about summary refs log tree commit diff
path: root/absl/container/internal/hash_function_defaults_test.cc
blob: 2d05a0b72a0da1acc409ace080818e467162ac36 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "absl/container/internal/hash_function_defaults.h"

#include <functional>
#include <type_traits>
#include <utility>

#include "gtest/gtest.h"
#include "absl/random/random.h"
#include "absl/strings/cord.h"
#include "absl/strings/cord_test_helpers.h"
#include "absl/strings/string_view.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace container_internal {
namespace {

using ::testing::Types;

TEST(Eq, Int32) {
  hash_default_eq<int32_t> eq;
  EXPECT_TRUE(eq(1, 1u));
  EXPECT_TRUE(eq(1, char{1}));
  EXPECT_TRUE(eq(1, true));
  EXPECT_TRUE(eq(1, double{1.1}));
  EXPECT_FALSE(eq(1, char{2}));
  EXPECT_FALSE(eq(1, 2u));
  EXPECT_FALSE(eq(1, false));
  EXPECT_FALSE(eq(1, 2.));
}

TEST(Hash, Int32) {
  hash_default_hash<int32_t> hash;
  auto h = hash(1);
  EXPECT_EQ(h, hash(1u));
  EXPECT_EQ(h, hash(char{1}));
  EXPECT_EQ(h, hash(true));
  EXPECT_EQ(h, hash(double{1.1}));
  EXPECT_NE(h, hash(2u));
  EXPECT_NE(h, hash(char{2}));
  EXPECT_NE(h, hash(false));
  EXPECT_NE(h, hash(2.));
}

enum class MyEnum { A, B, C, D };

TEST(Eq, Enum) {
  hash_default_eq<MyEnum> eq;
  EXPECT_TRUE(eq(MyEnum::A, MyEnum::A));
  EXPECT_FALSE(eq(MyEnum::A, MyEnum::B));
}

TEST(Hash, Enum) {
  hash_default_hash<MyEnum> hash;

  for (MyEnum e : {MyEnum::A, MyEnum::B, MyEnum::C}) {
    auto h = hash(e);
    EXPECT_EQ(h, hash_default_hash<int>{}(static_cast<int>(e)));
    EXPECT_NE(h, hash(MyEnum::D));
  }
}

using StringTypes = ::testing::Types<std::string, absl::string_view>;

template <class T>
struct EqString : ::testing::Test {
  hash_default_eq<T> key_eq;
};

TYPED_TEST_SUITE(EqString, StringTypes);

template <class T>
struct HashString : ::testing::Test {
  hash_default_hash<T> hasher;
};

TYPED_TEST_SUITE(HashString, StringTypes);

TYPED_TEST(EqString, Works) {
  auto eq = this->key_eq;
  EXPECT_TRUE(eq("a", "a"));
  EXPECT_TRUE(eq("a", absl::string_view("a")));
  EXPECT_TRUE(eq("a", std::string("a")));
  EXPECT_FALSE(eq("a", "b"));
  EXPECT_FALSE(eq("a", absl::string_view("b")));
  EXPECT_FALSE(eq("a", std::string("b")));
}

TYPED_TEST(HashString, Works) {
  auto hash = this->hasher;
  auto h = hash("a");
  EXPECT_EQ(h, hash(absl::string_view("a")));
  EXPECT_EQ(h, hash(std::string("a")));
  EXPECT_NE(h, hash(absl::string_view("b")));
  EXPECT_NE(h, hash(std::string("b")));
}

struct NoDeleter {
  template <class T>
  void operator()(const T* ptr) const {}
};

using PointerTypes =
    ::testing::Types<const int*, int*, std::unique_ptr<const int>,
                     std::unique_ptr<const int, NoDeleter>,
                     std::unique_ptr<int>, std::unique_ptr<int, NoDeleter>,
                     std::shared_ptr<const int>, std::shared_ptr<int>>;

template <class T>
struct EqPointer : ::testing::Test {
  hash_default_eq<T> key_eq;
};

TYPED_TEST_SUITE(EqPointer, PointerTypes);

template <class T>
struct HashPointer : ::testing::Test {
  hash_default_hash<T> hasher;
};

TYPED_TEST_SUITE(HashPointer, PointerTypes);

TYPED_TEST(EqPointer, Works) {
  int dummy;
  auto eq = this->key_eq;
  auto sptr = std::make_shared<int>();
  std::shared_ptr<const int> csptr = sptr;
  int* ptr = sptr.get();
  const int* cptr = ptr;
  std::unique_ptr<int, NoDeleter> uptr(ptr);
  std::unique_ptr<const int, NoDeleter> cuptr(ptr);

