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
37namespace blink {
38
39class CustomElementScheduler;
40
41class CustomElementProcessingStack {
42    WTF_MAKE_NONCOPYABLE(CustomElementProcessingStack);
43public:
44    // This is stack allocated in many DOM callbacks. Make it cheap.
45    class CallbackDeliveryScope {
46    public:
47        CallbackDeliveryScope()
48            : m_savedElementQueueStart(s_elementQueueStart)
49        {
50            s_elementQueueStart = s_elementQueueEnd;
51        }
52
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
64    static bool inCallbackDeliveryScope() { return s_elementQueueStart; }
65
66    static CustomElementProcessingStack& instance();
67    void enqueue(CustomElementCallbackQueue*);
68
69private:
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
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