plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/CDOCompareUtil.java

/*
 * Copyright (c) 2004 - 2012 Eike Stepper (Berlin, Germany) 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:
 *    Eike Stepper - initial API and implementation
 */
package org.eclipse.emf.cdo.compare;

import org.eclipse.emf.cdo.CDOObject;
import org.eclipse.emf.cdo.common.branch.CDOBranch;
import org.eclipse.emf.cdo.common.branch.CDOBranchPoint;
import org.eclipse.emf.cdo.common.commit.CDOChangeSetData;
import org.eclipse.emf.cdo.common.commit.CDOCommitInfo;
import org.eclipse.emf.cdo.common.id.CDOID;
import org.eclipse.emf.cdo.compare.CDOComparisonScope.AllContents;
import org.eclipse.emf.cdo.compare.CDOComparisonScope.Minimal;
import org.eclipse.emf.cdo.eresource.CDOResource;
import org.eclipse.emf.cdo.eresource.CDOResourceFolder;
import org.eclipse.emf.cdo.eresource.CDOResourceNode;
import org.eclipse.emf.cdo.session.CDOSession;
import org.eclipse.emf.cdo.spi.common.branch.CDOBranchUtil;
import org.eclipse.emf.cdo.transaction.CDOTransaction;
import org.eclipse.emf.cdo.util.CDOUtil;
import org.eclipse.emf.cdo.view.CDOView;

import org.eclipse.emf.common.notify.Notifier;
import org.eclipse.emf.compare.Comparison;
import org.eclipse.emf.compare.EMFCompare;
import org.eclipse.emf.compare.Match;
import org.eclipse.emf.compare.match.DefaultComparisonFactory;
import org.eclipse.emf.compare.match.DefaultEqualityHelperFactory;
import org.eclipse.emf.compare.match.DefaultMatchEngine;
import org.eclipse.emf.compare.match.IComparisonFactory;
import org.eclipse.emf.compare.match.eobject.IEObjectMatcher;
import org.eclipse.emf.compare.match.eobject.IdentifierEObjectMatcher;
import org.eclipse.emf.compare.scope.IComparisonScope;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.spi.cdo.InternalCDOSession;
import org.eclipse.emf.spi.cdo.InternalCDOSession.MergeData;

import com.google.common.base.Function;

import java.util.HashSet;
import java.util.Set;

/**
 * Provides static factory methods that return CDO-scoped {@link Comparison comparisons}.
 * <p>
 * Two different {@link IComparisonScope scopes} are supported:
 * <ul>
 * <li>{@link AllContents CDOComparisonScope.AllContents} takes an arbitrary {@link CDOObject object} (including {@link CDOResourceNode resource nodes})
 * and returns {@link Match matches} for <b>all</b> elements of its {@link EObject#eAllContents() content tree}. This scope has the advantage that the comparison can
 * be rooted at specific objects that are different from (below of) the root resource. The disadvantage is that all the transitive children of this specific object are
 * matched, whether they differ or not. Major parts of huge repositories can be loaded to the client side easily, if no attention is paid.
 * The following methods return comparisons that are based on this scope algorithm:
 * <ul>
 * <li>{@link #compare(EObject, CDOBranchPoint)}
 * <li>{@link #compare(EObject, CDOBranchPoint, boolean)}
 * </ul>
 * <li>{@link Minimal CDOComparisonScope.Minimal} takes a {@link CDOView view}/{@link CDOTransaction transaction}
 * and returns {@link Match matches} only for the <b>changed</b> elements of the entire content tree of its {@link CDOView#getRootResource() root resource}.
 * The advantage of this scope is that CDO-specific mechanisms are used to efficiently (remotely) determine the set of changed objects. Only those and their container
 * objects are considered as matches, making this scope scale seamlessly with the overall size of a repository.
 * The following methods return comparisons that are based on this scope algorithm:
 * <ul>
 * <li>{@link #compare(CDOView, CDOBranchPoint)}
 * <li>{@link #compare(CDOView, CDOBranchPoint, boolean)}
 * </ul>
 * </ul>
 * The {@link IComparisonScope#getRight() right side} of a comparison is specified as a {@link CDOBranchPoint} which, among others, can be another {@link CDOView}
 * (which then is not closed when the comparison is closed) or a {@link CDOCommitInfo}. The {@link IComparisonScope#getOrigin() origin side} of a comparison is
 * automatically {@link CDOBranchUtil#getAncestor(CDOBranchPoint, CDOBranchPoint) determined} by inspecting the {@link CDOBranch branch tree} and used if its different from the left or right side.
 * <p>
 * The comparions returned from these factory methods are all of the type {@link CloseableComparison} and the caller is responsible to call {@link CloseableComparison#close()}
 * on them when they're not needed anymore. The reason is that the scopes may or may not open a number of addional {@link CDOView views} on the local {@link CDOSession session}
 * that need to be closed at some point.
 * <p>
 * The {@link IEObjectMatcher matcher} used by the comparisons is based on an {@link CDOIDFunction ID function} that considers the {@link CDOID}s of the {@link CDOObject objects}.
 * {@link CDOResource Resources} and {@link CDOResourceFolder folders} are treated as normal {@link EObject}s.
 *
 * @author Eike Stepper
 */
public final class CDOCompareUtil
{
  private CDOCompareUtil()
  {
  }

