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 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer 12 * in the documentation and/or other materials provided with the 13 * distribution. 14 * 3. Neither the name of Google Inc. nor the names of its contributors 15 * may be used to endorse or promote products derived from this 16 * 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 CustomElementCallbackDispatcher_h 32 #define CustomElementCallbackDispatcher_h 33 34 #include "core/dom/custom/CustomElementBaseElementQueue.h" 35 #include "wtf/Vector.h" 36 37 namespace WebCore { 38 39 class CustomElementCallbackQueue; 40 class CustomElementCallbackScheduler; 41 42 class CustomElementCallbackDispatcher { 43 WTF_MAKE_NONCOPYABLE(CustomElementCallbackDispatcher); 44 public: 45 static CustomElementCallbackDispatcher& instance(); 46 47 // This is stack allocated in many DOM callbacks. Make it cheap. 48 class CallbackDeliveryScope { 49 public: CallbackDeliveryScope()50 CallbackDeliveryScope() 51 : m_savedElementQueueStart(s_elementQueueStart) 52 { 53 s_elementQueueStart = s_elementQueueEnd; 54 } 55 ~CallbackDeliveryScope()56 ~CallbackDeliveryScope() 57 { 58 if (s_elementQueueStart != s_elementQueueEnd) 59 processElementQueueAndPop(); 60 s_elementQueueStart = m_savedElementQueueStart; 61 } 62 63 private: 64 size_t m_savedElementQueueStart; 65 }; 66 67 // Returns true if more work may have to be performed at the 68 // checkpoint by this or other workers (for example, this work 69 // invoked author scripts) 70 bool dispatch(); 71 72 protected: 73 friend class CustomElementCallbackScheduler; 74 void enqueue(CustomElementCallbackQueue*); 75 76 private: CustomElementCallbackDispatcher()77 CustomElementCallbackDispatcher() 78 { 79 // Add a null element as a sentinel. This makes it possible to 80 // identify elements queued when there is no 81 // CallbackDeliveryScope active. Also, if the processing stack 82 // is popped when empty, this sentinel will cause a null deref 83 // crash. 84 CustomElementCallbackQueue* sentinel = 0; 85 for (size_t i = 0; i < kNumSentinels; i++) 86 m_flattenedProcessingStack.append(sentinel); 87 ASSERT(s_elementQueueEnd == m_flattenedProcessingStack.size()); 88 } 89 90 // The start of the element queue on the top of the processing 91 // stack. An offset into instance().m_flattenedProcessingStack. 92 static size_t s_elementQueueStart; 93 94 // The end of the element queue on the top of the processing 95 // stack. A cache of instance().m_flattenedProcessingStack.size(). 96 static size_t s_elementQueueEnd; 97 inCallbackDeliveryScope()98 static bool inCallbackDeliveryScope() { return s_elementQueueStart; } 99 100 typedef int ElementQueue; baseElementQueue()101 static ElementQueue baseElementQueue() { return ElementQueue(0); } currentElementQueue()102 static ElementQueue currentElementQueue() { return ElementQueue(s_elementQueueStart); } 103 104 static void processElementQueueAndPop(); 105 void processElementQueueAndPop(size_t start, size_t end); 106 107 // The base element queue, used when no CallbackDeliveryScope is 108 // active. Callbacks for elements created by the parser are 109 // enqueued here. 110 CustomElementBaseElementQueue m_baseElementQueue; 111 112 // The processing stack, flattened. Element queues lower in the 113 // stack appear toward the head of the vector. The first element 114 // is a null sentinel value. 115 static const size_t kNumSentinels = 1; 116 Vector<CustomElementCallbackQueue*> m_flattenedProcessingStack; 117 }; 118 119 } 120 121 #endif // CustomElementCallbackDispatcher_h 122