With x, x it will only go to 2 level deep.

With the plus you allow to go as far as the x rule succeed and your x rule always succeed because notA always succeed due to the star without consuming anything so you fall into infinite loop.

2014-12-18 6:47 GMT+01:00 James Foster <Smalltalk@jgfoster.net>:

There is something about plus that I don��t understand. In the following code if I parse for (x , x) then I get what I expect. If I parse for (x plus) then the image hangs. What am I doing wrong?

James

| a notA x y |
a := $a asParser.
notA := $a asParser negate star flatten.
x := a / notA.
y := x , x.�� works fine��
y := x plus. ��never finishes��
^y end parse: 'ab��.

Guillaume Larcheveque