convert some leftovers to use dataflow nodes

javascript/ql/lib/semmle/javascript/frameworks/Express.qll

@@ -56,13 +56,11 @@ module Express {
   }
 
   /**
+   * DEPRECATED: Use `isRouter()` instead.
    * An expression that refers to a route.
    */
-  class RouteExpr extends DataFlow::MethodCallNode {
-    RouteExpr() { isRouter(this) }
-
-    /** Gets the router from which this route was created, if it is known. */
-    RouterDefinition getRouter() { isRouter(this, result) }
+  deprecated class RouteExpr extends MethodCallExpr {
+    RouteExpr() { isRouter(this.flow()) }
   }
 
   /**

javascript/ql/lib/semmle/javascript/frameworks/Hapi.qll

@@ -19,29 +19,24 @@ module Hapi {
   /**
    * A Hapi route handler.
    */
-  class RouteHandler extends HTTP::Servers::StandardRouteHandler, DataFlow::ValueNode {
-    Function function;
-
-    RouteHandler() {
-      function = astNode and
-      exists(RouteSetup setup | this = setup.getARouteHandler())
-    }
+  class RouteHandler extends HTTP::Servers::StandardRouteHandler, DataFlow::FunctionNode {
+    RouteHandler() { exists(RouteSetup setup | this = setup.getARouteHandler()) }
 
     /**
      * Gets the parameter of the route handler that contains the request object.
      */
-    Parameter getRequestParameter() { result = function.getParameter(0) }
+    DataFlow::ParameterNode getRequestParameter() { result = getParameter(0) }
 
     /**
      * Gets the parameter of the route handler that contains the "request toolkit",
      * usually named `h`.
      */
-    Parameter getRequestToolkitParameter() { result = function.getParameter(1) }
+    DataFlow::ParameterNode getRequestToolkitParameter() { result = getParameter(1) }
 
     /**
      * Gets a source node referring to the request toolkit parameter, usually named `h`.
      */
-    DataFlow::SourceNode getRequestToolkit() { result = getRequestToolkitParameter().flow() }
+    DataFlow::SourceNode getRequestToolkit() { result = getRequestToolkitParameter() }
   }
 
   /**
@@ -66,7 +61,7 @@ module Hapi {
   private class RequestSource extends HTTP::Servers::RequestSource {
     RouteHandler rh;
 
-    RequestSource() { this = DataFlow::parameterNode(rh.getRequestParameter()) }
+    RequestSource() { this = rh.getRequestParameter() }
 
     /**
      * Gets the route handler that handles this request.

javascript/ql/lib/semmle/javascript/frameworks/Koa.qll

@@ -49,7 +49,7 @@ module Koa {
      * Gets an expression that contains the "context" object of
      * a route handler invocation.
      */
-    deprecated Expr getAContextExpr() { result.(ContextExpr).getRouteHandler() = this }
+    deprecated Expr getAContextExpr() { result = this.getAContextNode().asExpr() }
 
     /**
      * Gets an expression that contains the "context" object of
@@ -67,7 +67,7 @@ module Koa {
      * object of a route handler invocation.
      */
     deprecated Expr getAResponseOrContextExpr() {
-      result = this.getAResponseNode().asExpr() or result = this.getAContextExpr()
+      result = this.getAResponseOrContextNode().asExpr()
     }
 
     /**
@@ -83,9 +83,7 @@ module Koa {
      * Gets an expression that contains the context or request
      * object of a route handler invocation.
      */
-    deprecated Expr getARequestOrContextExpr() {
-      result = this.getARequestNode().asExpr() or result = this.getAContextExpr()
-    }
+    deprecated Expr getARequestOrContextExpr() { result = this.getARequestOrContextNode().asExpr() }
 
     /**
      * Gets an expression that contains the context or request
@@ -447,7 +445,7 @@ module Koa {
 
     override DataFlow::SourceNode getARouteHandler() {
       // `StandardRouteHandler` uses this predicate in it's charpred, so making this predicate return a `RouteHandler` would give an empty recursion.
-      result.flowsToExpr(this.getArgument(0).asExpr())
+      result.flowsTo(this.getArgument(0))
       or
       // For the route-handlers that does not depend on this predicate in their charpred.
       result.(RouteHandler).getARouteHandlerRegistrationObject().flowsTo(this.getArgument(0))

javascript/ql/test/library-tests/frameworks/Express/RouteExpr.qll

@@ -1,5 +0,0 @@
-import javascript
-
-query predicate test_RouteExpr(Express::RouteExpr e, Express::RouterDefinition res) {
-  res = e.getRouter()
-}

javascript/ql/test/library-tests/frameworks/Express/tests.ql

@@ -27,7 +27,6 @@ import RouterDefinition_getASubRouter
 import HeaderDefinition_getNameExpr
 import appCreation
 import RouteSetup_getRequestMethod
-import RouteExpr
 import RouteHandler_getAResponseExpr
 import isResponse
 import ResponseBody