/*
* 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.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.regex;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class NonConstantRegex implements RegexImpl {
private Pattern pattern = null;
private String oldString = null;
private Matcher matcher = null;
@Override
public boolean match(String lhs, String rhs) {
// We first check for length so the comparison is faster
// and then we directly check for difference.
// I havent used equals as first two comparisons,
// same Object and isInstanceOf does not apply in this case.
if( oldString == null
|| rhs.length() != oldString.length()
|| rhs.compareTo(oldString) != 0 ) {
oldString = rhs;
pattern = Pattern.compile(oldString);
matcher = pattern.matcher(lhs);
} else {
matcher.reset( lhs );
}
return matcher.matches();
}
}