Source/WebCore/bindings/js/JSPopStateEventCustom.cpp

/*
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#include "config.h"
#include "JSPopStateEvent.h"

#include "DOMWrapperWorld.h"
#include "JSHistory.h"
#include <JavaScriptCore/HeapInlines.h>
#include <JavaScriptCore/JSCJSValueInlines.h>

namespace WebCore {

JSValue JSPopStateEvent::state(ExecState& state) const
{
    if (m_state) {
        // We cannot use a cached object if we are in a different world than the one it was created in.
        if (isWorldCompatible(state, m_state.get()))
            return m_state.get();
        ASSERT_NOT_REACHED();
    }

    // Save the state value to the m_state member of a JSPopStateEvent, and return it, for convenience.
    auto cacheState = [&state, this] (JSC::JSValue eventState) {
        m_state.set(state.vm(), this, eventState);
        return eventState;
    };

    PopStateEvent& event = wrapped();

    if (JSC::JSValue eventState = event.state()) {
        // We need to make sure a PopStateEvent does not leak objects in its state property across isolated DOM worlds.
        // Ideally, we would check that the worlds have different privileges but that's not possible yet.
        if (!isWorldCompatible(state, eventState)) {
            if (auto serializedValue = event.trySerializeState(state))
                eventState = serializedValue->deserialize(state, globalObject());
            else
                eventState = jsNull();
        }
        return cacheState(eventState);
    }
    
    History* history = event.history();
    if (!history || !event.serializedState())
        return cacheState(jsNull());

    // There's no cached value from a previous invocation, nor a state value was provided by the
    // event, but there is a history object, so first we need to see if the state object has been
    // deserialized through the history object already.
    // The current history state object might've changed in the meantime, so we need to take care
    // of using the correct one, and always share the same deserialization with history.state.

    bool isSameState = history->isSameAsCurrentState(event.serializedState());
    JSValue result;

    if (isSameState) {
        JSHistory* jsHistory = jsCast<JSHistory*>(toJS(&state, globalObject(), *history).asCell());
        result = jsHistory->state(state);
    } else
        result = event.serializedState()->deserialize(state, globalObject());

    return cacheState(result);
}

void JSPopStateEvent::visitAdditionalChildren(JSC::SlotVisitor& visitor)
{
    wrapped().state().visit(visitor);
}

} // namespace WebCore