  /**
   * Same as {@link #compare(CDOView, CDOBranchPoint, boolean) compare(leftRoot, right, true)}.
   */
  public static CDOComparison compare(EObject leftRoot, CDOBranchPoint right)
  {
    return compare(leftRoot, right, true);
  }

  /**
   * Takes an arbitrary {@link CDOObject object} (including {@link CDOResourceNode resource nodes}) and returns {@link Match matches} for <b>all</b> elements of its {@link EObject#eAllContents() content tree}. This scope has the advantage that the comparison can
   * be rooted at specific objects that are different from (below of) the root resource. The disadvantage is that all the transitive children of this specific object are
   * matched, whether they differ or not. Major parts of huge repositories can be loaded to the client side easily, if no attention is paid.
   */
  public static CDOComparison compare(EObject leftRoot, CDOBranchPoint right, boolean tryThreeWay)
  {
    Set<Object> objectsToDeactivateOnClose = new HashSet<Object>();

    CDOObject leftObject = CDOUtil.getCDOObject(leftRoot);
    CDOView leftView = leftObject.cdoView();
    CDOBranchPoint left = CDOBranchUtil.copyBranchPoint(leftView);
    CDOSession session = leftView.getSession();

    CDOView rightView;
    if (right instanceof CDOView)
    {
      rightView = (CDOView)right;
      if (rightView.getSession() != session)
      {
        throw new IllegalArgumentException("Sessions are different");
      }
    }
    else
    {
      rightView = session.openView(right);
      objectsToDeactivateOnClose.add(rightView);
    }

    Notifier rightObject = rightView.getObject(leftObject);

    CDOView originView = null;
    Notifier originObject = null;
    if (tryThreeWay)
    {
      CDOBranchPoint ancestor = CDOBranchUtil.getAncestor(left, right);
      if (!ancestor.equals(left) && !ancestor.equals(right))
      {
        originView = session.openView(ancestor);
        originObject = originView.getObject(leftObject);
        objectsToDeactivateOnClose.add(originView);
      }
    }

    IComparisonScope scope = new CDOComparisonScope.AllContents(leftObject, rightObject, originObject);
    return createComparison(scope, objectsToDeactivateOnClose);
  }

  /**
   * Same as {@link #compare(EObject, CDOBranchPoint, boolean) compare(leftView, right, true)}.
   */
  public static CDOComparison compare(CDOView leftView, CDOBranchPoint right)
  {
    return compare(leftView, right, true);
  }

