Source/WebCore/bindings/js/JSPopStateEventCustom.cpp

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#include "config.h"

#include "History.h"
#include "JSHistory.h"
#include "JSPopStateEvent.h"

using namespace JSC;

namespace WebCore {

// Save the state value to the m_state member of a JSPopStateEvent, and return it, for convenience.
static const JSValue& cacheState(ExecState* exec, JSPopStateEvent* event, const JSValue& state)
{
    event->m_state.set(exec->vm(), event, state);
    return state;
}

JSValue JSPopStateEvent::state(ExecState* exec) const
{
    JSValue cachedValue = m_state.get();
    if (!cachedValue.isEmpty())
        return cachedValue;

    PopStateEvent& event = impl();

    if (!event.state().hasNoValue())
        return cacheState(exec, const_cast<JSPopStateEvent*>(this), event.state().jsValue());

    History* history = event.history();
    if (!history || !event.serializedState())
        return cacheState(exec, const_cast<JSPopStateEvent*>(this), 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().get());
    JSValue result;

    if (isSameState) {
        JSHistory* jsHistory = jsCast<JSHistory*>(toJS(exec, globalObject(), history).asCell());
        result = jsHistory->state(exec);
    } else
        result = event.serializedState()->deserialize(exec, globalObject(), 0);

    return cacheState(exec, const_cast<JSPopStateEvent*>(this), result);
}

} // namespace WebCore