// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.gui.history;
/// Feel free to move me somewhere else. Maybe a bit specific for josm.tools?
import java.awt.Color;
import java.util.ArrayList;
import java.util.List;
import org.openstreetmap.josm.gui.history.TwoColumnDiff.Item.DiffItemType;
import org.openstreetmap.josm.tools.Diff;
import org.openstreetmap.josm.tools.Utils;
/**
* Produces a "two column diff" of two lists. (same as diff -y)
*
* Each list is annotated with the changes relative to the other, and "empty" cells are inserted so the lists are comparable item by item.
*
* diff on [1 2 3 4] [1 a 4 5] yields:
*
* item(SAME, 1) item(SAME, 1)
* item(CHANGED, 2) item(CHANGED, 2)
* item(DELETED, 3) item(EMPTY)
* item(SAME, 4) item(SAME, 4)
* item(EMPTY) item(INSERTED, 5)
*
* @author olejorgenb
*/
class TwoColumnDiff {
public static class Item {
public enum DiffItemType {
INSERTED(new Color(0xDD, 0xFF, 0xDD)), DELETED(new Color(255,197,197)), CHANGED(new Color(255,234,213)),
SAME(new Color(234,234,234)), EMPTY(new Color(234,234,234));
private final Color color;
private DiffItemType(Color color) {
this.color = color;
}
public Color getColor() {
return color;
}
}
public Item(DiffItemType state, Object value) {
this.state = state;
this.value = state == DiffItemType.EMPTY ? null : value;
}
public final Object value;
public final DiffItemType state;
}
public List<Item> referenceDiff;
public List<Item> currentDiff;
Object[] reference;
Object[] current;
public TwoColumnDiff(Object[] reference, Object[] current) {
this.reference = Utils.copyArray(reference);
this.current = Utils.copyArray(current);
referenceDiff = new ArrayList<>();
currentDiff = new ArrayList<>();
diff();
}
private void diff() {
Diff diff = new Diff(reference, current);
Diff.Change script = diff.diff_2(false);
twoColumnDiffFromScript(script, reference, current);
}
/**
* The result from the diff algorithm is a "script" (a compressed description of the changes)
* This method expands this script into a full two column description.
*/
private void twoColumnDiffFromScript(Diff.Change script, Object[] a, Object[] b) {
int ia = 0;
int ib = 0;
while(script != null) {
int deleted = script.deleted;
int inserted = script.inserted;
while(ia < script.line0 && ib < script.line1){
Item cell = new Item(DiffItemType.SAME, a[ia]);
referenceDiff.add(cell);
currentDiff.add(cell);
ia++;
ib++;
}
while(inserted > 0 || deleted > 0) {
if(inserted > 0 && deleted > 0) {
referenceDiff.add(new Item(DiffItemType.CHANGED, a[ia++]));
currentDiff.add(new Item(DiffItemType.CHANGED, b[ib++]));
} else if(inserted > 0) {
referenceDiff.add(new Item(DiffItemType.EMPTY, null));
currentDiff.add(new Item(DiffItemType.INSERTED, b[ib++]));
} else if(deleted > 0) {
referenceDiff.add(new Item(DiffItemType.DELETED, a[ia++]));
currentDiff.add(new Item(DiffItemType.EMPTY, null));
}
inserted--;
deleted--;
}
script = script.link;
}
while(ia < a.length && ib < b.length) {
referenceDiff.add(new Item(DiffItemType.SAME, a[ia++]));
currentDiff.add(new Item(DiffItemType.SAME, b[ib++]));
}
}
}