plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvts2qvts/checks/CheckedCondition.java

/*******************************************************************************
 * Copyright (c) 2015, 2018 Willink Transformations and others.
 * All rights reserved.   This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v20.html
 *
 * Contributors:
 *   E.D.Willink - Initial API and implementation
 *******************************************************************************/
package org.eclipse.qvtd.compiler.internal.qvts2qvts.checks;

import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;
import org.eclipse.qvtd.pivot.qvtschedule.Edge;
import org.eclipse.qvtd.pivot.qvtschedule.Node;

/**
 * A CheckedCondition identifies a possible micromapping failure mechanism.
 *
 * Trace synthesis determines whether a success property is needed according to the presence of possible failures.
 *
 * Speculation determines whether checks require run-time evaluation.
 *
 * QVTi synthesis prioritises easily computed CheckedConditions to minimize the wasted effort in computing failures.
 */
public abstract class CheckedCondition implements Comparable<@NonNull CheckedCondition>
{
	/**
	 * CheckPriority defines an ordering criterion for sorting equal weight CheckedCondition instances
	 * in a lowest priority last order.
	 */
	protected enum CheckPriority {
		LOCAL_SUCCESS_EDGE,
		GLOBAL_SUCCESS_EDGE,
		CONSTANT_TARGET,
		LOWEST_PRIORITY
	}

	/**
	 * Return the result of invoking the derived-class-specific visitor method.
	 */
	public abstract <R> R accept(@NonNull CheckedConditionVisitor<R> visitor);

	/**
	 * CheckedCondition with a non-null getCheckPriority() are compared by that prioritu, else
	 * they are compared by their class names else by their toString() values.
	 */
	@Override
	public int compareTo(@NonNull CheckedCondition that) {
		CheckPriority thisPriority = getCheckPriority();
		CheckPriority thatPriority = that.getCheckPriority();
		int thisOrdinal = thisPriority.ordinal();
		int thatOrdinal = thatPriority.ordinal();
		if (thisOrdinal != thatOrdinal) {
			return thisOrdinal - thatOrdinal;
		}
		Class<?> thisClass = this.getClass();
		Class<?> thatClass = that.getClass();
		if (thisClass != thatClass) {
			return thisClass.getName().compareTo(thatClass.getName());
		}
		String thisString = this.toString();
		String thatString = that.toString();
		return thisString.compareTo(thatString);
	}

	@Override
	public abstract boolean equals(Object obj);

	/**
	 * Return a list of edges that contribute to the check, null for none.
	 */
	public @Nullable Iterable<@NonNull Edge> getEdges() {
		return null;
	}

	/**
	 * Return the node that contributes to the check, null for none.
	 */
	public @Nullable Node getNode() {
		return null;
	}

	protected @NonNull CheckPriority getCheckPriority() {
		return CheckPriority.LOWEST_PRIORITY;
	}

	@Override
	public abstract int hashCode();

	@Override
	public @NonNull String toString() {
		StringBuilder s = new StringBuilder();
		s.append(getClass().getSimpleName());
		s.append("(");
		boolean isFirst = true;
		Iterable<@NonNull Edge> edges = getEdges();
		if (edges != null) {
			for (@NonNull Edge edge : edges) {
				if (!isFirst) {
					s.append(",");
				}
				s.append(edge.getDisplayName());
				isFirst = false;
			}
		}
		Node node = getNode();
		if (node != null) {
			if (!isFirst) {
				s.append(",");
			}
			s.append(node.getDisplayName());
			isFirst = false;
		}
		s.append(")");
		return s.toString();
	}
}