/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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.karaf.packages.core.internal.filter;
import java.util.HashMap;
import java.util.Map;
public class ExprTokenizer {
private String expr;
private int currentPos;
String[] operators = {"(", ")", "!", "&", "=", ">="};
Map<Character, String> operatorMap;
public ExprTokenizer(String expr) {
this.expr = expr;
this.currentPos = 0;
operatorMap = new HashMap<Character, String>();
for (String operator : operators) {
operatorMap.put(operator.charAt(0), operator);
}
}
public String peekNextToken() {
int oldPos = currentPos;
String token = nextToken();
currentPos = oldPos;
return token;
}
public String nextToken() {
if (currentPos >= expr.length()) {
return null;
}
while (isWhiteSpace()) {
currentPos ++;
}
Character first = expr.charAt(currentPos);
String operator = operatorMap.get(first);
if (operator != null) {
currentPos += operator.length();
return operator;
}
int firstPos = currentPos;
while (currentPos < expr.length() && !operatorMap.containsKey(expr.charAt(currentPos)) && !isWhiteSpace()) {
currentPos ++;
}
return expr.substring(firstPos, currentPos);
}
private boolean isWhiteSpace() {
return expr.charAt(currentPos) == ' ';
}
public String toString() {
return expr.substring(currentPos);
}
}