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 ;
8 TUPLE: tree root count ;
10 : new-tree ( class -- tree )
20 TUPLE: node key value left right ;
22 : new-node ( key value class -- node )
27 : <node> ( key value -- node )
35 : key-side ( k1 k2 -- n )
42 : go-left? ( -- ? ) current-side get left eq? ;
44 : inc-count ( tree -- ) [ 1 + ] change-count drop ;
46 : dec-count ( tree -- ) [ 1 - ] change-count drop ;
48 : node-link@ ( node ? -- node )
49 go-left? xor [ left>> ] [ right>> ] if ;
51 : set-node-link@ ( left parent ? -- )
52 go-left? xor [ (>>left) ] [ (>>right) ] if ;
54 : node-link ( node -- child ) f node-link@ ;
56 : set-node-link ( child node -- ) f set-node-link@ ;
58 : node+link ( node -- child ) t node-link@ ;
60 : set-node+link ( child node -- ) t set-node-link@ ;
62 : with-side ( side quot -- )
63 [ swap current-side set call ] with-scope ; inline
65 : with-other-side ( quot -- )
66 current-side get neg swap with-side ; inline
68 : go-left ( quot -- ) left swap with-side ; inline
70 : go-right ( quot -- ) right swap with-side ; inline
73 [ left>> ] [ right>> ] bi or not ;
75 : random-side ( -- side )
76 left right 2array random ;
78 : choose-branch ( key node -- key node-left/right )
79 2dup key>> key-side [ node-link ] with-side ;
81 : node-at* ( key node -- value ? )
86 choose-branch node-at*
90 M: tree at* ( key tree -- value ? )
93 : node-set ( value key node -- node )
94 2dup key>> key-side dup 0 eq? [
98 [ node-link [ node-set ] [ swap <node> ] if* ] keep
99 [ set-node-link ] keep
103 M: tree set-at ( value key tree -- )
104 [ [ node-set ] [ swap <node> ] if* ] change-root drop ;
106 : valid-node? ( node -- ? )
108 dup dup left>> [ key>> swap key>> before? ] when*
110 dup dup right>> [ key>> swap key>> after? ] when* ] dip and swap
111 dup left>> valid-node? swap right>> valid-node? and and
114 : valid-tree? ( tree -- ? ) root>> valid-node? ;
116 : (node>alist) ( node -- )
118 [ left>> (node>alist) ]
119 [ [ key>> ] [ value>> ] bi 2array , ]
120 [ right>> (node>alist) ]
124 M: tree >alist [ root>> (node>alist) ] { } make ;
130 : copy-node-contents ( new old -- new )
132 [ value>> >>value ] bi ;
137 : (prune-extremity) ( parent node -- new-extremity )
139 rot drop (prune-extremity)
141 tuck delete-node swap set-node-link
144 : prune-extremity ( node -- new-extremity )
145 #! remove and return the leftmost or rightmost child of this node.
146 #! assumes at least one child
147 dup node-link (prune-extremity) ;
149 : replace-with-child ( node -- node )
150 dup node-link copy-node-contents dup node-link delete-node over set-node-link ;
152 : replace-with-extremity ( node -- node )
153 dup node-link dup node+link [
154 ! predecessor/successor is not the immediate child
155 [ prune-extremity ] with-other-side copy-node-contents
157 ! node-link is the predecessor/successor
158 drop replace-with-child
161 : delete-node-with-two-children ( node -- node )
162 #! randomised to minimise tree unbalancing
163 random-side [ replace-with-extremity ] with-side ;
165 : delete-node ( node -- node )
166 #! delete this node, returning its replacement
169 delete-node-with-two-children
171 left>> ! left but no right
175 right>> ! right but not left
181 : delete-bst-node ( key node -- node )
182 2dup key>> key-side dup 0 eq? [
185 [ tuck node-link delete-bst-node over set-node-link ] with-side
189 [ delete-bst-node ] change-root drop ;
194 M: tree clone dup assoc-clone-like ;
196 : >tree ( assoc -- tree )
197 T{ tree f f 0 } assoc-clone-like ;
199 M: tree assoc-like drop dup tree? [ >tree ] unless ;
202 \ } [ >tree ] parse-literal ;
204 M: tree assoc-size count>> ;
205 M: tree pprint-delims drop \ TREE{ \ } ;
206 M: tree >pprint-sequence >alist ;
207 M: tree pprint-narrow? drop t ;