core/plugins/org.eclipse.mdht.uml.validation/src/org/eclipse/mdht/uml/validation/util/EValidatorAdapter.java

/*******************************************************************************
 * Copyright (c) 2006, 2012 David A Carlson and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     David A Carlson (XMLmodeling.com) - initial API and implementation
 *     Christian W. Damus - refactor and delegate to the original validator (artf3285)
 *
 * $Id$
 *******************************************************************************/

package org.eclipse.mdht.uml.validation.util;

import java.util.Map;

import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.core.runtime.Status;
import org.eclipse.emf.common.util.BasicDiagnostic;
import org.eclipse.emf.common.util.DiagnosticChain;
import org.eclipse.emf.ecore.EClass;
import org.eclipse.emf.ecore.EDataType;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.EValidator;
import org.eclipse.emf.ecore.util.EObjectValidator;
import org.eclipse.emf.validation.model.EvaluationMode;
import org.eclipse.emf.validation.model.IConstraintStatus;
import org.eclipse.emf.validation.service.IBatchValidator;
import org.eclipse.emf.validation.service.ModelValidationService;

/**
 * An adapter that plugs the EMF Model Validation Service API into the {@link org.eclipse.emf.ecore.EValidator} API.
 */
public class EValidatorAdapter extends EObjectValidator {
	/** The package's original validator that I replace. */
	private final EValidator delegate;

	/**
	 * Model Validation Service interface for batch validation of EMF elements.
	 */
	private final IBatchValidator batchValidator;

	/**
	 * Initializes me.
	 */
	public EValidatorAdapter(EValidator delegate) {
		super();

		this.delegate = (delegate == null)
				? EObjectValidator.INSTANCE
				: delegate;

		batchValidator = (IBatchValidator) ModelValidationService.getInstance().newValidator(EvaluationMode.BATCH);
		batchValidator.setIncludeLiveConstraints(true);
		batchValidator.setReportSuccesses(false);
	}

	/*
	 * (non-Javadoc)
	 *
	 * @see org.eclipse.emf.ecore.util.EObjectValidator#validate(org.eclipse.emf.ecore.EObject, org.eclipse.emf.common.util.DiagnosticChain,
	 * java.util.Map)
	 *
	 * Map context is defined in EObjectValidator; suppress type safety
	 */
	@Override
	public boolean validate(EObject eObject, DiagnosticChain diagnostics, Map<Object, Object> context) {
		return validate(eObject.eClass(), eObject, diagnostics, context);
	}

	/**
	 * Implements validation by delegation to the EMF validation framework.
	 *
	 * Map context is defined in EObjectValidator; suppress type safety
	 */
	@Override
	public boolean validate(EClass eClass, EObject eObject, DiagnosticChain diagnostics, Map<Object, Object> context) {
		// first, do whatever the original validator (or, if none, the basic EcoreValidator) does
		delegate.validate(eClass, eObject, diagnostics, context);

		IStatus status = Status.OK_STATUS;

		// no point in validating if we can't report results
		if (diagnostics != null) {
			// if EMF Mode Validation Service already covered the sub-tree,
			// which it does for efficient computation and error reporting,
			// then don't repeat (the Diagnostician does the recursion
			// externally). If there is no context map, then we can't
			// help it
			if (!hasProcessed(eObject, context)) {
				status = batchValidator.validate(eObject, new NullProgressMonitor());

				processed(eObject, context, status);

				appendDiagnostics(status, diagnostics);
			}
		}

		return status.isOK();
	}

	/**
	 * Direct validation of {@link EDataType}s is not supported by the EMF
	 * validation framework; they are validated indirectly via the {@link EObject}s that hold their values.
	 *
	 * Map context is defined in EObjectValidator; suppress type safety
	 */
	@Override
	public boolean validate(EDataType eDataType, Object value, DiagnosticChain diagnostics,
			Map<Object, Object> context) {
		return super.validate(eDataType, value, diagnostics, context);
	}

	/**
	 * If we have a context map, record this object's <code>status</code> in it
	 * so that we will know later that we have processed it and its sub-tree.
	 *
	 * @param eObject
	 *            an element that we have validated
	 * @param context
	 *            the context (may be <code>null</code>)
	 * @param status
	 *            the element's validation status
	 *
	 *            Map context is defined in EObjectValidator; suppress type safety
	 */
	private void processed(EObject eObject, Map<Object, Object> context, IStatus status) {
		if (context != null) {
			context.put(eObject, status);
		}
	}

	/**
	 * Determines whether we have processed this <code>eObject</code> before,
	 * by automatic recursion of the EMF Model Validation Service. This is
	 * only possible if we do, indeed, have a context.
	 *
	 * @param eObject
	 *            an element to be validated (we hope not)
	 * @param context
	 *            the context (may be <code>null</code>)
	 * @return <code>true</code> if the context is not <code>null</code> and
	 *         the <code>eObject</code> or one of its containers has already been
	 *         validated; <code>false</code>, otherwise
	 *
	 *         Map context is defined in EObjectValidator; suppress type safety
	 */
	private boolean hasProcessed(EObject eObject, Map<Object, Object> context) {
		boolean result = false;

		if (context != null) {
			// this is O(NlogN) but there's no helping it
			while (eObject != null) {
				if (context.containsKey(eObject)) {
					result = true;
					eObject = null;
				} else {
					eObject = eObject.eContainer();
				}
			}
		}

		return result;
	}

	/**
	 * Converts a status result from the EMF validation service to diagnostics.
	 *
	 * @param status
	 *            the EMF validation service's status result
	 * @param diagnostics
	 *            a diagnostic chain to accumulate results on
	 */
	private void appendDiagnostics(IStatus status, DiagnosticChain diagnostics) {
		if (status.isMultiStatus()) {
			IStatus[] children = status.getChildren();

			for (int i = 0; i < children.length; i++) {
				appendDiagnostics(children[i], diagnostics);
			}
		} else if (status instanceof IConstraintStatus) {
			diagnostics.add(new BasicDiagnostic(
				status.getSeverity(), status.getPlugin(), status.getCode(), status.getMessage(),
				((IConstraintStatus) status).getResultLocus().toArray()));
		}
	}

}