Python: Refactor how we find a Class from API::Node

Using `getAnImmediateUse` might give better performance than `getAUse`.

Since all the changed code is about `API::Node`s that are found after
doing `.getASubclass*()`, this change is OK.

It's also nice to align how we actually do this.

python/ql/lib/semmle/python/frameworks/Aiohttp.qll

@@ -243,7 +243,9 @@ module AiohttpWebModel {
 
   /** A class that has a super-type which is an aiohttp.web View class. */
   class AiohttpViewClassFromSuperClass extends AiohttpViewClass {
-    AiohttpViewClassFromSuperClass() { this.getABase() = View::subclassRef().getAUse().asExpr() }
+    AiohttpViewClassFromSuperClass() {
+      this.getParent() = View::subclassRef().getAnImmediateUse().asExpr()
+    }
   }
 
   /** A class that is used in a route-setup, therefore being considered an aiohttp.web View class. */

python/ql/lib/semmle/python/frameworks/Django.qll

@@ -829,7 +829,7 @@ module PrivateDjango {
 
           /** Gets the (AST) class of the Django model class `modelClass`. */
           Class getModelClassClass(API::Node modelClass) {
-            result.getParent() = modelClass.getAUse().asExpr().(ClassExpr) and
+            result.getParent() = modelClass.getAnImmediateUse().asExpr() and
             modelClass = Model::subclassRef()
           }
 
@@ -2162,7 +2162,9 @@ module PrivateDjango {
    * thereby handling user input.
    */
   class DjangoFormClass extends Class, SelfRefMixin {
-    DjangoFormClass() { this.getABase() = Django::Forms::Form::subclassRef().getAUse().asExpr() }
+    DjangoFormClass() {
+      this.getParent() = Django::Forms::Form::subclassRef().getAnImmediateUse().asExpr()
+    }
   }
 
   /**
@@ -2195,7 +2197,7 @@ module PrivateDjango {
    */
   class DjangoFormFieldClass extends Class {
     DjangoFormFieldClass() {
-      this.getABase() = Django::Forms::Field::subclassRef().getAUse().asExpr()
+      this.getParent() = Django::Forms::Field::subclassRef().getAnImmediateUse().asExpr()
     }
   }
 
@@ -2298,7 +2300,7 @@ module PrivateDjango {
    */
   class DjangoViewClassFromSuperClass extends DjangoViewClass {
     DjangoViewClassFromSuperClass() {
-      this.getABase() = Django::Views::View::subclassRef().getAUse().asExpr()
+      this.getParent() = Django::Views::View::subclassRef().getAnImmediateUse().asExpr()
     }
   }
 

python/ql/lib/semmle/python/frameworks/Flask.qll

@@ -194,7 +194,7 @@ module Flask {
     API::Node api_node;
 
     FlaskViewClass() {
-      this.getABase() = Views::View::subclassRef().getAUse().asExpr() and
+      this.getParent() = Views::View::subclassRef().getAnImmediateUse().asExpr() and
       api_node.getAnImmediateUse().asExpr() = this.getParent()
     }
 
@@ -219,7 +219,7 @@ module Flask {
    */
   class FlaskMethodViewClass extends FlaskViewClass {
     FlaskMethodViewClass() {
-      this.getABase() = Views::MethodView::subclassRef().getAUse().asExpr() and
+      this.getParent() = Views::MethodView::subclassRef().getAnImmediateUse().asExpr() and
       api_node.getAnImmediateUse().asExpr() = this.getParent()
     }
 

python/ql/lib/semmle/python/frameworks/RestFramework.qll

@@ -115,7 +115,7 @@ private module RestFramework {
    */
   class RestFrameworkApiViewClass extends PrivateDjango::DjangoViewClassFromSuperClass {
     RestFrameworkApiViewClass() {
-      this.getABase() = any(ModeledApiViewClasses c).getASubclass*().getAUse().asExpr()
+      this.getParent() = any(ModeledApiViewClasses c).getASubclass*().getAnImmediateUse().asExpr()
     }
 
     override Function getARequestHandler() {

python/ql/lib/semmle/python/frameworks/Stdlib.qll

@@ -1934,7 +1934,7 @@ private module StdlibPrivate {
 
     /** A HttpRequestHandler class definition (most likely in project code). */
     class HttpRequestHandlerClassDef extends Class {
-      HttpRequestHandlerClassDef() { this.getParent() = subclassRef().getAUse().asExpr() }
+      HttpRequestHandlerClassDef() { this.getParent() = subclassRef().getAnImmediateUse().asExpr() }
     }
 
     /** DEPRECATED: Alias for HttpRequestHandlerClassDef */
@@ -2027,12 +2027,12 @@ private module StdlibPrivate {
   private module WsgirefSimpleServer {
     class WsgiServerSubclass extends Class, SelfRefMixin {
       WsgiServerSubclass() {
-        this.getABase() =
+        this.getParent() =
           API::moduleImport("wsgiref")
               .getMember("simple_server")
               .getMember("WSGIServer")
               .getASubclass*()
-              .getAUse()
+              .getAnImmediateUse()
               .asExpr()
       }
     }

python/ql/lib/semmle/python/frameworks/Tornado.qll

@@ -92,7 +92,7 @@ private module Tornado {
 
         /** A RequestHandler class (most likely in project code). */
         class RequestHandlerClass extends Class {
-          RequestHandlerClass() { this.getParent() = subclassRef().getAUse().asExpr() }
+          RequestHandlerClass() { this.getParent() = subclassRef().getAnImmediateUse().asExpr() }
 
           /** Gets a function that could handle incoming requests, if any. */
           Function getARequestHandler() {

python/ql/lib/semmle/python/frameworks/Twisted.qll

@@ -27,13 +27,13 @@ private module Twisted {
    */
   class TwistedResourceSubclass extends Class {
     TwistedResourceSubclass() {
-      this.getABase() =
+      this.getParent() =
         API::moduleImport("twisted")
             .getMember("web")
             .getMember("resource")
             .getMember("Resource")
             .getASubclass*()
-            .getAUse()
+            .getAnImmediateUse()
             .asExpr()
     }