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// 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 "gtest/gtest.h"
#include "absl/types/optional.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));
// The following doesn't compile:
// 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.
absl::optional<bool> has_value(false);
absl::optional<bool> no_value;
EXPECT_TRUE(ABSL_PREDICT_TRUE(has_value));
EXPECT_FALSE(ABSL_PREDICT_TRUE(no_value));
// The following doesn't compile:
// EXPECT_TRUE(ABSL_PREDICT_FALSE(has_value));
// EXPECT_FALSE(ABSL_PREDICT_FALSE(no_value));
}
class ImplictlyConvertibleToBool {
public:
explicit ImplictlyConvertibleToBool(bool value) : value_(value) {}
operator bool() const { // NOLINT(google-explicit-constructor)
return value_;
}
private:
bool value_;
};
TEST(PredictTest, ImplicitBoolConversion) {
const ImplictlyConvertibleToBool is_true(true);
const ImplictlyConvertibleToBool 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 ExplictlyConvertibleToBool {
public:
explicit ExplictlyConvertibleToBool(bool value) : value_(value) {}
explicit operator bool() const { return value_; }
private:
bool value_;
};
TEST(PredictTest, ExplicitBoolConversion) {
const ExplictlyConvertibleToBool is_true(true);
const ExplictlyConvertibleToBool is_false(false);
if (!ABSL_PREDICT_TRUE(is_true)) ADD_FAILURE();
if (ABSL_PREDICT_TRUE(is_false)) ADD_FAILURE();
// The following doesn't compile:
// if (!ABSL_PREDICT_FALSE(is_true)) ADD_FAILURE();
// if (ABSL_PREDICT_FALSE(is_false)) ADD_FAILURE();
}
} // namespace
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