about summary refs log blame commit diff
path: root/absl/hash/hash_test.cc
blob: 7b6fb2e7ac1cb0931c5e6b9833def64eace2ac77 (plain) (tree)
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
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425








































































































































































































































































































































































































































                                                                                     
// 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
//
//      http://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/hash/hash.h"

#include <array>
#include <cstring>
#include <deque>
#include <forward_list>
#include <functional>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <random>
#include <set>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <utility>
#include <vector>

#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/container/flat_hash_set.h"
#include "absl/hash/hash_testing.h"
#include "absl/hash/internal/spy_hash_state.h"
#include "absl/meta/type_traits.h"
#include "absl/numeric/int128.h"

namespace {

using absl::Hash;
using absl::hash_internal::SpyHashState;

template <typename T>
class HashValueIntTest : public testing::Test {
};
TYPED_TEST_CASE_P(HashValueIntTest);

template <typename T>
SpyHashState SpyHash(const T& value) {
  return SpyHashState::combine(SpyHashState(), value);
}

// Helper trait to verify if T is hashable. We use absl::Hash's poison status to
// detect it.
template <typename T>
using is_hashable = std::is_default_constructible<absl::Hash<T>>;

TYPED_TEST_P(HashValueIntTest, BasicUsage) {
  EXPECT_TRUE((is_hashable<TypeParam>::value));

  TypeParam n = 42;
  EXPECT_EQ(SpyHash(n), SpyHash(TypeParam{42}));
  EXPECT_NE(SpyHash(n), SpyHash(TypeParam{0}));
  EXPECT_NE(SpyHash(std::numeric_limits<TypeParam>::max()),
            SpyHash(std::numeric_limits<TypeParam>::min()));
}

TYPED_TEST_P(HashValueIntTest, FastPath) {
  // Test the fast-path to make sure the values are the same.
  TypeParam n = 42;
  EXPECT_EQ(absl::Hash<TypeParam>{}(n),
            absl::Hash<std::tuple<TypeParam>>{}(std::tuple<TypeParam>(n)));
}

REGISTER_TYPED_TEST_CASE_P(HashValueIntTest, BasicUsage, FastPath);
using IntTypes = testing::Types<unsigned char, char, int, int32_t, int64_t, uint32_t,
                                uint64_t, size_t>;
INSTANTIATE_TYPED_TEST_CASE_P(My, HashValueIntTest, IntTypes);

template <typename T, typename = void>
struct IsHashCallble : std::false_type {};

template <typename T>
struct IsHashCallble<T, absl::void_t<decltype(std::declval<absl::Hash<T>>()(
                            std::declval<const T&>()))>> : std::true_type {};

template <typename T, typename = void>
struct IsAggregateInitializable : std::false_type {};

template <typename T>
struct IsAggregateInitializable<T, absl::void_t<decltype(T{})>>
    : std::true_type {};

TEST(IsHashableTest, ValidHash) {
  EXPECT_TRUE((is_hashable<int>::value));
  EXPECT_TRUE(std::is_default_constructible<absl::Hash<int>>::value);
  EXPECT_TRUE(std::is_copy_constructible<absl::Hash<int>>::value);
  EXPECT_TRUE(std::is_move_constructible<absl::Hash<int>>::value);
  EXPECT_TRUE(absl::is_copy_assignable<absl::Hash<int>>::value);
  EXPECT_TRUE(absl::is_move_assignable<absl::Hash<int>>::value);
  EXPECT_TRUE(IsHashCallble<int>::value);
  EXPECT_TRUE(IsAggregateInitializable<absl::Hash<int>>::value);
}
#if ABSL_HASH_INTERNAL_CAN_POISON_ && !defined(__APPLE__)
TEST(IsHashableTest, PoisonHash) {
  struct X {};
  EXPECT_FALSE((is_hashable<X>::value));
  EXPECT_FALSE(std::is_default_constructible<absl::Hash<X>>::value);
  EXPECT_FALSE(std::is_copy_constructible<absl::Hash<X>>::value);
  EXPECT_FALSE(std::is_move_constructible<absl::Hash<X>>::value);
  EXPECT_FALSE(absl::is_copy_assignable<absl::Hash<X>>::value);
  EXPECT_FALSE(absl::is_move_assignable<absl::Hash<X>>::value);
  EXPECT_FALSE(IsHashCallble<X>::value);
  EXPECT_FALSE(IsAggregateInitializable<absl::Hash<X>>::value);
}
#endif  // ABSL_HASH_INTERNAL_CAN_POISON_

