flink-library-siddhi/src/test/java/org/apache/flink/streaming/siddhi/extension/CustomPlusFunctionExtension.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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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.flink.streaming.siddhi.extension;

import java.util.HashMap;
import java.util.Map;

import org.wso2.siddhi.core.config.SiddhiAppContext;
import org.wso2.siddhi.core.exception.SiddhiAppCreationException;
import org.wso2.siddhi.core.executor.ExpressionExecutor;
import org.wso2.siddhi.core.executor.function.FunctionExecutor;
import org.wso2.siddhi.core.util.config.ConfigReader;
import org.wso2.siddhi.query.api.definition.Attribute;

public class CustomPlusFunctionExtension extends FunctionExecutor {
    private Attribute.Type returnType;

    /**
     * The initialization method for FunctionExecutor, this method will be called before the other methods
     */
    @Override
    protected void init(ExpressionExecutor[] expressionExecutors, ConfigReader configReader, SiddhiAppContext siddhiAppContext) {
        for (ExpressionExecutor expressionExecutor : attributeExpressionExecutors) {
            Attribute.Type attributeType = expressionExecutor.getReturnType();
            if (attributeType == Attribute.Type.DOUBLE) {
                returnType = attributeType;

            } else if ((attributeType == Attribute.Type.STRING) || (attributeType == Attribute.Type.BOOL)) {
                throw new SiddhiAppCreationException("Plus cannot have parameters with types String or Bool");
            } else {
                returnType = Attribute.Type.LONG;
            }
        }
    }

    /**
     * The main execution method which will be called upon event arrival
     * when there are more then one function parameter
     *
     * @param data the runtime values of function parameters
     * @return the function result
     */
    @Override
    protected Object execute(Object[] data) {
        if (returnType == Attribute.Type.DOUBLE) {
            double total = 0;
            for (Object aObj : data) {
                total += Double.parseDouble(String.valueOf(aObj));
            }

            return total;
        } else {
            long total = 0;
            for (Object aObj : data) {
                total += Long.parseLong(String.valueOf(aObj));
            }
            return total;
        }
    }

    /**
     * The main execution method which will be called upon event arrival
     * when there are zero or one function parameter
     *
     * @param data null if the function parameter count is zero or
     *             runtime data value of the function parameter
     * @return the function result
     */
    @Override
    protected Object execute(Object data) {
        if (returnType == Attribute.Type.DOUBLE) {
            return Double.parseDouble(String.valueOf(data));
        } else {
            return Long.parseLong(String.valueOf(data));
        }
    }

    @Override
    public Attribute.Type getReturnType() {
        return returnType;
    }

    @Override
    public Map<String, Object> currentState() {
        return new HashMap<>();
    }

    @Override
    public void restoreState(Map<String, Object> map) {

    }
}