  /**
   * Takes a {@link CDOView view}/{@link CDOTransaction transaction}
   * and returns {@link Match matches} only for the <b>changed</b> elements of the entire content tree of its {@link CDOView#getRootResource() root resource}.
   * The advantage of this scope is that CDO-specific mechanisms are used to efficiently (remotely) determine the set of changed objects. Only those and their container
   * objects are considered as matches, making this scope scale seamlessly with the overall size of a repository.
   */
  public static CDOComparison compare(CDOView leftView, CDOBranchPoint right, boolean tryThreeWay)
  {
    Set<Object> objectsToDeactivateOnClose = new HashSet<Object>();
    CDOSession session = leftView.getSession();

    CDOView rightView;
    if (right instanceof CDOView)
    {
      rightView = (CDOView)right;
      if (rightView.getSession() != session)
      {
        throw new IllegalArgumentException("Sessions are different");
      }
    }
    else
    {
      rightView = session.openView(right);
      objectsToDeactivateOnClose.add(rightView);
    }

    CDOView originView = null;
    if (tryThreeWay)
    {
      CDOBranchPoint ancestor = CDOBranchUtil.getAncestor(leftView, rightView);
      if (!ancestor.equals(leftView) && !ancestor.equals(rightView))
      {
        originView = session.openView(ancestor);
        objectsToDeactivateOnClose.add(originView);
      }
    }

    Set<CDOID> ids;
    if (originView != null)
    {
      MergeData mergeData = ((InternalCDOSession)session).getMergeData(leftView, rightView, null, false);
      ids = mergeData.getIDs();
    }
    else
    {
      CDOChangeSetData changeSetData = leftView.compareRevisions(right);
      ids = new HashSet<CDOID>(changeSetData.getChangeKinds().keySet());
    }

    IComparisonScope scope = new CDOComparisonScope.Minimal(leftView, rightView, originView, ids);
    return createComparison(scope, objectsToDeactivateOnClose);
  }

  private static EMFCompare createComparator()
  {
    Function<EObject, String> idFunction = new CDOIDFunction();
    IEObjectMatcher matcher = new IdentifierEObjectMatcher(idFunction);

    IComparisonFactory comparisonFactory = new DefaultComparisonFactory(new DefaultEqualityHelperFactory());
    EMFCompare comparator = EMFCompare.builder().setMatchEngine(new DefaultMatchEngine(matcher, comparisonFactory))
        .build();
    return comparator;
  }

  private static CDOComparison createComparison(IComparisonScope scope, Set<Object> objectsToDeactivateOnClose)
  {
    EMFCompare comparator = createComparator();
    Comparison comparison = comparator.compare(scope);
    return new CDOComparison(scope, comparison, objectsToDeactivateOnClose);
  }

