-
Notifications
You must be signed in to change notification settings - Fork 11
/
pluspy.py
4330 lines (3763 loc) · 137 KB
/
pluspy.py
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
# Author: Robbert van Renesse, 2020
import os
import random
import traceback
import itertools
pluspypath = ".:./modules/lib:./modules/book:./modules/other"
def exit(status):
sys.stdout.flush()
os._exit(status)
# When compiling and running into an identifier, it should be clear
# exactly what that identifier refers to. It could be the name of:
#
# - a variable
# - a constant
# - an operator
# - an argument of that operator
# - a bounded variable (\E, ...)
# - a module
#
# In order to do this mapping, we keep a stack of dictionaries
# that map names to expressions for these things.
name_stack = [{}]
def name_lookup(name):
for d in reversed(name_stack):
ex = d.get(name)
if ex != None:
return ex
return False
# Like name_lookup but prints an error
def name_find(name):
e = name_lookup(name)
if not e:
print("Identifier", name, "not found")
return e
# Find a file using a directory path
def file_find(name, path):
sep = ";" if path.find(";") >= 0 else ":"
for dir in path.split(sep):
full = os.path.join(dir, name)
if os.path.exists(full):
return os.path.abspath(full)
return False
# For debugging, we give each bounded variable a unique identifier
bv_counter = 0
# kludge: as object definitions are properly nested, I maintain a stack
# of modules
modstk = []
# kludge: for transforming expression for initialization
initializing = False
# This is a dictionary of modules that have already been loaded
# from files.
modules = {}
# This is a dictionary of wrappers around Python functions
# Maps module names to dictionaries of (operator name, Wrapper) pairs
wrappers = {}
# Verbose output
silent = False
verbose = False
class FrozenDict:
def __init__(self, d):
self.d = d
def __str__(self):
return "FrozenDict(" + str(self.d) + ")"
def __hash__(self):
hash = 0
for x in self.d.items():
hash ^= x.__hash__()
return hash
# Two dictionaries are the same if they have the same (key, value) pairs
def __eq__(self, other):
if not isinstance(other, FrozenDict):
return False
if len(self.d.keys()) != len(other.d.keys()):
return False
for (k, v) in self.d.items():
if v != other.d.get(k):
return False
return True
def __len__(self):
return len(self.d.keys())
def format(self):
result = ""
keys = sorted(self.d.keys(), key=lambda x: key(x))
for k in keys:
if result != "":
result += ", "
if is_tla_id(k):
result += k + " |-> " + format(self.d[k])
else:
result += format(k) + " |-> " + format(self.d[k])
return "[ " + result + " ]"
# A Hashable "nonce" (to implement CHOOSE x: x \notin S)
class Nonce:
def __init__(self, id):
self.id = id # TODO: ideally a cryptographic hash
def __str__(self):
return "Nonce(" + str(self.id) + ")"
def __hash__(self):
return self.id
def __eq__(self, other):
return isinstance(other, Nonce) and other.id == self.id
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
#### Module specification
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
class Module:
def __init__(self):
self.name = None
self.constants = dict() # name -> ConstantExpression
self.variables = dict() # name -> VariableExpression
self.operators = dict() # name -> OperatorExpression