// Hashable types
//
// These types exist simply to exercise various AbslHashValue behaviors, so
// they are named by what their AbslHashValue overload does.
struct NoOp {
  template <typename HashCode>
  friend HashCode AbslHashValue(HashCode h, NoOp n) {
    return std::move(h);
  }
};

struct EmptyCombine {
  template <typename HashCode>
  friend HashCode AbslHashValue(HashCode h, EmptyCombine e) {
    return HashCode::combine(std::move(h));
  }
};

template <typename Int>
struct CombineIterative {
  template <typename HashCode>
  friend HashCode AbslHashValue(HashCode h, CombineIterative c) {
    for (int i = 0; i < 5; ++i) {
      h = HashCode::combine(std::move(h), Int(i));
    }
    return h;
  }
};

template <typename Int>
struct CombineVariadic {
  template <typename HashCode>
  friend HashCode AbslHashValue(HashCode h, CombineVariadic c) {
    return HashCode::combine(std::move(h), Int(0), Int(1), Int(2), Int(3),
                             Int(4));
  }
};

using InvokeTag = absl::hash_internal::InvokeHashTag;
template <InvokeTag T>
using InvokeTagConstant = std::integral_constant<InvokeTag, T>;

template <InvokeTag... Tags>
struct MinTag;

template <InvokeTag a, InvokeTag b, InvokeTag... Tags>
struct MinTag<a, b, Tags...> : MinTag<(a < b ? a : b), Tags...> {};

template <InvokeTag a>
struct MinTag<a> : InvokeTagConstant<a> {};

template <InvokeTag... Tags>
struct CustomHashType {
  size_t value;
};

template <InvokeTag allowed, InvokeTag... tags>
struct EnableIfContained
    : std::enable_if<absl::disjunction<
          std::integral_constant<bool, allowed == tags>...>::value> {};

template <
    typename H, InvokeTag... Tags,
    typename = typename EnableIfContained<InvokeTag::kHashValue, Tags...>::type>
H AbslHashValue(H state, CustomHashType<Tags...> t) {
  static_assert(MinTag<Tags...>::value == InvokeTag::kHashValue, "");
  return H::combine(std::move(state),
                    t.value + static_cast<int>(InvokeTag::kHashValue));
}

}  // namespace

namespace absl {
namespace hash_internal {
template <InvokeTag... Tags>
struct is_uniquely_represented<
    CustomHashType<Tags...>,
    typename EnableIfContained<InvokeTag::kUniquelyRepresented, Tags...>::type>
    : std::true_type {};
}  // namespace hash_internal
}  // namespace absl

#if ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
namespace ABSL_INTERNAL_LEGACY_HASH_NAMESPACE {
template <InvokeTag... Tags>
struct hash<CustomHashType<Tags...>> {
  template <InvokeTag... TagsIn, typename = typename EnableIfContained<
                                     InvokeTag::kLegacyHash, TagsIn...>::type>
  size_t operator()(CustomHashType<TagsIn...> t) const {
    static_assert(MinTag<Tags...>::value == InvokeTag::kLegacyHash, "");
    return t.value + static_cast<int>(InvokeTag::kLegacyHash);
  }
};
}  // namespace ABSL_INTERNAL_LEGACY_HASH_NAMESPACE
#endif  // ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_

namespace std {
template <InvokeTag... Tags>  // NOLINT
struct hash<CustomHashType<Tags...>> {
  template <InvokeTag... TagsIn, typename = typename EnableIfContained<
                                     InvokeTag::kStdHash, TagsIn...>::type>
  size_t operator()(CustomHashType<TagsIn...> t) const {
    static_assert(MinTag<Tags...>::value == InvokeTag::kStdHash, "");
    return t.value + static_cast<int>(InvokeTag::kStdHash);
  }
};
}  // namespace std

