| // Copyright 2016 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "core/css/ActiveStyleSheets.h" |
| |
| #include "core/css/CSSStyleSheet.h" |
| #include "core/css/RuleSet.h" |
| |
| namespace blink { |
| |
| ActiveSheetsChange compareActiveStyleSheets(const ActiveStyleSheetVector& oldStyleSheets, |
| const ActiveStyleSheetVector& newStyleSheets, |
| HeapVector<Member<RuleSet>>& changedRuleSets) |
| { |
| unsigned newStyleSheetCount = newStyleSheets.size(); |
| unsigned oldStyleSheetCount = oldStyleSheets.size(); |
| |
| unsigned minCount = std::min(newStyleSheetCount, oldStyleSheetCount); |
| unsigned index = 0; |
| |
| // Walk the common prefix of stylesheets. If the stylesheet rules were |
| // modified since last time, add them to the list of changed rulesets. |
| for (; index < minCount && newStyleSheets[index].first == oldStyleSheets[index].first; index++) { |
| if (newStyleSheets[index].second == oldStyleSheets[index].second) |
| continue; |
| |
| changedRuleSets.append(newStyleSheets[index].second); |
| changedRuleSets.append(oldStyleSheets[index].second); |
| } |
| |
| if (index == oldStyleSheetCount) { |
| if (index == newStyleSheetCount) |
| return changedRuleSets.size() ? ActiveSheetsChanged : NoActiveSheetsChanged; |
| |
| // Sheets added at the end. |
| for (; index < newStyleSheetCount; index++) |
| changedRuleSets.append(newStyleSheets[index].second); |
| return ActiveSheetsAppended; |
| } |
| |
| if (index == newStyleSheetCount) { |
| // Sheets removed from the end. |
| for (; index < oldStyleSheetCount; index++) |
| changedRuleSets.append(oldStyleSheets[index].second); |
| return ActiveSheetsChanged; |
| } |
| |
| DCHECK(index < oldStyleSheetCount && index < newStyleSheetCount); |
| |
| // Both the new and old active stylesheet vectors have stylesheets following |
| // the common prefix. Figure out which were added or removed by sorting the |
| // merged vector of old and new sheets. |
| |
| ActiveStyleSheetVector mergedSorted; |
| mergedSorted.reserveCapacity(oldStyleSheetCount + newStyleSheetCount - 2 * index); |
| mergedSorted.appendRange(oldStyleSheets.begin() + index, oldStyleSheets.end()); |
| mergedSorted.appendRange(newStyleSheets.begin() + index, newStyleSheets.end()); |
| |
| std::sort(mergedSorted.begin(), mergedSorted.end()); |
| |
| auto mergedIterator = mergedSorted.begin(); |
| while (mergedIterator != mergedSorted.end()) { |
| |
| const auto& sheet1 = *mergedIterator++; |
| if (mergedIterator == mergedSorted.end() || (*mergedIterator).first != sheet1.first) { |
| // Sheet either removed or inserted. |
| changedRuleSets.append(sheet1.second); |
| continue; |
| } |
| |
| // Sheet present in both old and new. |
| const auto& sheet2 = *mergedIterator++; |
| |
| if (sheet1.second == sheet2.second) |
| continue; |
| |
| // Active rules for the given stylesheet changed. |
| // DOM, CSSOM, or media query changes. |
| changedRuleSets.append(sheet1.second); |
| changedRuleSets.append(sheet2.second); |
| } |
| return ActiveSheetsChanged; |
| } |
| |
| } // namespace blink |