1 ! Copyright (C) 2019-2020 KUSUMOTO Norio.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: accessors arrays assocs classes classes.tuple combinators
4 combinators.short-circuit compiler.units continuations
5 formatting io kernel lexer lists math multiline namespaces
6 parser prettyprint quotations sequences sequences.deep
7 sequences.generalizations sets splitting strings vectors words
12 SYMBOL: !! ! cut operator in prolog: !
13 SYMBOL: __ ! anonymous variable in prolog: _
14 SYMBOL: ;; ! disjunction, or in prolog: ;
15 SYMBOL: \+ ! negation in prolog: not, \+
20 TUPLE: logic-pred name defs ;
22 : <pred> ( name -- pred )
28 SINGLETON: NORMAL-LOGIC-VAR
29 SINGLETON: ANONYMOUSE-LOGIC-VAR
30 INSTANCE: NORMAL-LOGIC-VAR LOGIC-VAR
31 INSTANCE: ANONYMOUSE-LOGIC-VAR LOGIC-VAR
33 : logic-var? ( obj -- ? )
34 dup symbol? [ get LOGIC-VAR? ] [ drop f ] if ; inline
36 SYMBOLS: *trace?* *trace-depth* ;
38 : define-logic-var ( name -- )
42 [ NORMAL-LOGIC-VAR swap set-global ] tri ;
44 : define-logic-pred ( name -- )
48 [ [ name>> <pred> ] keep set-global ] tri ;
52 : trace ( -- ) t *trace?* set-global ;
54 : notrace ( -- ) f *trace?* set-global ;
56 SYNTAX: LOGIC-VAR: scan-token define-logic-var ;
58 SYNTAX: LOGIC-VARS: ";" [ define-logic-var ] each-token ;
60 SYNTAX: LOGIC-PRED: scan-token define-logic-pred ;
62 SYNTAX: LOGIC-PREDS: ";" [ define-logic-pred ] each-token ;
66 "!%" parse-multiline-string drop ;
70 TUPLE: logic-goal pred args ;
72 : called-args ( args -- args' )
73 [ dup callable? [ call( -- term ) ] when ] map ; inline
75 :: <goal> ( pred args -- goal )
76 pred get args called-args logic-goal boa ; inline
78 : def>goal ( goal-def -- goal ) unclip swap <goal> ;
80 : normalize ( goal-def/defs -- goal-defs )
83 [ ?first dup symbol? [ get logic-pred? ] [ drop f ] if ]
84 } 1|| [ 1array ] when ;
86 TUPLE: logic-env table ;
88 : <env> ( -- env ) logic-env new H{ } clone >>table ; inline
90 :: env-put ( x pair env -- ) pair x env table>> set-at ; inline
92 : env-get ( x env -- pair/f ) table>> at ; inline
94 : env-delete ( x env -- ) table>> delete-at ; inline
96 : env-clear ( env -- ) table>> clear-assoc ; inline
98 : dereference ( term env -- term' env' )
99 [ 2dup env-get [ 2nip first2 t ] [ f ] if* ] loop ; inline
105 { [ over logic-goal? ] [
106 [ [ pred>> ] [ args>> ] bi ] dip at <goal> t ] }
108 '[ tuple-slots [ _ at ] map ]
109 [ class-of slots>tuple ] bi t ] }
110 { [ over sequence? ] [
117 TUPLE: callback-env env trail ;
119 C: <callback-env> callback-env inline
121 M: callback-env at* env>> at* ; inline
123 TUPLE: cut-info cut? ;
125 C: <cut> cut-info inline
127 : cut? ( cut-info -- ? ) cut?>> ; inline
129 : set-info ( ? cut-info -- ) cut?<< ; inline
131 : set-info-if-f ( ? cut-info -- )
132 dup cut?>> [ 2drop ] [ cut?<< ] if ; inline
134 : 2each-until ( seq1 seq2 quot -- all-failed? ) 2 nfind 2drop f = ; inline
138 :: (unify*) ( x! x-env! y! y-env! trail tmp-env -- success? )
139 f :> ret-value! f :> ret?! f :> ret2?!
