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 WebCore { 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 // Once the document starts shuting down, we cannot return 62 // to the style/layout/rendering states. 63 Stopping, 64 Stopped, 65 Disposed, 66 }; 67 68 class Scope { 69 WTF_MAKE_NONCOPYABLE(Scope); 70 public: 71 Scope(DocumentLifecycle&, State finalState); 72 ~Scope(); 73 74 void setFinalState(State finalState) { m_finalState = finalState; } 75 76 private: 77 DocumentLifecycle& m_lifecycle; 78 State m_finalState; 79 }; 80 81 class DeprecatedTransition { 82 WTF_MAKE_NONCOPYABLE(DeprecatedTransition); 83 public: 84 DeprecatedTransition(State from, State to); 85 ~DeprecatedTransition(); 86 87 State from() const { return m_from; } 88 State to() const { return m_to; } 89 90 private: 91 DeprecatedTransition* m_previous; 92 State m_from; 93 State m_to; 94 }; 95 96 class DetachScope { 97 WTF_MAKE_NONCOPYABLE(DetachScope); 98 public: 99 explicit DetachScope(DocumentLifecycle& documentLifecycle) 100 : m_documentLifecycle(documentLifecycle) 101 { 102 m_documentLifecycle.incrementDetachCount(); 103 } 104 105 ~DetachScope() 106 { 107 m_documentLifecycle.decrementDetachCount(); 108 } 109 110 private: 111 DocumentLifecycle& m_documentLifecycle; 112 }; 113 114 DocumentLifecycle(); 115 ~DocumentLifecycle(); 116 117 bool isActive() const { return m_state > Inactive && m_state < Stopping; } 118 State state() const { return m_state; } 119 120 bool stateAllowsTreeMutations() const; 121 bool stateAllowsRenderTreeMutations() const; 122 bool stateAllowsDetach() const; 123 124 void advanceTo(State); 125 void ensureStateAtMost(State); 126 127 void incrementDetachCount() { m_detachCount++; } 128 void decrementDetachCount() 129 { 130 ASSERT(m_detachCount > 0); 131 m_detachCount--; 132 } 133 134 private: 135 #if ASSERT_ENABLED 136 bool canAdvanceTo(State) const; 137 bool canRewindTo(State) const; 138 #endif 139 140 State m_state; 141 int m_detachCount; 142 }; 143 144 inline bool DocumentLifecycle::stateAllowsTreeMutations() const 145 { 146 // FIXME: We should not allow mutations in InPreLayout or AfterPerformLayout either, 147 // but we need to fix MediaList listeners and plugins first. 148 return m_state != InStyleRecalc 149 && m_state != InPerformLayout 150 && m_state != InCompositingUpdate; 151 } 152 153 inline bool DocumentLifecycle::stateAllowsRenderTreeMutations() const 154 { 155 return m_detachCount || m_state == InStyleRecalc; 156 } 157 158 inline bool DocumentLifecycle::stateAllowsDetach() const 159 { 160 return m_state == VisualUpdatePending 161 || m_state == InStyleRecalc 162 || m_state == StyleClean 163 || m_state == InPreLayout 164 || m_state == LayoutClean 165 || m_state == CompositingClean 166 || m_state == Stopping; 167 } 168 169 } 170 171 #endif 172