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 CustomElementProcessingStack_h 32 #define CustomElementProcessingStack_h 33 34 #include "core/dom/custom/CustomElementCallbackQueue.h" 35 #include "wtf/Vector.h" 36 37 namespace blink { 38 39 class CustomElementScheduler; 40 41 class CustomElementProcessingStack { 42 WTF_MAKE_NONCOPYABLE(CustomElementProcessingStack); 43 public: 44 // This is stack allocated in many DOM callbacks. Make it cheap. 45 class CallbackDeliveryScope { 46 public: CallbackDeliveryScope()47 CallbackDeliveryScope() 48 : m_savedElementQueueStart(s_elementQueueStart) 49 { 50 s_elementQueueStart = s_elementQueueEnd; 51 } 52 ~CallbackDeliveryScope()53 ~CallbackDeliveryScope() 54 { 55 if (s_elementQueueStart != s_elementQueueEnd) 56 processElementQueueAndPop(); 57 s_elementQueueStart = m_savedElementQueueStart; 58 } 59 60 private: 61 size_t m_savedElementQueueStart; 62 }; 63 inCallbackDeliveryScope()64 static bool inCallbackDeliveryScope() { return s_elementQueueStart; } 65 66 static CustomElementProcessingStack& instance(); 67 void enqueue(CustomElementCallbackQueue*); 68 69 private: CustomElementProcessingStack()70 CustomElementProcessingStack() 71 { 72 // Add a null element as a sentinel. This makes it possible to 73 // identify elements queued when there is no 74 // CallbackDeliveryScope active. Also, if the processing stack 75 // is popped when empty, this sentinel will cause a null deref 76 // crash. 77 CustomElementCallbackQueue* sentinel = 0; 78 for (size_t i = 0; i < kNumSentinels; i++) 79 m_flattenedProcessingStack.append(sentinel); 80 ASSERT(s_elementQueueEnd == m_flattenedProcessingStack.size()); 81 } 82 83 // The start of the element queue on the top of the processing 84 // stack. An offset into instance().m_flattenedProcessingStack. 85 static size_t s_elementQueueStart; 86 87 // The end of the element queue on the top of the processing 88 // stack. A cache of instance().m_flattenedProcessingStack.size(). 89 static size_t s_elementQueueEnd; 90 currentElementQueue()91 static CustomElementCallbackQueue::ElementQueueId currentElementQueue() { return CustomElementCallbackQueue::ElementQueueId(s_elementQueueStart); } 92 93 static void processElementQueueAndPop(); 94 void processElementQueueAndPop(size_t start, size_t end); 95 96 // The processing stack, flattened. Element queues lower in the 97 // stack appear toward the head of the vector. The first element 98 // is a null sentinel value. 99 static const size_t kNumSentinels = 1; 100 Vector<CustomElementCallbackQueue*> m_flattenedProcessingStack; 101 }; 102 103 } 104 105 #endif // CustomElementProcessingStack_h 106