self.wrappers = dict() # name -> BuiltinExpression
self.globals = set() # set of non-LOCAL names
def __str__(self):
return "Module(" + self.name + ", " + str(self.constants) \
+ ", " + str(self.variables) + ", " \
+ str(self.operators.keys()) + ")"
# handle a CONSTANT declaration
def compileConstantDeclaration(self, ast):
(t0, a0) = ast
assert t0 == "CommaList"
for (t1, a1) in a0:
assert t1 == "GOpDecl"
(t2, a2) = a1
if t2 == "Identifier":
id = lexeme(a2)
nargs = 0
elif t2 == "paramOp":
(t3, a3) = a2[0]
assert t3 == "Identifier"
(t4, a4) = a2[1]
assert t4 == "CommaList"
id = lexeme(a3)
nargs = len(a4)
elif t2 == "prefixOp" or t2 == "postfixOp":
id = a2
nargs = 1
elif t2 == "infixOp":
id = a2
nargs = 2
else:
assert False
ce = ConstantExpression(id, nargs)
self.constants[id] = ce
name_stack[-1][id] = ce
# handle a VARIABLE declaration
def compileVariableDeclaration(self, ast):
(t, a) = ast
assert t == "CommaList"
for (t2, a2) in a:
assert t2 == "Identifier"
id = lexeme(a2)
ve = VariableExpression(id)
self.variables[id] = ve
name_stack[-1][id] = ve
# handle an "Operator == INSTANCE name" definition
def compileModuleDefinition(self, md, isGlobal):
(t0, a0) = md[0]
assert t0 == "GNonFixLHS"
assert len(a0) == 2
inst = md[1]
(t2, a2) = a0[0]
assert t2 == "Identifier"
id = lexeme(a2)
(t3, a3) = a0[1]
assert t3 == "Optional"
if a3 == None:
args = []
else:
(t4, a4) = a3
assert t4 == "CommaList"
args = a4
cargs = []
for (t, a) in args:
assert t == "GOpDecl"
(t2, a2) = a
if t2 == "Identifier":
cargs = cargs + [(lexeme(a2), 0)]
elif t2 == "paramOp":
(t3, a3) = a2[0]
assert t3 == "Identifier"
(t4, a4) = a2[1]
assert t4 == "CommaList"
cargs = cargs + [(lexeme(a3), len(a4))]
elif t2 == "prefixOp" or t2 == "postfixOp":
cargs = cargs + [(a2, 1)]
elif t2 == "infixOp":
cargs = cargs + [(a2, 2)]
else:
assert False
# print("MD 1", id)
mi = ModInst()
args = [ArgumentExpression(a, c) for (a, c) in cargs]
name_stack.append({ a.id:a for a in args })
# print("MD 2", id, inst)
mi.compile(inst)
# print("MD 3", id, args, mi)
name_stack.pop()
# We put the ModInst inside the expr field of an OperatorExpression
od = OperatorExpression(id=id, args=args, expr=mi)
self.operators[id] = od
if isGlobal:
self.globals.add(id)
name_stack[-1][id] = od
if verbose:
print("++> ", od, mi)
# handle the next TLA "Unit" in the source
def compileUnit(self, ast):
(t, a) = ast
if t == "GVariableDeclaration":
self.compileVariableDeclaration(a)
elif t == "GConstantDeclaration":
self.compileConstantDeclaration(a)
elif t == "decl-op":
(tloc, aloc) = a[0]
assert tloc == "Optional"
(t1, a1) = a[1]
assert t1 == "GOperatorDefinition"
(id, args, expr) = compileOperatorDefinition(a1)
if id in self.wrappers.keys():
od = OperatorExpression(id, args,
BuiltinExpression(id, args, self.wrappers[id]))
else:
od = OperatorExpression(id, args, expr)
self.operators[id] = od
if aloc == None:
self.globals.add(id)
name_stack[-1][id] = od.expr if args == [] else od
if verbose:
print("+-> ", id, args, expr.primed, expr)
elif t == "decl-inst":
(tloc, aloc) = a[0]
assert tloc == "Optional"
mi = ModInst()
mi.compile(a[1])
for k in mi.globals:
self.operators[k] = mi.operators[k]
if aloc == None:
self.globals.add(k)
elif t == "decl-fun":
(tloc, aloc) = a[0]
assert tloc == "Optional"
(t1, a1) = a[1]
assert t1 == "GFunctionDefinition"