143 x x-env env-get :> xp
146 x x-env dereference x-env! x!
149 y y-env dereference y-env! y!
150 x y = x-env y-env eq? and [
151 x { y y-env } x-env env-put
153 { x x-env } trail push
160 x y x! y! x-env y-env x-env! y-env!
167 x y [ logic-goal? ] both? [
168 x pred>> y pred>> = [
169 x args>> x! y args>> y!
171 f ret-value! t ret2?!
176 { [ x y [ tuple? ] both? ] [
177 x y [ class-of ] same? [
178 x y [ tuple-slots ] bi@ [| x-item y-item |
179 x-item x-env y-item y-env trail tmp-env unify* not
181 ] [ f ] if ret-value! ] }
182 { [ x y [ sequence? ] both? ] [
183 x y [ class-of ] same? x y [ length ] same? and [
184 x y [| x-item y-item |
185 x-item x-env y-item y-env trail tmp-env unify* not
187 ] [ f ] if ret-value! ] }
194 :: unify* ( x x-env y y-env trail tmp-env -- success? )
195 *trace?* get-global :> trace?
198 *trace-depth* counter depth!
199 depth [ "\t" printf ] times
200 "Unification of " printf x-env x of pprint
201 " and " printf y pprint nl
203 x x-env y y-env trail tmp-env (unify*) :> success?
205 depth [ "\t" printf ] times
206 success? [ "==> Success\n" ] [ "==> Fail\n" ] if "%s\n" printf
207 *trace-depth* get-global 1 - *trace-depth* set-global
217 s-callable: s-callable/iter:
218 s-not-callable: s-not-callable/outer-iter: s-not-callable/inner-iter:
224 { state initial: s-start: }
226 first-goal rest-goals d-head d-body defs trail d-env d-cut
227 sub-resolver1 sub-resolver2 i loop-end
230 :: <resolver> ( body env cut -- resolver )
232 body >>body env >>env cut >>cut ; inline
234 GENERIC: next ( generator -- yield? )
236 M:: resolver-gen next ( resolver -- yield? )
242 resolver body>> empty? [
244 s-end: resolver state<<
246 s-not-empty: resolver state<<
249 resolver body>> unclip
250 [ resolver rest-goals<< ] [ resolver first-goal<< ] bi*
251 resolver first-goal>> !! = [ ! cut
252 s-cut: resolver state<<
254 s-not-cut: resolver state<<
257 resolver [ rest-goals>> ] [ env>> ] [ cut>> ] tri <resolver>
258 resolver sub-resolver1<<
259 s-cut/iter: resolver state<< ] }
261 resolver sub-resolver1>> next [
264 t resolver cut>> set-info
265 s-end: resolver state<<
268 resolver first-goal>> callable? [
269 resolver first-goal>> call( -- goal ) resolver first-goal<<
271 *trace?* get-global [
272 resolver first-goal>>
273 [ pred>> name>> "in: { %s " printf ]
274 [ args>> [ "%u " printf ] each "}\n" printf ] bi
276 <env> resolver d-env<<
277 f <cut> resolver d-cut<<
278 resolver first-goal>> pred>> defs>> dup resolver defs<<
279 length 1 - dup 0 >= [
282 s-defs-loop: resolver state<<
285 s-end: resolver state<<
288 resolver [ i>> ] [ defs>> ] bi nth
289 first2 [ resolver d-head<< ] [ resolver d-body<< ] bi*
290 resolver d-cut>> cut? resolver cut>> cut? or [
291 s-end: resolver state<<
293 V{ } clone resolver trail<<
302 resolver d-body>> callable? [
303 s-callable: resolver state<<
305 s-not-callable: resolver state<<
308 s-unify?-exit: resolver state<<
312 resolver [ d-env>> ] [ trail>> ] bi <callback-env>
313 resolver d-body>> call( cb-env -- ? ) [
314 resolver [ rest-goals>> ] [ env>> ] [ cut>> ] tri <resolver>
315 resolver sub-resolver1<<
