factor/extra/digraphs/digraphs.factor

52 lines
1.4 KiB
Factor

! Copyright (C) 2008 Alex Chapman
! See http://factorcode.org/license.txt for BSD license.
USING: accessors assocs hashtables hashtables.private kernel sequences vectors ;
IN: digraphs
TUPLE: digraph < hashtable ;
: <digraph> ( -- digraph )
0 digraph new [ reset-hash ] keep ;
TUPLE: vertex value edges ;
: <vertex> ( value -- vertex )
V{ } clone vertex boa ;
: add-vertex ( key value digraph -- )
[ <vertex> swap ] dip set-at ;
: children ( key digraph -- seq )
at edges>> ;
: @edges ( from to digraph -- to edges ) swapd at edges>> ;
: add-edge ( from to digraph -- ) @edges push ;
: delete-edge ( from to digraph -- ) @edges remove! drop ;
: delete-to-edges ( to digraph -- )
[ nip dupd edges>> remove! drop ] assoc-each drop ;
: delete-vertex ( key digraph -- )
2dup delete-at delete-to-edges ;
: unvisited? ( unvisited key -- ? ) swap key? ;
: visited ( unvisited key -- ) swap delete-at ;
DEFER: (topological-sort)
: visit-children ( seq unvisited key -- seq unvisited )
over children [ (topological-sort) ] each ;
: (topological-sort) ( seq unvisited key -- seq unvisited )
2dup unvisited? [
[ visit-children ] keep 2dup visited pick push
] [
drop
] if ;
: topological-sort ( digraph -- seq )
[ V{ } clone ] dip [ clone ] keep
[ drop (topological-sort) ] assoc-each drop reverse ;
: topological-sorted-values ( digraph -- seq )
dup topological-sort swap [ at value>> ] curry map ;