1 ;; ---------------------------------------------------------------------- ;;
2 ;; FICHIER : lalr.scm ;;
3 ;; DATE DE CREATION : Mon Jan 22 15:42:32 1996 ;;
4 ;; DERNIERE MODIFICATION : Mon Jun 3 10:24:43 1996 ;;
5 ;; ---------------------------------------------------------------------- ;;
6 ;; Copyright (C) 1984, 1989, 1990 Free Software Foundation, Inc. ;;
7 ;; (for the Bison source code translated in Scheme) ;;
8 ;; Copyright (C) 1996 Dominique Boucher ;;
9 ;; (for the translation in Scheme) ;;
10 ;; ---------------------------------------------------------------------- ;;
11 ;; An efficient Scheme LALR(1) Parser Generator -- lalr.scm ;;
12 ;; ---------------------------------------------------------------------- ;;
13 ;; This file contains yet another LALR(1) parser generator written in ;;
14 ;; Scheme. In contrast to other such parser generators, this one ;;
15 ;; implements a more efficient algorithm for computing the lookahead sets.;;
16 ;; The algorithm is the same as used in Bison (GNU yacc) and is described ;;
17 ;; in the following paper: ;;
19 ;; "Efficient Computation of LALR(1) Look-Ahead Set", F. DeRemer and ;;
20 ;; T. Pennello, TOPLAS, vol. 4, no. 4, october 1982. ;;
22 ;; As a consequence, it is not written in a fully functional style. ;;
23 ;; The program has been successfully tested on several Scheme ;;
24 ;; interpreters and compilers, including scm4d3, Gambit v2.2, and ;;
25 ;; MIT-Scheme 7.2.0 (microcode 11.127, runtime 14.160). ;;
26 ;; ---------------------------------------------------------------------- ;;
27 ;; HOW TO USE THE PROGRAM ;;
29 ;; To generate a parser for a given grammar, the latter must be first ;;
30 ;; written down in scheme. The next section will describe the syntax ;;
31 ;; of the grammar. Now suppose your grammar is defined like this: ;;
33 ;; (define my-grammar { grammar }) ;;
35 ;; All you need to do is evaluate the expression: ;;
37 ;; (gen-lalr1 my-grammar "file" [prefix]) ;;
39 ;; where "file" is the name of the file (a string) that will contain the ;;
40 ;; tables for LR-parsing. The last argument must be supplied if you want ;;
41 ;; multiple parsers coexist in the same application. It must be a symbol, ;;
42 ;; otherwise it will be ignored. ;;
44 ;; To run the parser, you must first load the LR parsing driver(also part ;;
45 ;; of this distribution): ;;
47 ;; (load "lr-dvr.scm") ;;
49 ;; The interface to the generated parser will be the function ;;
51 ;; ([prefix-]parse lexer errorp) ;;
53 ;; where lexer is the name of the scanner feeding the parser with pairs ;;
54 ;; (token . lval) and errorp is the name of a user-defined error ;;
55 ;; function (the standard error function can be used as well). ;;
58 ;; Here are some notes about the lexer and the error function: ;;
60 ;; - the tokens (which are the first components of the pairs returned ;;
61 ;; by the lexer) must agree with the tokens defined in the grammar. ;;
63 ;; - when the lexer wants to signal the end of the input, it must ;;
64 ;; return the pair '(0) each time it's invoked. ;;
66 ;; - the error function must accept two parameters (the standard error ;;
67 ;; function accepts a variable number of parameters, so it accepts ;;
70 ;; ---------------------------------------------------------------------- ;;
71 ;; THE GRAMMAR FORMAT ;;
73 ;; The grammar is specified by first giving the list of terminals and the ;;
74 ;; list of non-terminal definitions. Each non-terminal definition ;;
75 ;; is a list where the first element is the non-terminal and the other ;;
76 ;; elements are the right-hand sides (lists of grammar symbols). In ;;
77 ;; addition to this, each rhs can be followed by a semantic action. ;;
78 ;; By convention, use strings for tokens and atoms for non-terminals. ;;
80 ;; For example, consider the following (yacc) grammar: ;;
93 ;; The same grammar, written for the scheme parser generator, would look ;;
94 ;; like this (with semantic actions) ;;
96 ;; (define my-grammar ;;
98 ;; ; Terminal symbols ;;
101 ;; (e (e ADD t) : (+ $1 $3) ;;
104 ;; (t (t MULT f) : (* $1 $3) ;;
110 ;; In semantic actions, the symbol $<n> refers to the synthesized ;;
111 ;; attribute value of the nth symbol in the production. The value ;;
112 ;; associated with the non-terminal on the left is the result of ;;
113 ;; evaluating the semantic action (it defaults to #f). ;;
115 ;; If you evaluate ;;
117 ;; (gen-lalr1 my-grammar "foo.scm" 'my) ;;
119 ;; then the generated parser will be named 'my-parser'. ;;
121 ;; NOTE ON CONFLICT RESOLUTION ;;
123 ;; Conflicts in the grammar are handled in a conventional way. ;;
124 ;; Shift/Reduce conflicts are resolved by shifting, and Reduce/Reduce ;;
125 ;; conflicts are resolved by choosing the rule listed first in the ;;
126 ;; grammar definition. ;;
128 ;; You can print the states of the generated parser by evaluating ;;
129 ;; `(print-states)'. The format of the output is similar to the one ;;
130 ;; produced by bison when given the -v command-line option. ;;
131 ;; ---------------------------------------------------------------------- ;;
132 ;; lalr.scm is free software; you can redistribute it and/or modify ;;
133 ;; it under the terms of the GNU General Public License as published by ;;
134 ;; the Free Software Foundation; either version 2, or (at your option) ;;
135 ;; any later version. ;;
137 ;; lalr.scm is distributed in the hope that it will be useful, ;;
138 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;;
139 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;;
140 ;; GNU General Public License for more details. ;;
142 ;; You should have received a copy of the GNU General Public License ;;
143 ;; along with lalr.scm; see the file COPYING. If not, write to ;;
144 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. ;;
146 ;; Dominique Boucher -- Universite de Montreal ;;
148 ;; Send questions, comments or suggestions to boucherd@iro.umontreal.ca ;;
149 ;; ---------------------------------------------------------------------- ;;
151 ;; 1998/08/16: Tanaka Akira <akr@jaist.ac.jp> transplants generating code from Scheme to Emacs-Lisp.
