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#include "config.h"
32#include "core/dom/CSSSelectorWatch.h"
33
34#include "core/css/CSSSelectorList.h"
35#include "core/css/StylePropertySet.h"
36#include "core/css/parser/CSSParser.h"
37#include "core/dom/Document.h"
38#include "core/dom/ExecutionContext.h"
39#include "core/frame/LocalFrame.h"
40#include "core/loader/FrameLoaderClient.h"
41#include "core/rendering/style/StyleRareNonInheritedData.h"
42
43namespace blink {
44
45// The address of this string is important; its value is just documentation.
46static const char kSupplementName[] = "CSSSelectorWatch";
47
48CSSSelectorWatch::CSSSelectorWatch(Document& document)
49    : m_document(document)
50    , m_callbackSelectorChangeTimer(this, &CSSSelectorWatch::callbackSelectorChangeTimerFired)
51    , m_timerExpirations(0)
52{
53}
54
55CSSSelectorWatch& CSSSelectorWatch::from(Document& document)
56{
57    CSSSelectorWatch* watch = static_cast<CSSSelectorWatch*>(DocumentSupplement::from(document, kSupplementName));
58    if (!watch) {
59        watch = new CSSSelectorWatch(document);
60        DocumentSupplement::provideTo(document, kSupplementName, adoptPtrWillBeNoop(watch));
61    }
62    return *watch;
63}
64
65void CSSSelectorWatch::callbackSelectorChangeTimerFired(Timer<CSSSelectorWatch>*)
66{
67    // Should be ensured by updateSelectorMatches():
68    ASSERT(!m_addedSelectors.isEmpty() || !m_removedSelectors.isEmpty());
69
70    if (m_timerExpirations < 1) {
71        m_timerExpirations++;
72        m_callbackSelectorChangeTimer.startOneShot(0, FROM_HERE);
73        return;
74    }
75    if (document().frame()) {
76        Vector<String> addedSelectors;
77        Vector<String> removedSelectors;
78        copyToVector(m_addedSelectors, addedSelectors);
79        copyToVector(m_removedSelectors, removedSelectors);
80        document().frame()->loader().client()->selectorMatchChanged(addedSelectors, removedSelectors);
81    }
82    m_addedSelectors.clear();
83    m_removedSelectors.clear();
84    m_timerExpirations = 0;
85}
86
87void CSSSelectorWatch::updateSelectorMatches(const Vector<String>& removedSelectors, const Vector<String>& addedSelectors)
88{
89    bool shouldUpdateTimer = false;
90
91    for (unsigned i = 0; i < removedSelectors.size(); ++i) {
92        const String& selector = removedSelectors[i];
93        if (!m_matchingCallbackSelectors.remove(selector))
94            continue;
95
96        // Count reached 0.
97        shouldUpdateTimer = true;
98        if (m_addedSelectors.contains(selector))
99            m_addedSelectors.remove(selector);
100        else
101            m_removedSelectors.add(selector);
102    }
103
104    for (unsigned i = 0; i < addedSelectors.size(); ++i) {
105        const String& selector = addedSelectors[i];
106        HashCountedSet<String>::AddResult result = m_matchingCallbackSelectors.add(selector);
107        if (!result.isNewEntry)
108            continue;
109
110        shouldUpdateTimer = true;
111        if (m_removedSelectors.contains(selector))
112            m_removedSelectors.remove(selector);
113        else
114            m_addedSelectors.add(selector);
115    }
116
117    if (!shouldUpdateTimer)
118        return;
119
120    if (m_removedSelectors.isEmpty() && m_addedSelectors.isEmpty()) {
121        if (m_callbackSelectorChangeTimer.isActive()) {
122            m_timerExpirations = 0;
123            m_callbackSelectorChangeTimer.stop();
124        }
125    } else {
126        m_timerExpirations = 0;
127        if (!m_callbackSelectorChangeTimer.isActive())
128            m_callbackSelectorChangeTimer.startOneShot(0, FROM_HERE);
129    }
130}
131
132static bool allCompound(const CSSSelectorList& selectorList)
133{
134    for (const CSSSelector* selector = selectorList.first(); selector; selector = selectorList.next(*selector)) {
135        if (!selector->isCompound())
136            return false;
137    }
138    return true;
139}
140
141void CSSSelectorWatch::watchCSSSelectors(const Vector<String>& selectors)
142{
143    m_watchedCallbackSelectors.clear();
144    CSSParser parser(CSSParserContext(UASheetMode, 0));
145
146    const RefPtrWillBeRawPtr<StylePropertySet> callbackPropertySet = ImmutableStylePropertySet::create(nullptr, 0, UASheetMode);
147
148    CSSSelectorList selectorList;
149    for (unsigned i = 0; i < selectors.size(); ++i) {
150        parser.parseSelector(selectors[i], selectorList);
151        if (!selectorList.isValid())
152            continue;
153
154        // Only accept Compound Selectors, since they're cheaper to match.
155        if (!allCompound(selectorList))
156            continue;
157
158        RefPtrWillBeRawPtr<StyleRule> rule = StyleRule::create();
159        rule->wrapperAdoptSelectorList(selectorList);
160        rule->setProperties(callbackPropertySet);
161        m_watchedCallbackSelectors.append(rule.release());
162    }
163    document().changedSelectorWatch();
164}
165
166void CSSSelectorWatch::trace(Visitor* visitor)
167{
168    visitor->trace(m_watchedCallbackSelectors);
169    visitor->trace(m_document);
170    DocumentSupplement::trace(visitor);
171}
172
173} // namespace blink
174