aboutsummaryrefslogtreecommitdiff
path: root/src/boot/parser.boot
blob: 10970e826a946fbd2f18e22b6ee93bf7bdc0e783 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
-- Copyright (c) 1991-2002, The Numerical ALgorithms Group Ltd.
-- All rights reserved.
-- Copyright (C) 2007-2008, Gabriel Dos Reis.
-- All rights reserved.
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions are
-- met:
--
--     - Redistributions of source code must retain the above copyright
--       notice, this list of conditions and the following disclaimer.
--
--     - Redistributions in binary form must reproduce the above copyright
--       notice, this list of conditions and the following disclaimer in
--       the documentation and/or other materials provided with the
--       distribution.
--
--     - Neither the name of The Numerical ALgorithms Group Ltd. nor the
--       names of its contributors may be used to endorse or promote products
--       derived from this software without specific prior written permission.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
-- IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
-- TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
-- PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
-- OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
-- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
-- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
-- PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
-- LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
-- NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--

--
-- Abstract:
--   This file defines the Boot grammar and parser.  The parser
--   is hand-written based on `parser combinators' technology.
--


module '"boot-parser"
import '"includer"
import '"scanner"
import '"ast"
 
)package "BOOTTRAN"
 

++ true when the current function definition has its parameters 
++ written round parenthesis.
$sawParenthesizedHead := false

bpFirstToken()==
      $stok:=
          if null $inputStream
          then shoeTokConstruct("ERROR","NOMORE",shoeTokPosn $stok)
          else CAR $inputStream
      $ttok:=shoeTokPart $stok
      true
 
bpFirstTok()==
      $stok:=
          if null $inputStream
          then shoeTokConstruct("ERROR","NOMORE",shoeTokPosn $stok)
          else CAR $inputStream
      $ttok:=shoeTokPart $stok
      $bpParenCount>0 and EQCAR($stok,"KEY") =>
             EQ($ttok,"SETTAB")=>
                $bpCount:=$bpCount+1
                bpNext()
             EQ($ttok,"BACKTAB")=>
                $bpCount:=$bpCount-1
                bpNext()
             EQ($ttok,"BACKSET")=>
                bpNext()
             true
      true
 
bpNext() ==
     $inputStream := CDR($inputStream)
     bpFirstTok()
 
bpNextToken() ==
     $inputStream := CDR($inputStream)
     bpFirstToken()
 
bpState()== [$inputStream,$stack,$bpParenCount,$bpCount]
--cons($inputStream,$stack)
 
bpRestore(x)==
      $inputStream:=CAR x
      bpFirstToken()
      $stack:=CADR x
      $bpParenCount:=CADDR x
      $bpCount:=CADDDR x
      true
 
bpPush x==$stack:=CONS(x,$stack)
 
bpPushId()==
   $stack:=CONS(bfReName $ttok,$stack)
 
bpPop1()==
       a:=CAR $stack
       $stack:=CDR $stack
       a
 
bpPop2()==
       a:=CADR $stack
       RPLACD($stack,CDDR $stack)
       a
 
bpPop3()==
       a:=CADDR $stack
       RPLACD(CDR $stack,CDDDR $stack)
       a
 
bpIndentParenthesized f==
    $bpCount:local:=0
    a:=$stok
    if bpEqPeek "OPAREN"
    then
      $bpParenCount:=$bpParenCount+1
      bpNext()
      if APPLY(f,nil) and bpFirstTok() and
              (bpEqPeek "CPAREN" or bpParenTrap(a))
      then
            $bpParenCount:=$bpParenCount-1
            bpNextToken()
            $bpCount=0 => true
            $inputStream:=append( bpAddTokens $bpCount,$inputStream)
            bpFirstToken()
            $bpParenCount=0 =>
                     bpCancel()
                     true
            true
      else if bpEqPeek "CPAREN"
           then
              bpPush  bfTuple []
              $bpParenCount:=$bpParenCount-1
              bpNextToken()
              true
           else bpParenTrap(a)
    else false
 
bpParenthesized f==
    a:=$stok
    if bpEqKey "OPAREN"
    then
      if APPLY(f,nil) and (bpEqKey "CPAREN" or bpParenTrap(a))
      then true
      else if bpEqKey "CPAREN"
           then
              bpPush  bfTuple []
              true
           else bpParenTrap(a)
    else false
 
bpBracket f==
    a:=$stok
    if bpEqKey "OBRACK"
    then
      if APPLY(f,nil) and (bpEqKey "CBRACK" or bpBrackTrap(a))
      then bpPush bfBracket bpPop1 ()
      else if bpEqKey "CBRACK"
           then bpPush  []
           else bpBrackTrap(a)
    else false
 