153 ;;; ---------- SYSTEM DEPENDENT SECTION -----------------
157 (defmacro def-macro (args body)
158 `(defmacro ,(car args) ,(cdr args) ,body))
160 (def-macro (BITS-PER-WORD) 24)
161 (def-macro (logical-or x . y) `(logior ,x ,@y))
164 ;; -------- MIT-Scheme
166 (declare (usual-integrations))
168 (define-macro (def-macro form . body)
169 `(DEFINE-MACRO ,form (LET () ,@body)))
171 (def-macro (BITS-PER-WORD) 24)
172 (def-macro (logical-or x . y) `(fix:or ,x ,@y))
184 (define-macro (def-macro form . body)
185 `(DEFINE-MACRO ,form (LET () ,@body)))
187 (def-macro (BITS-PER-WORD) 28)
188 (def-macro (logical-or x . y) `(,(string->symbol "##logior") ,x ,@y))
194 (define-macro (def-macro form . body)
195 `(DEFINE-MACRO ,form (LET () ,@body)))
196 (def-macro (BITS-PER-WORD) 16)
197 (def-macro (logical-or x . y) `(bit-or ,x ,@y))
200 ;;; ---------- END OF SYSTEM DEPENDENT SECTION ------------
202 ;; - Macros pour la gestion des vecteurs de bits
204 (def-macro (set-bit v b)
205 `(let ((x (quotient ,b (BITS-PER-WORD)))
206 (y (expt 2 (remainder ,b (BITS-PER-WORD)))))
207 (vector-set! ,v x (logical-or (vector-ref ,v x) y))))
209 (def-macro (bit-union v1 v2 n)
212 (vector-set! ,v1 i (logical-or (vector-ref ,v1 i)
213 (vector-ref ,v2 i)))))
215 ;; - Macro pour les structures de donnees
217 (def-macro (new-core) `(make-vector 4 0))
218 (def-macro (set-core-number! c n) `(vector-set! ,c 0 ,n))
219 (def-macro (set-core-acc-sym! c s) `(vector-set! ,c 1 ,s))
220 (def-macro (set-core-nitems! c n) `(vector-set! ,c 2 ,n))
221 (def-macro (set-core-items! c i) `(vector-set! ,c 3 ,i))
222 (def-macro (core-number c) `(vector-ref ,c 0))
223 (def-macro (core-acc-sym c) `(vector-ref ,c 1))
224 (def-macro (core-nitems c) `(vector-ref ,c 2))
225 (def-macro (core-items c) `(vector-ref ,c 3))
227 (def-macro (new-shift) `(make-vector 3 0))
228 (def-macro (set-shift-number! c x) `(vector-set! ,c 0 ,x))
229 (def-macro (set-shift-nshifts! c x) `(vector-set! ,c 1 ,x))
230 (def-macro (set-shift-shifts! c x) `(vector-set! ,c 2 ,x))
231 (def-macro (shift-number s) `(vector-ref ,s 0))
232 (def-macro (shift-nshifts s) `(vector-ref ,s 1))
233 (def-macro (shift-shifts s) `(vector-ref ,s 2))
235 (def-macro (new-red) `(make-vector 3 0))
236 (def-macro (set-red-number! c x) `(vector-set! ,c 0 ,x))
237 (def-macro (set-red-nreds! c x) `(vector-set! ,c 1 ,x))
238 (def-macro (set-red-rules! c x) `(vector-set! ,c 2 ,x))
239 (def-macro (red-number c) `(vector-ref ,c 0))
240 (def-macro (red-nreds c) `(vector-ref ,c 1))
241 (def-macro (red-rules c) `(vector-ref ,c 2))
245 (def-macro (new-set nelem)
246 `(make-vector ,nelem 0))
249 (def-macro (vector-map f v)
250 `(let ((vm-n (- (vector-length ,v) 1)))
251 (let loop ((vm-low 0) (vm-high vm-n))
252 (if (= vm-low vm-high)
253 (vector-set! ,v vm-low (,f (vector-ref ,v vm-low) vm-low))
254 (let ((vm-middle (quotient (+ vm-low vm-high) 2)))
255 (loop vm-low vm-middle)
256 (loop (+ vm-middle 1) vm-high))))))
260 (define STATE-TABLE-SIZE 1009)
271 (define kernel-base #f)
272 (define kernel-end #f)
273 (define shift-symbol #f)
274 (define shift-set #f)
276 (define state-table #f)
277 (define acces-symbol #f)
278 (define reduction-table #f)
279 (define shift-table #f)
280 (define consistent #f)
281 (define lookaheads #f)
286 (define from-state #f)
290 (define action-table #f)
299 (define first-state #f)
300 (define last-state #f)
301 (define final-state #f)
302 (define first-shift #f)
303 (define last-shift #f)
304 (define first-reduction #f)
305 (define last-reduction #f)
309 (define token-set-size #f)
312 (define (gen-lalr1 gram output-file header footer . opt)
316 (lambda (terms vars gram gram/actions)
317 (set! the-terminals (list->vector terms))
318 (set! the-nonterminals (list->vector vars))
319 (set! nterms (length terms))
320 (set! nvars (length vars))
321 (set! nsyms (+ nterms nvars))
322 (let ((no-of-rules (length gram/actions))
323 (no-of-items (let loop ((l gram/actions) (count 0))
326 (loop (cdr l) (+ count (length (caar l))))))))
327 (pack-grammar no-of-rules no-of-items gram)
333 (compact-action-table)
334 (let* ((parser-name (if (and (pair? opt) (symbol? (car opt))) (car opt) #f))
335 (prefix (if parser-name
337 (symbol->string parser-name)
340 (parser-prefix (if parser-name
341 (string-append (symbol->string parser-name) "-")
