FOREACH(double, y, kDoubleValues) {
+      hash<Foo> h;
+      Foo foo = {x, y};
+      EXPECT_EQ(hash_combine(x, y), h(foo));
+    }
+  }
+}
+
+}  // namespace base
+}  // namespace v8