org.pragmaticminds.crunch.api.trigger.strategy.TriggerStrategies Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of crunch-api Show documentation
Programing Interfaces for other CRUNCH Projects.
The newest version!
/*
 * 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.pragmaticminds.crunch.api.trigger.strategy;

import org.pragmaticminds.crunch.api.records.MRecord;
import org.pragmaticminds.crunch.api.trigger.comparator.Supplier;
import org.pragmaticminds.crunch.api.values.TypedValues;

import java.io.Serializable;
import java.util.HashSet;


/**
 * A collection of {@link TriggerStrategy}s for boolean decision making.
 *
 * @author Erwin Wagasow
 * Created by Erwin Wagasow on 13.08.2018
 */
public class TriggerStrategies {
    private TriggerStrategies() { /* does nothing */}

    /**
     * This method triggers always on supplied value = true
     * @param supplier extracts the relevant values from a {@link TypedValues}
     * @return true if triggered
     */
    public static TriggerStrategy onTrue(Supplier supplier){
        return new LambdaTriggerStrategy(
                values -> supplier.extract(values) != null && supplier.extract(values),
                () -> new HashSet<>(supplier.getChannelIdentifiers())
        );
    }

    /**
     * This method triggers always on supplied value = false
     * @param supplier extracts the relevant values from a {@link TypedValues}
     * @return true if triggered, false if not or supplied value is null
     */
    public static TriggerStrategy onFalse(Supplier supplier){
        return new LambdaTriggerStrategy(
                values ->
                        // null check
                        supplier.extract(values) != null
                                // on false check
                                && !supplier.extract(values),
                () -> new HashSet<>(supplier.getChannelIdentifiers())
        );
    }

    /**
     * This method triggers on supplied value = true and the last supplied value = false
     * @param supplier extracts the relevant values from a {@link TypedValues}
     * @return true if triggered
     */
    public static TriggerStrategy onBecomeTrue(Supplier supplier){
        return onBecomeTrue(supplier, null);
    }

    /**
     * This method triggers on supplied value = true and the last supplied value = false
     * @param supplier extracts the relevant values from a {@link TypedValues}
     * @param initialValue the first value to compare with
     * @return true if triggered
     */
    public static TriggerStrategy onBecomeTrue(Supplier supplier, Boolean initialValue){
        return new MemoryTriggerStrategy(supplier, 1, initialValue) {
            @Override
            public boolean isToBeTriggered(Boolean decisionBase) {
                return
                        // null check
                        decisionBase != null
                                // condition check
                                && !lastDecisionBases.isEmpty() && !lastDecisionBases.get(0) && decisionBase;
            }
        };
    }

    /**
     * This method triggers on supplied value = false and the last supplied value = true
     * @param supplier extracts the relevant values from a {@link TypedValues}
     * @return true if triggered
     */
    public static TriggerStrategy onBecomeFalse(Supplier supplier){
        return onBecomeFalse(supplier, null);
    }

    /**
     * This method triggers on supplied value = false and the last supplied value = true
     * @param supplier extracts the relevant values from a {@link TypedValues}
     * @param initialValue the first value to compare with
     * @return true if triggered
     */
    public static TriggerStrategy onBecomeFalse(Supplier supplier, Boolean initialValue){
        return new MemoryTriggerStrategy(supplier, 1, initialValue) {
            @Override
            public boolean isToBeTriggered(Boolean decisionBase) {
                return
                        // null check
                        decisionBase != null
                                // condition check
                                && !lastDecisionBases.isEmpty() && lastDecisionBases.get(0) && !decisionBase;
            }
        };
    }

    /**
     * This method triggers on supplied value != last supplied value
     * @param supplier extracts the relevant values from a {@link TypedValues}
     * @return true if triggered
     */
    public static  TriggerStrategy onChange(Supplier supplier){
        return onChange(supplier, null);
    }

    /**
     * This method triggers on supplied value != last supplied value
     * @param supplier extracts the relevant values from a {@link TypedValues}
     * @param initialValue the first value to compare with
     * @return true if triggered
     */
    public static  TriggerStrategy onChange(Supplier supplier, T initialValue){
        return new MemoryTriggerStrategy(supplier, 1, initialValue) {
            /**
             * This method is to be implemented by the user of this class, with the final decision making.
             *
             * @param decisionBase the extracted value
             * @return true if triggered, otherwise false
             */
            @Override
            public boolean isToBeTriggered(T decisionBase) {
                return
                        // null check
                        decisionBase != null
                                // condition check
                                && !lastDecisionBases.isEmpty() && !lastDecisionBases.get(0).equals(decisionBase);
            }
        };
    }

    /**
     * This method triggers on supplied value is not available
     * @param supplier extracts the relevant values from a {@link MRecord}
     * @param  type of the Supplier
     * @return true if triggered
     */
    public static  TriggerStrategy onNull(Supplier supplier){
        return new LambdaTriggerStrategy(
                values -> supplier.extract(values) == null,
                () -> new HashSet<>(supplier.getChannelIdentifiers())
        );
    }

    /**
     * This method triggers on supplied value is available
     * @param supplier extracts the relevant values from a {@link MRecord}
     * @param  type of the Supplier
     * @return true if triggered
     */
    public static  TriggerStrategy onNotNull(Supplier supplier){
        return new LambdaTriggerStrategy(
                values -> supplier.extract(values) != null,
                () -> new HashSet<>(supplier.getChannelIdentifiers())
        );
    }

    /**
     * This method triggers always
     * @return always true
     */
    public static TriggerStrategy always(){
        return new LambdaTriggerStrategy(
                values -> true, HashSet::new
        );
    }
}