  EXPECT_TRUE(eq(ptr, cptr));
  EXPECT_TRUE(eq(ptr, sptr));
  EXPECT_TRUE(eq(ptr, uptr));
  EXPECT_TRUE(eq(ptr, csptr));
  EXPECT_TRUE(eq(ptr, cuptr));
  EXPECT_FALSE(eq(&dummy, cptr));
  EXPECT_FALSE(eq(&dummy, sptr));
  EXPECT_FALSE(eq(&dummy, uptr));
  EXPECT_FALSE(eq(&dummy, csptr));
  EXPECT_FALSE(eq(&dummy, cuptr));
}

TEST(Hash, DerivedAndBase) {
  struct Base {};
  struct Derived : Base {};

  hash_default_hash<Base*> hasher;

  Base base;
  Derived derived;
  EXPECT_NE(hasher(&base), hasher(&derived));
  EXPECT_EQ(hasher(static_cast<Base*>(&derived)), hasher(&derived));

  auto dp = std::make_shared<Derived>();
  EXPECT_EQ(hasher(static_cast<Base*>(dp.get())), hasher(dp));
}

TEST(Hash, FunctionPointer) {
  using Func = int (*)();
  hash_default_hash<Func> hasher;
  hash_default_eq<Func> eq;

  Func p1 = [] { return 1; }, p2 = [] { return 2; };
  EXPECT_EQ(hasher(p1), hasher(p1));
  EXPECT_TRUE(eq(p1, p1));

  EXPECT_NE(hasher(p1), hasher(p2));
  EXPECT_FALSE(eq(p1, p2));
}

TYPED_TEST(HashPointer, Works) {
  int dummy;
  auto hash = this->hasher;
  auto sptr = std::make_shared<int>();
  std::shared_ptr<const int> csptr = sptr;
  int* ptr = sptr.get();
  const int* cptr = ptr;
  std::unique_ptr<int, NoDeleter> uptr(ptr);
  std::unique_ptr<const int, NoDeleter> cuptr(ptr);

  EXPECT_EQ(hash(ptr), hash(cptr));
  EXPECT_EQ(hash(ptr), hash(sptr));
  EXPECT_EQ(hash(ptr), hash(uptr));
  EXPECT_EQ(hash(ptr), hash(csptr));
  EXPECT_EQ(hash(ptr), hash(cuptr));
  EXPECT_NE(hash(&dummy), hash(cptr));
  EXPECT_NE(hash(&dummy), hash(sptr));
  EXPECT_NE(hash(&dummy), hash(uptr));
  EXPECT_NE(hash(&dummy), hash(csptr));
  EXPECT_NE(hash(&dummy), hash(cuptr));
}

TEST(EqCord, Works) {
  hash_default_eq<absl::Cord> eq;
  const absl::string_view a_string_view = "a";
  const absl::Cord a_cord(a_string_view);
  const absl::string_view b_string_view = "b";
  const absl::Cord b_cord(b_string_view);

  EXPECT_TRUE(eq(a_cord, a_cord));
  EXPECT_TRUE(eq(a_cord, a_string_view));
  EXPECT_TRUE(eq(a_string_view, a_cord));
  EXPECT_FALSE(eq(a_cord, b_cord));
  EXPECT_FALSE(eq(a_cord, b_string_view));
  EXPECT_FALSE(eq(b_string_view, a_cord));
}

TEST(HashCord, Works) {
  hash_default_hash<absl::Cord> hash;
  const absl::string_view a_string_view = "a";
  const absl::Cord a_cord(a_string_view);
  const absl::string_view b_string_view = "b";
  const absl::Cord b_cord(b_string_view);

  EXPECT_EQ(hash(a_cord), hash(a_cord));
  EXPECT_EQ(hash(b_cord), hash(b_cord));
  EXPECT_EQ(hash(a_string_view), hash(a_cord));
  EXPECT_EQ(hash(b_string_view), hash(b_cord));
  EXPECT_EQ(hash(absl::Cord("")), hash(""));
  EXPECT_EQ(hash(absl::Cord()), hash(absl::string_view()));

  EXPECT_NE(hash(a_cord), hash(b_cord));
  EXPECT_NE(hash(a_cord), hash(b_string_view));
  EXPECT_NE(hash(a_string_view), hash(b_cord));
  EXPECT_NE(hash(a_string_view), hash(b_string_view));
}

void NoOpReleaser(absl::string_view data, void* arg) {}

TEST(HashCord, FragmentedCordWorks) {
  hash_default_hash<absl::Cord> hash;
  absl::Cord c = absl::MakeFragmentedCord({"a", "b", "c"});
  EXPECT_FALSE(c.TryFlat().has_value());
  EXPECT_EQ(hash(c), hash("abc"));
}