namespace {

template <typename... T>
void TestCustomHashType(InvokeTagConstant<InvokeTag::kNone>, T...) {
  using type = CustomHashType<T::value...>;
  SCOPED_TRACE(testing::PrintToString(std::vector<InvokeTag>{T::value...}));
  EXPECT_TRUE(is_hashable<type>());
  EXPECT_TRUE(is_hashable<const type>());
  EXPECT_TRUE(is_hashable<const type&>());

  const size_t offset = static_cast<int>(std::min({T::value...}));
  EXPECT_EQ(SpyHash(type{7}), SpyHash(size_t{7 + offset}));
}

void TestCustomHashType(InvokeTagConstant<InvokeTag::kNone>) {
#if ABSL_HASH_INTERNAL_CAN_POISON_
  // is_hashable is false if we don't support any of the hooks.
  using type = CustomHashType<>;
  EXPECT_FALSE(is_hashable<type>());
  EXPECT_FALSE(is_hashable<const type>());
  EXPECT_FALSE(is_hashable<const type&>());
#endif  // ABSL_HASH_INTERNAL_CAN_POISON_
}

template <InvokeTag Tag, typename... T>
void TestCustomHashType(InvokeTagConstant<Tag> tag, T... t) {
  constexpr auto next = static_cast<InvokeTag>(static_cast<int>(Tag) + 1);
  TestCustomHashType(InvokeTagConstant<next>(), tag, t...);
  TestCustomHashType(InvokeTagConstant<next>(), t...);
}

TEST(HashTest, CustomHashType) {
  TestCustomHashType(InvokeTagConstant<InvokeTag{}>());
}

TEST(HashTest, NoOpsAreEquivalent) {
  EXPECT_EQ(Hash<NoOp>()({}), Hash<NoOp>()({}));
  EXPECT_EQ(Hash<NoOp>()({}), Hash<EmptyCombine>()({}));
}

template <typename T>
class HashIntTest : public testing::Test {
};
TYPED_TEST_CASE_P(HashIntTest);

TYPED_TEST_P(HashIntTest, BasicUsage) {
  EXPECT_NE(Hash<NoOp>()({}), Hash<TypeParam>()(0));
  EXPECT_NE(Hash<NoOp>()({}),
            Hash<TypeParam>()(std::numeric_limits<TypeParam>::max()));
  if (std::numeric_limits<TypeParam>::min() != 0) {
    EXPECT_NE(Hash<NoOp>()({}),
              Hash<TypeParam>()(std::numeric_limits<TypeParam>::min()));
  }

  EXPECT_EQ(Hash<CombineIterative<TypeParam>>()({}),
            Hash<CombineVariadic<TypeParam>>()({}));
}

REGISTER_TYPED_TEST_CASE_P(HashIntTest, BasicUsage);
using IntTypes = testing::Types<unsigned char, char, int, int32_t, int64_t, uint32_t,
                                uint64_t, size_t>;
INSTANTIATE_TYPED_TEST_CASE_P(My, HashIntTest, IntTypes);

struct StructWithPadding {
  char c;
  int i;

  template <typename H>
  friend H AbslHashValue(H hash_state, const StructWithPadding& s) {
    return H::combine(std::move(hash_state), s.c, s.i);
  }
};

static_assert(sizeof(StructWithPadding) > sizeof(char) + sizeof(int),
              "StructWithPadding doesn't have padding");
static_assert(std::is_standard_layout<StructWithPadding>::value, "");

// This check has to be disabled because libstdc++ doesn't support it.
// static_assert(std::is_trivially_constructible<StructWithPadding>::value, "");

template <typename T>
struct ArraySlice {
  T* begin;
  T* end;

  template <typename H>
  friend H AbslHashValue(H hash_state, const ArraySlice& slice) {
    for (auto t = slice.begin; t != slice.end; ++t) {
      hash_state = H::combine(std::move(hash_state), *t);
    }
    return hash_state;
  }
};

