/**
* Copyright 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.waveprotocol.wave.model.document.operation.algorithm;
import org.waveprotocol.wave.model.document.operation.AnnotationBoundaryMap;
import org.waveprotocol.wave.model.document.operation.Attributes;
import org.waveprotocol.wave.model.document.operation.AttributesUpdate;
import org.waveprotocol.wave.model.document.operation.DocOp;
import org.waveprotocol.wave.model.document.operation.EvaluatingDocOpCursor;
import org.waveprotocol.wave.model.document.operation.impl.DocOpBuffer;
import org.waveprotocol.wave.model.util.Pair;
/**
* A utility class for decomposing an operation into an insertion operation and
* an operation that contains no insertions.
*
* @author Alexandre Mah
*/
final class Decomposer {
private static final class Target
implements EvaluatingDocOpCursor<Pair<DocOp, DocOp>> {
private final EvaluatingDocOpCursor<DocOp> insertionOp =
OperationNormalizer.createNormalizer(new DocOpBuffer());
private final EvaluatingDocOpCursor<DocOp> noninsertionOp =
OperationNormalizer.createNormalizer(new DocOpBuffer());
@Override
public Pair<DocOp, DocOp> finish() {
return new Pair<DocOp, DocOp>(insertionOp.finish(), noninsertionOp.finish());
}
@Override
public void retain(int itemCount) {
insertionOp.retain(itemCount);
noninsertionOp.retain(itemCount);
}
@Override
public void characters(String chars) {
insertionOp.characters(chars);
noninsertionOp.retain(chars.length());
}
@Override
public void elementStart(String type, Attributes attrs) {
insertionOp.elementStart(type, attrs);
noninsertionOp.retain(1);
}
@Override
public void elementEnd() {
insertionOp.elementEnd();
noninsertionOp.retain(1);
}
@Override
public void deleteCharacters(String chars) {
insertionOp.retain(chars.length());
noninsertionOp.deleteCharacters(chars);
}
@Override
public void deleteElementStart(String type, Attributes attrs) {
insertionOp.retain(1);
noninsertionOp.deleteElementStart(type, attrs);
}
@Override
public void deleteElementEnd() {
insertionOp.retain(1);
noninsertionOp.deleteElementEnd();
}
@Override
public void replaceAttributes(Attributes oldAttrs, Attributes newAttrs) {
insertionOp.retain(1);
noninsertionOp.replaceAttributes(oldAttrs, newAttrs);
}
@Override
public void updateAttributes(AttributesUpdate attrUpdate) {
insertionOp.retain(1);
noninsertionOp.updateAttributes(attrUpdate);
}
@Override
public void annotationBoundary(AnnotationBoundaryMap map) {
noninsertionOp.annotationBoundary(map);
}
}
/**
* Returns the decomposition of an operation into an insertion operation and
* an operation that contains no insertions.
*
* @param op the operation to decompose
* @return a pair of operations, where the first operation in an insertion
* operation and the second contains no insertions.
*/
static Pair<DocOp, DocOp> decompose(DocOp op) {
Target target = new Target();
op.apply(target);
return target.finish();
}
}