bpPileBracketed f==
              if bpEqKey "SETTAB"
              then if bpEqKey "BACKTAB"
                   then true
                   else if APPLY(f,nil) and
                            (bpEqKey "BACKTAB" or bpPileTrap())
                        then bpPush bfPile bpPop1()
                        else false
              else false
 
bpListof(f,str1,g)==
    if APPLY(f,nil)
    then
        if bpEqKey str1 and (APPLY(f,nil) or bpTrap())
        then
          a:=$stack
          $stack:=nil
          while bpEqKey str1 and (APPLY(f,nil) or bpTrap()) repeat 0
          $stack:=cons(NREVERSE $stack,a)
          bpPush FUNCALL(g, [bpPop3(),bpPop2(),:bpPop1()])
        else
          true
    else false
 
 
-- to do ,<backset>
bpListofFun(f,h,g)==
    if APPLY(f,nil)
    then
        if APPLY(h,nil) and (APPLY(f,nil) or bpTrap())
        then
          a:=$stack
          $stack:=nil
          while APPLY(h,nil) and (APPLY(f,nil) or bpTrap()) repeat 0
          $stack:=cons(NREVERSE $stack,a)
          bpPush FUNCALL(g, bfListOf [bpPop3(),bpPop2(),:bpPop1()])
        else
          true
    else false
 
bpList(f,str1,g)==
    if APPLY(f,nil)
    then
        if bpEqKey str1 and (APPLY(f,nil) or bpTrap())
        then
          a:=$stack
          $stack:=nil
          while bpEqKey str1 and (APPLY(f,nil) or bpTrap()) repeat 0
          $stack:=cons(NREVERSE $stack,a)
          bpPush FUNCALL(g,  [bpPop3(),bpPop2(),:bpPop1()])
        else
          bpPush FUNCALL(g, [bpPop1()])
    else bpPush FUNCALL(g, [])
 
bpOneOrMore f==
       APPLY(f,nil)=>
         a:=$stack
         $stack:=nil
         while APPLY(f,nil) repeat 0
         $stack:=cons(NREVERSE $stack,a)
         bpPush cons(bpPop2(),bpPop1())
       false
 
 
-- s must transform the head of the stack
bpAnyNo s==
     while APPLY(s,nil) repeat 0
     true
 
 
-- AndOr(k,p,f)= k p
bpAndOr(keyword,p,f)==
   bpEqKey keyword and (APPLY(p,nil) or bpTrap())
          and bpPush FUNCALL(f, bpPop1())
 
bpConditional f==
  if  bpEqKey "IF" and (bpWhere() or bpTrap()) and
                   (bpEqKey "BACKSET" or true)
  then
           if bpEqKey "SETTAB"
           then if bpEqKey "THEN"
                then  (APPLY(f,nil) or bpTrap()) and bpElse(f) and bpEqKey "BACKTAB"
                else  bpMissing "THEN"
           else if bpEqKey "THEN"
                then (APPLY(f,nil) or bpTrap()) and bpElse(f)
                else bpMissing "then"
  else false
 
bpElse(f)==
           a:=bpState()
           if bpBacksetElse()
           then  (APPLY(f,nil) or bpTrap()) and
                 bpPush bfIf(bpPop3(),bpPop2(),bpPop1())
           else
              bpRestore a
              bpPush bfIfThenOnly(bpPop2(),bpPop1())
 
bpBacksetElse()==
    if bpEqKey "BACKSET"
    then bpEqKey "ELSE"
    else bpEqKey "ELSE"
 
bpEqPeek s ==  EQCAR($stok,"KEY") and EQ(s,$ttok)
 
bpEqKey s ==   EQCAR($stok,"KEY") and EQ(s,$ttok) and bpNext()
bpEqKeyNextTok s ==   EQCAR($stok,"KEY") and EQ(s,$ttok) and
                  bpNextToken()
 
bpPileTrap()   == bpMissing  "BACKTAB"
bpBrackTrap(x) == bpMissingMate("]",x)
bpParenTrap(x) == bpMissingMate(")",x)
 
bpMissingMate(close,open)==
   bpSpecificErrorAtToken(open, '"possibly missing mate")
   bpMissing close
 
bpMissing s==
   bpSpecificErrorHere(CONCAT(PNAME s,'" possibly missing"))
   throw TRAPPOINT "TRAPPED"
 
bpCompMissing s == bpEqKey s or bpMissing s
 
bpTrap()==
   bpGeneralErrorHere()
   throw TRAPPOINT "TRAPPED"
 
