From 916accbd0011f83cce86c4f850fd2e40796f666a Mon Sep 17 00:00:00 2001
From: Geoffroy Couprie <contact@geoffroycouprie.com>
Date: Thu, 4 Jan 2024 18:32:21 +0100
Subject: [PATCH] beware the modifiable reference

---
 .../java/com/clevercloud/biscuit/datalog/Combinator.java    | 5 ++---
 src/main/java/com/clevercloud/biscuit/datalog/Origin.java   | 6 ++++--
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/main/java/com/clevercloud/biscuit/datalog/Combinator.java b/src/main/java/com/clevercloud/biscuit/datalog/Combinator.java
index bcde41cf..e32026c3 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/Combinator.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/Combinator.java
@@ -70,7 +70,7 @@ public Option<Tuple2<Origin, Map<Long, Term>>> getNext() {
                // we iterate over the facts that match the current predicate
                if (this.currentFacts.hasNext()) {
                   final Tuple2<Origin, Fact> t = this.currentFacts.next();
-                  Origin currentOrigin = t._1;
+                  Origin currentOrigin = t._1.clone();
                   Fact fact = t._2;
 
                   // create a new MatchedVariables in which we fix variables we could unify from our first predicate and the current fact
@@ -129,8 +129,7 @@ public Option<Tuple2<Origin, Map<Long, Term>>> getNext() {
 
          if (opt.isDefined()) {
             Tuple2<Origin, Map<Long, Term>> t = opt.get();
-            t._1.union(currentOrigin);
-            return Option.some(t);
+            return Option.some(new Tuple2<>(t._1.union(currentOrigin), t._2));
          } else {
             currentOrigin = null;
             currentIt = null;
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/Origin.java b/src/main/java/com/clevercloud/biscuit/datalog/Origin.java
index d18df2d7..8f1b86e9 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/Origin.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/Origin.java
@@ -33,8 +33,10 @@ public void add(long i) {
         inner.add(i);
     }
 
-    public void union(Origin other) {
-        this.inner.addAll(other.inner);
+    public Origin union(Origin other) {
+        Origin o = this.clone();
+        o.inner.addAll(other.inner);
+        return o;
     }
 
     public Origin clone() {