Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 119 insertions, 0 deletions

diff --git a/third_party/libwebrtc/api/make_ref_counted.h b/third_party/libwebrtc/api/make_ref_counted.h
new file mode 100644
index 0000000000..cc8871784a
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+++ b/third_party/libwebrtc/api/make_ref_counted.h
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+/*
+ *  Copyright 2022 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef API_MAKE_REF_COUNTED_H_
+#define API_MAKE_REF_COUNTED_H_
+
+#include <utility>
+
+#include "rtc_base/ref_counted_object.h"
+
+namespace rtc {
+
+namespace webrtc_make_ref_counted_internal {
+// Determines if the given class has AddRef and Release methods.
+template <typename T>
+class HasAddRefAndRelease {
+ private:
+  template <typename C,
+            decltype(std::declval<C>().AddRef())* = nullptr,
+            decltype(std::declval<C>().Release())* = nullptr>
+  static int Test(int);
+  template <typename>
+  static char Test(...);
+
+ public:
+  static constexpr bool value = std::is_same_v<decltype(Test<T>(0)), int>;
+};
+}  // namespace webrtc_make_ref_counted_internal
+
+// General utilities for constructing a reference counted class and the
+// appropriate reference count implementation for that class.
+//
+// These utilities select either the `RefCountedObject` implementation or
+// `FinalRefCountedObject` depending on whether the to-be-shared class is
+// derived from the RefCountInterface interface or not (respectively).
+
+// `make_ref_counted`:
+//
+// Use this when you want to construct a reference counted object of type T and
+// get a `scoped_refptr<>` back. Example:
+//
+//   auto p = make_ref_counted<Foo>("bar", 123);
+//
+// For a class that inherits from RefCountInterface, this is equivalent to:
+//
+//   auto p = scoped_refptr<Foo>(new RefCountedObject<Foo>("bar", 123));
+//
+// If the class does not inherit from RefCountInterface, but does have
+// AddRef/Release methods (so a T* is convertible to rtc::scoped_refptr), this
+// is equivalent to just
+//
+//   auto p = scoped_refptr<Foo>(new Foo("bar", 123));
+//
+// Otherwise, the example is equivalent to:
+//
+//   auto p = scoped_refptr<FinalRefCountedObject<Foo>>(
+//       new FinalRefCountedObject<Foo>("bar", 123));
+//
+// In these cases, `make_ref_counted` reduces the amount of boilerplate code but
+// also helps with the most commonly intended usage of RefCountedObject whereby
+// methods for reference counting, are virtual and designed to satisfy the need
+// of an interface. When such a need does not exist, it is more efficient to use
+// the `FinalRefCountedObject` template, which does not add the vtable overhead.
+//
+// Note that in some cases, using RefCountedObject directly may still be what's
+// needed.
+
+// `make_ref_counted` for abstract classes that are convertible to
+// RefCountInterface. The is_abstract requirement rejects classes that inherit
+// both RefCountInterface and RefCounted object, which is a a discouraged
+// pattern, and would result in double inheritance of RefCountedObject if this
+// template was applied.
+template <
+    typename T,
+    typename... Args,
+    typename std::enable_if<std::is_convertible_v<T*, RefCountInterface*> &&
+                                std::is_abstract_v<T>,
+                            T>::type* = nullptr>
+scoped_refptr<T> make_ref_counted(Args&&... args) {
+  return scoped_refptr<T>(new RefCountedObject<T>(std::forward<Args>(args)...));
+}
+
+// `make_ref_counted` for complete classes that are not convertible to
+// RefCountInterface and already carry a ref count.
+template <
+    typename T,
+    typename... Args,
+    typename std::enable_if<
+        !std::is_convertible_v<T*, RefCountInterface*> &&
+            webrtc_make_ref_counted_internal::HasAddRefAndRelease<T>::value,
+        T>::type* = nullptr>
+scoped_refptr<T> make_ref_counted(Args&&... args) {
+  return scoped_refptr<T>(new T(std::forward<Args>(args)...));
+}
+
+// `make_ref_counted` for complete classes that are not convertible to
+// RefCountInterface and have no ref count of their own.
+template <
+    typename T,
+    typename... Args,
+    typename std::enable_if<
+        !std::is_convertible_v<T*, RefCountInterface*> &&
+            !webrtc_make_ref_counted_internal::HasAddRefAndRelease<T>::value,
+
+        T>::type* = nullptr>
+scoped_refptr<FinalRefCountedObject<T>> make_ref_counted(Args&&... args) {
+  return scoped_refptr<FinalRefCountedObject<T>>(
+      new FinalRefCountedObject<T>(std::forward<Args>(args)...));
+}
+
+}  // namespace rtc
+
+#endif  // API_MAKE_REF_COUNTED_H_