SYMBOL: current-side
-: go-left? ( -- ? ) current-side get +lt+ eq? ;
+: left ( -- symbol ) -1 ; inline
+: right ( -- symbol ) 1 ; inline
+
+: key-side ( k1 k2 -- n )
+ <=> {
+ { +lt+ [ -1 ] }
+ { +eq+ [ 0 ] }
+ { +gt+ [ 1 ] }
+ } case ;
+
+: go-left? ( -- ? ) current-side get left eq? ;
: inc-count ( tree -- ) [ 1+ ] change-count drop ;
: with-side ( side quot -- ) [ swap current-side set call ] with-scope ; inline
: with-other-side ( quot -- )
- current-side get invert-comparison swap with-side ; inline
-: go-left ( quot -- ) +lt+ swap with-side ; inline
-: go-right ( quot -- ) +gt+ swap with-side ; inline
+ current-side get neg swap with-side ; inline
+: go-left ( quot -- ) left swap with-side ; inline
+: go-right ( quot -- ) right swap with-side ; inline
: change-root ( tree quot -- )
swap [ root>> swap call ] keep set-tree-root ; inline
: leaf? ( node -- ? )
[ left>> ] [ right>> ] bi or not ;
-: random-side ( -- side ) +lt+ +gt+ 2array random ;
+: random-side ( -- side ) left right 2array random ;
: choose-branch ( key node -- key node-left/right )
- 2dup node-key <=> [ node-link ] with-side ;
+ 2dup node-key key-side [ node-link ] with-side ;
: node-at* ( key node -- value ? )
[
root>> node-at* ;
: node-set ( value key node -- node )
- 2dup key>> <=> dup +eq+ eq? [
+ 2dup key>> key-side dup 0 eq? [
drop nip swap >>value
] [
[
] if ;
: delete-bst-node ( key node -- node )
- 2dup node-key <=> dup +eq+ eq? [
+ 2dup node-key key-side dup 0 eq? [
drop nip delete-node
] [
[ tuck node-link delete-bst-node over set-node-link ] with-side