343 (with-output-to-file output-file
345 (display "; *** Header ***")
347 (output-header header parser-prefix)
348 (display "; *** Token Definitions ***")
350 (output-token-defs terms prefix)
351 (display "; *** Action Table ***")
353 (output-action-table prefix)
354 (display "; *** Goto Table ***")
356 (output-goto-table prefix)
357 (display "; *** Reduction Table ***")
359 (output-reduction-table gram/actions prefix)
360 (display "; *** Parser Definition ***")
362 (output-parser-def parser-prefix prefix)
363 (display "; *** Footer ***")
365 (output-footer footer)
369 (define (initialize-all)
377 (set! kernel-base #f)
379 (set! shift-symbol #f)
382 (set! state-table (make-vector STATE-TABLE-SIZE '()))
383 (set! acces-symbol #f)
384 (set! reduction-table #f)
385 (set! shift-table #f)
396 (set! action-table #f)
398 (set! first-state #f)
400 (set! final-state #f)
401 (set! first-shift #f)
403 (set! first-reduction #f)
404 (set! last-reduction #f)
408 (set! token-set-size #f))
411 (define (pack-grammar no-of-rules no-of-items gram)
412 (set! nrules (+ no-of-rules 1))
413 (set! nitems no-of-items)
414 (set! rlhs (make-vector nrules #f))
415 (set! rrhs (make-vector nrules #f))
416 (set! ritem (make-vector (+ 1 nitems) #f))
418 (let loop ((p gram) (item-no 0) (rule-no 1))
421 (let loop2 ((prods (cdar p)) (it-no2 item-no) (rl-no2 rule-no))
423 (loop (cdr p) it-no2 rl-no2)
425 (vector-set! rlhs rl-no2 nt)
426 (vector-set! rrhs rl-no2 it-no2)
427 (let loop3 ((rhs (car prods)) (it-no3 it-no2))
430 (vector-set! ritem it-no3 (- rl-no2))
431 (loop2 (cdr prods) (+ it-no3 1) (+ rl-no2 1)))
433 (vector-set! ritem it-no3 (car rhs))
434 (loop3 (cdr rhs) (+ it-no3 1))))))))))))
437 ;; Fonction set-derives
438 ;; --------------------
439 (define (set-derives)
440 (define delts (make-vector (+ nrules 1) 0))
441 (define dset (make-vector nvars -1))
443 (let loop ((i 1) (j 0)) ; i = 0
445 (let ((lhs (vector-ref rlhs i)))
448 (vector-set! delts j (cons i (vector-ref dset lhs)))
449 (vector-set! dset lhs j)
450 (loop (+ i 1) (+ j 1)))
453 (set! derives (make-vector nvars 0))
457 (let ((q (let loop2 ((j (vector-ref dset i)) (s '()))
460 (let ((x (vector-ref delts j)))
461 (loop2 (cdr x) (cons (car x) s)))))))
462 (vector-set! derives i q)
467 (define (set-nullable)
468 (set! nullable (make-vector nvars #f))
469 (let ((squeue (make-vector nvars #f))
470 (rcount (make-vector (+ nrules 1) 0))
471 (rsets (make-vector nvars #f))
472 (relts (make-vector (+ nitems nvars 1) #f)))
473 (let loop ((r 0) (s2 0) (p 0))
474 (let ((*r (vector-ref ritem r)))
477 (let ((symbol (vector-ref rlhs (- *r))))
478 (if (and (>= symbol 0)
479 (not (vector-ref nullable symbol)))
481 (vector-set! nullable symbol #t)
482 (vector-set! squeue s2 symbol)
483 (loop (+ r 1) (+ s2 1) p))))
484 (let loop2 ((r1 r) (any-tokens #f))
485 (let* ((symbol (vector-ref ritem r1)))
487 (loop2 (+ r1 1) (or any-tokens (>= symbol nvars)))
489 (let ((ruleno (- symbol)))
490 (let loop3 ((r2 r) (p2 p))
491 (let ((symbol (vector-ref ritem r2)))
494 (vector-set! rcount ruleno
495 (+ (vector-ref rcount ruleno) 1))
496 (vector-set! relts p2
497 (cons (vector-ref rsets symbol)
499 (vector-set! rsets symbol p2)
500 (loop3 (+ r2 1) (+ p2 1)))
501 (loop (+ r2 1) s2 p2)))))
502 (loop (+ r1 1) s2 p))))))
503 (let loop ((s1 0) (s3 s2))
505 (let loop2 ((p (vector-ref rsets (vector-ref squeue s1))) (s4 s3))
507 (let* ((x (vector-ref relts p))
509 (y (- (vector-ref rcount ruleno) 1)))
510 (vector-set! rcount ruleno y)
512 (let ((symbol (vector-ref rlhs ruleno)))
513 (if (and (>= symbol 0)
514 (not (vector-ref nullable symbol)))
516 (vector-set! nullable symbol #t)
517 (vector-set! squeue s4 symbol)
518 (loop2 (car x) (+ s4 1)))
520 (loop2 (car x) s4))))
521 (loop (+ s1 1) s4)))))))))
525 ; Fonction set-firsts qui calcule un tableau de taille
526 ; nvars et qui donne, pour chaque non-terminal X, une liste des
527 ; non-terminaux pouvant apparaitre au debut d'une derivation a
531 (set! firsts (make-vector nvars '()))
536 (let loop2 ((sp (vector-ref derives i)))
539 (let ((sym (vector-ref ritem (vector-ref rrhs (car sp)))))
541 (vector-set! firsts i (sinsert sym (vector-ref firsts i))))
542 (loop2 (cdr sp)))))))
544 ;; -- reflexive and transitive closure
545 (let loop ((continue #t))
547 (let loop2 ((i 0) (cont #f))
