Clean up and refactor Propagation and Assignment

Author: joke1196

python-frontend/src/main/java/org/sonar/python/semantic/v2/types/Assignment.java

@@ -37,9 +37,9 @@ public Assignment(SymbolV2 lhsSymbol, Name lhsName, Expression rhs, Map<SymbolV2
     this.propagationsByLhs = propagationsByLhs;
   }
 
-  void computeDependencies(Expression expression, Set<SymbolV2> trackedVars) {
+  void computeDependencies(Set<SymbolV2> trackedVars) {
     Deque<Expression> workList = new ArrayDeque<>();
-    workList.push(expression);
+    workList.push(rhs);
     while (!workList.isEmpty()) {
       Expression e = workList.pop();
       if (e instanceof Name name) {

python-frontend/src/main/java/org/sonar/python/semantic/v2/types/ProgramStateTypeInferenceVisitor.java

@@ -65,11 +65,7 @@ public void visitQualifiedExpression(QualifiedExpression qualifiedExpression) {
     }
   }
 
-  private static PythonType or(PythonType t1, PythonType t2) {
-    return UnionType.or(t1, t2);
-  }
-
   private static PythonType union(Stream<PythonType> types) {
-    return types.reduce(ProgramStateTypeInferenceVisitor::or).orElse(PythonType.UNKNOWN);
+    return types.reduce(UnionType::or).orElse(PythonType.UNKNOWN);
   }
 }

python-frontend/src/main/java/org/sonar/python/semantic/v2/types/Propagation.java

@@ -111,12 +111,8 @@ Set<Propagation> dependents() {
   static PythonType currentType(Name lhsName) {
     return Optional.ofNullable(lhsName.symbolV2())
       .stream()
-      .map(SymbolV2::usages)
-      .flatMap(List::stream)
-      .filter(u -> !SymbolV2Utils.isDeclaration(u))
-      .map(UsageV2::tree)
-      .filter(Expression.class::isInstance)
-      .map(Expression.class::cast)
+      .flatMap(Propagation::getSymbolNonDeclarationUsageTrees)
+      .flatMap(TreeUtils.toStreamInstanceOfMapper(Expression.class))
       .findFirst()
       .map(Expression::typeV2)
       .orElse(null);

python-frontend/src/main/java/org/sonar/python/semantic/v2/types/PropagationVisitor.java

@@ -209,7 +209,7 @@ public Map<SymbolV2, Set<PythonType>> processPropagations(Set<SymbolV2> trackedV
         props.stream()
           .filter(Assignment.class::isInstance)
           .map(Assignment.class::cast)
-          .forEach(a -> a.computeDependencies(a.rhs(), trackedVars));
+          .forEach(a -> a.computeDependencies(trackedVars));
         propagations.addAll(props);
       }
     });