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      1 /*
      2  * Copyright (C) 2013 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef DocumentLifecycle_h
     32 #define DocumentLifecycle_h
     33 
     34 #include "wtf/Assertions.h"
     35 #include "wtf/Noncopyable.h"
     36 
     37 namespace blink {
     38 
     39 class DocumentLifecycle {
     40     WTF_MAKE_NONCOPYABLE(DocumentLifecycle);
     41 public:
     42     enum State {
     43         Uninitialized,
     44         Inactive,
     45 
     46         // When the document is active, it traverses these states.
     47 
     48         VisualUpdatePending,
     49 
     50         InStyleRecalc,
     51         StyleClean,
     52 
     53         InPreLayout,
     54         InPerformLayout,
     55         AfterPerformLayout,
     56         LayoutClean,
     57 
     58         InCompositingUpdate,
     59         CompositingClean,
     60 
     61         InPaintInvalidation,
     62         PaintInvalidationClean,
     63 
     64         // Once the document starts shuting down, we cannot return
     65         // to the style/layout/rendering states.
     66         Stopping,
     67         Stopped,
     68         Disposed,
     69     };
     70 
     71     class Scope {
     72         WTF_MAKE_NONCOPYABLE(Scope);
     73     public:
     74         Scope(DocumentLifecycle&, State finalState);
     75         ~Scope();
     76 
     77         void setFinalState(State finalState) { m_finalState = finalState; }
     78 
     79     private:
     80         DocumentLifecycle& m_lifecycle;
     81         State m_finalState;
     82     };
     83 
     84     class DeprecatedTransition {
     85         WTF_MAKE_NONCOPYABLE(DeprecatedTransition);
     86     public:
     87         DeprecatedTransition(State from, State to);
     88         ~DeprecatedTransition();
     89 
     90         State from() const { return m_from; }
     91         State to() const { return m_to; }
     92 
     93     private:
     94         DeprecatedTransition* m_previous;
     95         State m_from;
     96         State m_to;
     97     };
     98 
     99     class DetachScope {
    100         WTF_MAKE_NONCOPYABLE(DetachScope);
    101     public:
    102         explicit DetachScope(DocumentLifecycle& documentLifecycle)
    103             : m_documentLifecycle(documentLifecycle)
    104         {
    105             m_documentLifecycle.incrementDetachCount();
    106         }
    107 
    108         ~DetachScope()
    109         {
    110             m_documentLifecycle.decrementDetachCount();
    111         }
    112 
    113     private:
    114         DocumentLifecycle& m_documentLifecycle;
    115     };
    116 
    117     DocumentLifecycle();
    118     ~DocumentLifecycle();
    119 
    120     bool isActive() const { return m_state > Inactive && m_state < Stopping; }
    121     State state() const { return m_state; }
    122 
    123     bool stateAllowsTreeMutations() const;
    124     bool stateAllowsRenderTreeMutations() const;
    125     bool stateAllowsDetach() const;
    126 
    127     void advanceTo(State);
    128     void ensureStateAtMost(State);
    129 
    130     void incrementDetachCount() { m_detachCount++; }
    131     void decrementDetachCount()
    132     {
    133         ASSERT(m_detachCount > 0);
    134         m_detachCount--;
    135     }
    136 
    137 private:
    138 #if ENABLE(ASSERT)
    139     bool canAdvanceTo(State) const;
    140     bool canRewindTo(State) const;
    141 #endif
    142 
    143     State m_state;
    144     int m_detachCount;
    145 };
    146 
    147 inline bool DocumentLifecycle::stateAllowsTreeMutations() const
    148 {
    149     // FIXME: We should not allow mutations in InPreLayout or AfterPerformLayout either,
    150     // but we need to fix MediaList listeners and plugins first.
    151     return m_state != InStyleRecalc
    152         && m_state != InPerformLayout
    153         && m_state != InCompositingUpdate;
    154 }
    155 
    156 inline bool DocumentLifecycle::stateAllowsRenderTreeMutations() const
    157 {
    158     return m_detachCount || m_state == InStyleRecalc;
    159 }
    160 
    161 inline bool DocumentLifecycle::stateAllowsDetach() const
    162 {
    163     return m_state == VisualUpdatePending
    164         || m_state == InStyleRecalc
    165         || m_state == StyleClean
    166         || m_state == InPreLayout
    167         || m_state == LayoutClean
    168         || m_state == CompositingClean
    169         || m_state == PaintInvalidationClean
    170         || m_state == Stopping;
    171 }
    172 
    173 }
    174 
    175 #endif
    176