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package org.openoffice.xmerge.merger.diff;
import org.w3c.dom.Node;
import org.w3c.dom.Element;
import java.util.Vector;
import org.openoffice.xmerge.merger.DiffAlgorithm;
import org.openoffice.xmerge.merger.Difference;
import org.openoffice.xmerge.merger.Iterator;
import org.openoffice.xmerge.converter.xml.OfficeConstants;
/**
* <p>A very simple and direct difference algorithm for row
* <code>Node</code> objects in a spreadsheet. Basically, it will
* compare objects in sequence and does not look ahead (unlike LCS).</p>
*
* <p><ol><li>
* If two objects are the same, skip to next one.
* </li><li>
* Otherwise check whether the row repeated attribute is the same.
* </li><li>
* If the row repeated attribute is the same, then compare two rows
* and mark it as <i>change</i> if those rows are different.
* </li><li>
* If the row repeated attribute is different, then split the rows and
* continue to compare.
* </li><li>
* If there are more objects in the modseq than the original sequence,
* then all of the extra ones in the modified sequence are marked as add.
* </li><li>
* If there are more objects in the original sequence than the modified
* sequence, then all the extra one in the modified sequence are marked
* as delete.
* </li></ol></p>
*
* <p>NOTE: The algorithm will have potential side effect to split rows.</p>
*
* @author smak
*/
public class IteratorRowCompare implements DiffAlgorithm {
/**
* Compute the differences of the given two sequences.
* Refer to the class description.
*
* Return an array of <code>Difference</code> objects. This method finds
* out the difference between two sequences.
*
* @param orgSeq The original sequence.
* @param modSeq The modified (or changed) sequence to
* compare against with the origial.
*
* @return An array of Difference objects.
*/
public Difference[] computeDiffs(Iterator orgSeq, Iterator modSeq) {
int orgSeqlen = orgSeq.elementCount();
int modSeqlen = modSeq.elementCount();
Vector diffVector = new Vector();
// i and j are counters to keep track the current position in the
// iterator
int i = 0;
int j = 0;
Object orgSeqObject = orgSeq.start();
Object modSeqObject = modSeq.start();
Element orgRow, modRow;
boolean different = false;
boolean orgSplited = false;
boolean modSplited = false;
while (orgSeqObject != null) {
different = true;
if (modSeqObject == null) {
// no more modsequence, all the remaining org sequence objs
// should consider as a delete.
Difference diff = new Difference(Difference.DELETE, i, j);
diffVector.add(diff);
orgSeqObject = orgSeq.next();
} else {
if (!orgSeq.equivalent(orgSeqObject, modSeqObject)) {
orgRow = (Element)orgSeqObject;
modRow = (Element)modSeqObject;
// check whether the original Row with multiple row
// if so, need to split one out for merge
String orgRowRepeated = orgRow.getAttribute(
OfficeConstants.ATTRIBUTE_TABLE_NUM_ROWS_REPEATED);
String modRowRepeated = modRow.getAttribute(
OfficeConstants.ATTRIBUTE_TABLE_NUM_ROWS_REPEATED);
int orgRowNum = 1;
int modRowNum = 1;
if (orgRowRepeated.length() > 0) {
orgRowNum =
Integer.valueOf(orgRowRepeated).intValue();
}
if (modRowRepeated.length() > 0) {
modRowNum =
Integer.valueOf(modRowRepeated).intValue();
}
// try to find out the common number of repeated Rows
if (orgRowNum == modRowNum) {
orgSeqObject = orgSeq.next();
modSeqObject = modSeq.next();
// cut the original row into two halves, first half
// have the repeated attribute = modify row attr
} else if (orgRowNum > modRowNum) {
Element orgSplitRow = splitRepeatedRow(
orgRow, modRowNum,
orgRowNum - modRowNum);
// it may equal after the split!
if (orgSeq.equivalent(orgSplitRow, modRow)) {
different = false;
}
orgSplited = true;
modSeqObject = modSeq.next();
// cut the modified Row into two halves, first half
// have the repeated attribute = original Row attr
} else {
Element modSplitRow = splitRepeatedRow(
modRow, orgRowNum,
modRowNum - orgRowNum);
// check whether rows are equal after the split
if (modSeq.equivalent(orgRow, modSplitRow)) {
different = false;
}
modSplited = true;
orgSeqObject = orgSeq.next();
}
if (different) {
Difference diff = new Difference(Difference.CHANGE,
i, j);
diffVector.add(diff);
}
} else {
// Rows are equivalent, move on to next one.
orgSeqObject = orgSeq.next();
modSeqObject = modSeq.next();
} // end if-else
j++;
} // end if-else
i++;
} // end while loop
// any extra objects in modify sequence should consider as an add
// to the original sequence
for (; modSeqObject != null; modSeqObject = modSeq.next(), j++) {
Difference diff = new Difference(Difference.ADD, i, j);
diffVector.add(diff);
}
// need to refresh the iterator if we split the rows
if (orgSplited) {
orgSeq.refresh();
}
if (modSplited) {
modSeq.refresh();
}
// convert the vector to array
Difference[] diffArray = new Difference[diffVector.size()];
diffVector.copyInto(diffArray);
return diffArray;
}
private Element splitRepeatedRow(Element orgRow, int splitNum, int orgNum) {
// NOTE: should we really want to do deep clone?
// in most the case, it is an empty Row, but the
// specification didn't forbid any node to use multiple
// column attributes. i.e. the node can contain text
// nodes or other things under it.
Element splitRow = (Element)(orgRow.cloneNode(true));
if (splitNum > 1) {
splitRow.setAttribute(
OfficeConstants.ATTRIBUTE_TABLE_NUM_ROWS_REPEATED,
String.valueOf(splitNum));
} else if (splitNum == 1) {
splitRow.removeAttribute(
OfficeConstants.ATTRIBUTE_TABLE_NUM_ROWS_REPEATED);
}
if (orgNum > 1) {
orgRow.setAttribute(
OfficeConstants.ATTRIBUTE_TABLE_NUM_ROWS_REPEATED,
String.valueOf(orgNum));
} else if (orgNum == 1) {
orgRow.removeAttribute(
OfficeConstants.ATTRIBUTE_TABLE_NUM_ROWS_REPEATED);
}
Node parentNode = orgRow.getParentNode();
parentNode.insertBefore(splitRow, orgRow);
return splitRow;
}
}