Source/bindings/v8/ScriptPromiseResolver.h

/*
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 * modification, are permitted provided that the following conditions are
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 *
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 * in the documentation and/or other materials provided with the
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#ifndef ScriptPromiseResolver_h
#define ScriptPromiseResolver_h

#include "bindings/v8/ScopedPersistent.h"
#include "bindings/v8/ScriptObject.h"
#include "bindings/v8/ScriptPromise.h"
#include "bindings/v8/ScriptState.h"
#include "bindings/v8/ScriptValue.h"
#include "wtf/RefPtr.h"

#include <v8.h>

namespace WebCore {

class ScriptExecutionContext;

// ScriptPromiseResolver is a class for performing operations on Promise
// (resolve / reject) from C++ world.
// ScriptPromiseResolver holds a Promise and a PromiseResolver.
// All methods of this class must be called from the main thread.
// Here is a typical usage:
//  1. Create a ScriptPromiseResolver.
//  2. Pass the promise object of the holder to a JavaScript program
//     (such as XMLHttpRequest return value).
//  3. Detach the promise object if you no longer need it.
//  4. Call resolve or reject when the operation completes or
//     the operation fails respectively.
//
// Most methods including constructors must be called within a v8 context.
// To use ScriptPromiseResolver out of a v8 context the caller must
// enter a v8 context, for example by using ScriptScope and ScriptState.
//
// If you hold ScriptPromiseResolver as a member variable in a DOM object,
// it causes memory leaks unless you detach the promise object manually.
// Logically ScriptPromiseResolver has 2 references to the promise object.
// One is for exposing the promise object, another is for resolving it.
// To prevent memory leaks, you should release these 2 references manually.
// Following operations release references to the promise object.
//  1. detachPromise releases the reference for exposing.
//  2. resolve / reject operations release the reference for resolving.
//  3. detach releases both references.
//  4. Destroying ScriptPromiseResolver releases both references.
//
// So if you no longer need the promise object, you should call detachPromise.
// And if the operation completes or fails, you should call resolve / reject.
// Destroying ScriptPromiseResolver will also detach the promise object.
//
class ScriptPromiseResolver : public RefCounted<ScriptPromiseResolver> {
    WTF_MAKE_NONCOPYABLE(ScriptPromiseResolver);
public:
    static PassRefPtr<ScriptPromiseResolver> create(ScriptExecutionContext*);
    static PassRefPtr<ScriptPromiseResolver> create();

    // A ScriptPromiseResolver should be resolved / rejected before
    // its destruction.
    // A ScriptPromiseResolver can be destructed safely without
    // entering a v8 context.
    ~ScriptPromiseResolver();

    // Reject the promise with undefined and detach it.
    void detach();

    // Detach the promise object.
    void detachPromise();

    // Return true if the promise object is in pending state.
    bool isPending() const;

    ScriptPromise promise()
    {
        ASSERT(v8::Context::InContext());
        return m_promise;
    }

    // Fulfill with a C++ object which can be converted to a v8 object by toV8.
    // This method "fulfill" is the deprecated alias to resolve.
    template<typename T>
    inline void fulfill(PassRefPtr<T>);
    // Resolve with a C++ object which can be converted to a v8 object by toV8.
    template<typename T>
    inline void resolve(PassRefPtr<T>);
    // Reject with a C++ object which can be converted to a v8 object by toV8.
    template<typename T>
    inline void reject(PassRefPtr<T>);

    // This method "fulfill" is the deprecated alias to resolve.
    void fulfill(ScriptValue);
    void resolve(ScriptValue);
    void reject(ScriptValue);

private:
    ScriptPromiseResolver(v8::Handle<v8::Object> creationContext, v8::Isolate*);
    void fulfill(v8::Handle<v8::Value>);
    void resolve(v8::Handle<v8::Value>);
    void reject(v8::Handle<v8::Value>);

    v8::Isolate* m_isolate;
    ScriptPromise m_promise;
    bool m_promiseForExposeDetached : 1;
    bool m_promiseForResolveDetached : 1;

    void detachPromiseForExpose();
    void detachPromiseForResolve();
};

template<typename T>
void ScriptPromiseResolver::fulfill(PassRefPtr<T> value)
{
    ASSERT(v8::Context::InContext());
    fulfill(toV8(value.get(), v8::Object::New(), m_isolate));
}

template<typename T>
void ScriptPromiseResolver::resolve(PassRefPtr<T> value)
{
    ASSERT(v8::Context::InContext());
    resolve(toV8(value.get(), v8::Object::New(), m_isolate));
}

template<typename T>
void ScriptPromiseResolver::reject(PassRefPtr<T> value)
{
    ASSERT(v8::Context::InContext());
    reject(toV8(value.get(), v8::Object::New(), m_isolate));
}

} // namespace WebCore


#endif // ScriptPromiseResolver_h