Repo created

TMessagesProj/jni/voip/webrtc/absl/strings/has_absl_stringify.h

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+// 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.
+
+#ifndef ABSL_STRINGS_HAS_ABSL_STRINGIFY_H_
+#define ABSL_STRINGS_HAS_ABSL_STRINGIFY_H_
+
+#include <type_traits>
+#include <utility>
+
+#include "absl/base/config.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+namespace strings_internal {
+
+// This is an empty class not intended to be used. It exists so that
+// `HasAbslStringify` can reference a universal class rather than needing to be
+// copied for each new sink.
+class UnimplementedSink {
+ public:
+  void Append(size_t count, char ch);
+
+  void Append(string_view v);
+
+  // Support `absl::Format(&sink, format, args...)`.
+  friend void AbslFormatFlush(UnimplementedSink* sink, absl::string_view v);
+};
+
+}  // namespace strings_internal
+
+// `HasAbslStringify<T>` detects if type `T` supports the `AbslStringify()`
+// customization point (see
+// https://abseil.io/docs/cpp/guides/format#abslstringify for the
+// documentation).
+//
+// Note that there are types that can be `StrCat`-ed that do not use the
+// `AbslStringify` customization point (for example, `int`).
+
+template <typename T, typename = void>
+struct HasAbslStringify : std::false_type {};
+
+template <typename T>
+struct HasAbslStringify<
+    T, std::enable_if_t<std::is_void<decltype(AbslStringify(
+           std::declval<strings_internal::UnimplementedSink&>(),
+           std::declval<const T&>()))>::value>> : std::true_type {};
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_HAS_ABSL_STRINGIFY_H_