Java tutorial
/* * Copyright 2000-2013 Vaadin Ltd. * * 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.vaadin.sass.internal.visitor; import java.util.ArrayList; import java.util.regex.Matcher; import java.util.regex.Pattern; import org.apache.commons.jexl2.Expression; import org.apache.commons.jexl2.JexlEngine; import org.apache.commons.jexl2.JexlException; import org.w3c.flute.parser.ParseException; import com.vaadin.sass.internal.tree.Node; import com.vaadin.sass.internal.tree.controldirective.ElseNode; import com.vaadin.sass.internal.tree.controldirective.IfElseDefNode; import com.vaadin.sass.internal.tree.controldirective.IfElseNode; import com.vaadin.sass.internal.tree.controldirective.IfNode; public class IfElseNodeHandler { private static final JexlEngine evaluator = new JexlEngine(); private static final Pattern pattern = Pattern.compile("[a-zA-Z0-9]*[a-zA-Z]+[a-zA-Z0-9]*"); public static void traverse(IfElseDefNode node) throws Exception { for (final Node child : node.getChildren()) { if (child instanceof IfNode) { try { String expression = ((IfElseNode) child).getExpression(); // We need to add ' ' for strings in the expression for // jexl to understand that is should do a string // comparison expression = replaceStrings(expression); Expression e = evaluator.createExpression(expression); try { Object eval = e.evaluate(null); Boolean result = false; if (eval instanceof Boolean) { result = (Boolean) eval; } else if (eval instanceof String) { result = Boolean.valueOf((String) eval); } if (result) { replaceDefNodeWithCorrectChild(node, node.getParentNode(), child); break; } } catch (ClassCastException ex) { throw new ParseException( "Invalid @if/@else in scss file, not a boolean expression : " + child.toString()); } catch (NullPointerException ex) { throw new ParseException( "Invalid @if/@else in scss file, not a boolean expression : " + child.toString()); } } catch (JexlException e) { throw new ParseException("Invalid @if/@else in scss file for " + child.toString()); } } else { if (!(child instanceof ElseNode) && node.getChildren().indexOf(child) == node.getChildren().size() - 1) { throw new ParseException("Invalid @if/@else in scss file for " + node); } else { replaceDefNodeWithCorrectChild(node, node.getParentNode(), child); break; } } } node.getParentNode().removeChild(node); } private static String replaceStrings(String expression) { expression = expression.replaceAll("\"", ""); Matcher m = pattern.matcher(expression); StringBuffer b = new StringBuffer(); while (m.find()) { String group = m.group(); m.appendReplacement(b, "'" + group + "'"); } m.appendTail(b); if (b.length() != 0) { return b.toString(); } return expression; } private static void replaceDefNodeWithCorrectChild(IfElseDefNode defNode, Node parent, final Node child) { for (final Node n : new ArrayList<Node>(child.getChildren())) { parent.appendChild(n, defNode); } } }