80 lines
2.4 KiB
Factor
80 lines
2.4 KiB
Factor
! Copyright (C) 2008, 2009 Doug Coleman, Daniel Ehrenberg.
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! See http://factorcode.org/license.txt for BSD license.
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USING: accessors arrays assocs combinators fry kernel locals
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math math.order regexp.nfa regexp.transition-tables sequences
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sets sorting vectors regexp.ast ;
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IN: regexp.dfa
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:: (while-changes) ( obj quot: ( obj -- obj' ) comp: ( obj -- key ) old-key -- obj )
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obj quot call :> new-obj
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new-obj comp call :> new-key
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new-key old-key =
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[ new-obj ]
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[ new-obj quot comp new-key (while-changes) ]
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if ; inline recursive
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: while-changes ( obj quot pred -- obj' )
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3dup nip call (while-changes) ; inline
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: find-delta ( states transition nfa -- new-states )
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transitions>> '[ _ swap _ at at ] gather sift ;
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: (find-epsilon-closure) ( states nfa -- new-states )
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epsilon swap find-delta ;
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: find-epsilon-closure ( states nfa -- new-states )
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'[ dup _ (find-epsilon-closure) union ] [ length ] while-changes
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natural-sort ;
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: find-closure ( states transition nfa -- new-states )
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[ find-delta ] keep find-epsilon-closure ;
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: find-start-state ( nfa -- state )
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[ start-state>> 1vector ] keep find-epsilon-closure ;
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: find-transitions ( dfa-state nfa -- next-dfa-state )
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transitions>>
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'[ _ at keys ] gather
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epsilon swap remove ;
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: add-todo-state ( state visited-states new-states -- )
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3dup drop key? [ 3drop ] [
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[ conjoin ] [ push ] bi-curry* bi
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] if ;
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:: new-transitions ( nfa dfa new-states visited-states -- nfa dfa )
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new-states [ nfa dfa ] [
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pop :> state
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state nfa find-transitions
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[| trans |
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state trans nfa find-closure :> new-state
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new-state visited-states new-states add-todo-state
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state new-state trans dfa add-transition
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] each
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nfa dfa new-states visited-states new-transitions
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] if-empty ;
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: states ( hashtable -- array )
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[ keys ]
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[ values [ values concat ] map concat ] bi
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append ;
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: set-final-states ( nfa dfa -- )
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[
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[ final-states>> keys ]
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[ transitions>> states ] bi*
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[ intersects? ] with filter
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] [ final-states>> ] bi
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[ conjoin ] curry each ;
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: initialize-dfa ( nfa -- dfa )
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<transition-table>
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swap find-start-state >>start-state ;
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: construct-dfa ( nfa -- dfa )
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dup initialize-dfa
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dup start-state>> 1vector
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H{ } clone
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new-transitions
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[ set-final-states ] keep ;
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