(id, args, expr) = compileFunctionDefinition(a1)
od = OperatorExpression(id, args, expr)
self.operators[id] = od
if aloc == None:
self.globals.add(id)
assert args == []
# name_stack[-1][id] = od
name_stack[-1][id] = expr
if verbose:
print("++> ", id, args, expr.primed, expr)
elif t == "decl-mod":
(tloc, aloc) = a[0]
assert tloc == "Optional"
(t1, a1) = a[1]
assert t1 == "GModuleDefinition"
self.compileModuleDefinition(a1, tloc != None)
elif t in { "GTheorem", "GAssumption", "GDivider" }:
pass
elif t == "GModule":
mod = Module()
mod.compile(ast)
name_stack[-1][mod.name] = mod
else:
print("compileUnit", ast)
assert False
# Get operators from EXTENDS clause
def extends(self, ast):
for (n, m) in ast:
assert n == "Name"
mod = load_module(lexeme(m))
assert mod.constants == dict()
assert mod.variables == dict()
for k in mod.globals:
self.operators[k] = mod.operators[k]
self.globals.add(k)
if mod.wrappers.get(k) != None:
self.wrappers[k] = mod.wrappers[k]
name_stack[-1][k] = mod.operators[k]
# Given AST, handle all the TLA+ units in the AST
def compile(self, ast):
(t, a) = ast
if t == False:
return False
assert t == "GModule"
assert len(a) == 3
(t0, a0) = a[0]
assert t0 == "Name"
self.name = lexeme(a0)
# Set wrappers
global wrappers
self.wrappers = wrappers.get(self.name)
if self.wrappers == None:
self.wrappers = {}
# Add a new dictionary to the name stack
name_stack.append({})
(t1, a1) = a[1]
assert t1 == "Optional"
if a1 != None:
(tx, ax) = a1
assert tx == "CommaList"
self.extends(ax)
(t2, a2) = a[2]
assert t2 == "AtLeast0"
for ast2 in a2:
self.compileUnit(ast2)
if verbose:
print("Variables", self.name, self.variables)
name_stack.pop()
return True
# Load and compile the given TLA+ source, which is a string
def load_from_string(self, source, srcid):
# First run source through lexical analysis
r = lexer(source, srcid)
if verbose:
print()
print("---------------")
print("Output from Lexer")
print("---------------")
print(r)
# Parse the output from the lexer into an AST
gmod = GModule()
# Error handling
global shortest, error
shortest = r
(t, a, r) = gmod.parse(r)
# t is the type of the AST root node (False if error)
# a is the content (or error message list if error)
# r is the suffix of the lexer output that could not be parsed
if False:
print()
print("---------------")
print("AST")
print("---------------")
printAST((t, a), "")
if t == False:
print("Parsing failed", a)
print(error)
print("At position", shortest[0])
return False
if r != []:
print("Remainder", r[0])
# Handle all TLA+ units in the AST
if verbose:
print()
print("---------------")
print("Compile", source.split("\n")[0].replace("-", ""))
print("---------------")
modstk.append(self)
result = self.compile((t, a))
modstk.pop()
return result
def load(self, f, srcid):
all = ""
for line in f:
all += line
return self.load_from_string(all, srcid)
def load_from_file(self, file):
full = file_find(file, pluspypath)
if not full:
return False
with open(full) as f:
return self.load(f, file)
def load_module(name):
mod = name_lookup(name)
if mod == False:
if modules.get(name) == None:
mod = Module()
name_stack.append({})
if not mod.load_from_file(name + ".tla"):
print("can't load", name, ": fatal error", file=sys.stderr)
exit(1)
name_stack.pop()
modules[name] = mod
else:
mod = modules[name]
