third_party/WebKit/Source/core/dom/CSSSelectorWatch.cpp

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