bpRecoverTrap()==
  bpFirstToken()
  pos1 := shoeTokPosn $stok
  bpMoveTo 0
  pos2 := shoeTokPosn $stok
  bpIgnoredFromTo(pos1, pos2)
  bpPush  [['"pile syntax error"]]
 
bpListAndRecover(f)==
   a:=$stack
   b:=nil
   $stack:=nil
   done:=false
   c:=$inputStream
   while not done repeat
--   $trapped:local:=false
     found:=try APPLY(f,nil) catch TRAPPOINT
     if found="TRAPPED"
     then
        $inputStream:=c
        bpRecoverTrap()
     else if not found
          then
            $inputStream:=c
            bpGeneralErrorHere()
            bpRecoverTrap()
     if bpEqKey "BACKSET"
     then
        c:=$inputStream
     else if bpEqPeek "BACKTAB"  or null $inputStream
          then
             done:=true
          else
            $inputStream:=c
            bpGeneralErrorHere()
            bpRecoverTrap()
            if bpEqPeek "BACKTAB"  or null $inputStream
            then done:=true
            else
                bpNext()
                c:=$inputStream
     b:=cons(bpPop1(),b)
   $stack:=a
   bpPush NREVERSE b
 
bpMoveTo n==
     null $inputStream  => true
     bpEqPeek "BACKTAB" =>
                n=0  => true
                bpNextToken()
                $bpCount:=$bpCount-1
                bpMoveTo(n-1)
     bpEqPeek "BACKSET" =>
                n=0  => true
                bpNextToken()
                bpMoveTo n
     bpEqPeek "SETTAB"  =>
                bpNextToken()
                bpMoveTo(n+1)
     bpEqPeek "OPAREN"  =>
                bpNextToken()
                $bpParenCount:=$bpParenCount+1
                bpMoveTo n
     bpEqPeek "CPAREN"  =>
                bpNextToken()
                $bpParenCount:=$bpParenCount-1
                bpMoveTo n
     bpNextToken()
     bpMoveTo n
 
-- A fully qualified name could be interpreted as a left reduction
-- of an '::' infix operator.  At the moment, we don't use
-- that general interpretation.

-- When this routine is called, a symbol is already pushed on the
-- stack.  When this routine finished execution, we have either
-- reduced a '::' and a name, or nothing.  In either case, a 
-- symbol is present on the stack.
bpQualifiedName() ==
  bpEqPeek "COLON-COLON" =>
    bpNext()
    EQCAR($stok, "ID") and bpPushId() and bpNext()
      and bpPush bfColonColon(bpPop2(), bpPop1())
  false

++ Name:
++   ID
++   Name :: ID
bpName() ==
  EQCAR( $stok,"ID") =>
    bpPushId()
    bpNext()
    bpAnyNo function bpQualifiedName
  false


++ Constant:
++   INTEGER
++   FLOAT
++   LISP
++   LISPEXPR
++   LINE
++   QUOTE S-Expression
++   STRING
bpConstTok() ==
     MEMQ(shoeTokType $stok, '(INTEGER FLOAT)) =>
          bpPush $ttok
          bpNext()
     EQCAR($stok,"LISP")=> bpPush bfReadLisp $ttok and bpNext()
     EQCAR($stok,"LISPEXP")=> bpPush $ttok and bpNext()
     EQCAR($stok,"LINE")=> bpPush ["+LINE", $ttok] and bpNext()
     bpEqPeek "QUOTE" =>
          bpNext()
          (bpSexp() or bpTrap()) and
               bpPush bfSymbol bpPop1()
     bpString()

++ Parse a module definitoin
++   Module:
++     MODULE QUOTE String
bpModule() ==
  bpEqKey "MODULE" =>
    -- we really want to check that the next token is indeed
    -- a string.  For the moment, we delay the type checking
    -- to the Lisp compiler/interpreter.  That is likely to 
    -- cause cryptic diagnostics.  To be fixed.
    bpConstTok() and bpPush Module bpPop1()
  false

++ Parse a module import, or a import declaration for a foreign entity.
++ Import:
++    IMPORT Name for Signature
++    IMPORT QUOTE String
bpImport() ==
  bpEqKey "IMPORT" =>
    (bpName() and (bpEqKey "FOR" or bpTrap()) and bpSignature()
       and bpPush ImportSignature(bpPop2(), bpPop1()))
         or 
          -- we really want to check that the next token is indeed
          -- a string.  For the moment, we delay the type checking
          -- to the Lisp compiler/interpreter.  That is likely to 
          -- cause cryptic diagnostics.  To be fixed.
           (bpConstTok() and bpPush Import bpPop1())
  false

