/*
* Copyright (c) 2005-2010, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
*
* WSO2 Inc. licenses this file to you 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 org.apache.synapse.commons.templates.uri.parser;
import org.apache.synapse.commons.templates.uri.URITemplateException;
public class URITemplateParser {
private static final char[] operators = new char[] { '+', '.', '/', ';', '?', '&', '#' };
private Node syntaxTree;
private Node currentNode;
public Node parse(String template) throws URITemplateException {
if (!"/".equals(template) && template.endsWith("/")) {
template = template.substring(0, template.length() - 1);
}
boolean expression = false;
int startIndex = 0;
int maxIndex = template.length() - 1;
for (int pointerIndex = 0; pointerIndex < template.length(); pointerIndex++) {
char ch = template.charAt(pointerIndex);
switch (ch) {
case '{':
if (!expression) {
if (pointerIndex + 1 >= maxIndex) {
throw new URITemplateException("Illegal open brace character");
}
expression = true;
if (pointerIndex > startIndex) {
addNode(new Literal(template.substring(startIndex, pointerIndex)));
startIndex = pointerIndex + 1;
} else if (template.charAt(pointerIndex - 1) != '}') {
throw new URITemplateException("Illegal empty literal");
} else {
startIndex++;
}
} else {
throw new URITemplateException("Already in expression");
}
break;
case '}':
if (expression) {
expression = false;
if (pointerIndex > startIndex) {
createExpressionNode(template.substring(startIndex, pointerIndex));
startIndex = pointerIndex + 1;
} else {
throw new URITemplateException("Illegal empty expression");
}
} else {
throw new URITemplateException("Illegal closing brace detected");
}
break;
default:
if (pointerIndex == maxIndex) {
String token = template.substring(startIndex);
if (expression) {
createExpressionNode(token);
} else {
addNode(new Literal(token));
}
}
}
}
return syntaxTree;
}
private void addNode(Node node) {
if (syntaxTree == null) {
syntaxTree = node;
currentNode = syntaxTree;
} else {
currentNode.setNext(node);
currentNode = node;
}
}
private void createExpressionNode(String expression) throws URITemplateException {
Node node = null;
if (isSimpleString(expression)) {
node = new SimpleStringExpression(expression);
}
if (expression.length() <= 1) {
throw new URITemplateException("Invalid template expression: {" + expression + "}");
}
if (expression.startsWith("#")) {
node = new FragmentExpression(expression.substring(1));
} else if (expression.startsWith("+")) {
node = new ReservedStringExpression(expression.substring(1));
} else if (expression.startsWith(".")) {
node = new LabelExpression(expression.substring(1));
} else if (expression.startsWith("/")) {
node = new PathSegmentExpression(expression.substring(1));
}
if (node != null) {
addNode(node);
} else {
throw new URITemplateException("Unsupported template expression: {" + expression + "}");
}
}
private boolean isSimpleString(String expression) {
for (char op : operators) {
if (expression.indexOf(op) == 0) {
return false;
}
}
return true;
}
}