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SirixDB is a hybrid on-disk and in-memory document oriented, versioned database system. It has a lightweight buffer manager, stores everything in a huge persistent and durable tree and allows efficient reconstruction of every revision. Furthermore, SirixDB implements change tracking, diffing and supports time travel queries.
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/**
 * Copyright (c) 2011, University of Konstanz, Distributed Systems Group All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met: * Redistributions of source code must retain the
 * above copyright notice, this list of conditions and the following disclaimer. * Redistributions
 * in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * * Neither the name of the University of Konstanz nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL  BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package io.sirix.diff;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

import io.sirix.api.xml.XmlNodeReadOnlyTrx;
import io.sirix.api.xml.XmlNodeTrx;
import io.sirix.node.NodeKind;
import io.sirix.exception.SirixException;

/**
 * Full diff including attributes and namespaces. Note that this class is thread safe.
 *
 * @author Johannes Lichtenberger, University of Konstanz
 *
 */
final class XmlFullDiff extends AbstractDiff {

  /**
   * Constructor.
   *
   * @param builder {@link DiffFactory.Builder} reference
   * @throws SirixException if anything goes wrong while setting up sirix transactions
   */
  XmlFullDiff(final DiffFactory.Builder builder) throws SirixException {
    super(builder);
  }

  @Override
  NodeKind documentNode() {
    return NodeKind.XML_DOCUMENT;
  }

  @Override
  boolean checkNodes(final XmlNodeReadOnlyTrx newRtx, final XmlNodeReadOnlyTrx oldRtx) {
    boolean found = false;
    if (newRtx.getNodeKey() == oldRtx.getNodeKey() && newRtx.getParentKey() == oldRtx.getParentKey()
        && newRtx.getKind() == oldRtx.getKind()) {
      switch (newRtx.getKind()) {
        case ELEMENT:
          if (checkNamesForEquality(newRtx, oldRtx)
              && newRtx.getAttributeKeys().equals(oldRtx.getAttributeKeys())
              && newRtx.getNamespaceKeys().equals(oldRtx.getNamespaceKeys())) {
            found = true;

            final long newNodeKey = newRtx.getNodeKey();
            final long oldNodeKey = oldRtx.getNodeKey();

            for (final long nsp : newRtx.getNamespaceKeys()) {
              newRtx.moveTo(nsp);
              oldRtx.moveTo(nsp);

              if (!checkNamesForEquality(newRtx, oldRtx)) {
                found = false;
                break;
              }
            }
            newRtx.moveTo(newNodeKey);
            oldRtx.moveTo(oldNodeKey);

            if (found) {
              for (final long attr : newRtx.getAttributeKeys()) {
                newRtx.moveTo(attr);
                oldRtx.moveTo(attr);

                if (!(checkNamesForEquality(newRtx, oldRtx)
                    && Objects.equals(newRtx.getValue(), oldRtx.getValue()))) {
                  found = false;
                  break;
                }
              }

              newRtx.moveTo(newNodeKey);
              oldRtx.moveTo(oldNodeKey);
            }
          }
          break;
        case PROCESSING_INSTRUCTION:
          found = newRtx.getValue().equals(oldRtx.getValue()) && checkNamesForEquality(newRtx, oldRtx);
          break;
        case TEXT:
        case COMMENT:
          found = newRtx.getValue().equals(oldRtx.getValue());
          break;
        // $CASES-OMITTED$
        default:
          throw new IllegalStateException("Other node types currently not supported!");
      }
    }

    return found;
  }

  @Override
  void emitNonStructuralDiff(final XmlNodeReadOnlyTrx newRtx, final XmlNodeReadOnlyTrx oldRtx, final DiffDepth depth,
      final DiffFactory.DiffType diff) {
    if (newRtx.isElement() || oldRtx.isElement()) {
      if (diff == DiffFactory.DiffType.UPDATED) {
        // Emit diffing.
        final long newNodeKey = newRtx.getNodeKey();
        final long oldNodeKey = oldRtx.getNodeKey();

        final List insertedNamespaces = new ArrayList<>(newRtx.getNamespaceKeys());
        insertedNamespaces.removeAll(oldRtx.getNamespaceKeys());

        for (final long nsp : insertedNamespaces) {
          newRtx.moveTo(nsp);
          fireDiff(DiffFactory.DiffType.INSERTED, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);
        }
        newRtx.moveTo(newNodeKey);

        final List removedNamespaces = new ArrayList<>(oldRtx.getNamespaceKeys());
        removedNamespaces.removeAll(newRtx.getNamespaceKeys());

        for (final long nsp : removedNamespaces) {
          oldRtx.moveTo(nsp);
          fireDiff(DiffFactory.DiffType.DELETED, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);
        }
        oldRtx.moveTo(oldNodeKey);

        final List insertedAttributes = new ArrayList<>(newRtx.getAttributeKeys());
        insertedAttributes.removeAll(oldRtx.getAttributeKeys());

        for (final long attribute : insertedAttributes) {
          newRtx.moveTo(attribute);
          fireDiff(DiffFactory.DiffType.INSERTED, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);
        }
        newRtx.moveTo(newNodeKey);

        final List removedAttributes = new ArrayList<>(oldRtx.getAttributeKeys());
        removedAttributes.removeAll(newRtx.getAttributeKeys());

        for (final long attribute : removedAttributes) {
          oldRtx.moveTo(attribute);
          fireDiff(DiffFactory.DiffType.DELETED, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);
        }
        oldRtx.moveTo(oldNodeKey);