316 s-callable/iter: resolver state<<
318 s-unify?-exit: resolver state<<
321 resolver sub-resolver1>> next [
324 s-unify?-exit: resolver state<<
327 resolver [ d-body>> ] [ d-env>> ] [ d-cut>> ] tri <resolver>
328 resolver sub-resolver1<<
329 s-not-callable/outer-iter: resolver state<< ] }
330 { s-not-callable/outer-iter: [
331 resolver sub-resolver1>> next [
332 resolver [ rest-goals>> ] [ env>> ] [ cut>> ] tri <resolver>
333 resolver sub-resolver2<<
334 s-not-callable/inner-iter: resolver state<<
336 s-unify?-exit: resolver state<<
338 { s-not-callable/inner-iter: [
339 resolver sub-resolver2>> next [
342 resolver cut>> cut? resolver d-cut>> set-info-if-f
343 s-not-callable/outer-iter: resolver state<<
346 resolver trail>> [ first2 env-delete ] each
347 resolver d-env>> env-clear
348 s-defs-loop-end: resolver state<< ] }
350 resolver [ i>> ] [ loop-end>> ] bi >= [
351 s-end: resolver state<<
353 resolver [ 1 + ] change-i drop
354 s-defs-loop: resolver state<<
357 t resolver return?<< ] }
359 resolver [ yield?>> ] [ return?>> ] bi or not
363 : split-body ( body -- bodies ) { ;; } split [ >array ] map ;
365 SYMBOL: *anonymouse-var-no*
367 : reset-anonymouse-var-no ( -- ) 0 *anonymouse-var-no* set-global ;
369 : proxy-var-for-'__' ( -- var-symbol )
371 *anonymouse-var-no* counter "ANON-%d_" sprintf
372 "logic.private" create-word dup dup
374 ANONYMOUSE-LOGIC-VAR swap set-global
375 ] with-compilation-unit ;
377 : replace-'__' ( before -- after )
379 { [ dup __ = ] [ drop proxy-var-for-'__' ] }
380 { [ dup sequence? ] [ [ replace-'__' ] map ] }
382 [ tuple-slots [ replace-'__' ] map ]
383 [ class-of slots>tuple ] bi ] }
387 : collect-logic-vars ( seq -- vars-array )
388 [ logic-var? ] deep-filter members ;
392 :: negation-goal ( goal -- negation-goal )
393 "failo_" <pred> :> f-pred
394 f-pred { } clone logic-goal boa :> f-goal
395 V{ { f-goal [ drop f ] } } f-pred defs<<
396 goal pred>> name>> "\\+%s_" sprintf <pred> :> negation-pred
397 negation-pred goal args>> clone logic-goal boa :> negation-goal
399 { negation-goal { goal !! f-goal } } ! \+P_ { P !! { failo_ } } rule
400 { negation-goal { } } ! \+P_ fact
401 } negation-pred defs<<
404 SYMBOLS: at-the-beginning at-the-end ;
406 :: (rule) ( head body pos -- )
407 reset-anonymouse-var-no
408 head replace-'__' def>goal :> head-goal
409 body replace-'__' normalize
410 split-body pos at-the-beginning = [ reverse ] when ! disjunction
412 head-goal swap 2array 1vector
414 pos at-the-end = [ swap ] when append!
421 { [ dup \+ = ] [ drop dummy-item t negation?! ] }
423 def>goal negation? [ negation-goal ] when
425 { [ dup callable? ] [
426 call( -- goal ) negation? [ negation-goal ] when
428 { [ dup [ t = ] [ f = ] bi or ] [
429 :> t/f! negation? [ t/f not t/f! ] when
430 t/f "trueo_" "failo_" ? <pred> :> t/f-pred
431 t/f-pred { } clone logic-goal boa :> t/f-goal
432 V{ { t/f-goal [ drop t/f ] } } t/f-pred defs<<
435 { [ dup !! = ] [ f negation?! ] } ! as '!!'
436 [ drop dummy-item f negation?! ]
438 ] map dummy-item swap remove :> body-goals
439 V{ { head-goal body-goals } }
441 pos at-the-end = [ swap ] when append!
