001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *      http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.oozie.util;
019    
020    import java.util.regex.Matcher;
021    import java.util.regex.Pattern;
022    
023    /**
024     * Class for rule mapping
025     */
026    public class MappingRule {
027    
028        private static Pattern variableNamePattern = Pattern.compile("\\$\\{[0-9]\\}");
029        private Pattern fromPattern;
030        private String fromString;
031        private String toString;
032        private boolean patternMatch;
033    
034        /**
035         * Maps from source rule to destination rule
036         * @param fromRule - Rule for which input needs to be matched
037         * @param toRule - Rule for value to be returned
038         */
039        public MappingRule(String fromRule, String toRule) {
040            if (fromRule.contains("$")) {
041                patternMatch = true;
042                fromRule = fromRule.replaceAll("\\.", "\\\\.");
043                Matcher match = variableNamePattern.matcher(fromRule);
044                fromRule = match.replaceAll("(.*)");
045                fromPattern = Pattern.compile(fromRule);
046            }
047            else {
048                fromString = fromRule;
049            }
050            toString = toRule;
051        }
052    
053        /**
054         * Gets the from rule
055         * @return
056         */
057        public String getFromRule() {
058            return fromString;
059        }
060    
061        /**
062         * Gets the to rule
063         * @return
064         */
065        public String getToRule() {
066            return toString;
067        }
068    
069        /**
070         * Applies rules based on the input
071         * @param input
072         * @return
073         */
074        public String applyRule(String input) {
075            if (patternMatch) {
076                Matcher match = fromPattern.matcher(input);
077                if (match.matches()) {
078                    String result = toString;
079                    int count = match.groupCount();
080                    for (int i = 1; i <= count; i++) {
081                        result = result.replace("${" + (i) + "}", match.group(i));
082                    }
083                    return result;
084                }
085            }
086            else if (input.equals(fromString)) {
087                return toString;
088            }
089            return null;
090        }
091    }