        // Emit same.
        final List sameNamespaces = new ArrayList<>(newRtx.getNamespaceKeys());
        sameNamespaces.retainAll(oldRtx.getNamespaceKeys());

        for (final long nsp : sameNamespaces) {
          newRtx.moveTo(nsp);
          oldRtx.moveTo(nsp);

          if (newRtx.getName().equals(oldRtx.getName()))
            fireDiff(DiffFactory.DiffType.SAME, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);
          else
            fireDiff(DiffFactory.DiffType.UPDATED, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);
        }
        newRtx.moveTo(newNodeKey);
        oldRtx.moveTo(oldNodeKey);

        final List sameAttributes = new ArrayList<>(newRtx.getAttributeKeys());
        sameAttributes.retainAll(oldRtx.getAttributeKeys());

        for (final long attr : sameAttributes) {
          newRtx.moveTo(attr);
          oldRtx.moveTo(attr);

          if (checkNamesForEquality(newRtx, oldRtx)
              && Objects.equals(newRtx.getValue(), oldRtx.getValue()))
            fireDiff(DiffFactory.DiffType.SAME, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);
          else
            fireDiff(DiffFactory.DiffType.UPDATED, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);
        }

        // Move back to original element nodes.
        newRtx.moveTo(newNodeKey);
        oldRtx.moveTo(oldNodeKey);
      } else if (diff == DiffFactory.DiffType.SAME) {
        for (int i = 0, nspCount = newRtx.getNamespaceCount(); i < nspCount; i++) {
          newRtx.moveToNamespace(i);
          final long newNodeKey = newRtx.getNodeKey();
          oldRtx.moveTo(newNodeKey);

          fireDiff(diff, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);

          newRtx.moveToParent();
          oldRtx.moveToParent();
        }

        for (int i = 0, attCount = newRtx.getAttributeCount(); i < attCount; i++) {
          newRtx.moveToAttribute(i);
          final long newNodeKey = newRtx.getNodeKey();
          oldRtx.moveTo(newNodeKey);

          fireDiff(diff, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);

          newRtx.moveToParent();
          oldRtx.moveToParent();
        }
      } else if (diff == DiffFactory.DiffType.DELETED) {
        for (int i = 0, nspCount = oldRtx.getNamespaceCount(); i < nspCount; i++) {
          oldRtx.moveToNamespace(i);

          fireDiff(diff, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);

          oldRtx.moveToParent();
        }

        for (int i = 0, attCount = oldRtx.getAttributeCount(); i < attCount; i++) {
          oldRtx.moveToAttribute(i);

          fireDiff(diff, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);

          oldRtx.moveToParent();
        }
      } else if (diff == DiffFactory.DiffType.INSERTED) {
        for (int i = 0, nspCount = newRtx.getNamespaceCount(); i < nspCount; i++) {
          newRtx.moveToNamespace(i);

          fireDiff(diff, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);

          newRtx.moveToParent();
        }

        for (int i = 0, attCount = newRtx.getAttributeCount(); i < attCount; i++) {
          newRtx.moveToAttribute(i);

          fireDiff(diff, newRtx.getNodeKey(), oldRtx.getNodeKey(), depth);

          newRtx.moveToParent();
        }
      }
    }
  }

  @Override
  boolean checkNodeNamesOrValues(final XmlNodeReadOnlyTrx newRtx, final XmlNodeReadOnlyTrx oldRtx) {
    boolean found = false;
    if (newRtx.getKind() == oldRtx.getKind()) {
      switch (newRtx.getKind()) {
        case ELEMENT:
        case PROCESSING_INSTRUCTION:
          if (checkNamesForEquality(newRtx, oldRtx)) {
            found = true;
          }
          break;
        case TEXT:
        case COMMENT:
          if (newRtx.getValue().equals(oldRtx.getValue())) {
            found = true;
          }
          break;
        // $CASES-OMITTED$
        default:
      }
    }
    return found;
  }

  private boolean checkNamesForEquality(final XmlNodeReadOnlyTrx newRtx, final XmlNodeReadOnlyTrx oldRtx) {
    return newRtx.getURIKey() == oldRtx.getURIKey()
        && newRtx.getLocalNameKey() == oldRtx.getLocalNameKey()
        && newRtx.getPrefixKey() == oldRtx.getPrefixKey();
  }
}