[antlr-interest] Manually creating tree - infinite loop

[Edward Povazan]

> I can't really follow what rule was getting you into trouble, but infinite
> loops are usually caused because people forget that trees and nodes are
the
> same object.  A node contains the down and right pointers.  So if you were
> to do something like #(a1, a2, a1) you would create an infinite loop.
Often
> people forget to copy a node if they want something like the above.
>
> Monty

Thanks for the input,
The loop is gone now by excluding nodes from the auto tree contruction. They
were as indicated below.
You mention copying nodes? Is there a shortcut for this?
a1:add_op
(
gt1:GT! a2:add_op!
{ ## = #(#gt1, #a1, #a2); }    <----loop
(
gt2:GT! a3:add_op!
{ ## = #([AND, "and"], ##, #(#gt2, #a2, #a3)); #a2 = #a3; }  <----loop
)*
)?
;

The tree is now correct with this code, I still don't see how adding child
## results in a bad tree.
{
AST childroot = astFactory.dupTree(##);
## = #([AND, "and"], childroot, #(#gt2, #a2, #a3));
#a2 = #a3;
}

vs

{
## = #([AND, "and"], ##, #(#gt2, #a2, #a3));
#a2 = #a3;
}

Thanks - it works now, but I don't like when I don't know why something
works.
-Ed


 

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