plugins/org.eclipse.sirius.server.diagram.sprotty/src/org/eclipse/sirius/server/diagram/internal/interpreter/SiriusServerInterpreter.java

/*******************************************************************************
 * Copyright (c) 2018, 2019 Obeo
 * 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
 *
 * Contributors:
 *    Obeo - initial API and implementation
 *******************************************************************************/
package org.eclipse.sirius.server.diagram.internal.interpreter;

import java.util.Collection;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;
import java.util.Set;

import org.eclipse.emf.common.util.BasicDiagnostic;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.transaction.RecordingCommand;
import org.eclipse.emf.transaction.TransactionalEditingDomain;
import org.eclipse.sirius.business.api.session.Session;
import org.eclipse.sirius.common.interpreter.api.EvaluationResult;
import org.eclipse.sirius.common.interpreter.api.IEvaluationResult;
import org.eclipse.sirius.common.tools.api.interpreter.EvaluationException;
import org.eclipse.sirius.common.tools.api.interpreter.IInterpreter;

/**
 * Provides an implementation of {@link IInterpreter} backed by an old-style {@link IInterpreterWithDiagnostic}.
 *
 * @author pcdavid
 */
public class SiriusServerInterpreter implements org.eclipse.sirius.common.interpreter.api.IInterpreter {

	private IInterpreter interpreter;

	/**
	 * The constructor.
	 *
	 * @param session
	 *            The Sirius session
	 */
	public SiriusServerInterpreter(Session session) {
		this(session.getInterpreter());
	}

	/**
	 * The constructor.
	 *
	 * @param interpreterWithDiagnostic
	 *            An interpreter
	 */
	public SiriusServerInterpreter(IInterpreter interpreterWithDiagnostic) {
		this.interpreter = Objects.requireNonNull(interpreterWithDiagnostic);
	}

	@Override
	public IEvaluationResult evaluateExpression(Map<String, Object> variables, String expr) {
		IEvaluationResult result = EvaluationResult.noEvaluation();
		Object self = variables.get("self"); //$NON-NLS-1$
		if (self instanceof EObject) {
			try {
				setupInterpreter(variables);

				org.eclipse.sirius.common.tools.api.interpreter.IEvaluationResult evaluationResult = this.interpreter
						.evaluateExpression((EObject) self, expr);
				result = EvaluationResult.of(evaluationResult.getValue(), evaluationResult.getDiagnostic());
			} catch (EvaluationException e) {
				result = EvaluationResult.withError(BasicDiagnostic.toDiagnostic(e));
			} finally {
				tearDownInterpreter(variables);
			}
		}
		return result;
	}

	private void setupInterpreter(Map<String, Object> variables) {
		org.eclipse.sirius.common.tools.api.interpreter.IInterpreter i = this.interpreter;
		i.addImport(SiriusServerServices.class.getName());
		declareLocals(variables, i);
	}

	private void declareLocals(Map<String, Object> variables, org.eclipse.sirius.common.tools.api.interpreter.IInterpreter i) {
		Set<Entry<String, Object>> entries = variables.entrySet();
		for (Entry<String, Object> entry : entries) {
			i.setVariable(entry.getKey(), entry.getValue());
		}
	}

	private void tearDownInterpreter(Map<String, Object> variables) {
		unsetLocals(variables, this.interpreter);
	}

	private void unsetLocals(Map<String, Object> variables, org.eclipse.sirius.common.tools.api.interpreter.IInterpreter i) {
		Set<Entry<String, Object>> entries = variables.entrySet();
		for (Entry<String, Object> entry : entries) {
			i.unSetVariable(entry.getKey());
		}
	}

	public static Collection<?> executeExpression(Session session, Map<String, Object> variables, String expression) {
		TransactionalEditingDomain ted = session.getTransactionalEditingDomain();
		RecordingCommand cmd = new RecordingCommand(ted) {
			@Override
			protected void doExecute() {
				new SiriusServerInterpreter(session).evaluateExpression(variables, expression);
			}
		};
		ted.getCommandStack().execute(cmd);
		return cmd.getResult();
	}

}