550 (let* ((x (vector-ref firsts i))
551 (y (let loop3 ((l x) (z x))
555 (sunion (vector-ref firsts (car l)) z))))))
559 (vector-set! firsts i y)
560 (loop2 (+ i 1) #t))))))))
565 (vector-set! firsts i (sinsert i (vector-ref firsts i)))
571 ; Fonction set-fderives qui calcule un tableau de taille
572 ; nvars et qui donne, pour chaque non-terminal, une liste des regles pouvant
573 ; etre derivees a partir de ce non-terminal. (se sert de firsts)
575 (define (set-fderives)
576 (set! fderives (make-vector nvars #f))
582 (let ((x (let loop2 ((l (vector-ref firsts i)) (fd '()))
586 (sunion (vector-ref derives (car l)) fd))))))
587 (vector-set! fderives i x)
591 ; Fonction calculant la fermeture d'un ensemble d'items LR0
592 ; ou core est une liste d'items
594 (define (closure core)
596 (define ruleset (make-vector nrules #f))
598 (let loop ((csp core))
599 (if (not (null? csp))
600 (let ((sym (vector-ref ritem (car csp))))
602 (let loop2 ((dsp (vector-ref fderives sym)))
603 (if (not (null? dsp))
605 (vector-set! ruleset (car dsp) #t)
606 (loop2 (cdr dsp))))))
609 (let loop ((ruleno 1) (csp core) (itemsetv '())) ; ruleno = 0
610 (if (< ruleno nrules)
611 (if (vector-ref ruleset ruleno)
612 (let ((itemno (vector-ref rrhs ruleno)))
613 (let loop2 ((c csp) (itemsetv2 itemsetv))
616 (loop2 (cdr c) (cons (car c) itemsetv2))
617 (loop (+ ruleno 1) c (cons itemno itemsetv2)))))
618 (loop (+ ruleno 1) csp itemsetv))
619 (let loop2 ((c csp) (itemsetv2 itemsetv))
621 (loop2 (cdr c) (cons (car c) itemsetv2))
622 (reverse itemsetv2))))))
626 (define (allocate-item-sets)
627 (set! kernel-base (make-vector nsyms 0))
628 (set! kernel-end (make-vector nsyms #f)))
631 (define (allocate-storage)
633 (set! red-set (make-vector (+ nrules 1) 0)))
638 (define (initialize-states)
639 (let ((p (new-core)))
640 (set-core-number! p 0)
641 (set-core-acc-sym! p #f)
642 (set-core-nitems! p 1)
643 (set-core-items! p '(0))
645 (set! first-state (list p))
646 (set! last-state first-state)
651 (define (generate-states)
655 (let loop ((this-state first-state))
656 (if (pair? this-state)
657 (let* ((x (car this-state))
658 (is (closure (core-items x))))
659 (save-reductions x is)
664 (loop (cdr this-state))))))
667 ;; Fonction calculant les symboles sur lesquels il faut "shifter"
668 ;; et regroupe les items en fonction de ces symboles
670 (define (new-itemsets itemset)
672 (set! shift-symbol '())
676 (vector-set! kernel-end i '())
679 (let loop ((isp itemset))
682 (sym (vector-ref ritem i)))
685 (set! shift-symbol (sinsert sym shift-symbol))
686 (let ((x (vector-ref kernel-end sym)))
689 (vector-set! kernel-base sym (cons (+ i 1) x))
690 (vector-set! kernel-end sym (vector-ref kernel-base sym)))
692 (set-cdr! x (list (+ i 1)))
693 (vector-set! kernel-end sym (cdr x)))))))
696 (set! nshifts (length shift-symbol)))
700 (define (get-state sym)
701 (let* ((isp (vector-ref kernel-base sym))
703 (key (let loop ((isp1 isp) (k 0))
705 (modulo k STATE-TABLE-SIZE)
706 (loop (cdr isp1) (+ k (car isp1))))))
707 (sp (vector-ref state-table key)))
709 (let ((x (new-state sym)))
710 (vector-set! state-table key (list x))
713 (if (and (= n (core-nitems (car sp1)))
714 (let loop2 ((i1 isp) (t (core-items (car sp1))))
718 (loop2 (cdr i1) (cdr t))
720 (core-number (car sp1))
721 (if (null? (cdr sp1))
722 (let ((x (new-state sym)))
723 (set-cdr! sp1 (list x))
725 (loop (cdr sp1))))))))
728 (define (new-state sym)
729 (let* ((isp (vector-ref kernel-base sym))
732 (set-core-number! p nstates)
733 (set-core-acc-sym! p sym)
734 (if (= sym nvars) (set! final-state nstates))
735 (set-core-nitems! p n)
736 (set-core-items! p isp)
737 (set-cdr! last-state (list p))
738 (set! last-state (cdr last-state))
739 (set! nstates (+ nstates 1))
745 (define (append-states)
747 (let loop ((l (reverse shift-symbol)))
750 (cons (get-state (car l)) (loop (cdr l)))))))
754 (define (save-shifts core)
755 (let ((p (new-shift)))
756 (set-shift-number! p (core-number core))
757 (set-shift-nshifts! p nshifts)
758 (set-shift-shifts! p shift-set)
761 (set-cdr! last-shift (list p))
762 (set! last-shift (cdr last-shift)))
764 (set! first-shift (list p))
765 (set! last-shift first-shift)))))
767 (define (save-reductions core itemset)
768 (let ((rs (let loop ((l itemset))
771 (let ((item (vector-ref ritem (car l))))
