/*
* Copyright 2013 Julien Dramaix.
*
* 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.gss;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableList.Builder;
import com.google.common.collect.Queues;
import com.google.common.css.compiler.ast.CssBooleanExpressionNode;
import com.google.common.css.compiler.ast.CssBooleanExpressionNode.Type;
import com.google.common.css.compiler.ast.CssCompilerPass;
import com.google.common.css.compiler.ast.CssConditionalRuleNode;
import com.google.common.css.compiler.ast.CssValueNode;
import com.google.common.css.compiler.ast.DefaultTreeVisitor;
import com.google.common.css.compiler.ast.ErrorManager;
import com.google.common.css.compiler.ast.GssError;
import com.google.common.css.compiler.ast.MutatingVisitController;
import java.util.Deque;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class PermutationsCollector extends DefaultTreeVisitor implements CssCompilerPass {
private static final Pattern IS_FUNCTION = Pattern.compile("^is\\([\"']([^\"']*)[\"'](?:,[\"']([^\"']*)[\"'])?\\)$");
private static final String USER_AGENT_PERMUTATION = "user.agent";
private final MutatingVisitController delegate;
private final ErrorManager errorManager;
private Deque<CssBooleanExpressionNode> childrenStack;
private ImmutableList.Builder<String> permutationAxesListBuilder;
public PermutationsCollector(MutatingVisitController delegate, ErrorManager errorManager) {
this.delegate = delegate;
this.errorManager = errorManager;
}
@Override
public boolean enterConditionalRule(CssConditionalRuleNode node) {
// unfortunately the VisitController doesn't visit the children of a CssConditionalRuleNode
for (CssValueNode children : node.getChildren()) {
if (children instanceof CssBooleanExpressionNode) {
childrenStack.addFirst((CssBooleanExpressionNode) children);
}
}
while (!childrenStack.isEmpty()) {
CssBooleanExpressionNode visitingNode = childrenStack.pop();
visitBooleanExpression(visitingNode);
if (visitingNode.getLeft() != null) {
childrenStack.addFirst(visitingNode.getLeft());
}
if (visitingNode.getRight() != null) {
childrenStack.addFirst(visitingNode.getRight());
}
}
return true;
}
public List<String> getPermutationAxes() {
return permutationAxesListBuilder.build();
}
private void visitBooleanExpression(CssBooleanExpressionNode booleanExpressionNode) {
if (booleanExpressionNode.getType() == Type.CONSTANT && booleanExpressionNode.getValue() != null) {
Matcher m = IS_FUNCTION.matcher(booleanExpressionNode.getValue());
if (m.matches()) {
String permutationName = m.group(1);
String permutationValue = m.group(2);
if (permutationValue == null) {
permutationValue = permutationName;
permutationName = USER_AGENT_PERMUTATION;
}
booleanExpressionNode.setValue(permutationName + ":" + permutationValue);
permutationAxesListBuilder.add(permutationName);
} else {
GssError warning = new GssError("The expression [" + booleanExpressionNode.getValue() +
"] cannot be evaluated. It will be considered as false.",
booleanExpressionNode.getSourceCodeLocation());
errorManager.reportWarning(warning);
}
}
}
@Override
public void runPass() {
childrenStack = Queues.newArrayDeque();
permutationAxesListBuilder = new Builder<String>();
delegate.startVisit(this);
}
}