-- Parse a type alias defnition:
--    type-alias-definition: 
--          identifier <=> logical-expression
bpTypeAliasDefition() ==
  (bpName() or bpTrap()) and 
    bpEqKey "TDEF" and bpLogical() and
      bpPush TypeAlias(bpPop2(), nil, bpPop1())

++ Parse a signature declaration
++  Signature:
++    Name COLON Mapping
bpSignature() ==
  bpName() and bpEqKey "COLON" and bpMapping()
    and bpPush Signature(bpPop2(), bpPop1())

++ Parse a mapping expression
++   Mapping:
++      (Name | IdList) -> Name
bpMapping() ==
  (bpName() or bpParenthesized function bpIdList) and 
     bpEqKey "ARROW" and bpName() and 
       bpPush Mapping(bpPop1(), bfUntuple bpPop1())

bpCancel()==
    a:=bpState()
    if bpEqKeyNextTok  "SETTAB"
    then if bpCancel()
         then  if bpEqKeyNextTok  "BACKTAB"
               then true
               else
                   bpRestore a
                   false
         else
           if bpEqKeyNextTok "BACKTAB"
           then true
           else
              bpRestore a
              false
    else false
bpAddTokens n==
         n=0 => nil
         n>0=> cons(shoeTokConstruct("KEY","SETTAB",shoeTokPosn $stok),bpAddTokens(n-1))
         cons(shoeTokConstruct("KEY","BACKTAB",shoeTokPosn $stok),bpAddTokens(n+1))
 
bpExceptions()==
     bpEqPeek "DOT" or bpEqPeek "QUOTE" or
          bpEqPeek "OPAREN" or bpEqPeek "CPAREN" or
             bpEqPeek "SETTAB" or bpEqPeek "BACKTAB"
                or bpEqPeek "BACKSET"
 
 
bpSexpKey()==
      EQCAR( $stok,"KEY") and not bpExceptions()=>
               a:=GET($ttok,"SHOEINF")
               null a=>  bpPush $ttok and bpNext()
               bpPush a and bpNext()
      false
 
bpAnyId()==
  bpEqKey "MINUS"  and (EQCAR($stok,"INTEGER") or bpTrap()) and
          bpPush MINUS $ttok and bpNext() or
             bpSexpKey() or
                   MEMQ(shoeTokType $stok, '(ID INTEGER STRING FLOAT))
                      and  bpPush $ttok and  bpNext()
 
bpSexp()==
    bpAnyId() or
        bpEqKey "QUOTE"  and  (bpSexp() or bpTrap())
           and bpPush bfSymbol bpPop1() or
               bpIndentParenthesized function bpSexp1
 
bpSexp1()== bpFirstTok() and
    bpSexp() and
     (bpEqKey "DOT" and bpSexp() and bpPush CONS (bpPop2(),bpPop1())or
           bpSexp1() and bpPush CONS (bpPop2(),bpPop1())) or
               bpPush nil
 
bpPrimary1() ==
   bpName() or
     bpDot() or
      bpConstTok() or
       bpConstruct() or
        bpCase() or
         bpStruct() or
          bpPDefinition() or
           bpBPileDefinition()
 
bpPrimary()==  bpFirstTok() and (bpPrimary1() or bpPrefixOperator())
 
bpDot()== bpEqKey "DOT" and bpPush bfDot ()
 
bpPrefixOperator()==
   EQCAR( $stok,"KEY") and
     GET($ttok,"SHOEPRE") and bpPushId() and  bpNext()
 
bpInfixOperator()==
  EQCAR( $stok,"KEY") and
    GET($ttok,"SHOEINF") and bpPushId() and  bpNext()
 
bpSelector()==
            bpEqKey "DOT" and (bpPrimary()
               and bpPush(bfElt(bpPop2(),bpPop1()))
                  or bpPush bfSuffixDot bpPop1() )
 
bpOperator()==   bpPrimary() and bpAnyNo function bpSelector
 
bpApplication()==
   bpPrimary() and bpAnyNo function bpSelector and
      (bpApplication() and
            bpPush(bfApplication(bpPop2(),bpPop1())) or true)
 
++ Typing:
++   SimpleType
++   Mapping
bpTyping() ==
  bpApplication() and
    (bpEqKey "ARROW" and (bpApplication() or bpTrap()) and
      bpPush Mapping(bpPop1(), bfUntuple bpPop1()) or true) or bpMapping()