return mod
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
#### Module instance
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
# Describes an "INSTANCE module-name WITH k <- e ..." expression.
# Here each k is either a constant or variable name of the module, and e
# some expression that should be substituted for it
class ModInst:
def __init__(self, module=None, substitutions=None, operators=None, wrappers=None, globals=None):
self.module = module
self.substitutions = substitutions
self.operators = operators
self.wrappers = wrappers
self.globals = globals
self.primed = False
def __str__(self):
subs = ""
for (k, v) in self.substitutions.items():
if subs != "":
subs += ", "
subs += str(k) + ": " + str(v)
return "Instance(" + self.module.name + ", [" + subs + "])"
def __repr__(self):
return self.__str__()
def substitute(self, subs):
substitutions = {
k:v.substitute(subs) for (k, v) in self.substitutions.items()
}
return ModInst(module=self.module, substitutions=substitutions, operators={}, globals=set())
def set(self, module, substitutions):
self.module = module
self.substitutions = substitutions
def compile(self, ast):
(t, a) = ast
assert t == "GInstance"
(t1, a1) = a[0]
assert t1 == "Name"
self.module = load_module(lexeme(a1))
(t2, a2) = a[1]
assert t2 == "Optional"
d = {}
if a2 != None:
(t3, a3) = a2
assert t3 == "CommaList"
for (t4, a4) in a3:
assert t4 == "GSubstitution"
(t5, a5) = a4[0]
assert t5 == "Identifier"
(t6, a6) = a4[1]
assert t6 == "GArgument"
d[lexeme(a5)] = compileExpression(a6)
# We now need to replace all the constants and variables in the
# operators of the module. Some may have been specified using
# WITH (captured in 'd'), others are implicit.
self.substitutions = {}
for (k, v) in self.module.constants.items():
if k in d.keys():
self.substitutions[v] = d[k]
else:
self.substitutions[v] = name_find(k)
for (k, v) in self.module.variables.items():
if k in d.keys():
self.substitutions[v] = d[k]
else:
self.substitutions[v] = name_find(k)
self.operators = {}
self.globals = set()
self.wrappers = {}
for k in self.module.globals:
assert k not in self.globals
assert self.operators.get(k) == None
d = self.module.operators[k]
self.operators[k] = d.substitute(self.substitutions)
# print("AAA", k, d, self.operators[k])
self.globals.add(k)
if self.module.wrappers.get(k) != None:
self.wrappers[k] = self.module.wrappers[k]
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
#### Compiler: convenient routines
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
def islower(c):
return c in "abcdefghijklmnopqrstuvwxyz"
def isupper(c):
return c in "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
def isletter(c):
return islower(c) or isupper(c)
def isnumeral(c):
return c in "0123456789"
def isalnum(c):
return isletter(c) or isnumeral(c)
def isnamechar(c):
return isalnum(c) or c == "_"
def isprint(c):
return isinstance(c, str) and len(c) == 1 and (
isalnum(c) or c in " ~`!@#$%^&*()-_=+[{]}\\|;:'\",<.>/?")
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
#### Compiler: various tables copied from book
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
ReservedWords = [
"ASSUME", "ELSE", "LOCAL", "UNION", "ASSUMPTION", "ENABLED", "MODULE",
