1 ! Copyright (C) 2008 Doug Coleman.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: accessors arrays assocs combinators fry kernel locals
4 math math.order regexp.nfa regexp.transition-tables sequences
5 sets sorting vectors sequences.deep ;
6 USING: io prettyprint threads ;
9 : (while-changes) ( obj quot: ( obj -- obj' ) pred: ( obj -- <=> ) pred-ret -- obj )
10 [ [ dup slip ] dip pick over call ] dip dupd =
11 [ 3drop ] [ (while-changes) ] if ; inline recursive
13 : while-changes ( obj quot pred -- obj' )
14 3dup nip call (while-changes) ; inline
16 : find-delta ( states transition nfa -- new-states )
17 transitions>> '[ _ swap _ at at ] gather sift ;
19 : (find-epsilon-closure) ( states nfa -- new-states )
22 : find-epsilon-closure ( states nfa -- new-states )
23 '[ dup _ (find-epsilon-closure) union ] [ length ] while-changes
26 : find-closure ( states transition nfa -- new-states )
27 [ find-delta ] keep find-epsilon-closure ;
29 : find-start-state ( nfa -- state )
30 [ start-state>> 1vector ] keep find-epsilon-closure ;
32 : find-transitions ( dfa-state nfa -- next-dfa-state )
37 : add-todo-state ( state visited-states new-states -- )
38 3dup drop key? [ 3drop ] [
39 [ conjoin ] [ push ] bi-curry* bi
42 :: new-transitions ( nfa dfa new-states visited-states -- nfa dfa )
43 new-states [ nfa dfa ] [
45 state nfa find-transitions
47 state trans nfa find-closure :> new-state
48 new-state visited-states new-states add-todo-state
49 state new-state trans transition make-transition dfa add-transition
51 nfa dfa new-states visited-states new-transitions
54 : states ( hashtable -- array )
56 [ values [ values concat ] map concat append ] bi ;
58 : set-final-states ( nfa dfa -- )
60 [ final-states>> keys ]
61 [ transitions>> states ] bi*
62 [ intersects? ] with filter
63 ] [ final-states>> ] bi
64 [ conjoin ] curry each ;
66 : initialize-dfa ( nfa -- dfa )
68 swap find-start-state >>start-state ;
70 : construct-dfa ( nfa -- dfa )
72 dup start-state>> 1vector
75 [ set-final-states ] keep ;