| // Copyright 2017 The Cobalt Authors. All Rights Reserved. |
| // |
| // 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 |
| // |
| // http://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 COBALT_SCRIPT_TRACER_H_ |
| #define COBALT_SCRIPT_TRACER_H_ |
| |
| #include <memory> |
| |
| #include "base/memory/ref_counted.h" |
| #include "base/memory/weak_ptr.h" |
| #include "cobalt/script/sequence.h" |
| |
| namespace cobalt { |
| namespace script { |
| |
| class Tracer; |
| |
| class Traceable { |
| public: |
| virtual ~Traceable() {} |
| |
| // Trace all native |Traceable|s accessible by the |Traceable|. Any class |
| // that owns a |Traceable| must implement this interface and trace each of |
| // its |Traceable| members. Note that here, "owns" means is accessible from |
| // JavaScript, which means that weak and raw pointers must be traced in |
| // addition to |std::unique_ptr|s and |scoped_refptr|s. Consider, for |
| // example, a list IDL interface, with parent and child references. A C++ |
| // implementation backed by |scoped__refptr| will be forced to demote the |
| // pointer from a child to a parent to a |base::WeakPtr| or raw pointer, in |
| // order to break the reference cycle. In JavaScript however, holding a |
| // reference to a child implies that the parent is still reachable, and |
| // should not be garbage collected. |
| virtual void TraceMembers(Tracer* tracer) = 0; |
| |
| // Whether the |Traceable| is a |Wrappable| or not. This should never be |
| // implemented by any class other than |Traceable| and |Wrappable|. |
| virtual bool IsWrappable() const { return false; } |
| }; |
| |
| // Traverses |Traceable|s, while marking found JavaScript wrappers as |
| // reachable. |
| class Tracer { |
| public: |
| // Trace a |Traceable| by forwarding its wrapper (which is engine specific) |
| // to the engine's internal tracer, or manually tracing reachable |
| // |Traceable|s in the case where the wrapper did not exist. |
| virtual void Trace(Traceable* traceable) = 0; |
| |
| void Trace(const Traceable& traceable) { |
| Trace(const_cast<Traceable*>(&traceable)); |
| } |
| |
| template <typename T> |
| void Trace(const scoped_refptr<T>& ptr) { |
| Trace(ptr.get()); |
| } |
| |
| template <typename T> |
| void Trace(const base::WeakPtr<T>& ptr) { |
| Trace(ptr.get()); |
| } |
| |
| template <typename T> |
| void Trace(const std::unique_ptr<T>& ptr) { |
| Trace(ptr.get()); |
| } |
| |
| // Trace the items of a container of |Traceable|s, such as |std::vector|. |
| template <typename T> |
| void TraceItems(const T& items) { |
| for (const auto& item : items) { |
| Trace(item); |
| } |
| } |
| |
| // Trace the value part of a container of key value pairs, where the values |
| // are |Traceable|s, such as |std::map|. |
| template <typename T> |
| void TraceValues(const T& key_value_pairs) { |
| for (const auto& pair : key_value_pairs) { |
| Trace(pair.second); |
| } |
| } |
| |
| // Note: If your new class wants to own a container of |Traceable|s that |
| // does not have an iteration helper function here, you should add one. |
| }; |
| |
| } // namespace script |
| } // namespace cobalt |
| |
| #endif // COBALT_SCRIPT_TRACER_H_ |