  // /**
  // * FIXME: To be removed when bug 390849 is resolved.
  // *
  // * @author Eike Stepper
  // */
  // private static final class _EMFCompare
  // {
  // private IEObjectMatcher eObjectMatcher;
  //
  // private Monitor progressMonitor;
  //
  // private final IComparisonScope scope;
  //
  // private _EMFCompare(IComparisonScope scope)
  // {
  // com.google.common.base.Preconditions.checkNotNull(scope);
  // this.scope = scope;
  // }
  //
  // public static EMFCompare newComparator(IComparisonScope scope)
  // {
  // return null; // Just temporary fix to make the Kepler train run again!
  //
  // // return new EMFCompare(scope);
  // }
  //
  // private static Comparison compare(IComparisonScope scope, EMFCompareConfiguration configuration,
  // IEObjectMatcher matcher)
  // {
  // final IMatchEngine matchEngine = new DefaultMatchEngine(matcher)
  // {
  // /**
  // * FIXME: CDO-specific.
  // */
  // @Override
  // protected void match(Notifier left, Notifier right, Notifier origin)
  // {
  // match((EObject)left, (EObject)right, (EObject)origin);
  // }
  // };
  //
  // Comparison comparison = matchEngine.match(scope, configuration);
  //
  // IPostProcessor postProcessor = getPostProcessor(scope);
  // if (postProcessor != null)
  // {
  // postProcessor.postMatch(comparison);
  // }
  //
  // final IDiffProcessor diffBuilder = new DiffBuilder();
  //
  // final IDiffEngine diffEngine = new DefaultDiffEngine(diffBuilder);
  // diffEngine.diff(comparison);
  //
  // if (postProcessor != null)
  // {
  // postProcessor.postDiff(comparison);
  // }
  //
  // final IReqEngine reqEngine = new DefaultReqEngine();
  // reqEngine.computeRequirements(comparison);
  //
  // if (postProcessor != null)
  // {
  // postProcessor.postRequirements(comparison);
  // }
  //
  // final IEquiEngine equiEngine = new DefaultEquiEngine();
  // equiEngine.computeEquivalences(comparison);
  //
  // if (postProcessor != null)
  // {
  // postProcessor.postEquivalences(comparison);
  // }
  //
  // if (comparison.isThreeWay())
  // {
  // final IConflictDetector conflictDetector = new DefaultConflictDetector();
  // conflictDetector.detect(comparison);
  //
  // if (postProcessor != null)
  // {
  // postProcessor.postConflicts(comparison);
  // }
  // }
  //
  // return comparison;
  // }
  //
  // private static IPostProcessor getPostProcessor(IComparisonScope scope)
  // {
  // IPostProcessor postProcessor = null;
  // final Iterator<PostProcessorDescriptor> postProcessorIterator = EMFCompareExtensionRegistry
  // .getRegisteredPostProcessors().iterator();
  // while (postProcessorIterator.hasNext() && postProcessor == null)
  // {
  // final PostProcessorDescriptor descriptor = postProcessorIterator.next();
  // if (descriptor.getNsURI() != null && descriptor.getNsURI().trim().length() != 0)
  // {
  // final Iterator<String> nsUris = scope.getNsURIs().iterator();
  // while (nsUris.hasNext() && postProcessor == null)
  // {
  // if (nsUris.next().matches(descriptor.getNsURI()))
  // {
  // postProcessor = descriptor.getPostProcessor();
  // }
  // }
  // }
  //
  // if (descriptor.getResourceURI() != null && descriptor.getResourceURI().trim().length() != 0)
  // {
  // final Iterator<String> resourceUris = scope.getResourceURIs().iterator();
  // while (resourceUris.hasNext() && postProcessor == null)
  // {
  // if (resourceUris.next().matches(descriptor.getResourceURI()))
  // {
  // postProcessor = descriptor.getPostProcessor();
  // }
  // }
  // }
  // }
  // return postProcessor;
  // }
  //
  // public Comparison compare()
  // {
  // final Monitor monitor;
  // if (progressMonitor != null)
  // {
  // monitor = progressMonitor;
  // }
  // else
  // {
  // monitor = new BasicMonitor();
  // }
  //
  // EqualityHelper helper = new EqualityHelper();
  // EMFCompareConfiguration configuration = new EMFCompareConfiguration(monitor, helper);
  // IEObjectMatcher matcher = createMatcher(helper);
