Add NodeID to AST nodes

[bvanjoi]

I propose adding a NodeId field to each AST node:

struct BinaryExpr {
+   id: NodeID;
    left: Box<Expr>;
    right: Box<Expr>
}

And these values auto-incremented during the parsing phase, for example:

struct Parser {
     node_id_count: usize;
}

impl Parser {
   fn create_binary_expr(&mut self, left: Expr, right: Expr) -> BinaryExpr {
        let id = NodeId::from(self.node_id_count);
        self.node_id_count += 1;
        BinaryExpr { id, left, right }
   }
}

[magic-akari]

If two node IDs are equal, what does it signify?

For example, consider the following transformation:

Input

var foo = function () {};

Output

var foo = function foo() {};

In this transformation, the foo is duplicated, and do they share the same node ID?

[bvanjoi]

I think should not generate duplicate NodeID (excluding dummy_node_id)

[kdy1]

I really want to have this. It would resolve lots of perf issues caused by lack of proper scoping.