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 prettyprint.backend ;
10 TUPLE: tree root count ;
13 f 0 tree construct-boa ;
15 : construct-tree ( class -- tree )
16 construct-empty <tree> over set-delegate ; inline
18 INSTANCE: tree tree-mixin
20 INSTANCE: tree-mixin assoc
22 TUPLE: node key value left right ;
23 : <node> ( key value -- node )
24 f f node construct-boa ;
31 : go-left? ( -- ? ) current-side get left = ;
33 : inc-count ( tree -- )
34 dup tree-count 1+ swap set-tree-count ;
36 : dec-count ( tree -- )
37 dup tree-count 1- swap set-tree-count ;
39 : node-link@ ( node ? -- node )
40 go-left? xor [ node-left ] [ node-right ] if ;
41 : set-node-link@ ( left parent ? -- )
42 go-left? xor [ set-node-left ] [ set-node-right ] if ;
44 : node-link ( node -- child ) f node-link@ ;
45 : set-node-link ( child node -- ) f set-node-link@ ;
46 : node+link ( node -- child ) t node-link@ ;
47 : set-node+link ( child node -- ) t set-node-link@ ;
49 : with-side ( side quot -- ) [ swap current-side set call ] with-scope ; inline
50 : with-other-side ( quot -- ) current-side get neg swap with-side ; inline
51 : go-left ( quot -- ) left swap with-side ; inline
52 : go-right ( quot -- ) right swap with-side ; inline
54 : change-root ( tree quot -- )
55 swap [ tree-root swap call ] keep set-tree-root ; inline
58 dup node-left swap node-right or not ;
60 : key-side ( k1 k2 -- side )
61 #! side is -1 if k1 < k2, 0 if they are equal, or 1 if k1 > k2
64 : random-side ( -- side ) left right 2array random ;
66 : choose-branch ( key node -- key node-left/right )
67 2dup node-key key-side [ node-link ] with-side ;
69 : node-at* ( key node -- value ? )
74 choose-branch node-at*
78 M: tree at* ( key tree -- value ? )
81 : node-set ( value key node -- node )
82 2dup node-key key-side dup zero? [
83 drop nip [ set-node-value ] keep
86 [ node-link [ node-set ] [ swap <node> ] if* ] keep
87 [ set-node-link ] keep
91 M: tree set-at ( value key tree -- )
92 [ [ node-set ] [ swap <node> ] if* ] change-root ;
94 : valid-node? ( node -- ? )
96 dup dup node-left [ node-key swap node-key before? ] when* >r
97 dup dup node-right [ node-key swap node-key after? ] when* r> and swap
98 dup node-left valid-node? swap node-right valid-node? and and
101 : valid-tree? ( tree -- ? ) tree-root valid-node? ;
103 : tree-call ( node call -- )
104 >r [ node-key ] keep node-value r> call ; inline
106 : find-node ( node quot -- key value ? )
108 { [ over not ] [ 2drop f f f ] }
110 >r node-left r> find-node
113 { [ >r 2nip r> [ tree-call ] 2keep rot ]
114 [ drop [ node-key ] keep node-value t ] }
115 { [ t ] [ >r node-right r> find-node ] }
118 M: tree-mixin assoc-find ( tree quot -- key value ? )
119 >r tree-root r> find-node ;
121 M: tree-mixin clear-assoc
122 0 over set-tree-count
123 f swap set-tree-root ;
125 : copy-node-contents ( new old -- )
126 dup node-key pick set-node-key node-value swap set-node-value ;
131 : (prune-extremity) ( parent node -- new-extremity )
133 rot drop (prune-extremity)
135 tuck delete-node swap set-node-link
138 : prune-extremity ( node -- new-extremity )
139 #! remove and return the leftmost or rightmost child of this node.
140 #! assumes at least one child
141 dup node-link (prune-extremity) ;
143 : replace-with-child ( node -- node )
144 dup dup node-link copy-node-contents dup node-link delete-node over set-node-link ;
146 : replace-with-extremity ( node -- node )
147 dup node-link dup node+link [
148 ! predecessor/successor is not the immediate child
149 [ prune-extremity ] with-other-side dupd copy-node-contents
151 ! node-link is the predecessor/successor
152 drop replace-with-child
155 : delete-node-with-two-children ( node -- node )
156 #! randomised to minimise tree unbalancing
157 random-side [ replace-with-extremity ] with-side ;
159 : delete-node ( node -- node )
160 #! delete this node, returning its replacement
163 delete-node-with-two-children
165 node-left ! left but no right
169 node-right ! right but not left
175 : delete-bst-node ( key node -- node )
176 2dup node-key key-side dup zero? [
179 [ tuck node-link delete-bst-node over set-node-link ] with-side
183 [ delete-bst-node ] change-root ;
188 M: tree clone dup assoc-clone-like ;
190 : >tree ( assoc -- tree )
191 T{ tree f f 0 } assoc-clone-like ;
193 M: tree-mixin assoc-like drop dup tree? [ >tree ] unless ;
196 \ } [ >tree ] parse-literal ; parsing
198 M: tree pprint-delims drop \ TREE{ \ } ;
200 M: tree-mixin assoc-size tree-count ;
201 M: tree-mixin clone dup assoc-clone-like ;
202 M: tree-mixin >pprint-sequence >alist ;
203 M: tree-mixin pprint-narrow? drop t ;