  //
  // return compare(scope, configuration, matcher);
  // }
  //
  // public EMFCompare setEObjectMatcher(IEObjectMatcher matcher)
  // {
  // if (matcher != null)
  // {
  // eObjectMatcher = matcher;
  // }
  // return this;
  // }
  //
  // private IEObjectMatcher createMatcher(EqualityHelper helper)
  // {
  // return eObjectMatcher;
  // }
  //
  // /**
  // * FIXME: Remove this when bug 390846 has been resolved.
  // *
  // * @author Eike Stepper
  // */
  // private static class DefaultMatchEngine implements IMatchEngine
  // {
  // private Comparison comparison;
  //
  // private IComparisonScope comparisonScope;
  //
  // private IEObjectMatcher eObjectMatcher;
  //
  // public DefaultMatchEngine(IEObjectMatcher matcher)
  // {
  // com.google.common.base.Preconditions.checkNotNull(matcher);
  // eObjectMatcher = matcher;
  // }
  //
  // public Comparison match(IComparisonScope scope, EMFCompareConfiguration configuration)
  // {
  // comparisonScope = scope;
  // associate(getComparison(), configuration);
  //
  // final Notifier left = getScope().getLeft();
  // final Notifier right = getScope().getRight();
  // final Notifier origin = getScope().getOrigin();
  //
  // getComparison().setThreeWay(origin != null);
  //
  // match(left, right, origin);
  //
  // return getComparison();
  // }
  //
  // protected void match(final Notifier left, final Notifier right, final Notifier origin)
  // {
  // if (left instanceof ResourceSet || right instanceof ResourceSet)
  // {
  // match((ResourceSet)left, (ResourceSet)right, (ResourceSet)origin);
  // }
  // else if (left instanceof Resource || right instanceof Resource)
  // {
  // match((Resource)left, (Resource)right, (Resource)origin);
  // }
  // else if (left instanceof EObject || right instanceof EObject)
  // {
  // match((EObject)left, (EObject)right, (EObject)origin);
  // }
  // }
  //
  // protected void match(ResourceSet left, ResourceSet right, ResourceSet origin)
  // {
  // final Iterator<? extends Resource> leftChildren = getScope().getCoveredResources(left);
  // final Iterator<? extends Resource> rightChildren = getScope().getCoveredResources(right);
  // final Iterator<? extends Resource> originChildren;
  // if (origin != null)
  // {
  // originChildren = getScope().getCoveredResources(origin);
  // }
  // else
  // {
  // originChildren = Iterators.emptyIterator();
  // }
  //
  // final IResourceMatcher resourceMatcher = getResourceMatcher();
  // final Iterable<MatchResource> mappings = resourceMatcher.createMappings(leftChildren, rightChildren,
  // originChildren);
  //
  // Iterator<? extends EObject> leftEObjects = Iterators.emptyIterator();
  // Iterator<? extends EObject> rightEObjects = Iterators.emptyIterator();
  // Iterator<? extends EObject> originEObjects = Iterators.emptyIterator();
  //
  // for (MatchResource mapping : mappings)
  // {
  // getComparison().getMatchedResources().add(mapping);
  //
  // final Resource leftRes = mapping.getLeft();
  // final Resource rightRes = mapping.getRight();
  // final Resource originRes = mapping.getOrigin();
  //
  // if (leftRes != null)
  // {
  // leftEObjects = Iterators.concat(leftEObjects, getScope().getCoveredEObjects(leftRes));
  // }
  //
  // if (rightRes != null)
  // {
  // rightEObjects = Iterators.concat(rightEObjects, getScope().getCoveredEObjects(rightRes));
  // }
  //
  // if (originRes != null)
  // {
  // originEObjects = Iterators.concat(originEObjects, getScope().getCoveredEObjects(originRes));
  // }
  // }
  //
  // final Iterable<Match> matches = getEObjectMatcher().createMatches(leftEObjects, rightEObjects, originEObjects);
  // Iterables.addAll(getComparison().getMatches(), matches);
  // }
  //
  // protected void match(Resource left, Resource right, Resource origin)
  // {
  // // Our "roots" are Resources. Consider them matched
  // final MatchResource match = CompareFactory.eINSTANCE.createMatchResource();
  //
