Flatten Variable Derivation Chains

liquidjava-verifier/pom.xml

@@ -11,7 +11,7 @@
 
 	<groupId>io.github.liquid-java</groupId>
 	<artifactId>liquidjava-verifier</artifactId>
-	<version>0.0.8</version>
+	<version>0.0.10</version>
 	<name>liquidjava-verifier</name>
 	<description>LiquidJava Verifier</description>
 	<url>https://github.com/liquid-java/liquidjava</url>

liquidjava-verifier/src/main/java/liquidjava/rj_language/opt/ConstantPropagation.java

@@ -9,6 +9,7 @@
 import liquidjava.rj_language.opt.derivation_node.UnaryDerivationNode;
 import liquidjava.rj_language.opt.derivation_node.ValDerivationNode;
 import liquidjava.rj_language.opt.derivation_node.VarDerivationNode;
+import liquidjava.utils.Utils;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -47,8 +48,7 @@ private static ValDerivationNode propagateRecursive(Expression exp, Map<String,
                 DerivationNode previousOrigin = varOrigins.get(name);
 
                 // preserve origin if value came from previous derivation
-                DerivationNode origin = previousOrigin != null ? new VarDerivationNode(name, previousOrigin)
-                        : new VarDerivationNode(name);
+                DerivationNode origin = flattenVarOrigin(name, previousOrigin);
                 return new ValDerivationNode(value.clone(), origin);
             }
 
@@ -138,4 +138,14 @@ private static void extractVarOrigins(ValDerivationNode node, Map<String, Deriva
             extractVarOrigins(valOrigin, varOrigins);
         }
     }
+
+    /**
+     * Flattens same instance variable derivations to avoid redundancy by collapsing var -> var chains
+     */
+    private static VarDerivationNode flattenVarOrigin(String varName, DerivationNode origin) {
+        if (origin instanceof VarDerivationNode varOrigin && Utils.isSameVariable(varOrigin.getVar(), varName)) {
+            return flattenVarOrigin(varOrigin.getVar(), varOrigin.getOrigin()); // recursively flatten
+        }
+        return origin != null ? new VarDerivationNode(varName, origin) : new VarDerivationNode(varName);
+    }
 }

liquidjava-verifier/src/main/java/liquidjava/utils/Utils.java

@@ -42,4 +42,17 @@ public static SourcePosition getRefinementAnnotationPosition(CtElement element,
             return unquoted.equals(refinement);
         }).findFirst().map(CtElement::getPosition).orElse(element.getPosition());
     }
+
+    public static boolean isSameVariable(String var1, String var2) {
+        int index1 = var1.lastIndexOf('_');
+        int index2 = var2.lastIndexOf('_');
+        // no format
+        if (index1 < 0 || index2 < 0) {
+            return var1.equals(var2);
+        }
+        // #(.*)_n format
+        String name1 = var1.substring(0, index1);
+        String name2 = var2.substring(0, index2);
+        return name1.equals(name2);
+    }
 }