773 (cons (- item) (loop (cdr l)))
777 (set-red-number! p (core-number core))
778 (set-red-nreds! p (length rs))
779 (set-red-rules! p rs)
782 (set-cdr! last-reduction (list p))
783 (set! last-reduction (cdr last-reduction)))
785 (set! first-reduction (list p))
786 (set! last-reduction first-reduction)))))))
792 (set! token-set-size (+ 1 (quotient nterms (BITS-PER-WORD))))
793 (set-accessing-symbol)
795 (set-reduction-table)
802 (compute-lookaheads))
804 (define (set-accessing-symbol)
805 (set! acces-symbol (make-vector nstates #f))
806 (let loop ((l first-state))
809 (vector-set! acces-symbol (core-number x) (core-acc-sym x))
812 (define (set-shift-table)
813 (set! shift-table (make-vector nstates #f))
814 (let loop ((l first-shift))
817 (vector-set! shift-table (shift-number x) x)
820 (define (set-reduction-table)
821 (set! reduction-table (make-vector nstates #f))
822 (let loop ((l first-reduction))
825 (vector-set! reduction-table (red-number x) x)
828 (define (set-max-rhs)
829 (let loop ((p 0) (curmax 0) (length 0))
830 (let ((x (vector-ref ritem p)))
833 (loop (+ p 1) curmax (+ length 1))
834 (loop (+ p 1) (max curmax length) 0))
835 (set! maxrhs curmax)))))
837 (define (initialize-LA)
843 (set! consistent (make-vector nstates #f))
844 (set! lookaheads (make-vector (+ nstates 1) #f))
846 (let loop ((count 0) (i 0))
849 (vector-set! lookaheads i count)
850 (let ((rp (vector-ref reduction-table i))
851 (sp (vector-ref shift-table i)))
853 (or (> (red-nreds rp) 1)
856 (< (vector-ref acces-symbol
857 (last (shift-shifts sp)))
859 (loop (+ count (red-nreds rp)) (+ i 1))
861 (vector-set! consistent i #t)
862 (loop count (+ i 1))))))
865 (vector-set! lookaheads nstates count)
866 (let ((c (max count 1)))
867 (set! LA (make-vector c #f))
868 (do ((j 0 (+ j 1))) ((= j c)) (vector-set! LA j (new-set token-set-size)))
869 (set! LAruleno (make-vector c -1))
870 (set! lookback (make-vector c #f)))
871 (let loop ((i 0) (np 0))
873 (if (vector-ref consistent i)
875 (let ((rp (vector-ref reduction-table i)))
877 (let loop2 ((j (red-rules rp)) (np2 np))
881 (vector-set! LAruleno np2 (car j))
882 (loop2 (cdr j) (+ np2 1)))))
883 (loop (+ i 1) np))))))))))
886 (define (set-goto-map)
887 (set! goto-map (make-vector (+ nvars 1) 0))
888 (let ((temp-map (make-vector (+ nvars 1) 0)))
889 (let loop ((ng 0) (sp first-shift))
891 (let loop2 ((i (reverse (shift-shifts (car sp)))) (ng2 ng))
893 (let ((symbol (vector-ref acces-symbol (car i))))
896 (vector-set! goto-map symbol
897 (+ 1 (vector-ref goto-map symbol)))
898 (loop2 (cdr i) (+ ng2 1)))
899 (loop2 (cdr i) ng2)))
900 (loop ng2 (cdr sp))))
902 (let loop ((k 0) (i 0))
905 (vector-set! temp-map i k)
906 (loop (+ k (vector-ref goto-map i)) (+ i 1)))
911 (vector-set! goto-map i (vector-ref temp-map i)))
914 (vector-set! goto-map nvars ngotos)
915 (vector-set! temp-map nvars ngotos)
916 (set! from-state (make-vector ngotos #f))
917 (set! to-state (make-vector ngotos #f))
919 (do ((sp first-shift (cdr sp)))
922 (state1 (shift-number x)))
923 (do ((i (shift-shifts x) (cdr i)))
925 (let* ((state2 (car i))
926 (symbol (vector-ref acces-symbol state2)))
928 (let ((k (vector-ref temp-map symbol)))
929 (vector-set! temp-map symbol (+ k 1))
930 (vector-set! from-state k state1)
931 (vector-set! to-state k state2))))))))))))))
934 (define (map-goto state symbol)
935 (let loop ((low (vector-ref goto-map symbol))
936 (high (- (vector-ref goto-map (+ symbol 1)) 1)))
939 (display (list "Error in map-goto" state symbol)) (newline)
941 (let* ((middle (quotient (+ low high) 2))
942 (s (vector-ref from-state middle)))
947 (loop (+ middle 1) high))
949 (loop low (- middle 1))))))))
952 (define (initialize-F)
953 (set! F (make-vector ngotos #f))
954 (do ((i 0 (+ i 1))) ((= i ngotos)) (vector-set! F i (new-set token-set-size)))
956 (let ((reads (make-vector ngotos #f)))
958 (let loop ((i 0) (rowp 0))
960 (let* ((rowf (vector-ref F rowp))
961 (stateno (vector-ref to-state i))
962 (sp (vector-ref shift-table stateno)))
964 (let loop2 ((j (shift-shifts sp)) (edges '()))
966 (let ((symbol (vector-ref acces-symbol (car j))))
968 (if (vector-ref nullable symbol)
969 (loop2 (cdr j) (cons (map-goto stateno symbol)
971 (loop2 (cdr j) edges))
973 (set-bit rowf (- symbol nvars))
974 (loop2 (cdr j) edges))))
976 (vector-set! reads i (reverse edges))))))
