89 lines
2.8 KiB
C++
89 lines
2.8 KiB
C++
// 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 <array>
|
|
#include <cstddef>
|
|
|
|
#include "absl/base/attributes.h"
|
|
#include "absl/base/config.h"
|
|
|
|
namespace absl {
|
|
ABSL_NAMESPACE_BEGIN
|
|
namespace log_internal {
|
|
|
|
ABSL_CONST_INIT ABSL_DLL extern const std::array<char, 7> kCharNull;
|
|
ABSL_CONST_INIT ABSL_DLL extern const std::array<signed char, 7>
|
|
kSignedCharNull;
|
|
ABSL_CONST_INIT ABSL_DLL extern const std::array<unsigned char, 7>
|
|
kUnsignedCharNull;
|
|
|
|
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 : kCharNull.data(); }
|
|
};
|
|
template <>
|
|
struct NullGuard<const char*> final {
|
|
static const char* Guard(const char* v) { return v ? v : kCharNull.data(); }
|
|
};
|
|
template <>
|
|
struct NullGuard<signed char*> final {
|
|
static const signed char* Guard(const signed char* v) {
|
|
return v ? v : kSignedCharNull.data();
|
|
}
|
|
};
|
|
template <>
|
|
struct NullGuard<const signed char*> final {
|
|
static const signed char* Guard(const signed char* v) {
|
|
return v ? v : kSignedCharNull.data();
|
|
}
|
|
};
|
|
template <>
|
|
struct NullGuard<unsigned char*> final {
|
|
static const unsigned char* Guard(const unsigned char* v) {
|
|
return v ? v : kUnsignedCharNull.data();
|
|
}
|
|
};
|
|
template <>
|
|
struct NullGuard<const unsigned char*> final {
|
|
static const unsigned char* Guard(const unsigned char* v) {
|
|
return v ? v : kUnsignedCharNull.data();
|
|
}
|
|
};
|
|
template <>
|
|
struct NullGuard<std::nullptr_t> final {
|
|
static const char* Guard(const std::nullptr_t&) { return kCharNull.data(); }
|
|
};
|
|
|
|
} // namespace log_internal
|
|
ABSL_NAMESPACE_END
|
|
} // namespace absl
|
|
|
|
#endif // ABSL_LOG_INTERNAL_NULLGUARD_H_
|