AsDeepAsPossible.java

/*
 * Copyright (c) 2012 Data Harmonisation Panel
 * 
 * All rights reserved. This program and the accompanying materials are made
 * available under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution. If not, see <http://www.gnu.org/licenses/>.
 * 
 * Contributors:
 *     HUMBOLDT EU Integrated Project #030962
 *     Data Harmonisation Panel <http://www.dhpanel.eu>
 */

package eu.esdihumboldt.hale.common.align.model.transformation.tree.context.impl.matcher;

import java.util.Stack;

import eu.esdihumboldt.hale.common.align.model.transformation.tree.SourceNode;
import eu.esdihumboldt.hale.common.align.model.transformation.tree.TargetNode;
import eu.esdihumboldt.hale.common.align.model.transformation.tree.TransformationNodeVisitor;
import eu.esdihumboldt.hale.common.align.model.transformation.tree.TransformationTree;
import eu.esdihumboldt.hale.common.align.model.transformation.tree.context.ContextMatcher;
import eu.esdihumboldt.hale.common.align.model.transformation.tree.context.TransformationContext;
import eu.esdihumboldt.hale.common.align.model.transformation.tree.context.impl.TargetContext;
import eu.esdihumboldt.hale.common.align.model.transformation.tree.visitor.AbstractTargetToSourceVisitor;
import eu.esdihumboldt.hale.common.core.service.ServiceProvider;
import eu.esdihumboldt.hale.common.schema.model.ChildDefinition;
import eu.esdihumboldt.hale.common.schema.model.DefinitionUtil;
import eu.esdihumboldt.hale.common.schema.model.constraint.property.Cardinality;

/**
 * Simple context matching strategy that looks for connected
 * 
 * @author Simon Templer
 */
public class AsDeepAsPossible implements ContextMatcher {

	/**
	 * Builds a stack of target node candidates that while traversing the
	 * transformation tree, assigning the last candidate to source nodes as a
	 * transformation context.
	 */
	private class ContextVisitor extends AbstractTargetToSourceVisitor {

		private final Stack<TargetNode> candidates = new Stack<TargetNode>();

		@Override
		public boolean visit(TargetNode target) {
			if (isCandidate(target)) {
				candidates.push(target);
			}
			return true;
		}

		@Override
		public void leave(TargetNode target) {
			if (isCandidate(target)) {
				candidates.pop();
			}
		}

		@Override
		public boolean visit(SourceNode source) {
			if (!candidates.isEmpty()) {
				// Do not always override the context information!
				// Each path leading to this source can have different
				// candidates.
				TransformationContext context = source.getContext();
				if (context == null) {
					TargetContext newContext = new TargetContext(serviceProvider);
					source.setContext(newContext);
					newContext.addContextTargets(candidates);
				}
				else if (context instanceof TargetContext) {
					((TargetContext) context).addContextTargets(candidates);
				}
				else {
					throw new IllegalStateException("Unknown TransformationContext present.");
				}
			}
			return true;
		}

		/**
		 * Determines if a target node is a candidate for a context match. For
		 * this the cardinality of the corresponding definition is checked.
		 * 
		 * @param target the target node to check
		 * @return if the target node is a candidate for a context match
		 */
		private boolean isCandidate(TargetNode target) {
			ChildDefinition<?> def = target.getDefinition();
			Cardinality cardinality = DefinitionUtil.getCardinality(def);
			if (cardinality != null) {
				return cardinality.getMaxOccurs() == Cardinality.UNBOUNDED
						|| cardinality.getMaxOccurs() > 1;
			}
			return false;
		}

		/**
		 * @see TransformationNodeVisitor#includeAnnotatedNodes()
		 */
		@Override
		public boolean includeAnnotatedNodes() {
			// if there are any, just deal with them also
			// though in reality, annotated nodes only should be there AFTER
			// context matching
			return true;
		}

	}

	private final ServiceProvider serviceProvider;

	@SuppressWarnings("javadoc")
	public AsDeepAsPossible(ServiceProvider serviceProvider) {
		this.serviceProvider = serviceProvider;
	}

	/**
	 * @see eu.esdihumboldt.hale.common.align.model.transformation.tree.context.ContextMatcher#findMatches(eu.esdihumboldt.hale.common.align.model.transformation.tree.TransformationTree)
	 */
	@Override
	public void findMatches(TransformationTree tree) {
		tree.accept(new ContextVisitor());
	}

}