refactor: avoid unnecessary Literal substitutions

1 files changed, 9 insertions, 3 deletions

diff --git a/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/ClausePostProcessor.java b/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/ClausePostProcessor.java
index 7a56145c..72bc06a1 100644
--- a/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/ClausePostProcessor.java
+++ b/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/ClausePostProcessor.java
@@ -11,6 +11,7 @@ import tools.refinery.store.query.literal.Literal;
 import tools.refinery.store.query.literal.VariableDirection;
 import tools.refinery.store.query.substitution.MapBasedSubstitution;
 import tools.refinery.store.query.substitution.StatelessSubstitution;
+import tools.refinery.store.query.substitution.Substitution;
 import tools.refinery.store.query.term.NodeVariable;
 import tools.refinery.store.query.term.Variable;
 
@@ -135,15 +136,20 @@ class ClausePostProcessor {
         }
 
         private void substituteLiterals() {
-                var substitution = new MapBasedSubstitution(Collections.unmodifiableMap(representatives),
-                                StatelessSubstitution.IDENTITY);
+                Substitution substitution;
+                if (representatives.isEmpty()) {
+                        substitution = null;
+                } else {
+                        substitution = new MapBasedSubstitution(Collections.unmodifiableMap(representatives),
+                                        StatelessSubstitution.IDENTITY);
+                }
                 for (var literal : literals) {
                         if (isPositiveEquivalence(literal)) {
                                 // We already retained all equivalences that cannot be replaced with substitutions in
                                 // {@link#keepParameterEquivalences()}.
                                 continue;
                         }
-                        var substitutedLiteral = literal.substitute(substitution);
+                        var substitutedLiteral = substitution == null ? literal : literal.substitute(substitution);
                         substitutedLiterals.add(substitutedLiteral);
                 }
         }