++ Tagged:
++   Name : Typing
bpTagged()==
      bpApplication() and
         (bpEqKey "COLON" and (bpTyping() or bpTrap()) and
           bpPush bfTagged(bpPop2(),bpPop1()) or true)
 
bpExpt()== bpRightAssoc('(POWER),function bpTagged)
 
bpInfKey s==
 EQCAR( $stok,"KEY") and
   MEMBER($ttok,s) and bpPushId() and bpNext()
 
bpInfGeneric s== bpInfKey s and  (bpEqKey "BACKSET" or true)
 
bpRightAssoc(o,p)==
    a:=bpState()
    if APPLY(p,nil)
    then
       while  bpInfGeneric o and (bpRightAssoc(o,p) or bpTrap()) repeat
             bpPush bfInfApplication(bpPop2(),bpPop2(),bpPop1())
       true
    else
       bpRestore a
       false
 
bpLeftAssoc(operations,parser)==
    if APPLY(parser,nil)
    then
       while bpInfGeneric(operations) and
         (APPLY(parser,nil) or bpTrap())
           repeat
             bpPush bfInfApplication(bpPop2(),bpPop2(),bpPop1())
       true
    else false
 
bpString()==
     EQ(shoeTokType $stok,"STRING") and
         bpPush(["QUOTE",INTERN $ttok]) and bpNext()
 
bpThetaName() ==
        if EQCAR( $stok,"ID") and GET($ttok,"SHOETHETA")
        then
           bpPushId()
           bpNext()
        else false
 
bpReduceOperator()==
         bpInfixOperator() or bpString()
                or bpThetaName()
 
bpReduce()==
     a:=bpState()
     if bpReduceOperator() and bpEqKey "SLASH"
     then
        bpEqPeek "OBRACK" => (bpDConstruct() or bpTrap()) and
                     bpPush bfReduceCollect(bpPop2(),bpPop1())
        (bpApplication() or bpTrap()) and
                bpPush bfReduce(bpPop2(),bpPop1())
     else
        bpRestore a
        false
 
bpTimes()==
    bpReduce() or bpLeftAssoc('(TIMES  SLASH),function bpExpt)
 
bpMinus()==
   bpInfGeneric '(MINUS) and (bpTimes() or bpTrap())
        and bpPush(bfApplication(bpPop2(),bpPop1()))
          or bpTimes()
 
bpArith()==bpLeftAssoc('(PLUS MINUS),function bpMinus)
 
bpIs()==
     bpArith() and (bpInfKey '(IS ISNT) and (bpPattern() or bpTrap())
        and bpPush bfISApplication(bpPop2(),bpPop2(),bpPop1())
           or true)
 
bpBracketConstruct(f)==
        bpBracket f and bpPush bfConstruct bpPop1 ()
 
bpCompare()==
     bpIs() and (bpInfKey  '(SHOEEQ SHOENE LT LE GT GE IN)
        and (bpIs() or bpTrap())
           and bpPush bfInfApplication(bpPop2(),bpPop2(),bpPop1())
               or true)
 
bpAnd()== bpLeftAssoc('(AND),function bpCompare)

bpThrow() ==
  bpEqKey "THROW" and bpApplication() and 
    bpPush bfThrow bpPop1()

++  Try:
++    try Assign CatchItems
bpTry() ==
  bpEqKey "TRY" and bpAssign() and 
    (bpEqKey "BACKSET" or true) and 
      (bpEqKey "CATCH" or bpMissing "CATCH") and
        (bpPiledCatchItems() or bpSimpleCatch() or bpTrap()) and
           bpPush bfTry(bpPop2(), bpPop1())

++ SimpleCatch:
++   catch Name
bpSimpleCatch() ==
  bpCatchItem() and bpPush [bpPop1()]

bpPiledCatchItems() ==
  bpPileBracketed function bpCatchItemList

bpCatchItemList() ==
  bpListAndRecover function bpCatchItem

bpExceptionHead() ==
  (bpName() or bpTrap()) and
    ((bpParenthesized function bpIdList and
      bpPush bfNameArgs (bpPop2(),bpPop1()))
	or bpName() and bpPush bfNameArgs(bpPop2(),bpPop1()))
          or true

bpExceptionTail() ==
  bpEqKey "EXIT" and (bpAssign() or bpTrap()) and
    bpPush Exit(bpPop2(),bpPop1())

++ Exception:
++   ExpcetionHead
++   ExceptionHead => Assign
bpException() ==
  bpExceptionHead() and (bpExceptionTail() or true)

