| /* |
| * 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.CssProperty; |
| import com.google.gwt.resources.css.ast.CssRule; |
| 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 identical content. |
| */ |
| public class MergeRulesByContentVisitor extends CssModVisitor { |
| private Map<String, CssRule> rulesByContents = 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) { |
| StringBuilder b = new StringBuilder(); |
| for (CssProperty p : x.getProperties()) { |
| b.append(p.getName()).append(":").append(p.getValues().getExpression()); |
| if (p.isImportant()) { |
| b.append("!important"); |
| } |
| } |
| |
| String content = b.toString(); |
| CssRule canonical = rulesByContents.get(content); |
| |
| // 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. |
| if (canonical != null) { |
| 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) { |
| canonical.getSelectors().addAll(x.getSelectors()); |
| ctx.removeMe(); |
| return false; |
| } |
| } |
| |
| rulesByContents.put(content, x); |
| rulesInOrder.add(x); |
| return false; |
| } |
| |
| private void visitInNewContext(List<CssNode> nodes) { |
| MergeRulesByContentVisitor v = new MergeRulesByContentVisitor(); |
| v.acceptWithInsertRemove(nodes); |
| rulesInOrder.addAll(v.rulesInOrder); |
| } |
| } |