  // match.setLeft(left);
  // match.setRight(right);
  // match.setOrigin(origin);
  //
  // if (left != null)
  // {
  // URI uri = left.getURI();
  // if (uri != null)
  // {
  // match.setLeftURI(uri.toString());
  // }
  // }
  //
  // if (right != null)
  // {
  // URI uri = right.getURI();
  // if (uri != null)
  // {
  // match.setRightURI(uri.toString());
  // }
  // }
  //
  // if (origin != null)
  // {
  // URI uri = origin.getURI();
  // if (uri != null)
  // {
  // match.setOriginURI(uri.toString());
  // }
  // }
  //
  // getComparison().getMatchedResources().add(match);
  //
  // // We need at least two resources to match them
  // if (atLeastTwo(left == null, right == null, origin == null))
  // {
  // return;
  // }
  //
  // final Iterator<? extends EObject> leftEObjects;
  // if (left != null)
  // {
  // leftEObjects = getScope().getCoveredEObjects(left);
  // }
  // else
  // {
  // leftEObjects = Iterators.emptyIterator();
  // }
  // final Iterator<? extends EObject> rightEObjects;
  // if (right != null)
  // {
  // rightEObjects = getScope().getCoveredEObjects(right);
  // }
  // else
  // {
  // rightEObjects = Iterators.emptyIterator();
  // }
  // final Iterator<? extends EObject> originEObjects;
  // if (origin != null)
  // {
  // originEObjects = getScope().getCoveredEObjects(origin);
  // }
  // else
  // {
  // originEObjects = Iterators.emptyIterator();
  // }
  //
  // final Iterable<Match> matches = getEObjectMatcher().createMatches(leftEObjects, rightEObjects, originEObjects);
  //
  // Iterables.addAll(getComparison().getMatches(), matches);
  // }
  //
  // protected void match(EObject left, EObject right, EObject origin)
  // {
  // if (left == null || right == null)
  // {
  // throw new IllegalArgumentException();
  // }
  //
  // final Iterator<? extends EObject> leftEObjects = Iterators.concat(Iterators.singletonIterator(left), getScope()
  // .getChildren(left));
  // final Iterator<? extends EObject> rightEObjects = Iterators.concat(Iterators.singletonIterator(right),
  // getScope().getChildren(right));
  // final Iterator<? extends EObject> originEObjects;
  // if (origin != null)
  // {
  // originEObjects = Iterators.concat(Iterators.singletonIterator(origin), getScope().getChildren(origin));
  // }
  // else
  // {
  // originEObjects = Iterators.emptyIterator();
  // }
  //
  // final Iterable<Match> matches = getEObjectMatcher().createMatches(leftEObjects, rightEObjects, originEObjects);
  //
  // Iterables.addAll(getComparison().getMatches(), matches);
  // }
  //
  // protected IResourceMatcher getResourceMatcher()
  // {
  // return new StrategyResourceMatcher();
  // }
  //
  // protected IEObjectMatcher getEObjectMatcher()
  // {
  // return eObjectMatcher;
  // }
  //
  // protected Comparison getComparison()
  // {
  // if (comparison == null)
  // {
  // comparison = CompareFactory.eINSTANCE.createComparison();
  // }
  // return comparison;
  // }
  //
  // protected IComparisonScope getScope()
  // {
  // return comparisonScope;
  // }
  //
  // protected static boolean atLeastTwo(boolean condition1, boolean condition2, boolean condition3)
  // {
  // // CHECKSTYLE:OFF This expression is alone in its method, and documented.
  // return condition1 && (condition2 || condition3) || condition2 && condition3;
  // // CHECKSTYLE:ON
  // }
  //
  // private static void associate(Comparison comparison, EMFCompareConfiguration configuration)
  // {
  // Iterator<Adapter> eAdapters = comparison.eAdapters().iterator();
  // while (eAdapters.hasNext())
  // {
  // Adapter eAdapter = eAdapters.next();
  // if (eAdapter.isAdapterForType(EMFCompareConfiguration.class))
  // {
  // eAdapters.remove();
  // if (eAdapter instanceof Adapter.Internal)
  // {
  // ((Adapter.Internal)eAdapter).unsetTarget(comparison);
  // }
  // }
  // }
  //
  // comparison.eAdapters().add(configuration);
  // configuration.setTarget(comparison);
  // }
  // }
  // }
}