TEST(HashTest, HashNonUniquelyRepresentedType) {
  // Create equal StructWithPadding objects that are known to have non-equal
  // padding bytes.
  static const size_t kNumStructs = 10;
  unsigned char buffer1[kNumStructs * sizeof(StructWithPadding)];
  std::memset(buffer1, 0, sizeof(buffer1));
  auto* s1 = reinterpret_cast<StructWithPadding*>(buffer1);

  unsigned char buffer2[kNumStructs * sizeof(StructWithPadding)];
  std::memset(buffer2, 255, sizeof(buffer2));
  auto* s2 = reinterpret_cast<StructWithPadding*>(buffer2);
  for (int i = 0; i < kNumStructs; ++i) {
    SCOPED_TRACE(i);
    s1[i].c = s2[i].c = '0' + i;
    s1[i].i = s2[i].i = i;
    ASSERT_FALSE(memcmp(buffer1 + i * sizeof(StructWithPadding),
                        buffer2 + i * sizeof(StructWithPadding),
                        sizeof(StructWithPadding)) == 0)
        << "Bug in test code: objects do not have unequal"
        << " object representations";
  }

  EXPECT_EQ(Hash<StructWithPadding>()(s1[0]), Hash<StructWithPadding>()(s2[0]));
  EXPECT_EQ(Hash<ArraySlice<StructWithPadding>>()({s1, s1 + kNumStructs}),
            Hash<ArraySlice<StructWithPadding>>()({s2, s2 + kNumStructs}));
}

TEST(HashTest, StandardHashContainerUsage) {
  std::unordered_map<int, std::string, Hash<int>> map = {{0, "foo"}, { 42, "bar" }};

  EXPECT_NE(map.find(0), map.end());
  EXPECT_EQ(map.find(1), map.end());
  EXPECT_NE(map.find(0u), map.end());
}

struct ConvertibleFromNoOp {
  ConvertibleFromNoOp(NoOp) {}  // NOLINT(runtime/explicit)

  template <typename H>
  friend H AbslHashValue(H hash_state, ConvertibleFromNoOp) {
    return H::combine(std::move(hash_state), 1);
  }
};

TEST(HashTest, HeterogeneousCall) {
  EXPECT_NE(Hash<ConvertibleFromNoOp>()(NoOp()),
            Hash<NoOp>()(NoOp()));
}

TEST(IsUniquelyRepresentedTest, SanityTest) {
  using absl::hash_internal::is_uniquely_represented;

  EXPECT_TRUE(is_uniquely_represented<unsigned char>::value);
  EXPECT_TRUE(is_uniquely_represented<int>::value);
  EXPECT_FALSE(is_uniquely_represented<bool>::value);
  EXPECT_FALSE(is_uniquely_represented<int*>::value);
}

struct IntAndString {
  int i;
  std::string s;

  template <typename H>
  friend H AbslHashValue(H hash_state, IntAndString int_and_string) {
    return H::combine(std::move(hash_state), int_and_string.s,
                      int_and_string.i);
  }
};

TEST(HashTest, SmallValueOn64ByteBoundary) {
  Hash<IntAndString>()(IntAndString{0, std::string(63, '0')});
}

struct TypeErased {
  size_t n;

  template <typename H>
  friend H AbslHashValue(H hash_state, const TypeErased& v) {
    v.HashValue(absl::HashState::Create(&hash_state));
    return hash_state;
  }

  void HashValue(absl::HashState state) const {
    absl::HashState::combine(std::move(state), n);
  }
};

TEST(HashTest, TypeErased) {
  EXPECT_TRUE((is_hashable<TypeErased>::value));
  EXPECT_TRUE((is_hashable<std::pair<TypeErased, int>>::value));

  EXPECT_EQ(SpyHash(TypeErased{7}), SpyHash(size_t{7}));
  EXPECT_NE(SpyHash(TypeErased{7}), SpyHash(size_t{13}));

  EXPECT_EQ(SpyHash(std::make_pair(TypeErased{7}, 17)),
            SpyHash(std::make_pair(size_t{7}, 17)));
}

}  // namespace