977 (loop (+ i 1) (+ rowp 1)))))
980 (define (add-lookback-edge stateno ruleno gotono)
981 (let ((k (vector-ref lookaheads (+ stateno 1))))
982 (let loop ((found #f) (i (vector-ref lookaheads stateno)))
983 (if (and (not found) (< i k))
984 (if (= (vector-ref LAruleno i) ruleno)
986 (loop found (+ i 1)))
989 (begin (display "Error in add-lookback-edge : ")
990 (display (list stateno ruleno gotono)) (newline))
991 (vector-set! lookback i
992 (cons gotono (vector-ref lookback i))))))))
995 (define (transpose r-arg n)
996 (let ((new-end (make-vector n #f))
997 (new-R (make-vector n #f)))
1000 (let ((x (list 'bidon)))
1001 (vector-set! new-R i x)
1002 (vector-set! new-end i x)))
1005 (let ((sp (vector-ref r-arg i)))
1007 (let loop ((sp2 sp))
1009 (let* ((x (car sp2))
1010 (y (vector-ref new-end x)))
1011 (set-cdr! y (cons i (cdr y)))
1012 (vector-set! new-end x (cdr y))
1013 (loop (cdr sp2))))))))
1016 (vector-set! new-R i (cdr (vector-ref new-R i))))
1022 (define (build-relations)
1024 (define (get-state stateno symbol)
1025 (let loop ((j (shift-shifts (vector-ref shift-table stateno)))
1029 (let ((st2 (car j)))
1030 (if (= (vector-ref acces-symbol st2) symbol)
1032 (loop (cdr j) st2))))))
1034 (set! includes (make-vector ngotos #f))
1037 (let ((state1 (vector-ref from-state i))
1038 (symbol1 (vector-ref acces-symbol (vector-ref to-state i))))
1039 (let loop ((rulep (vector-ref derives symbol1))
1042 (let ((*rulep (car rulep)))
1043 (let loop2 ((rp (vector-ref rrhs *rulep))
1045 (states (list state1)))
1046 (let ((*rp (vector-ref ritem rp)))
1048 (let ((st (get-state stateno *rp)))
1049 (loop2 (+ rp 1) st (cons st states)))
1052 (if (not (vector-ref consistent stateno))
1053 (add-lookback-edge stateno *rulep i))
1055 (let loop2 ((done #f)
1060 (let ((*rp (vector-ref ritem rp2)))
1061 (if (< -1 *rp nvars)
1062 (loop2 (not (vector-ref nullable *rp))
1065 (cons (map-goto (car stp) *rp) edgp))
1066 (loop2 #t stp rp2 edgp)))
1068 (loop (cdr rulep) edgp))))))))
1069 (vector-set! includes i edges)))))
1070 (set! includes (transpose includes ngotos)))
1074 (define (compute-lookaheads)
1075 (let ((n (vector-ref lookaheads nstates)))
1078 (let loop2 ((sp (vector-ref lookback i)))
1080 (let ((LA-i (vector-ref LA i))
1081 (F-j (vector-ref F (car sp))))
1082 (bit-union LA-i F-j token-set-size)
1084 (loop (+ i 1))))))))
1088 (define (digraph relation)
1089 (define infinity (+ ngotos 2))
1090 (define INDEX (make-vector (+ ngotos 1) 0))
1091 (define VERTICES (make-vector (+ ngotos 1) 0))
1095 (define (traverse i)
1096 (set! top (+ 1 top))
1097 (vector-set! VERTICES top i)
1099 (vector-set! INDEX i height)
1100 (let ((rp (vector-ref R i)))
1102 (let loop ((rp2 rp))
1104 (let ((j (car rp2)))
1105 (if (= 0 (vector-ref INDEX j))
1107 (if (> (vector-ref INDEX i)
1108 (vector-ref INDEX j))
1109 (vector-set! INDEX i (vector-ref INDEX j)))
1110 (let ((F-i (vector-ref F i))
1111 (F-j (vector-ref F j)))
1112 (bit-union F-i F-j token-set-size))
1113 (loop (cdr rp2))))))
1114 (if (= (vector-ref INDEX i) height)
1116 (let ((j (vector-ref VERTICES top)))
1117 (set! top (- top 1))
1118 (vector-set! INDEX j infinity)
1121 (bit-union (vector-ref F i)
1129 (if (and (= 0 (vector-ref INDEX i))
1130 (pair? (vector-ref R i)))
1137 (define (build-tables)
1138 (define (add-action St Sym Act)
1139 (let* ((x (vector-ref ACTION-TABLE St))
1142 (if (not (= Act (cdr y)))
1143 ;; -- there is a conflict
1145 (if (and (<= (cdr y) 0)
1148 (display "%% Reduce/Reduce conflict ")
1149 (display "(reduce ") (display (- Act))
1150 (display ", reduce ") (display (- (cdr y)))
1151 (display ") on ") (print-symbol (+ Sym nvars))
1152 (display " in state ") (display St)
1154 (set-cdr! y (max (cdr y) Act)))
1156 (display "%% Shift/Reduce conflict ")
1157 (display "(shift ") (display Act)
1158 (display ", reduce ") (display (- (cdr y)))
1159 (display ") on ") (print-symbol (+ Sym nvars))
1160 (display " in state ") (display St)
1162 (set-cdr! y Act)))))
1163 (vector-set! ACTION-TABLE St
1164 (cons (cons Sym Act) x)))))
1166 (set! action-table (make-vector nstates '()))
1168 (do ((i 0 (+ i 1))) ; i = state
1170 (let ((red (vector-ref reduction-table i)))
1171 (if (and red (>= (red-nreds red) 1))
1172 (if (and (= (red-nreds red) 1) (vector-ref consistent i))
