CREATE tree.txt  \ Leo Wong  25 March 02003 fyj +
\ >children >data add-sibling level link tree tree.txt xtree

\ See: folderol.txt

from linked.txt

: tree  linked ;
: link  ( list -- link' )
   CELL+ ALIGN HERE TUCK SWAP 2DUP @ ! ! 0 , ;
: >children  ( node -- child-list )  CELL+ ;
: >data  ( node -- data )  3 CELLS + ;
: add-sibling  ( a u node -- node' )  link node ;
VARIABLE level  \ Mostly for display
: xTree  ( tree -- )
   @ ?DUP 0= ?? EXIT
   DUP xNode  DUP 1 level +! >children RECURSE  -1 level +!  RECURSE ;