Abseil Common Libraries (C++) (grcp 依赖)
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77 lines
2.8 KiB
77 lines
2.8 KiB
2 years ago
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// 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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