From 98a38454b675b59587d66dae693222f5eb36c2df Mon Sep 17 00:00:00 2001
From: Ties de Kock <ties@tiesdekock.nl>
Date: Mon, 28 Nov 2022 07:45:17 +0100
Subject: [PATCH 1/2] Rename difference -> minus

---
 .../net/ripe/ipresource/ImmutableResourceSet.java  | 14 ++++++++++++++
 .../ripe/ipresource/ImmutableResourceSetTest.java  | 13 ++++++++++---
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/src/main/java/net/ripe/ipresource/ImmutableResourceSet.java b/src/main/java/net/ripe/ipresource/ImmutableResourceSet.java
index 7c1e667..63584dc 100644
--- a/src/main/java/net/ripe/ipresource/ImmutableResourceSet.java
+++ b/src/main/java/net/ripe/ipresource/ImmutableResourceSet.java
@@ -133,6 +133,9 @@ public ImmutableResourceSet remove(IpResource value) {
         return new Builder(this).remove(value).build();
     }
 
+    /**
+     * @return $this \cup that$
+     */
     public ImmutableResourceSet union(ImmutableResourceSet that) {
         if (this.isEmpty()) {
             return that;
@@ -145,6 +148,9 @@ public ImmutableResourceSet union(ImmutableResourceSet that) {
         }
     }
 
+    /**
+     * @return $this \cap that$
+     */
     public ImmutableResourceSet intersection(ImmutableResourceSet that) {
         if (this.isEmpty()) {
             return this;
@@ -173,7 +179,15 @@ public ImmutableResourceSet intersection(ImmutableResourceSet that) {
         }
     }
 
+    @Deprecated
     public ImmutableResourceSet difference(ImmutableResourceSet that) {
+        return this.minus(that);
+    }
+
+    /**
+     * @return $this \setminus that$
+     */
+    public ImmutableResourceSet minus(ImmutableResourceSet that) {
         if (!this.intersects(that)) {
             return this;
         } else {
diff --git a/src/test/java/net/ripe/ipresource/ImmutableResourceSetTest.java b/src/test/java/net/ripe/ipresource/ImmutableResourceSetTest.java
index 6a57940..c5fff32 100644
--- a/src/test/java/net/ripe/ipresource/ImmutableResourceSetTest.java
+++ b/src/test/java/net/ripe/ipresource/ImmutableResourceSetTest.java
@@ -199,6 +199,13 @@ public void test_difference() {
         assertEquals(ImmutableResourceSet.parse("AS3333-AS3334, AS3336-AS4444, 10.0.0.0-10.4.255.255, 10.6.0.0-10.255.255.255"), difference);
     }
 
+    @Test
+    public void test_minus() {
+        ImmutableResourceSet a = ImmutableResourceSet.parse("AS3333-AS4444,10.0.0.0/8");
+        ImmutableResourceSet difference = a.minus(ImmutableResourceSet.parse("10.5.0.0/16, AS3335"));
+        assertEquals(ImmutableResourceSet.parse("AS3333-AS3334, AS3336-AS4444, 10.0.0.0-10.4.255.255, 10.6.0.0-10.255.255.255"), difference);
+    }
+
     @Test
     public void test_intersection() {
         ImmutableResourceSet empty = ImmutableResourceSet.parse("");
@@ -335,9 +342,9 @@ public void difference_laws() {
             ImmutableResourceSet b = randomSet(i);
             ImmutableResourceSet c = randomSet(i);
 
-            assertEquals(c.difference(a.intersection(b)), (c.difference(a)).union(c.difference(b)));
-            assertEquals(c.difference(a.union(b)), (c.difference(a)).intersection(c.difference(b)));
-            assertEquals(c.difference(b.difference(a)), (a.intersection(c)).union(c.difference(b)));
+            assertEquals(c.minus(a.intersection(b)), (c.minus(a)).union(c.minus(b)));
+            assertEquals(c.minus(a.union(b)), (c.minus(a)).intersection(c.minus(b)));
+            assertEquals(c.minus(b.minus(a)), (a.intersection(c)).union(c.minus(b)));
         }
 
     }

From 81b98cd28865de9ac3d5206b6498e0ae1e1d65e2 Mon Sep 17 00:00:00 2001
From: Ties de Kock <ties@tiesdekock.nl>
Date: Mon, 28 Nov 2022 07:54:54 +0100
Subject: [PATCH 2/2] Add symmetricDifference to ImmutableResourceSet

---
 .../java/net/ripe/ipresource/ImmutableResourceSet.java    | 8 ++++++++
 .../net/ripe/ipresource/ImmutableResourceSetTest.java     | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/src/main/java/net/ripe/ipresource/ImmutableResourceSet.java b/src/main/java/net/ripe/ipresource/ImmutableResourceSet.java
index 63584dc..a050f34 100644
--- a/src/main/java/net/ripe/ipresource/ImmutableResourceSet.java
+++ b/src/main/java/net/ripe/ipresource/ImmutableResourceSet.java
@@ -195,6 +195,14 @@ public ImmutableResourceSet minus(ImmutableResourceSet that) {
         }
     }
 
+    /**
+     * @return $this \Delta that$
+     */
+    public ImmutableResourceSet symmetricDifference(ImmutableResourceSet that) {
+        // $this \Delta that = (this \setminus that) \cup (that \setminus this)$
+        return (this.minus(that)).union((that.minus(this)));
+    }
+
     public ImmutableResourceSet complement() {
         return universal().difference(this);
     }
diff --git a/src/test/java/net/ripe/ipresource/ImmutableResourceSetTest.java b/src/test/java/net/ripe/ipresource/ImmutableResourceSetTest.java
index c5fff32..518b71f 100644
--- a/src/test/java/net/ripe/ipresource/ImmutableResourceSetTest.java
+++ b/src/test/java/net/ripe/ipresource/ImmutableResourceSetTest.java
@@ -206,6 +206,14 @@ public void test_minus() {
         assertEquals(ImmutableResourceSet.parse("AS3333-AS3334, AS3336-AS4444, 10.0.0.0-10.4.255.255, 10.6.0.0-10.255.255.255"), difference);
     }
 
+    @Test
+    public void test_symmetricDifference() {
+        ImmutableResourceSet a = ImmutableResourceSet.parse("AS64512-AS64513");
+        ImmutableResourceSet b = ImmutableResourceSet.parse("AS64513-AS64514");
+        ImmutableResourceSet symDiff = a.symmetricDifference(b);
+        assertEquals(ImmutableResourceSet.parse("AS64512, AS64514"), symDiff);
+    }
+
     @Test
     public void test_intersection() {
         ImmutableResourceSet empty = ImmutableResourceSet.parse("");