1173 (add-action i 'default (- (car (red-rules red))))
1174 (let ((k (vector-ref lookaheads (+ i 1))))
1175 (let loop ((j (vector-ref lookaheads i)))
1177 (let ((rule (- (vector-ref LAruleno j)))
1178 (lav (vector-ref LA j)))
1179 (let loop2 ((token 0) (x (vector-ref lav 0)) (y 1) (z 0))
1180 (if (< token nterms)
1182 (let ((in-la-set? (modulo x 2)))
1183 (if (= in-la-set? 1)
1184 (add-action i token rule)))
1185 (if (= y (BITS-PER-WORD))
1187 (vector-ref lav (+ z 1))
1190 (loop2 (+ token 1) (quotient x 2) (+ y 1) z)))))
1191 (loop (+ j 1)))))))))
1193 (let ((shiftp (vector-ref shift-table i)))
1195 (let loop ((k (shift-shifts shiftp)))
1197 (let* ((state (car k))
1198 (symbol (vector-ref acces-symbol state)))
1199 (if (>= symbol nvars)
1200 (add-action i (- symbol nvars) state))
1201 (loop (cdr k))))))))
1203 (add-action final-state 0 'accept))
1205 (define (compact-action-table)
1206 (define (most-common-action acts)
1208 (let loop ((l acts))
1211 (y (assv x accums)))
1212 (if (and (number? x) (< x 0))
1214 (set-cdr! y (+ 1 (cdr y)))
1215 (set! accums (cons `(,x . 1) accums))))
1218 (let loop ((l accums) (max 0) (sym #f))
1223 (loop (cdr l) (cdr x) (car x))
1224 (loop (cdr l) max sym)))))))
1228 (let ((acts (vector-ref action-table i)))
1229 (if (vector? (vector-ref reduction-table i))
1230 (let ((act (most-common-action acts)))
1231 (vector-set! action-table i
1232 (cons `(default . ,(if act act 'error))
1234 (not (eq? (cdr x) act)))
1236 (vector-set! action-table i
1237 (cons `(default . *error*) acts))))))
1240 (define (output-action-table prefix)
1241 (display "(defconst ") (display prefix) (display "action-table") (newline)
1242 (display " [") (newline)
1246 (write (vector-ref action-table i))
1248 (display " ])") (newline)
1251 (define (output-goto-table prefix)
1252 (display "(defconst ") (display prefix) (display "goto-table") (newline)
1253 (display " [") (newline)
1257 (let ((shifts (vector-ref shift-table i)))
1261 (let loop ((l (shift-shifts shifts)))
1264 (let* ((state (car l))
1265 (symbol (vector-ref acces-symbol state)))
1266 (if (< symbol nvars)
1267 (display `(,symbol . ,state)))
1271 (display " ])") (newline)
1274 (define (output-reduction-table gram/actions prefix)
1275 (display "(defconst ") (display prefix) (display "reduction-table") (newline)
1276 (display " (vector") (newline)
1277 (display " '()") (newline)
1280 (let ((act (cdr p)))
1281 (display " (lambda (stack sp goto-table $look)") (newline)
1282 (let* ((nt (caar p)) (rhs (cdar p)) (n (length rhs)))
1283 (display " (let* (")
1285 (let loop ((i 1) (l rhs))
1287 (let ((rest (cdr l)))
1288 (if (> i 1) (begin (newline) (display " ")))
1289 (display "($") (display (+ (- n i) 1)) (display " ")
1290 (display "(aref stack (- sp ")
1291 (display (- (* i 2) 1))
1293 (loop (+ i 1) rest)))))
1298 (display "(accept $1)")
1300 (display "(lr-push stack (- sp ")
1304 (display " goto-table ")
1307 (display "))") (newline))))
1309 (display " ))") (newline)
1312 (define (output-header header parser-prefix)
1314 (display "(require 'lr-driver)") (newline)
1317 (define (output-footer footer)
1318 (display footer) (newline)
1321 (define (output-parser-def parser-prefix prefix)
1322 (display "(defun ") (display parser-prefix) (display "parse") (display "(scanner errorhandler)") (newline)
1323 (display " (lr-parse scanner errorhandler ") (newline)
1324 (display " ") (display prefix) (display "action-table") (newline)
1325 (display " ") (display prefix) (display "goto-table") (newline)
1326 (display " ") (display prefix) (display "reduction-table") (newline)
1327 (display " ") (display prefix) (display "token-defs))") (newline)
1330 (define (output-token-defs terms prefix)
1331 (let loop ((i 0) (l terms))
1334 (display "(defconst ") (display prefix)
1340 (loop (+ i 1) (cdr l)))))
1342 (display "(defconst ") (display prefix) (display "token-defs") (newline)
1343 (display " (list ") (newline)
1344 (let loop ((i 0) (l terms))
1349 (display " \"") (display (car l)) (display "\")")
1351 (loop (+ i 1) (cdr l)))))
1352 (display " ))") (newline)
1357 (define (rewrite-grammar grammar proc)
1361 (if (not (pair? grammar))
1362 (error "Grammar definition must be a non-empty list")
1363 (let loop1 ((lst grammar) (rev-terms '()))
1364 (if (and (pair? lst) (not (pair? (car lst)))) ; definition d'un terminal?
