1 files changed, 73 insertions, 0 deletions

diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/literal/ConstantLiteral.java b/subprojects/logic/src/main/java/tools/refinery/logic/literal/ConstantLiteral.java
new file mode 100644
index 00000000..688ddfa0
--- /dev/null
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/literal/ConstantLiteral.java
@@ -0,0 +1,73 @@
+/*
+ * 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.equality.LiteralEqualityHelper;
+import tools.refinery.logic.equality.LiteralHashCodeHelper;
+import tools.refinery.logic.substitution.Substitution;
+import tools.refinery.logic.term.NodeVariable;
+import tools.refinery.logic.term.Variable;
+
+import java.util.Objects;
+import java.util.Set;
+
+public class ConstantLiteral extends AbstractLiteral {
+        private final NodeVariable variable;
+        private final int nodeId;
+
+        public ConstantLiteral(NodeVariable variable, int nodeId) {
+                this.variable = variable;
+                this.nodeId = nodeId;
+        }
+
+        public NodeVariable getVariable() {
+                return variable;
+        }
+
+        public int getNodeId() {
+                return nodeId;
+        }
+
+
+        @Override
+        public Set<Variable> getOutputVariables() {
+                return Set.of(variable);
+        }
+
+        @Override
+        public Set<Variable> getInputVariables(Set<? extends Variable> positiveVariablesInClause) {
+                return Set.of();
+        }
+
+        @Override
+        public Set<Variable> getPrivateVariables(Set<? extends Variable> positiveVariablesInClause) {
+                return Set.of();
+        }
+
+        @Override
+        public ConstantLiteral substitute(Substitution substitution) {
+                return new ConstantLiteral(substitution.getTypeSafeSubstitute(variable), nodeId);
+        }
+
+        @Override
+        public boolean equalsWithSubstitution(LiteralEqualityHelper helper, Literal other) {
+                if (other.getClass() != getClass()) {
+                        return false;
+                }
+                var otherConstantLiteral = (ConstantLiteral) other;
+                return helper.variableEqual(variable, otherConstantLiteral.variable) && nodeId == otherConstantLiteral.nodeId;
+        }
+
+        @Override
+        public int hashCodeWithSubstitution(LiteralHashCodeHelper helper) {
+                return Objects.hash(super.hashCodeWithSubstitution(helper), helper.getVariableHashCode(variable), nodeId);
+        }
+
+        @Override
+        public String toString() {
+                return "%s === @Constant %d".formatted(variable, nodeId);
+        }
+}