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      1 /*
      2  * Copyright (C) 2012 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/shadow/SelectRuleFeatureSet.h"
     33 
     34 #include "core/css/CSSSelector.h"
     35 #include "core/css/CSSSelectorList.h"
     36 
     37 #include "wtf/BitVector.h"
     38 
     39 namespace blink {
     40 
     41 void SelectRuleFeatureSet::collectFeaturesFromSelector(const CSSSelector& selector)
     42 {
     43     for (const CSSSelector* current = &selector; current; current = current->tagHistory()) {
     44         if (invalidationSetForSelector(*current))
     45             continue;
     46 
     47         if (!current->selectorList())
     48             continue;
     49 
     50         for (const CSSSelector* selector = current->selectorList()->first(); selector; selector = CSSSelectorList::next(*selector))
     51             collectFeaturesFromSelector(*selector);
     52     }
     53 }
     54 
     55 bool SelectRuleFeatureSet::checkSelectorsForClassChange(const SpaceSplitString& changedClasses) const
     56 {
     57     unsigned changedSize = changedClasses.size();
     58     for (unsigned i = 0; i < changedSize; ++i) {
     59         if (hasSelectorForClass(changedClasses[i]))
     60             return true;
     61     }
     62     return false;
     63 }
     64 
     65 bool SelectRuleFeatureSet::checkSelectorsForClassChange(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses) const
     66 {
     67     if (!oldClasses.size())
     68         return checkSelectorsForClassChange(newClasses);
     69 
     70     // Class vectors tend to be very short. This is faster than using a hash table.
     71     BitVector remainingClassBits;
     72     remainingClassBits.ensureSize(oldClasses.size());
     73 
     74     for (unsigned i = 0; i < newClasses.size(); ++i) {
     75         bool found = false;
     76         for (unsigned j = 0; j < oldClasses.size(); ++j) {
     77             if (newClasses[i] == oldClasses[j]) {
     78                 // Mark each class that is still in the newClasses so we can skip doing
     79                 // an n^2 search below when looking for removals. We can't break from
     80                 // this loop early since a class can appear more than once.
     81                 remainingClassBits.quickSet(j);
     82                 found = true;
     83             }
     84         }
     85         // Class was added.
     86         if (!found) {
     87             if (hasSelectorForClass(newClasses[i]))
     88                 return true;
     89         }
     90     }
     91 
     92     for (unsigned i = 0; i < oldClasses.size(); ++i) {
     93         if (remainingClassBits.quickGet(i))
     94             continue;
     95 
     96         // Class was removed.
     97         if (hasSelectorForClass(oldClasses[i]))
     98             return true;
     99     }
    100     return false;
    101 }
    102 
    103 }
    104 
    105