eagle-core/eagle-query/eagle-query-base/src/main/java/org/apache/eagle/query/aggregate/AggregateFunctionType.java

/*
 * 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.eagle.query.aggregate;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public enum AggregateFunctionType {
    count("^(count)$"),
    sum("^sum\\((.*)\\)$"),
    avg("^avg\\((.*)\\)$"),
    max("^max\\((.*)\\)$"),
    min("^min\\((.*)\\)$");

    private Pattern pattern;
    private AggregateFunctionType(String patternString) {
        this.pattern = Pattern.compile(patternString);
    }

    /**
     * This method is thread safe
     * match and retrieve back the aggregated fields, for count, aggregateFields can be null
     * @param function
     * @return
     */
    public AggregateFunctionTypeMatcher matcher(String function) {
        Matcher m = pattern.matcher(function);

        if (m.find()) {
            return new AggregateFunctionTypeMatcher(this, true, m.group(1));
        } else {
            return new AggregateFunctionTypeMatcher(this, false, null);
        }
    }

    public static AggregateFunctionTypeMatcher matchAll(String function) {
        for (AggregateFunctionType type : values()) {
            Matcher m = type.pattern.matcher(function);
            if (m.find()) {
                return new AggregateFunctionTypeMatcher(type, true, m.group(1));
            }
        }
        return new AggregateFunctionTypeMatcher(null, false, null);
    }

    public static byte[] serialize(AggregateFunctionType type) {
        return type.name().getBytes();
    }

    public static AggregateFunctionType deserialize(byte[] type) {
        return valueOf(new String(type));
    }

    public static List<byte[]> toBytesList(List<AggregateFunctionType> types) {
        List<byte[]> result = new ArrayList<byte[]>();
        for (AggregateFunctionType type:types) {
            result.add(serialize(type));
        }
        return result;
    }

    public static List<AggregateFunctionType> fromBytesList(List<byte[]> types) {
        List<AggregateFunctionType> result = new ArrayList<AggregateFunctionType>();
        for (byte[] bs:types) {
            result.add(deserialize(bs));
        }
        return result;
    }
}