Abseil Common Libraries (C++) (grcp 依赖)
https://abseil.io/
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
56 lines
1.8 KiB
56 lines
1.8 KiB
// Copyright 2022 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. |
|
// |
|
// ----------------------------------------------------------------------------- |
|
// File: log/internal/nullguard.h |
|
// ----------------------------------------------------------------------------- |
|
// |
|
// NullGuard exists such that NullGuard<T>::Guard(v) returns v, unless passed a |
|
// nullptr_t, or a null char* or const char*, in which case it returns "(null)". |
|
// This allows streaming NullGuard<T>::Guard(v) to an output stream without |
|
// hitting undefined behavior for null values. |
|
|
|
#ifndef ABSL_LOG_INTERNAL_NULLGUARD_H_ |
|
#define ABSL_LOG_INTERNAL_NULLGUARD_H_ |
|
|
|
#include <cstddef> |
|
|
|
#include "absl/base/config.h" |
|
|
|
namespace absl { |
|
ABSL_NAMESPACE_BEGIN |
|
namespace log_internal { |
|
|
|
template <typename T> |
|
struct NullGuard final { |
|
static const T& Guard(const T& v) { return v; } |
|
}; |
|
template <> |
|
struct NullGuard<char*> final { |
|
static const char* Guard(const char* v) { return v ? v : "(null)"; } |
|
}; |
|
template <> |
|
struct NullGuard<const char*> final { |
|
static const char* Guard(const char* v) { return v ? v : "(null)"; } |
|
}; |
|
template <> |
|
struct NullGuard<std::nullptr_t> final { |
|
static const char* Guard(const std::nullptr_t&) { return "(null)"; } |
|
}; |
|
|
|
} // namespace log_internal |
|
ABSL_NAMESPACE_END |
|
} // namespace absl |
|
|
|
#endif // ABSL_LOG_INTERNAL_NULLGUARD_H_
|
|
|