Source/core/dom/DocumentLifecycle.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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 */

#ifndef DocumentLifecycle_h
#define DocumentLifecycle_h

#include "wtf/Noncopyable.h"

namespace WebCore {

class DocumentLifecycle {
    WTF_MAKE_NONCOPYABLE(DocumentLifecycle);
public:
    enum State {
        Uninitialized,
        Inactive,

        // When the document is active, it traverses these states.

        StyleRecalcPending,
        InStyleRecalc,
        StyleClean,

        InPreLayout,
        InPerformLayout,
        AfterPerformLayout,
        LayoutClean,

        InCompositingUpdate,
        CompositingClean,

        // Once the document starts shuting down, we cannot return
        // to the style/layout/rendering states.
        Stopping,
        Stopped,
        Disposed,
    };

    class Scope {
        WTF_MAKE_NONCOPYABLE(Scope);
    public:
        Scope(DocumentLifecycle&, State finalState);
        ~Scope();

        void setFinalState(State finalState) { m_finalState = finalState; }

    private:
        DocumentLifecycle& m_lifecycle;
        State m_finalState;
    };

    class DeprecatedTransition {
        WTF_MAKE_NONCOPYABLE(DeprecatedTransition);
    public:
        DeprecatedTransition(State from, State to);
        ~DeprecatedTransition();

        State from() const { return m_from; }
        State to() const { return m_to; }

    private:
        DeprecatedTransition* m_previous;
        State m_from;
        State m_to;
    };

    DocumentLifecycle();
    ~DocumentLifecycle();

    bool isActive() const { return m_state > Inactive && m_state < Stopping; }
    State state() const { return m_state; }

    void advanceTo(State);
    void rewindTo(State);

private:
#if !ASSERT_DISABLED
    bool canAdvanceTo(State) const;
#endif

    State m_state;
};

}

#endif