| /* |
| * Copyright 2009 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| * use this file except in compliance with the License. You may obtain a copy of |
| * the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| * License for the specific language governing permissions and limitations under |
| * the License. |
| */ |
| package com.google.gwt.resources.css; |
| |
| import com.google.gwt.resources.css.ast.Context; |
| import com.google.gwt.resources.css.ast.CssIf; |
| import com.google.gwt.resources.css.ast.CssMediaRule; |
| import com.google.gwt.resources.css.ast.CssModVisitor; |
| import com.google.gwt.resources.css.ast.CssNode; |
| import com.google.gwt.resources.css.ast.CssRule; |
| import com.google.gwt.resources.css.ast.CssSelector; |
| import com.google.gwt.resources.rg.CssResourceGenerator; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| |
| /** |
| * Merges rules that have matching selectors. |
| */ |
| public class MergeIdenticalSelectorsVisitor extends CssModVisitor { |
| private final Map<String, CssRule> canonicalRules = new HashMap<String, CssRule>(); |
| private final List<CssRule> rulesInOrder = new ArrayList<CssRule>(); |
| |
| @Override |
| public boolean visit(CssIf x, Context ctx) { |
| visitInNewContext(x.getNodes()); |
| visitInNewContext(x.getElseNodes()); |
| return false; |
| } |
| |
| @Override |
| public boolean visit(CssMediaRule x, Context ctx) { |
| visitInNewContext(x.getNodes()); |
| return false; |
| } |
| |
| @Override |
| public boolean visit(CssRule x, Context ctx) { |
| // Assumed to run immediately after SplitRulesVisitor |
| assert x.getSelectors().size() == 1; |
| CssSelector sel = x.getSelectors().get(0); |
| |
| if (canonicalRules.containsKey(sel.getSelector())) { |
| CssRule canonical = canonicalRules.get(sel.getSelector()); |
| |
| // Check everything between the canonical rule and this rule for common |
| // properties. If there are common properties, it would be unsafe to |
| // promote the rule. |
| boolean hasCommon = false; |
| int index = rulesInOrder.indexOf(canonical) + 1; |
| assert index != 0; |
| |
| for (Iterator<CssRule> i = rulesInOrder.listIterator(index); i.hasNext() |
| && !hasCommon;) { |
| hasCommon = CssResourceGenerator.haveCommonProperties(i.next(), x); |
| } |
| |
| if (!hasCommon) { |
| // It's safe to promote the rule |
| canonical.getProperties().addAll(x.getProperties()); |
| ctx.removeMe(); |
| return false; |
| } |
| } |
| |
| canonicalRules.put(sel.getSelector(), x); |
| rulesInOrder.add(x); |
| return false; |
| } |
| |
| private void visitInNewContext(List<CssNode> nodes) { |
| MergeIdenticalSelectorsVisitor v = new MergeIdenticalSelectorsVisitor(); |
| v.acceptWithInsertRemove(nodes); |
| rulesInOrder.addAll(v.rulesInOrder); |
| } |
| } |