/**
* 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.hadoop.hive.ql.udf;
import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.hive.ql.exec.description;
/**
* UDF to extract a specific group identified by a java regex.
* Note that if a regexp has a backslash ('\'), then need to specify '\\'
* For example, regexp_extract('100-200', '(\\d+)-(\\d+)', 1) will return '100'
*/
@description(
name = "regexp_extract",
value = "_FUNC_(str, regexp[, idx]) - extracts a group that matches regexp",
extended = "Example:\n" +
" > SELECT _FUNC_('100-200', '(\\d+)-(\\d+)', 1) FROM src LIMIT 1;\n" +
" '100'"
)
public class UDFRegExpExtract extends UDF {
private static Log LOG = LogFactory.getLog(UDFRegExpExtract.class.getName());
private String lastRegex = null;
private Pattern p = null;
public UDFRegExpExtract() {
}
public String evaluate(String s, String regex, Integer extractIndex) {
if (s == null || regex == null) {
return null;
}
if (!regex.equals(lastRegex) || p == null) {
lastRegex = regex;
p = Pattern.compile(regex);
}
Matcher m = p.matcher(s);
if (m.find()) {
MatchResult mr = m.toMatchResult();
return mr.group(extractIndex);
}
return "";
}
public String evaluate(String s, String regex) {
return this.evaluate(s, regex, 1);
}
}