1 files changed, 64 insertions, 0 deletions

diff --git a/subprojects/store/src/main/java/tools/refinery/store/map/Cursors.java b/subprojects/store/src/main/java/tools/refinery/store/map/Cursors.java
index 0a94d449..5e69e7af 100644
--- a/subprojects/store/src/main/java/tools/refinery/store/map/Cursors.java
+++ b/subprojects/store/src/main/java/tools/refinery/store/map/Cursors.java
@@ -5,6 +5,9 @@
  */
 package tools.refinery.store.map;
 
+import java.util.Iterator;
+import java.util.Map;
+
 public final class Cursors {
     private Cursors() {
         throw new IllegalStateException("This is a static utility class and should not be instantiated directly");
@@ -14,6 +17,18 @@ public final class Cursors {
         return new Empty<>();
     }
 
+        public static <K, V> Cursor<K, V> singleton(K key, V value) {
+                return new Singleton<>(key, value);
+        }
+
+        public static <K, V> Cursor<K, V> of(Iterator<Map.Entry<K, V>> iterator) {
+                return new IteratorBasedCursor<>(iterator);
+        }
+
+        public static <K, V> Cursor<K, V> of(Map<K, V> map) {
+                return of(map.entrySet().iterator());
+        }
+
     private static class Empty<K, V> implements Cursor<K, V> {
         private boolean terminated = false;
 
@@ -38,4 +53,53 @@ public final class Cursors {
             return false;
         }
     }
+
+        private static class Singleton<K, V> implements Cursor<K, V> {
+                private State state = State.INITIAL;
+                private final K key;
+                private final V value;
+
+                public Singleton(K key, V value) {
+                        this.key = key;
+                        this.value = value;
+                }
+
+                @Override
+                public K getKey() {
+                        if (state == State.STARTED) {
+                                return key;
+                        }
+                        return null;
+                }
+
+                @Override
+                public V getValue() {
+                        if (state == State.STARTED) {
+                                return value;
+                        }
+                        return null;
+                }
+
+                @Override
+                public boolean isTerminated() {
+                        return state == State.TERMINATED;
+                }
+
+                @Override
+                public boolean move() {
+                        if (state == State.INITIAL) {
+                                state = State.STARTED;
+                                return true;
+                        }
+                        state = State.TERMINATED;
+                        return false;
+                }
+
+
+                private enum State {
+                        INITIAL,
+                        STARTED,
+                        TERMINATED
+                }
+        }
 }