scripting/bundles/org.eclipse.papyrus.moka.ease/src/org/eclipse/papyrus/moka/ease/semantics/proxy/LoggedValue.java

/*****************************************************************************
 * Copyright (c) 2018 CEA LIST
 * 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
    
 *****************************************************************************/
package org.eclipse.papyrus.moka.ease.semantics.proxy;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.List;

/**
 *This class is used to hold the reference to a Locus object and access to a given feature value of this object.
 *It will copy and append the current value of this feature into the "values" list when "logValue" is called.
 * It provides a getByteArray method for Double or Integer values allowing efficient data transfer between
 * java and python.
 */
public class LoggedValue {
	private static final String DOUBLE_TYPE = "Double";
	private static final String INTEGER_TYPE = "Integer";
	public String alias;
	public MapProxy context;
	public String loggedFeature;
	public List<Object> values = new ArrayList<>();
	 
	String[] path;
	
	public LoggedValue() {
		
	}


	
	/**
	 * @param variablePath : "." separated feature path starting from the context object
	 * @param alias : alias used for this variable in the log
	 * @param context : root object from which feature path is computed
	 */
	public LoggedValue(String variablePath, String alias, MapProxy context) {
		this.alias = alias;
		path = variablePath.split("\\.");
		this.context = context;
		loggedFeature = path[path.length - 1];
	}

	
	/**
	 * Gets the current locus object and feature and returns its value.
	 *  The locus object as to be found for each call to getValue since it can change during the simulation 
	 * @return : the current value of the logged feature
	 */
	public Object getValue() {
		MapProxy owningProxy = context;
		for (int i = 0; i < path.length - 1; i++) {
			owningProxy = (MapProxy) owningProxy.get(path[i]);
		}
		return owningProxy.get(loggedFeature);
	}

	/**
	 * Get the current value and puts it in the values list
	 */
	public void logValue() {
		 values.add(getValue());
	}

	/**
	 * Function returning the values collection as a byte array, for java to python performance optimization
	 * Only works for Integer and Double types.
	 * Warning, the collection has to be homogeneous, if is it contains a mix of Double and Integer, data will be corrupted.
	 * 
	 * @return a Byte array representation of the collection
	 */
	public byte[] getByteArray() {
		int typeSize = 0;
		if (DOUBLE_TYPE.equals(getType())) {
			typeSize = Double.BYTES;
		} else if (INTEGER_TYPE.equals(getType())) {
			typeSize = Integer.BYTES;
		}

		if (typeSize != 0) {
			ByteBuffer byteBuffer = ByteBuffer.allocate(typeSize * values.size());

			byteBuffer.order(ByteOrder.LITTLE_ENDIAN);
			if (DOUBLE_TYPE.equals(getType())){
				for (Object obj : values) {
					byteBuffer.putDouble((double) obj);
				}
			}else {
				for (Object obj : values) {
					byteBuffer.putInt((int) obj);
				}
			}
			

			byte[] byteArray = byteBuffer.array();
			return byteArray;
		} else {
			return null;
		}

	}
	
	/**
	 * @return the alias of the logged feature value
	 */
	public String getAlias() {
		return alias;
	}

	/**
	 * This function returns the collection of recorded values.
	 * It can be directly called from Python, but will be about 50 times slower than {@link #getByteArray()} to initialize numpy arrays  
	 * @return the list of values
	 */
	public List<Object> getValues() {
		return values;
	}

	/**
	 * Tries to guess the type of the logged object using the first object of the values list.
	 * This function will be used from python side to know if we can use the {@link #getByteArray()} to initialize numpy arrays
	 * @return : "Double", "Integer" or "Object" 
	 */
	public String getType() {
		if (!values.isEmpty()) {
			Object first = values.get(0);
			if (first instanceof Double) {
				return DOUBLE_TYPE;
			} else if (first instanceof Integer) {
				return INTEGER_TYPE;
			}
			
		}
		return "Object";
	}
}