1 files changed, 42 insertions, 7 deletions

diff --git a/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/AssignLiteral.java b/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/AssignLiteral.java
index 8cc3fae6..4da92b90 100644
--- a/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/AssignLiteral.java
+++ b/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/AssignLiteral.java
@@ -9,21 +9,43 @@ import tools.refinery.store.query.equality.LiteralEqualityHelper;
 import tools.refinery.store.query.substitution.Substitution;
 import tools.refinery.store.query.term.DataVariable;
 import tools.refinery.store.query.term.Term;
-import tools.refinery.store.query.term.Variable;
 
-import java.util.Set;
+import java.util.Objects;
 
-public record AssignLiteral<T>(DataVariable<T> variable, Term<T> term) implements Literal {
-        public AssignLiteral {
+public final class AssignLiteral<T> implements Literal {
+        private final DataVariable<T> variable;
+        private final Term<T> term;
+        private final VariableBinder variableBinder;
+
+        public AssignLiteral(DataVariable<T> variable, Term<T> term) {
                 if (!term.getType().equals(variable.getType())) {
                         throw new IllegalArgumentException("Term %s must be of type %s, got %s instead".formatted(
                                         term, variable.getType().getName(), term.getType().getName()));
                 }
+                this.variable = variable;
+                this.term = term;
+                var inputVariables = term.getInputVariables();
+                if (inputVariables.contains(variable)) {
+                        throw new IllegalArgumentException("Result variable %s must not appear in the term %s".formatted(
+                                        variable, term));
+                }
+                variableBinder = VariableBinder.builder()
+                                .variable(variable, VariableDirection.OUT)
+                                .variables(inputVariables, VariableDirection.IN)
+                                .build();
+        }
+
+        public DataVariable<T> getTargetVariable() {
+                return variable;
+        }
+
+        public Term<T> getTerm() {
+                return term;
         }
 
         @Override
-        public Set<Variable> getBoundVariables() {
-                return Set.of(variable);
+        public VariableBinder getVariableBinder() {
+                return variableBinder;
         }
 
         @Override
@@ -41,9 +63,22 @@ public record AssignLiteral<T>(DataVariable<T> variable, Term<T> term) implement
                                 otherLetLiteral.term);
         }
 
-
         @Override
         public String toString() {
                 return "%s is (%s)".formatted(variable, term);
         }
+
+        @Override
+        public boolean equals(Object obj) {
+                if (obj == this) return true;
+                if (obj == null || obj.getClass() != this.getClass()) return false;
+                var that = (AssignLiteral<?>) obj;
+                return Objects.equals(this.variable, that.variable) &&
+                                Objects.equals(this.term, that.term);
+        }
+
+        @Override
+        public int hashCode() {
+                return Objects.hash(getClass(), variable, term);
+        }
 }