v8 147.3.0

Rust bindings to V8
Documentation 
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

// Copyright 2020 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/base/optimization.h"

#include <optional>

#include "gtest/gtest.h"

namespace {

// Tests for the ABSL_PREDICT_TRUE and ABSL_PREDICT_FALSE macros.
// The tests only verify that the macros are functionally correct - i.e. code
// behaves as if they weren't used. They don't try to check their impact on
// optimization.

TEST(PredictTest, PredictTrue) {
  EXPECT_TRUE(ABSL_PREDICT_TRUE(true));
  EXPECT_FALSE(ABSL_PREDICT_TRUE(false));
  EXPECT_TRUE(ABSL_PREDICT_TRUE(1 == 1));
  EXPECT_FALSE(ABSL_PREDICT_TRUE(1 == 2));

  if (ABSL_PREDICT_TRUE(false)) ADD_FAILURE();
  if (!ABSL_PREDICT_TRUE(true)) ADD_FAILURE();

  EXPECT_TRUE(ABSL_PREDICT_TRUE(true) && true);
  EXPECT_TRUE(ABSL_PREDICT_TRUE(true) || false);
}

TEST(PredictTest, PredictFalse) {
  EXPECT_TRUE(ABSL_PREDICT_FALSE(true));
  EXPECT_FALSE(ABSL_PREDICT_FALSE(false));
  EXPECT_TRUE(ABSL_PREDICT_FALSE(1 == 1));
  EXPECT_FALSE(ABSL_PREDICT_FALSE(1 == 2));

  if (ABSL_PREDICT_FALSE(false)) ADD_FAILURE();
  if (!ABSL_PREDICT_FALSE(true)) ADD_FAILURE();

  EXPECT_TRUE(ABSL_PREDICT_FALSE(true) && true);
  EXPECT_TRUE(ABSL_PREDICT_FALSE(true) || false);
}

TEST(PredictTest, OneEvaluation) {
  // Verify that the expression is only evaluated once.
  int x = 0;
  if (ABSL_PREDICT_TRUE((++x) == 0)) ADD_FAILURE();
  EXPECT_EQ(x, 1);
  if (ABSL_PREDICT_FALSE((++x) == 0)) ADD_FAILURE();
  EXPECT_EQ(x, 2);
}

TEST(PredictTest, OperatorOrder) {
  // Verify that operator order inside and outside the macro behaves well.
  // These would fail for a naive '#define ABSL_PREDICT_TRUE(x) x'
  EXPECT_TRUE(ABSL_PREDICT_TRUE(1 && 2) == true);
  EXPECT_TRUE(ABSL_PREDICT_FALSE(1 && 2) == true);
  EXPECT_TRUE(!ABSL_PREDICT_TRUE(1 == 2));
  EXPECT_TRUE(!ABSL_PREDICT_FALSE(1 == 2));
}

TEST(PredictTest, Pointer) {
  const int x = 3;
  const int *good_intptr = &x;
  const int *null_intptr = nullptr;
  EXPECT_TRUE(ABSL_PREDICT_TRUE(good_intptr));
  EXPECT_FALSE(ABSL_PREDICT_TRUE(null_intptr));
  EXPECT_TRUE(ABSL_PREDICT_FALSE(good_intptr));
  EXPECT_FALSE(ABSL_PREDICT_FALSE(null_intptr));
}

TEST(PredictTest, Optional) {
  // Note: An optional's truth value is the value's existence, not its truth.
  std::optional<bool> has_value(false);
  std::optional<bool> no_value;
  EXPECT_TRUE(ABSL_PREDICT_TRUE(has_value));
  EXPECT_FALSE(ABSL_PREDICT_TRUE(no_value));
  EXPECT_TRUE(ABSL_PREDICT_FALSE(has_value));
  EXPECT_FALSE(ABSL_PREDICT_FALSE(no_value));
}

class ImplicitlyConvertibleToBool {
 public:
  explicit ImplicitlyConvertibleToBool(bool value) : value_(value) {}
  operator bool() const {  // NOLINT(google-explicit-constructor)
    return value_;
  }

 private:
  bool value_;
};

TEST(PredictTest, ImplicitBoolConversion) {
  const ImplicitlyConvertibleToBool is_true(true);
  const ImplicitlyConvertibleToBool is_false(false);
  if (!ABSL_PREDICT_TRUE(is_true)) ADD_FAILURE();
  if (ABSL_PREDICT_TRUE(is_false)) ADD_FAILURE();
  if (!ABSL_PREDICT_FALSE(is_true)) ADD_FAILURE();
  if (ABSL_PREDICT_FALSE(is_false)) ADD_FAILURE();
}

class ExplicitlyConvertibleToBool {
 public:
  explicit ExplicitlyConvertibleToBool(bool value) : value_(value) {}
  explicit operator bool() const { return value_; }

 private:
  bool value_;
};

TEST(PredictTest, ExplicitBoolConversion) {
  const ExplicitlyConvertibleToBool is_true(true);
  const ExplicitlyConvertibleToBool is_false(false);
  if (!ABSL_PREDICT_TRUE(is_true)) ADD_FAILURE();
  if (ABSL_PREDICT_TRUE(is_false)) ADD_FAILURE();
  if (!ABSL_PREDICT_FALSE(is_true)) ADD_FAILURE();
  if (ABSL_PREDICT_FALSE(is_false)) ADD_FAILURE();
}

// This verifies that ABSL_ASSUME compiles in a variety of contexts.
// It does not test optimization.
TEST(AbslAssume, Compiles) {
  int x = 0;
  ABSL_ASSUME(x >= 0);
  EXPECT_EQ(x, 0);

  // https://github.com/abseil/abseil-cpp/issues/1814
  ABSL_ASSUME(x >= 0), (x >= 0) ? ++x : --x;
  EXPECT_EQ(x, 1);
}

}  // namespace