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// Copyright 2014 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_WRAPPABLE_H_
#define COBALT_SCRIPT_WRAPPABLE_H_
#include <memory>
#include "base/bind.h"
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "cobalt/base/source_location.h"
#include "cobalt/base/type_id.h"
#include "cobalt/script/sequence.h"
#include "cobalt/script/tracer.h"
namespace cobalt {
namespace script {
class Wrappable : public base::RefCounted<Wrappable>, public Traceable {
public:
// A handle to this Wrappable's corresponding Wrapper object. It may be
// NULL if no wrapper has been created. A Wrapper may get garbage collected
// independent of the lifetime of its corresponding Wrappable object.
class WeakWrapperHandle {
protected:
WeakWrapperHandle() {}
virtual ~WeakWrapperHandle() {}
private:
friend std::unique_ptr<WeakWrapperHandle>::deleter_type;
};
// A class that creates ValueHandles should inherit from this interface
// so that it can get/set the cached wrapper handle.
class CachedWrapperAccessor {
protected:
WeakWrapperHandle* GetCachedWrapper(Wrappable* wrappable) const {
return wrappable->cached_wrapper_.get();
}
void SetCachedWrapper(Wrappable* wrappable,
std::unique_ptr<WeakWrapperHandle> wrapper) const {
wrappable->cached_wrapper_ = std::move(wrapper);
}
};
enum class JSObjectType {
kObject,
kNode,
kArray,
kError,
kBlob,
};
// Used for RTTI on wrappable types. This is implemented within the
// DEFINE_WRAPPABLE_TYPE macro, defined below, which should be added to the
// class definition of each wrappable type.
virtual base::TypeId GetWrappableType() const = 0;
virtual base::SourceLocation GetInlineSourceLocation() const = 0;
// Our implementation of the |Traceable| interface. All |Wrappable|s that
// own any |Traceable|s must override |TraceMembers| and trace them.
void TraceMembers(Tracer* tracer) override {}
bool IsWrappable() const final { return true; }
virtual JSObjectType GetJSObjectType() { return JSObjectType::kObject; }
protected:
virtual ~Wrappable() { }
private:
// A cached weak reference to the interface's corresponding wrapper object.
// This may get garbage-collected before the associated Wrappable is
// destroyed.
std::unique_ptr<WeakWrapperHandle> cached_wrapper_;
friend class base::RefCounted<Wrappable>;
};
} // namespace script
} // namespace cobalt
// This macro should be added with public accessibility in a class that inherits
// from Wrappable. It is used to implement RTTI that is used by the bindings
// layer to downcast a wrappable class if necessary before creating the JS
// wrapper.
//
// Using the interface name as the template parameter for the GetTypeId()
// function allows us to ensure at compile time that the static method is
// defined for a given type, and not just on one of its ancestors.
//
// It is also used to implement GetSourceLocationName() and
// GetInlineSourceLocation() that are used to generate source locations
// returned in messages from the parsers.
#define DEFINE_WRAPPABLE_TYPE(INTERFACE_NAME) \
static base::TypeId INTERFACE_NAME##WrappableType() { \
return base::GetTypeId<INTERFACE_NAME>(); \
} \
base::TypeId GetWrappableType() const override { \
return INTERFACE_NAME##WrappableType(); \
} \
static const char* GetSourceLocationName() { \
return "[object " #INTERFACE_NAME "]"; \
} \
base::SourceLocation GetInlineSourceLocation() const override { \
return base::SourceLocation(GetSourceLocationName(), 1, 1); \
}
#endif // COBALT_SCRIPT_WRAPPABLE_H_