TEST(HashCord, FragmentedLongCordWorks) {
  hash_default_hash<absl::Cord> hash;
  // Crete some large strings which do not fit on the stack.
  std::string a(65536, 'a');
  std::string b(65536, 'b');
  absl::Cord c = absl::MakeFragmentedCord({a, b});
  EXPECT_FALSE(c.TryFlat().has_value());
  EXPECT_EQ(hash(c), hash(a + b));
}

TEST(HashCord, RandomCord) {
  hash_default_hash<absl::Cord> hash;
  auto bitgen = absl::BitGen();
  for (int i = 0; i < 1000; ++i) {
    const int number_of_segments = absl::Uniform(bitgen, 0, 10);
    std::vector<std::string> pieces;
    for (size_t s = 0; s < number_of_segments; ++s) {
      std::string str;
      str.resize(absl::Uniform(bitgen, 0, 4096));
      // MSVC needed the explicit return type in the lambda.
      std::generate(str.begin(), str.end(), [&]() -> char {
        return static_cast<char>(absl::Uniform<unsigned char>(bitgen));
      });
      pieces.push_back(str);
    }
    absl::Cord c = absl::MakeFragmentedCord(pieces);
    EXPECT_EQ(hash(c), hash(std::string(c)));
  }
}

// Cartesian product of (std::string, absl::string_view)
// with (std::string, absl::string_view, const char*, absl::Cord).
using StringTypesCartesianProduct = Types<
    // clang-format off
    std::pair<absl::Cord, std::string>,
    std::pair<absl::Cord, absl::string_view>,
    std::pair<absl::Cord, absl::Cord>,
    std::pair<absl::Cord, const char*>,

    std::pair<std::string, absl::Cord>,
    std::pair<absl::string_view, absl::Cord>,

    std::pair<absl::string_view, std::string>,
    std::pair<absl::string_view, absl::string_view>,
    std::pair<absl::string_view, const char*>>;
// clang-format on

constexpr char kFirstString[] = "abc123";
constexpr char kSecondString[] = "ijk456";

template <typename T>
struct StringLikeTest : public ::testing::Test {
  typename T::first_type a1{kFirstString};
  typename T::second_type b1{kFirstString};
  typename T::first_type a2{kSecondString};
  typename T::second_type b2{kSecondString};
  hash_default_eq<typename T::first_type> eq;
  hash_default_hash<typename T::first_type> hash;
};

TYPED_TEST_CASE_P(StringLikeTest);

TYPED_TEST_P(StringLikeTest, Eq) {
  EXPECT_TRUE(this->eq(this->a1, this->b1));
  EXPECT_TRUE(this->eq(this->b1, this->a1));
}

TYPED_TEST_P(StringLikeTest, NotEq) {
  EXPECT_FALSE(this->eq(this->a1, this->b2));
  EXPECT_FALSE(this->eq(this->b2, this->a1));
}

TYPED_TEST_P(StringLikeTest, HashEq) {
  EXPECT_EQ(this->hash(this->a1), this->hash(this->b1));
  EXPECT_EQ(this->hash(this->a2), this->hash(this->b2));
  // It would be a poor hash function which collides on these strings.
  EXPECT_NE(this->hash(this->a1), this->hash(this->b2));
}

TYPED_TEST_SUITE(StringLikeTest, StringTypesCartesianProduct);

}  // namespace
}  // namespace container_internal
ABSL_NAMESPACE_END
}  // namespace absl

enum Hash : size_t {
  kStd = 0x2,       // std::hash
#ifdef _MSC_VER
  kExtension = kStd,  // In MSVC, std::hash == ::hash
#else                 // _MSC_VER
  kExtension = 0x4,  // ::hash (GCC extension)
#endif                // _MSC_VER
};

// H is a bitmask of Hash enumerations.
// Hashable<H> is hashable via all means specified in H.
template <int H>
struct Hashable {
  static constexpr bool HashableBy(Hash h) { return h & H; }
};

namespace std {
template <int H>
struct hash<Hashable<H>> {
  template <class E = Hashable<H>,
            class = typename std::enable_if<E::HashableBy(kStd)>::type>
  size_t operator()(E) const {
    return kStd;
  }
};
}  // namespace std

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace container_internal {
namespace {

template <class T>
size_t Hash(const T& v) {
  return hash_default_hash<T>()(v);
}

TEST(Delegate, HashDispatch) {
  EXPECT_EQ(Hash(kStd), Hash(Hashable<kStd>()));
}

}  // namespace
}  // namespace container_internal
ABSL_NAMESPACE_END
}  // namespace absl