++ Catch:
++   catch Exception
bpCatchItem() ==
  (bpException() or bpTrap()) and 
    bpPush %Catch bpPop1()

bpReturn()==
  (bpEqKey "RETURN" and  (bpAnd() or bpTrap()) and
	 bpPush bfReturnNoName bpPop1()) 
    or bpThrow()
      or bpAnd()
 
 
bpLogical()== bpLeftAssoc('(OR),function bpReturn)
 
bpExpression()==
     bpEqKey "COLON" and (bpLogical() and
              bpPush bfApplication ("COLON",bpPop1())
                    or bpTrap()) or bpLogical()
 
bpStatement()==
  bpConditional function bpWhere or bpLoop()  
    or bpExpression()
      or bpTry()
 
bpLoop()==
     bpIterators() and
      (bpCompMissing "REPEAT" and
         (bpWhere() or bpTrap()) and
            bpPush bfLp(bpPop2(),bpPop1()))
                or
                  bpEqKey "REPEAT" and (bpLogical() or bpTrap()) and
                       bpPush bfLoop1 bpPop1 ()
 
bpSuchThat()==bpAndOr("BAR",function bpWhere,function bfSuchthat)
 
bpWhile()==bpAndOr ("WHILE",function bpLogical,function bfWhile)
 
bpUntil()==bpAndOr ("UNTIL",function bpLogical,function bfUntil)
 
bpForIn()==
  bpEqKey "FOR" and (bpVariable() or bpTrap()) and (bpCompMissing "IN")
      and ((bpSeg()  or bpTrap()) and
       (bpEqKey "BY" and (bpArith() or bpTrap()) and
        bpPush bfForInBy(bpPop3(),bpPop2(),bpPop1())) or
         bpPush bfForin(bpPop2(),bpPop1()))
 
bpSeg()==
   bpArith() and
      (bpEqKey "SEG" and
       (bpArith() and bpPush(bfSegment2(bpPop2(),bpPop1()))
         or bpPush(bfSegment1(bpPop1()))) or true)
 
bpIterator()==
  bpForIn() or bpSuchThat() or bpWhile() or bpUntil()
 
bpIteratorList()==bpOneOrMore function bpIterator
       and bpPush bfIterators bpPop1 ()
 
bpCrossBackSet()== bpEqKey "CROSS" and (bpEqKey "BACKSET" or true)
 
bpIterators()==
         bpListofFun(function bpIteratorList,
              function bpCrossBackSet,function bfCross)
 
bpAssign()==
            a:=bpState()
            if bpStatement()
            then
                 if bpEqPeek "BEC"
                 then
                   bpRestore a
                   bpAssignment() or bpTrap()
                 else true
            else
                 bpRestore a
                 false
 
bpAssignment()==
  bpAssignVariable() and
    bpEqKey "BEC" and
      (bpAssign() or bpTrap()) and
	 bpPush bfAssign (bpPop2(),bpPop1())
 
-- should only be allowed in sequences
bpExit()==
     bpAssign() and (bpEqKey "EXIT" and
         ((bpWhere() or bpTrap()) and
            bpPush bfExit (bpPop2(),bpPop1()))
              or true)

++ returns true if the next token introduces a definition.
bpBeginDefinition() ==
  bpEqPeek "DEF" or 
    $sawParenthesizedHead and bpEqPeek "COLON"

bpDefinition()==
        a:=bpState()
        bpExit() =>
             bpBeginDefinition() =>
                bpRestore a
                bpDef()
             bpEqPeek "TDEF" =>
                bpRestore a
                bpTypeAliasDefition()
             bpEqPeek "MDEF" =>
                bpRestore a
                bpMdef()
             true
        bpRestore a
        false
 
bpStoreName()==
  $op := car $stack
  $wheredefs := nil
  $typings := nil
  $returnType := true           -- assume we may return anything
  true

bpReturnType() ==
  -- a return type is acceptable for a function definition only
  -- if its parameters are written in round parenthesis.  
  -- In particular, we reject the situation `foo x:Integer == ...'
  $sawParenthesizedHead and bpEqKey "COLON" =>
    bpApplication() or bpTrap()
    $returnType := bpPop1()
    true
  true
 
bpDef() ==  
  bpName() and bpStoreName() and
    bpDefTail() and bpPush bfCompDef bpPop1 ()
 
bpDDef() ==  bpName() and bpDefTail()

++ Parse the remaining of a simple definition.
bpSimpleDefinitionTail() ==
  bpEqKey "DEF" and
    (bpWhere() or bpTrap())
      and bpPush ConstantDefinition(bpPop2(), bpPop1())

++ Parse the remaining of a compound definition.
bpCompoundDefinitionTail() ==
  bpVariable()  and bpReturnType()  and
    bpEqKey "DEF" and (bpWhere() or bpTrap())
      and bpPush bfDefinition(bpPop3(),bpPop2(),bpPop1())


