Motown: Remove LPCM optimizations, fix prepare, add flush, add ActiveMultistreamSink model/stage

services/media/framework/refs.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SERVICES_MEDIA_FRAMEWORK_REFS_H_
+#define SERVICES_MEDIA_FRAMEWORK_REFS_H_
+
+#include <stdint.h>
+
+namespace mojo {
+namespace media {
+
+class Graph;
+class Stage;
+class Input;
+class Output;
+class Engine;
+class InputRef;
+class OutputRef;
+
+// Opaque Stage pointer used for graph building.
+class PartRef {
+ public:
+  PartRef() : stage_(nullptr) {}
+
+  PartRef& operator=(std::nullptr_t) {
+    stage_ = nullptr;
+    return *this;
+  }
+
+  // Returns the number of inputs the part has.
+  size_t input_count() const;
+
+  // Returns a reference to the specified input.
+  InputRef input(size_t index) const;
+
+  // Returns a reference to the only input. input_count must return 1 for this
+  // call to be valid.
+  InputRef input() const;
+
+  // Returns the number of outputs the part has.
+  size_t output_count() const;
+
+  // Returns a reference to the specified output.
+  OutputRef output(size_t index) const;
+
+  // Returns a reference to the only output. output_count must return 1 for this
+  // call to be valid.
+  OutputRef output() const;
+
+  // Returns true if the reference refers to a part, false if it's null.
+  explicit operator bool() const { return stage_ != nullptr; }
+
+ private:
+  explicit PartRef(Stage* stage) : stage_(stage) {}
+
+  // Determines if the reference is non-null and otherwise valid. Useful for
+  // DCHECKs.
+  bool valid() const { return stage_ != nullptr; }
+
+  Stage* stage_;
+
+  friend Graph;
+  friend InputRef;
+  friend OutputRef;
+  friend Engine;
+};
+
+// Opaque Input pointer used for graph building.
+class InputRef {
+ public:
+  InputRef() : stage_(nullptr), index_(0) {}
+
+  InputRef& operator=(std::nullptr_t) {
+    stage_ = nullptr;
+    index_ = 0;
+    return *this;
+  }
+
+  // Returns true if the reference refers to an input, false if it's null.
+  explicit operator bool() const { return stage_ != nullptr; }
+
+  // Returns a reference to the part that owns this input. Returns a null
+  // reference if this reference is null.
+  PartRef part() const { return PartRef(stage_); }
+
+  // Indicates whether this input is connected to an output.
+  bool connected() const;
+
+  // Returns a reference to the output to which this input is connected. Returns

[johngro, 2016/02/09 21:00:36]

wording nit,

Can we say something more like "an invalid OutputRef" instead of a
null-reference?  When I first read this, I thought that you were going to return
something like (*static_cast<OutputRef*>(nullptr)) instead of a reference to an
OutputRef object which had a null stage internally.  It took some searching
around in the code to convince myself that this was not true.

[dalesat, 2016/02/10 21:37:24]

Done.

+  // a null reference if this input isn't connected to an output.
+  const OutputRef& mate() const;
+
+ private:
+  InputRef(Stage* stage, size_t index);
+
+  // Returns the actual input referenced by this object.
+  Input& actual() const;
+
+  // Determines if the reference is non-null and otherwise valid. Useful for
+  // DCHECKs.
+  bool valid() const;
+
+  Stage* stage_;
+  size_t index_;
+
+  friend Graph;
+  friend PartRef;
+  friend OutputRef;
+  friend Output;
+  friend Engine;
+};
+
+// Opaque Output pointer used for graph building.
+class OutputRef {
+ public:
+  OutputRef() : stage_(nullptr), index_(0) {}
+
+  OutputRef& operator=(std::nullptr_t) {
+    stage_ = nullptr;
+    index_ = 0;
+    return *this;
+  }
+
+  // Returns true if the reference refers to an output, false if it's null.
+  explicit operator bool() const { return stage_ != nullptr; }
+
+  // Returns a reference to the part that owns this output. Returns a null
+  // reference if this reference is null.
+  PartRef part() const { return PartRef(stage_); }
+
+  // Indicates whether this output is connected to an input.
+  bool connected() const;
+
+  // Returns a reference to the input to which this output is connected. Returns
+  // a null reference if this output isn't connected to an input.
+  const InputRef& mate() const;
+
+ private:
+  OutputRef(Stage* stage, size_t index);
+
+  // Returns the actual input referenced by this object.
+  Output& actual() const;
+
+  // Determines if the reference is non-null and otherwise valid. Useful for
+  // DCHECKs.
+  bool valid() const;
+
+  Stage* stage_;
+  size_t index_;
+
+  friend Graph;
+  friend PartRef;
+  friend InputRef;
+  friend Input;
+  friend Engine;
+};
+
+}  // namespace media
+}  // namespace mojo
+
+#endif  // SERVICES_MEDIA_FRAMEWORK_REFS_H_