Use #deepCopy instead of #copy when copying RB parse tree
...because #copy make a copy if child nodes but does not set their parents properly.
Therefore node replacing does not work because it replaces it in wrong tree (original,
not the copy).
"{ Package: 'stx:goodies/petitparser' }"
PPParser subclass:#PPStartOfLine
instanceVariableNames:''
classVariableNames:''
poolDictionaries:''
category:'PetitParser-Parsers'
!
!PPStartOfLine methodsFor:'parsing'!
parseOn: aPPContext
(aPPContext isStartOfLine) ifTrue: [
^ #startOfLine
].
^ PPFailure message: 'Start of line expected' context: aPPContext at: aPPContext position
! !