++ Parse the remainding of a definition.  When we reach this point
++ we know we must parse a definition and we have already parsed
++ the name of the main operator in the definition.
bpDefTail() ==
  bpSimpleDefinitionTail()
    or bpCompoundDefinitionTail()
 
 
bpMDefTail()==
 --   bpEqKey "MDEF" and
 --   (bpWhere() or bpTrap())
 --     and bpPush bfMDefinition1(bpPop2(),bpPop1())
 --      or
           (bpVariable() or bpTrap()) and
             bpEqKey "MDEF" and (bpWhere() or bpTrap())
                 and bpPush bfMDefinition(bpPop3(),bpPop2(),bpPop1())
 
bpMdef()== bpName() and bpStoreName() and bpMDefTail()
 
bpWhere()==
    bpDefinition() and
       (bpEqKey "WHERE" and (bpDefinitionItem() or bpTrap())
           and bpPush bfWhere(bpPop1(),bpPop1()) or true)
 
bpDefinitionItem()==
          a:=bpState()
          if bpDDef()
          then true
          else
             bpRestore a
             if bpBDefinitionPileItems()
             then true
             else
               bpRestore a
               if bpPDefinitionItems()
               then true
               else
                   bpRestore a
                   bpWhere()
 
bpDefinitionPileItems()==
    bpListAndRecover function bpDefinitionItem
           and bpPush bfDefSequence bpPop1()
 
bpBDefinitionPileItems()== bpPileBracketed function bpDefinitionPileItems
 
bpSemiColonDefinition()==bpSemiListing
    (function bpDefinitionItem,function bfDefSequence)
 
bpPDefinitionItems()==bpParenthesized function bpSemiColonDefinition
 
bpComma()== 
  bpModule() or bpImport() or
    bpTuple function bpWhere
 
bpTuple(p)==bpListofFun(p,function bpCommaBackSet,function bfTuple)
 
bpCommaBackSet()== bpEqKey "COMMA" and (bpEqKey "BACKSET" or true)
 
bpSemiColon()==bpSemiListing (function bpComma,function bfSequence)
 
bpSemiListing(p,f)==bpListofFun(p,function bpSemiBackSet,f)
 
bpSemiBackSet()== bpEqKey "SEMICOLON" and (bpEqKey "BACKSET" or true)
 
bpPDefinition()==  bpIndentParenthesized function bpSemiColon
 
bpPileItems()==
    bpListAndRecover function bpSemiColon and bpPush bfSequence bpPop1()
 
bpBPileDefinition()==  bpPileBracketed function bpPileItems
 
bpIteratorTail()==
     (bpEqKey "REPEAT" or true) and bpIterators()
 
--bpExpression()==  bpLogical()
 
bpConstruct()==bpBracket function bpConstruction
 
bpConstruction()==
     bpComma() and
        (bpIteratorTail() and
             bpPush bfCollect (bpPop2(),bpPop1()) or
                bpPush bfTupleConstruct bpPop1())
 
bpDConstruct()==bpBracket function bpDConstruction
 
bpDConstruction()==
     bpComma() and
        (bpIteratorTail() and
             bpPush bfDCollect (bpPop2(),bpPop1()) or
                bpPush bfDTuple bpPop1())
 
 
 
--PATTERN
 
--bpNameOrDot() == bpName() or bpDot() or bpEqual()
 
bpPattern()== bpBracketConstruct function bpPatternL
                or bpName() or bpConstTok()
 
bpEqual()==
   bpEqKey "SHOEEQ" and (bpApplication() or bpConstTok() or
                bpTrap()) and bpPush bfEqual bpPop1()
 
bpRegularPatternItem() ==
   bpEqual() or
     bpConstTok() or bpDot() or
      bpName() and
         ((bpEqKey "BEC" and (bpPattern() or bpTrap())
              and bpPush bfAssign(bpPop2(),bpPop1())) or true)
                    or bpBracketConstruct function bpPatternL
 
bpRegularPatternItemL()==
      bpRegularPatternItem() and bpPush [bpPop1()]
 
bpRegularList()==
       bpListof(function bpRegularPatternItemL,"COMMA",function bfAppend)
 
bpPatternColon()==
     bpEqKey "COLON" and (bpRegularPatternItem() or bpTrap())
              and bpPush [bfColon bpPop1()]
 
