Squashed 'third_party/abseil_cpp/' changes from 768eb2ca2..ccdbb5941

ccdbb5941 Export of internal Abseil changes
01f5f81f9 Export of internal Abseil changes
2c92bdc7c Export of internal Abseil changes
e7ebf9803 Export of internal Abseil changes
2eba343b5 Export of internal Abseil changes
a8b03d90e Export of internal Abseil changes
1d31b5c36 Export of internal Abseil changes
da3a87690 Export of internal Abseil changes
8faf20461 Exclude empty directories (#697)
2069dc796 Export of internal Abseil changes
4832bf6bf Added a BUILD file in root to expose license. (#695)
af8f994af Export of internal Abseil changes
33caf1097 Export of internal Abseil changes
cf1a02e2d Export of internal Abseil changes

git-subtree-dir: third_party/abseil_cpp
git-subtree-split: ccdbb5941f992fabda7eae3ce72f55efc17c826a

1 files changed, 85 insertions, 0 deletions

diff --git a/absl/flags/reflection.h b/absl/flags/reflection.h
new file mode 100644
index 000000000000..045f9784e269
--- /dev/null
+++ b/absl/flags/reflection.h
@@ -0,0 +1,85 @@
+//
+// Copyright 2020 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: reflection.h
+// -----------------------------------------------------------------------------
+//
+// This file defines the routines to access and operate on an Abseil Flag's
+// reflection handle.
+
+#ifndef ABSL_FLAGS_REFLECTION_H_
+#define ABSL_FLAGS_REFLECTION_H_
+
+#include <string>
+
+#include "absl/base/config.h"
+#include "absl/flags/commandlineflag.h"
+#include "absl/flags/internal/commandlineflag.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+class FlagSaverImpl;
+}  // namespace flags_internal
+
+// FindCommandLineFlag()
+//
+// Returns the reflection handle of an Abseil flag of the specified name, or
+// `nullptr` if not found. This function will emit a warning if the name of a
+// 'retired' flag is specified.
+CommandLineFlag* FindCommandLineFlag(absl::string_view name);
+
+//------------------------------------------------------------------------------
+// FlagSaver
+//------------------------------------------------------------------------------
+//
+// A FlagSaver object stores the state of flags in the scope where the FlagSaver
+// is defined, allowing modification of those flags within that scope and
+// automatic restoration of the flags to their previous state upon leaving the
+// scope.
+//
+// A FlagSaver can be used within tests to temporarily change the test
+// environment and restore the test case to its previous state.
+//
+// Example:
+//
+//   void MyFunc() {
+//    absl::FlagSaver fs;
+//    ...
+//    absl::SetFlag(FLAGS_myFlag, otherValue);
+//    ...
+//  } // scope of FlagSaver left, flags return to previous state
+//
+// This class is thread-safe.
+
+class FlagSaver {
+ public:
+  FlagSaver();
+  ~FlagSaver();
+
+  FlagSaver(const FlagSaver&) = delete;
+  void operator=(const FlagSaver&) = delete;
+
+ private:
+  flags_internal::FlagSaverImpl* impl_;
+};
+
+//-----------------------------------------------------------------------------
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_FLAGS_REFLECTION_H_