Rhino - Is there a way to restore a modified AST to its original version without re-parsing the code?

Question

I am using a mutation testing tool for JavaScript. AST is modified and test cases run against modified code. After running the test cases, I want to restore the modified AST to the original one so that I can repeat the mutation process. But I do not know how to restore it. Any help?

Rhino API Documentation

Answer 1

I don’t know Rhino specifically, so I don’t know if he offers specific help for this. But in general, you can directly do it yourself by tracking the changes you make as “anti-changes.” This scheme works for any AST system, and not just for rhinos.

A tree consists of nodes and the relationship between a node and its children.

To build a tree, you can execute commands to create a node, create its children and bind them together. Of course, the Rhino API offers primitive support for this.

To rebuild the tree at a later time, we simply compile a list of actions to perform based on the node construct and the child join / disconnect.

Imagine the following tree:

          1:*
       /      \
     2:+      3:[]
    /  \       /  \
  4:x  5:17  6:a  7:i

n: t, n - node, t - node. node 1, 2,...

( "" ) , 2: + node 8: mod 5:17 9: j. , :

    disconnect(2,1);  // disconnect node N from its Mth child
    disconnect(2,2);
    disconnect(1,1);
    delete(2);
    delete(5);
    n1=create(mod); // node 8
    n2=create(j); // node 9
    connect(1,1,n1); // connect node 1 child 1 to n1
    connect(n1,1,4);
    connect(n1,2,n2);

(), :

    [ [disconnect,n1,2],
      [disconnect,n1,1],
      [disconnect,1,1],
      [delete,n2],
      [delete,n1],
      [create,n5,17],
      [create,n2,+],
      [connect,1,1,n2],
      [connect,2,2,n5],
      [connect,2,1,4] ]

"" , .

; . , tree-mutate-and-remember-inverse, ,

      fn disconnect_and_remember_inverse(node,child) {
            push(undo_list,[connect,node,child,nth_child(node,child)]);
            disconnect(node,child);
       }

"", node, , , node "":

    [ [disconnect,n1,2],
      [disconnect,n1,1],
      [disconnect,1,1],
      [delete,n2],
      [delete,n1],
      // [create,n5,17],
      // [create,n2,+],
      [connect,1,1,2],
      [connect,2,2,5],
      [connect,2,1,4] ]

, , - , Rhino; , , , ign_inverse . ; .

, . ( JavaScript, , ).