 
-- only one colon
bpPatternL() == bpPatternList() and bpPush bfTuple bpPop1()
 
bpPatternList()==
     if bpRegularPatternItemL()
     then
        while (bpEqKey  "COMMA" and (bpRegularPatternItemL() or
            (bpPatternTail()
              and bpPush append(bpPop2(),bpPop1())
                or bpTrap();false) )) repeat
                  bpPush append(bpPop2(),bpPop1())
        true
     else bpPatternTail()
 
bpPatternTail()==
     bpPatternColon() and
         (bpEqKey "COMMA" and (bpRegularList() or bpTrap())
              and bpPush append (bpPop2(),bpPop1()) or true)
 
-- BOUND VARIABLE
bpRegularBVItem() ==
  bpBVString() or
     bpConstTok() or
      (bpName() and
         (bpEqKey "COLON" and (bpApplication() or bpTrap())
            and bpPush bfTagged(bpPop2(), bpPop1()) or
              bpEqKey "BEC" and (bpPattern() or bpTrap())
                and bpPush bfAssign(bpPop2(),bpPop1()) or
                  (bpEqKey "IS" and (bpPattern() or bpTrap())
                     and bpPush bfAssign(bpPop2(),bpPop1())) or true))
                       or bpBracketConstruct function bpPatternL
 
bpBVString()==
     EQ(shoeTokType $stok,"STRING") and
         bpPush(["BVQUOTE",INTERN $ttok]) and bpNext()
 
bpRegularBVItemL() ==
      bpRegularBVItem() and bpPush [bpPop1()]
 
bpColonName()==
     bpEqKey "COLON" and (bpName() or bpBVString() or bpTrap())
 
 
-- at most one colon at end
bpBoundVariablelist()==
     if bpRegularBVItemL()
     then
        while (bpEqKey  "COMMA" and (bpRegularBVItemL() or
            (bpColonName()
              and bpPush  bfColonAppend(bpPop2(),bpPop1())
                or bpTrap();false) )) repeat
                   bpPush append(bpPop2(),bpPop1())
        true
     else bpColonName() and bpPush bfColonAppend(nil,bpPop1())
 

++ Mark the start of parameter list enclosed in round parenthesis
bpBeginParameterList() ==
  $sawParenthesizedHead := false
  true

++ Mark the end of parameter list enclosed in round parenthesis
bpEndParameterList() ==
  $sawParenthesizedHead := true

bpVariable()==
  bpBeginParameterList() and
    bpParenthesized function bpBoundVariablelist and
       bpPush bfTupleIf bpPop1() and bpEndParameterList()
         or bpBracketConstruct function bpPatternL
                or bpName() or bpConstTok()
 
bpAssignVariable()==
      bpBracketConstruct function bpPatternL or bpAssignLHS()
 
bpAssignLHS()==
   bpName() and (bpEqKey "COLON" and (bpApplication() or bpTrap())
     and bpPush bfLocal(bpPop2(),bpPop1())
        or bpEqKey "DOT" and bpList(function bpPrimary,"DOT",
              function bfListOf)
          and bpChecknull() and
            bpPush bfTuple(cons(bpPop2(),bpPop1()))
                 or true)
bpChecknull()==
      a:=bpPop1()
      if null a
      then bpTrap()
      else bpPush a

bpStruct()==
   bpEqKey "STRUCTURE" and
      (bpName() or bpTrap()) and
        (bpEqKey "DEF" or bpTrap()) and
           bpTypeList() and bpPush bfStruct(bpPop2(),bpPop1())
 
bpTypeList() == bpPileBracketed function bpTypeItemList
       or bpTerm() and bpPush [bpPop1()]
 
bpTypeItemList() ==  bpListAndRecover function bpTerm
 
bpTerm() ==
          (bpName() or bpTrap()) and
            ((bpParenthesized function bpIdList and
              bpPush bfNameArgs (bpPop2(),bpPop1()))
                or bpName() and bpPush bfNameArgs(bpPop2(),bpPop1()))
                 or bpPush(bfNameOnly bpPop1())
 
bpIdList()== bpTuple function bpName
 
bpCase()==
      bpEqKey "CASE" and
        (bpWhere() or bpTrap()) and
           (bpEqKey "OF" or bpMissing "OF") and
                 bpPiledCaseItems()
 
bpPiledCaseItems()==
   bpPileBracketed function bpCaseItemList and
       bpPush bfCase(bpPop2(),bpPop1())
bpCaseItemList()==
   bpListAndRecover function bpCaseItem
 
bpCaseItem()==
    (bpTerm() or bpTrap()) and
       (bpEqKey "EXIT" or bpTrap()) and
         (bpWhere() or bpTrap()) and
            bpPush bfCaseItem (bpPop2(),bpPop1())