446 : (fact) ( head pos -- ) { } clone swap (rule) ;
450 : rule ( head body -- ) at-the-end (rule) ;
452 : rule* ( head body -- ) at-the-beginning (rule) ;
454 : rules ( defs -- ) [ first2 rule ] each ;
456 : fact ( head -- ) at-the-end (fact) ;
458 : fact* ( head -- ) at-the-beginning (fact) ;
460 : facts ( defs -- ) [ fact ] each ;
462 :: callback ( head quot: ( callback-env -- ? ) -- )
463 head def>goal :> head-goal
465 { head-goal quot } suffix!
468 : callbacks ( defs -- ) [ first2 callback ] each ; inline
470 :: retract ( head-def -- )
471 head-def replace-'__' def>goal :> head-goal
472 head-goal pred>> defs>> :> defs
473 defs [ first <env> head-goal <env> V{ } clone <env> (unify*) ] find [
474 head-goal pred>> [ remove-nth! ] change-defs drop
477 :: retract-all ( head-def -- )
478 head-def replace-'__' def>goal :> head-goal
479 head-goal pred>> defs>> :> defs
481 first <env> head-goal <env> V{ } clone <env> (unify*)
482 ] reject! head-goal pred>> defs<< ;
484 : clear-pred ( pred -- ) get V{ } clone swap defs<< ;
486 :: unify ( cb-env x y -- success? )
488 x env y env cb-env trail>> env (unify*) ;
490 :: is ( quot: ( env -- value ) dist -- goal )
491 quot collect-logic-vars
492 dup dist swap member? [ dist suffix ] unless :> args
493 quot dist "[ %u %s is ]" sprintf <pred> :> is-pred
494 is-pred args logic-goal boa :> is-goal
498 [| env | env dist env quot call( env -- value ) unify ]
503 :: =:= ( quot: ( env -- n m ) -- goal )
504 quot collect-logic-vars :> args
505 quot "[ %u =:= ]" sprintf <pred> :> =:=-pred
506 =:=-pred args logic-goal boa :> =:=-goal
511 env quot call( env -- n m )
512 2dup [ number? ] both? [ = ] [ 2drop f ] if ]
517 :: =\= ( quot: ( env -- n m ) -- goal )
518 quot collect-logic-vars :> args
519 quot "[ %u =\\= ]" sprintf <pred> :> =\=-pred
520 =\=-pred args logic-goal boa :> =\=-goal
525 env quot call( env -- n m )
526 2dup [ number? ] both? [ = not ] [ 2drop f ] if ]
531 :: invoke ( quot: ( env -- ) -- goal )
532 quot collect-logic-vars :> args
533 quot "[ %u invoke ]" sprintf <pred> :> invoke-pred
534 invoke-pred args logic-goal boa :> invoke-goal
536 { invoke-goal [| env | env quot call( env -- ) t ] }
540 :: invoke* ( quot: ( env -- ? ) -- goal )
541 quot collect-logic-vars :> args
542 quot "[ %u invoke* ]" sprintf <pred> :> invoke*-pred
543 invoke*-pred args logic-goal boa :> invoke*-goal
545 { invoke*-goal [| env | env quot call( env -- ? ) ] }
546 } invoke*-pred defs<<
549 :: nquery ( goal-def/defs n/f -- bindings-array/success? )
550 *trace?* get-global :> trace?
553 V{ } clone :> bindings
555 goal-def/defs replace-'__' normalize [ def>goal ] map
557 <resolver> :> resolver
561 resolver env>> table>> keys [ get NORMAL-LOGIC-VAR? ] filter
562 [ dup env at ] H{ } map>assoc
563 trace? get-global [ dup [ "%u: %u\n" printf ] assoc-each ] when
568 n n/f >= [ return ] when
575 [ first keys empty? ]
576 } 1|| [ drop success? ] [ >array ] if ;
578 : query ( goal-def/defs -- bindings-array/success? ) f nquery ;
580 ! nquery has been modified to use generators created by finite
581 ! state machines to reduce stack consumption.
582 ! Since the processing algorithm of the code is difficult
583 ! to understand, the words no longer used are kept as private
584 ! words for verification.
