Abseil Common Libraries (C++) (grcp 依赖)
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76 lines
2.8 KiB
76 lines
2.8 KiB
// Copyright 2022 The Abseil Authors. |
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// |
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// Licensed under the Apache License, Version 2.0 (the "License"); |
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// you may not use this file except in compliance with the License. |
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// You may obtain a copy of the License at |
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// |
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// https://www.apache.org/licenses/LICENSE-2.0 |
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// |
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// Unless required by applicable law or agreed to in writing, software |
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// distributed under the License is distributed on an "AS IS" BASIS, |
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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// See the License for the specific language governing permissions and |
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// limitations under the License. |
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// |
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// ----------------------------------------------------------------------------- |
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// File: log/die_if_null.h |
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// ----------------------------------------------------------------------------- |
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// |
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// This header declares macro `ABSL_DIE_IF_NULL`. |
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#ifndef ABSL_LOG_DIE_IF_NULL_H_ |
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#define ABSL_LOG_DIE_IF_NULL_H_ |
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#include <stdint.h> |
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#include <utility> |
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#include "absl/base/attributes.h" |
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#include "absl/base/config.h" |
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#include "absl/base/optimization.h" |
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// ABSL_DIE_IF_NULL() |
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// |
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// `ABSL_DIE_IF_NULL` behaves as `CHECK_NE` against `nullptr` but *also* |
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// "returns" its argument. It is useful in initializers where statements (like |
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// `CHECK_NE`) can't be used. Outside initializers, prefer `CHECK` or |
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// `CHECK_NE`. `ABSL_DIE_IF_NULL` works for both raw pointers and (compatible) |
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// smart pointers including `std::unique_ptr` and `std::shared_ptr`; more |
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// generally, it works for any type that can be compared to nullptr_t. For |
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// types that aren't raw pointers, `ABSL_DIE_IF_NULL` returns a reference to |
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// its argument, preserving the value category. Example: |
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// |
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// Foo() : bar_(ABSL_DIE_IF_NULL(MethodReturningUniquePtr())) {} |
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// |
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// Use `CHECK(ptr)` or `CHECK(ptr != nullptr)` if the returned pointer is |
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// unused. |
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#define ABSL_DIE_IF_NULL(val) \ |
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::absl::log_internal::DieIfNull(__FILE__, __LINE__, #val, (val)) |
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namespace absl { |
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ABSL_NAMESPACE_BEGIN |
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namespace log_internal { |
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// Crashes the process after logging `exprtext` annotated at the `file` and |
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// `line` location. Called when `ABSL_DIE_IF_NULL` fails. Calling this function |
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// generates less code than its implementation would if inlined, for a slight |
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// code size reduction each time `ABSL_DIE_IF_NULL` is called. |
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ABSL_ATTRIBUTE_NORETURN ABSL_ATTRIBUTE_NOINLINE void DieBecauseNull( |
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const char* file, int line, const char* exprtext); |
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// Helper for `ABSL_DIE_IF_NULL`. |
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template <typename T> |
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ABSL_MUST_USE_RESULT T DieIfNull(const char* file, int line, |
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const char* exprtext, T&& t) { |
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if (ABSL_PREDICT_FALSE(t == nullptr)) { |
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// Call a non-inline helper function for a small code size improvement. |
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DieBecauseNull(file, line, exprtext); |
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} |
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return std::forward<T>(t); |
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} |
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} // namespace log_internal |
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ABSL_NAMESPACE_END |
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} // namespace absl |
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#endif // ABSL_LOG_DIE_IF_NULL_H_
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