1 files changed, 39 insertions, 0 deletions

diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/literal/CallPolarity.java b/subprojects/logic/src/main/java/tools/refinery/logic/literal/CallPolarity.java
new file mode 100644
index 00000000..4f3bca15
--- /dev/null
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/literal/CallPolarity.java
@@ -0,0 +1,39 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.logic.literal;
+
+import tools.refinery.logic.InvalidQueryException;
+
+public enum CallPolarity {
+        POSITIVE(true, false),
+        NEGATIVE(false, false),
+        TRANSITIVE(true, true);
+
+        private final boolean positive;
+
+        private final boolean transitive;
+
+        CallPolarity(boolean positive, boolean transitive) {
+                this.positive = positive;
+                this.transitive = transitive;
+        }
+
+        public boolean isPositive() {
+                return positive;
+        }
+
+        public boolean isTransitive() {
+                return transitive;
+        }
+
+        public CallPolarity negate() {
+                return switch (this) {
+                        case POSITIVE -> NEGATIVE;
+                        case NEGATIVE -> POSITIVE;
+                        case TRANSITIVE -> throw new InvalidQueryException("Transitive polarity cannot be negated");
+                };
+        }
+}