1 ! Copyright (C) 2007 Alex Chapman
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: kernel generic math sequences arrays io namespaces
4 prettyprint.private kernel.private assocs random combinators
5 parser math.order accessors deques make prettyprint.custom
9 TUPLE: tree root count ;
11 : new-tree ( class -- tree )
21 TUPLE: node key value left right ;
23 : new-node ( key value class -- node )
28 : <node> ( key value -- node )
36 : key-side ( k1 k2 -- n )
43 : go-left? ( -- ? ) current-side get left eq? ;
45 : inc-count ( tree -- ) [ 1 + ] change-count drop ;
47 : dec-count ( tree -- ) [ 1 - ] change-count drop ;
49 : node-link@ ( node ? -- node )
50 go-left? xor [ left>> ] [ right>> ] if ;
52 : set-node-link@ ( left parent ? -- )
53 go-left? xor [ (>>left) ] [ (>>right) ] if ;
55 : node-link ( node -- child ) f node-link@ ;
57 : set-node-link ( child node -- ) f set-node-link@ ;
59 : node+link ( node -- child ) t node-link@ ;
61 : set-node+link ( child node -- ) t set-node-link@ ;
63 : with-side ( side quot -- )
64 [ swap current-side set call ] with-scope ; inline
66 : with-other-side ( quot -- )
67 current-side get neg swap with-side ; inline
69 : go-left ( quot -- ) left swap with-side ; inline
71 : go-right ( quot -- ) right swap with-side ; inline
74 [ left>> ] [ right>> ] bi or not ;
76 : random-side ( -- side )
77 left right 2array random ;
79 : choose-branch ( key node -- key node-left/right )
80 2dup key>> key-side [ node-link ] with-side ;
82 : node-at* ( key node -- value ? )
87 choose-branch node-at*
91 M: tree at* ( key tree -- value ? )
94 : node-set ( value key node -- node )
95 2dup key>> key-side dup 0 eq? [
99 [ node-link [ node-set ] [ swap <node> ] if* ] keep
100 [ set-node-link ] keep
104 M: tree set-at ( value key tree -- )
105 [ [ node-set ] [ swap <node> ] if* ] change-root drop ;
107 : valid-node? ( node -- ? )
109 dup dup left>> [ key>> swap key>> before? ] when*
111 dup dup right>> [ key>> swap key>> after? ] when* ] dip and swap
112 dup left>> valid-node? swap right>> valid-node? and and
115 : valid-tree? ( tree -- ? ) root>> valid-node? ;
117 : (node>alist) ( node -- )
119 [ left>> (node>alist) ]
120 [ [ key>> ] [ value>> ] bi 2array , ]
121 [ right>> (node>alist) ]
125 M: tree >alist [ root>> (node>alist) ] { } make ;
131 : copy-node-contents ( new old -- new )
133 [ value>> >>value ] bi ;
138 : (prune-extremity) ( parent node -- new-extremity )
140 rot drop (prune-extremity)
142 tuck delete-node swap set-node-link
145 : prune-extremity ( node -- new-extremity )
146 #! remove and return the leftmost or rightmost child of this node.
147 #! assumes at least one child
148 dup node-link (prune-extremity) ;
150 : replace-with-child ( node -- node )
151 dup node-link copy-node-contents dup node-link delete-node over set-node-link ;
153 : replace-with-extremity ( node -- node )
154 dup node-link dup node+link [
155 ! predecessor/successor is not the immediate child
156 [ prune-extremity ] with-other-side copy-node-contents
158 ! node-link is the predecessor/successor
159 drop replace-with-child
162 : delete-node-with-two-children ( node -- node )
163 #! randomised to minimise tree unbalancing
164 random-side [ replace-with-extremity ] with-side ;
166 : delete-node ( node -- node )
167 #! delete this node, returning its replacement
170 delete-node-with-two-children
172 left>> ! left but no right
176 right>> ! right but not left
182 : delete-bst-node ( key node -- node )
183 2dup key>> key-side dup 0 eq? [
186 [ tuck node-link delete-bst-node over set-node-link ] with-side
190 [ delete-bst-node ] change-root drop ;
195 M: tree clone dup assoc-clone-like ;
197 : >tree ( assoc -- tree )
198 T{ tree f f 0 } assoc-clone-like ;
200 M: tree assoc-like drop dup tree? [ >tree ] unless ;
203 \ } [ >tree ] parse-literal ;
205 M: tree assoc-size count>> ;
206 M: tree pprint-delims drop \ TREE{ \ } ;
207 M: tree >pprint-sequence >alist ;
208 M: tree pprint-narrow? drop t ;