From fdf4d0b8a96f3dfc579c28e363be7944033f53a7 Mon Sep 17 00:00:00 2001
From: Bart Jacobs <bart.jacobs@cs.kuleuven.be>
Date: Mon, 28 Jun 2021 21:41:30 +0200
Subject: [PATCH] LogicalMap: add methods `plus` and `minus`

---
 .../src/logicalcollections/LogicalMap.java    | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/logicalcollections/src/logicalcollections/LogicalMap.java b/logicalcollections/src/logicalcollections/LogicalMap.java
index dd070f8..5e19998 100644
--- a/logicalcollections/src/logicalcollections/LogicalMap.java
+++ b/logicalcollections/src/logicalcollections/LogicalMap.java
@@ -113,4 +113,24 @@ public static <K, V> boolean allEntriesMatch(Map<K, V> map, BiPredicate<K, V> pr
 		return map.keySet().stream().allMatch(k -> predicate.test(k, map.get(k)));
 	}
 	
+	/**
+	 * Returns a map that contains the entries of the given map
+	 * as well as the given entry.
+	 */
+	public static <K, V> Map<K, V> plus(Map<K, V> map, K key, V value) {
+		var result = new HashMap<>(map);
+		result.put(key, value);
+		return result;
+	}
+	
+	/**
+	 * Returns a map that contains the entries of the given map
+	 * except for the entry with the given key.
+	 */
+	public static <K, V> Map<K, V> minus(Map<K, V> map, K key) {
+		var result = new HashMap<>(map);
+		result.remove(key);
+		return result;
+	}
+	
 }