1 files changed, 88 insertions, 0 deletions
diff --git a/abseil-cpp/absl/log/internal/nullguard.h b/abseil-cpp/absl/log/internal/nullguard.h
new file mode 100644
index 0000000..623943c
--- /dev/null
+++ b/abseil-cpp/absl/log/internal/nullguard.h
@@ -0,0 +1,88 @@
+// 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_