From c5fe88455146ca948b28f85b39b1554d99529b20 Mon Sep 17 00:00:00 2001
From: OszkarSemerath <semerath@mit.bme.hu>
Date: Sun, 5 Feb 2023 01:33:46 +0100
Subject: Cursor comparison bugfix with empty cursors (and null values).

---
 .../main/java/tools/refinery/store/map/internal/MapCursor.java   | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'subprojects/store')

diff --git a/subprojects/store/src/main/java/tools/refinery/store/map/internal/MapCursor.java b/subprojects/store/src/main/java/tools/refinery/store/map/internal/MapCursor.java
index f874137b..50fcfcd3 100644
--- a/subprojects/store/src/main/java/tools/refinery/store/map/internal/MapCursor.java
+++ b/subprojects/store/src/main/java/tools/refinery/store/map/internal/MapCursor.java
@@ -117,7 +117,12 @@ public class MapCursor<K, V> implements Cursor<K, V> {
 	 * same position.
 	 */
 	public static <K, V> int compare(MapCursor<K, V> cursor1, MapCursor<K, V> cursor2) {
-		// two cursors are equally deep
+		// Checking the state of the cursors
+		if(!cursor1.isTerminated() && cursor2.isTerminated()) return -1;
+		else if(cursor1.isTerminated() && !cursor2.isTerminated()) return 1;
+		else if(cursor1.isTerminated() && cursor2.isTerminated()) return 0;
+
+		// If the state does not determine the order, then compare @nodeIndexStack.
 		Iterator<Integer> stack1 = cursor1.nodeIndexStack.descendingIterator();
 		Iterator<Integer> stack2 = cursor2.nodeIndexStack.descendingIterator();
 		if (stack1.hasNext()) {
@@ -137,6 +142,8 @@ public class MapCursor<K, V> implements Cursor<K, V> {
 			// stack 2 has more element, thus stack 2 is deeper
 			return 1;
 		}
+
+		// two cursors are equally deep decide by data index
 		return Integer.compare(cursor1.dataIndex, cursor2.dataIndex);
 	}
 }
-- 
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