1365 (let ((term (car lst)))
1366 (cond ((not (valid-terminal? term))
1367 (error "Invalid terminal:" term))
1368 ((member term rev-terms)
1369 (error "Terminal previously defined:" term))
1371 (loop1 (cdr lst) (cons term rev-terms)))))
1372 (let loop2 ((lst lst) (rev-nonterm-defs '()))
1374 (let ((def (car lst)))
1375 (if (not (pair? def))
1376 (error "Nonterminal definition must be a non-empty list")
1377 (let ((nonterm (car def)))
1378 (cond ((not (valid-nonterminal? nonterm))
1379 (error "Invalid nonterminal:" nonterm))
1380 ((or (member nonterm rev-terms)
1381 (assoc nonterm rev-nonterm-defs))
1382 (error "Nonterminal previously defined:" nonterm))
1385 (cons def rev-nonterm-defs)))))))
1386 (let* ((terms (cons eoi (reverse rev-terms)))
1387 (nonterm-defs (reverse rev-nonterm-defs))
1388 (nonterms (cons '*start* (map car nonterm-defs))))
1389 (if (= (length nonterms) 1)
1390 (error "Grammar must contain at least one nonterminal")
1391 (let ((compiled-nonterminals
1392 (map (lambda (nonterm-def)
1393 (rewrite-nonterm-def nonterm-def
1396 (cons `(*start* (,(cadr nonterms) ,eoi) : $1)
1400 (map (lambda (x) (cons (caaar x) (map cdar x)))
1401 compiled-nonterminals)
1402 (apply append compiled-nonterminals)))))))))))
1405 (define (rewrite-nonterm-def nonterm-def terms nonterms)
1407 (define No-NT (length nonterms))
1410 (let ((PosInNT (pos-in-list x nonterms)))
1413 (let ((PosInT (pos-in-list x terms)))
1416 (error "undefined symbol : " x))))))
1418 (if (not (pair? (cdr nonterm-def)))
1419 (error "At least one production needed for nonterminal" (car nonterm-def))
1420 (let ((name (symbol->string (car nonterm-def))))
1421 (let loop1 ((lst (cdr nonterm-def))
1423 (rev-productions-and-actions '()))
1424 (if (not (pair? lst))
1425 (reverse rev-productions-and-actions)
1426 (let* ((rhs (car lst))
1428 (prod (map encode (cons (car nonterm-def) rhs))))
1429 (for-each (lambda (x)
1430 (if (not (or (member x terms) (member x nonterms)))
1431 (error "Invalid terminal or nonterminal" x)))
1433 (if (and (pair? rest)
1438 (cons (cons prod (cadr rest))
1439 rev-productions-and-actions))
1440 (let* ((rhs-length (length rhs))
1443 (cons (list 'QUOTE (string->symbol
1447 (number->string i))))
1449 (if (> j rhs-length)
1451 (cons (string->symbol
1454 (number->string j)))
1455 (loop-j (+ j 1)))))))))
1458 (cons (cons prod action)
1459 rev-productions-and-actions))))))))))
1461 (define (valid-nonterminal? x)
1464 (define (valid-terminal? x)
1467 ;; ---------------------------------------------------------------------- ;;
1469 ;; ---------------------------------------------------------------------- ;;
1470 (define (pos-in-list x lst)
1471 (let loop ((lst lst) (i 0))
1472 (cond ((not (pair? lst)) #f)
1473 ((equal? (car lst) x) i)
1474 (else (loop (cdr lst) (+ i 1))))))
1476 (define (sunion lst1 lst2) ; union of sorted lists
1477 (let loop ((L1 lst1)
1479 (cond ((null? L1) L2)
1482 (let ((x (car L1)) (y (car L2)))
1485 (cons y (loop L1 (cdr L2))))
1487 (cons x (loop (cdr L1) L2)))
1492 (define (sinsert elem lst)
1493 (let loop ((l1 lst))
1500 (cons x (loop (cdr l1))))
1504 (define (filter p lst)
1508 (let ((x (car l)) (y (cdr l)))
1513 ;; ---------------------------------------------------------------------- ;;
1514 ;; Debugging tools ... ;;
1515 ;; ---------------------------------------------------------------------- ;;
1516 (define the-terminals #f)
1517 (define the-nonterminals #f)
1519 (define (print-item item-no)
1520 (let loop ((i item-no))
1521 (let ((v (vector-ref ritem i)))
1525 (nt (vector-ref rlhs rlno)))
1526 (display (vector-ref the-nonterminals nt)) (display " --> ")
1527 (let loop ((i (vector-ref rrhs rlno)))
1528 (let ((v (vector-ref ritem i)))
1542 (define (print-symbol n)
1543 (display (if (>= n nvars)
1544 (vector-ref the-terminals (- n nvars))
1545 (vector-ref the-nonterminals n))))
1547 (define (print-states)
1548 (define (print-action act)
1551 (display " : Error"))
1553 (display " : Accept input"))
1555 (display " : reduce using rule ")
1558 (display " : shift and goto state ")
1563 (define (print-actions acts)
1564 (let loop ((l acts))
1567 (let ((sym (caar l))
1572 (display "default action"))
1574 (print-symbol (+ sym nvars))))
1578 (if (not action-table)
1580 (display "No generated parser available!")
1584 (display "State table") (newline)
1585 (display "-----------") (newline) (newline)
1587 (let loop ((l first-state))
1590 (let* ((core (car l))
1591 (i (core-number core))
1592 (items (core-items core))
1593 (actions (vector-ref action-table i)))
1594 (display "state ") (display i) (newline)
1596 (for-each (lambda (x) (display " ") (print-item x))
1599 (print-actions actions)
1601 (loop (cdr l))))))))