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+; SILex - Scheme Implementation of Lex
+; Copyright (C) 2001 Danny Dube'
+;
+; This program is free software; you can redistribute it and/or
+; modify it under the terms of the GNU General Public License
+; as published by the Free Software Foundation; either version 2
+; of the License, or (at your option) any later version.
+;
+; This program is distributed in the hope that it will be useful,
+; but WITHOUT ANY WARRANTY; without even the implied warranty of
+; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+; GNU General Public License for more details.
+;
+; You should have received a copy of the GNU General Public License
+; along with this program; if not, write to the Free Software
+; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+; Fonction "merge" qui elimine les repetitions
+(define noeps-merge-1
+ (lambda (l1 l2)
+ (cond ((null? l1)
+ l2)
+ ((null? l2)
+ l1)
+ (else
+ (let ((t1 (car l1))
+ (t2 (car l2)))
+ (cond ((< t1 t2)
+ (cons t1 (noeps-merge-1 (cdr l1) l2)))
+ ((= t1 t2)
+ (cons t1 (noeps-merge-1 (cdr l1) (cdr l2))))
+ (else
+ (cons t2 (noeps-merge-1 l1 (cdr l2))))))))))
+
+; Fabrication des voisinages externes
+(define noeps-mkvois
+ (lambda (trans-v)
+ (let* ((nbnodes (vector-length trans-v))
+ (arcs (make-vector nbnodes '())))
+ (let loop1 ((n 0))
+ (if (< n nbnodes)
+ (begin
+ (let loop2 ((trans (vector-ref trans-v n)) (ends '()))
+ (if (null? trans)
+ (vector-set! arcs n ends)
+ (let* ((tran (car trans))
+ (class (car tran))
+ (end (cdr tran)))
+ (loop2 (cdr trans) (if (eq? class 'eps)
+ (noeps-merge-1 ends (list end))
+ ends)))))
+ (loop1 (+ n 1)))))
+ arcs)))
+
+; Fabrication des valeurs initiales
+(define noeps-mkinit
+ (lambda (trans-v)
+ (let* ((nbnodes (vector-length trans-v))
+ (init (make-vector nbnodes)))
+ (let loop ((n 0))
+ (if (< n nbnodes)
+ (begin
+ (vector-set! init n (list n))
+ (loop (+ n 1)))))
+ init)))
+
+; Traduction d'une liste d'arcs
+(define noeps-trad-arcs
+ (lambda (trans dict)
+ (let loop ((trans trans))
+ (if (null? trans)
+ '()
+ (let* ((tran (car trans))
+ (class (car tran))
+ (end (cdr tran)))
+ (if (eq? class 'eps)
+ (loop (cdr trans))
+ (let* ((new-end (vector-ref dict end))
+ (new-tran (cons class new-end)))
+ (cons new-tran (loop (cdr trans))))))))))
+
+; Elimination des transitions eps
+(define noeps
+ (lambda (nl-start no-nl-start arcs acc)
+ (let* ((digraph-arcs (noeps-mkvois arcs))
+ (digraph-init (noeps-mkinit arcs))
+ (dict (digraph digraph-arcs digraph-init noeps-merge-1))
+ (new-nl-start (vector-ref dict nl-start))
+ (new-no-nl-start (vector-ref dict no-nl-start)))
+ (let loop ((i (- (vector-length arcs) 1)))
+ (if (>= i 0)
+ (begin
+ (vector-set! arcs i (noeps-trad-arcs (vector-ref arcs i) dict))
+ (loop (- i 1)))))
+ (list new-nl-start new-no-nl-start arcs acc))))