588 : each-until ( seq quot -- ) find 2drop ; inline
590 :: resolve-body ( body env cut quot: ( -- ) -- )
594 body unclip :> ( rest-goals! first-goal! )
595 first-goal !! = [ ! cut
596 rest-goals env cut quot resolve-body
599 first-goal callable? [
600 first-goal call( -- goal ) first-goal!
602 *trace?* get-global [
604 [ pred>> name>> "in: { %s " printf ]
605 [ args>> [ "%u " printf ] each "}\n" printf ] bi
609 first-goal pred>> defs>> [
610 first2 :> ( d-head d-body )
611 first-goal d-head [ args>> length ] same? [
612 d-cut cut? cut cut? or [ t ] [
614 first-goal env d-head d-env trail d-env unify* [
616 d-env trail <callback-env> d-body call( cb-env -- ? ) [
617 rest-goals env cut quot resolve-body
621 rest-goals env cut quot resolve-body
622 cut cut? d-cut set-info-if-f
626 trail [ first2 env-delete ] each
635 :: (resolve) ( goal-def/defs quot: ( env -- ) -- )
636 goal-def/defs replace-'__' normalize [ def>goal ] map :> goals
638 goals env f <cut> [ env quot call( env -- ) ] resolve-body ;
640 : resolve ( goal-def/defs quot: ( env -- ) -- ) (resolve) ;
642 :: nquery/rec ( goal-def/defs n/f -- bindings-array/success? )
643 *trace?* get-global :> trace?
646 V{ } clone :> bindings
648 goal-def/defs normalize [| env |
649 env table>> keys [ get NORMAL-LOGIC-VAR? ] filter
650 [ dup env at ] H{ } map>assoc
651 trace? get-global [ dup [ "%u: %u\n" printf ] assoc-each ] when
656 n n/f >= [ return ] when
662 [ first keys empty? ]
663 } 1|| [ drop success? ] [ >array ] if ;
665 : query/rec ( goal-def/defs -- bindings-array/success? )
670 ! Built-in predicate definitions -----------------------------------------------------
675 (<) (>) (>=) (=<) (==) (\==) (=) (\=)
677 membero appendo lengtho listo ;
679 { trueo } [ drop t ] callback
681 { failo } [ drop f ] callback
684 <PRIVATE LOGIC-VARS: X Y Z ; PRIVATE>
686 { varo X } [ X of logic-var? ] callback
688 { nonvaro X } [ X of logic-var? not ] callback
692 [ X of ] [ Y of ] bi 2dup [ number? ] both? [ < ] [ 2drop f ] if
696 [ X of ] [ Y of ] bi 2dup [ number? ] both? [ > ] [ 2drop f ] if
700 [ X of ] [ Y of ] bi 2dup [ number? ] both? [ >= ] [ 2drop f ] if
704 [ X of ] [ Y of ] bi 2dup [ number? ] both? [ <= ] [ 2drop f ] if
707 { (==) X Y } [ [ X of ] [ Y of ] bi = ] callback
709 { (\==) X Y } [ [ X of ] [ Y of ] bi = not ] callback
711 { (=) X Y } [ dup [ X of ] [ Y of ] bi unify ] callback
714 clone [ clone ] change-env [ clone ] change-trail
715 dup [ X of ] [ Y of ] bi unify not
721 [ dup string? [ printf ] [ pprint ] if ] each
723 dup string? [ printf ] [ pprint ] if
729 [ dup string? [ printf ] [ pprint ] if ] each
731 dup string? [ printf ] [ pprint ] if
735 { nlo } [ drop nl t ] callback
738 <PRIVATE LOGIC-VARS: L L1 L2 L3 Head Tail N N1 ; PRIVATE>
740 { membero X L{ X . Tail } } fact
741 { membero X L{ Head . Tail } } { membero X Tail } rule
743 { appendo L{ } L L } fact
744 { appendo L{ X . L1 } L2 L{ X . L3 } } {
748 { lengtho L{ } 0 } fact
749 { lengtho L{ __ . Tail } N } {
751 [ [ N1 of 1 + ] N is ]
755 { listo L{ __ . __ } } fact