"VARIABLE", "AXIOM", "EXCEPT", "OTHER", "VARIABLES", "CASE", "EXTENDS",
"CHOOSE", "IF", "SUBSET", "WITH", "CONSTANT", "IN", "THEN", "CONSTANTS",
"INSTANCE", "THEOREM", "DOMAIN", "LET", "UNCHANGED", "SF_", "WF_"
]
PrefixOps = {
"-": (12, 12),
"-.": (12, 12),
"~": (4, 4),
"\\lnot": (4, 4),
"\\neg": (4, 4),
"[]": (4, 15),
"<>": (4, 15),
"DOMAIN": (9, 9),
"ENABLED": (4, 15),
"SUBSET": (8, 8),
"UNCHANGED": (4, 15),
"UNION": (8, 8)
}
InfixOps = {
"!!": (9, 13),
"#": (5, 5),
"##": (9, 13),
"$": (9, 13),
"$$": (9, 13),
"%": (10, 11),
"%%": (10, 11),
"&": (13, 13),
"&&": (13, 13),
"(+)": (10, 10),
"(-)": (11, 11),
"(.)": (13, 13),
"(/)": (13, 13),
"(\\X)": (13, 13),
"*": (13, 13),
"**": (13, 13),
"+": (10, 10),
"++": (10, 10),
"-": (11, 11),
"-+->": (2, 2),
"--": (11, 11),
"-|": (5, 5),
"..": (9, 9),
"...": (9, 9),
"/": (13, 13),
"//": (13, 13),
"/=": (5, 5),
"/\\": (3, 3),
"::=": (5, 5),
":=": (5, 5),
":>": (7, 7),
"<": (5, 5),
"<:": (7, 7),
"<=>": (2, 2),
"=": (5, 5),
"<=": (5, 5),
"=<": (5, 5),
"=>": (1, 1),
"=|": (5, 5),
">": (5, 5),
">=": (5, 5),
"??": (9, 13),
"@@": (6, 6),
"\\": (8, 8),
"\\/": (3, 3),
"^": (14, 14),
"^^": (14, 14),
"|": (10, 11),
"|-": (5, 5),
"|=": (5, 5),
"||": (10, 11),
"~>": (2, 2),
".": (17, 17),
"\\approx": (5, 5),
"\\geq": (5, 5),
"\\oslash": (13, 13),
"\\sqsupseteq": (5, 5),
"\\asymp": (5, 5),
"\\gg": (5, 5),
"\\otimes": (13, 13),
"\\star": (13, 13),
"\\bigcirc": (13, 13),
"\\in": (5, 5),
"\\notin": (5, 5),
"\\prec": (5, 5),
"\\subset": (5, 5),
"\\bullet": (13, 13),
"\\intersect": (8, 8),
"\\preceq": (5, 5),
"\\subseteq": (5, 5),
"\\cap": (8, 8),
"\\land": (3, 3),
"\\propto": (5, 5),
"\\succ": (5, 5),
"\\cdot": (5, 14),
"\\leq": (5, 5),
"\\sim": (5, 5),
"\\succeq": (5, 5),
"\\circ": (13, 13),
"\\ll": (5, 5),
"\\simeq": (5, 5),
"\\supset": (5, 5),
"\\cong": (5, 5),
"\\lor": (3, 3),
"\\sqcap": (9, 13),
"\\supseteq": (5, 5),
"\\cup": (8, 8),
"\\o": (13, 13),
"\\sqcup": (9, 13),
"\\union": (8, 8),
"\\div": (13, 13),
"\\odot": (13, 13),
"\\sqsubset": (5, 5),
"\\uplus": (9, 13),
"\\doteq": (5, 5),
"\\ominus": (11, 11),
"\\sqsubseteq": (5, 5),
"\\wr": (9, 14),
"\\equiv": (2, 2),
"\\oplus": (10, 10),
"\\sqsupset": (5, 5),
# The following are Cartesian product ops, not infix operators
"\\X": (10, 13),
"\\times": (10, 13)
}
PostfixOps = {
"[": (16, 16),
"^+": (15, 15),
"^*": (15, 15),
"^#": (15, 15),
"'": (15, 15)
}
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
#### Compiler: AST pretty printer
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
# For printAST: AST nodes that have lists of nodes as arguments
listNodes = [
"Concat", "Index", "GModule", "AtLeast0", "AtLeast1", "CommaList",
"GOperatorDefinition", "GQuantifierBound",
"op", "lambda", "except", "if", "forall", "exists", "square"
]
# printAST: AST nodes that have another AST node as argument
tagNodes = [
"GUnit", "GTheorem", "GBasicExpression", "GExpression18", "GArgument",
"GVariableDeclaration", "GConstantDeclaration", "Tuple",
"parentheses", "set", "wf", "sf"
]
# Pretty printer for AST. Every node in the AST is of the form (t, a),
# where 't' is the type and 'a' is what's in the node
def printAST(x, indent):
(t, a) = x
if not t:
print("ERROR: " + str(a))
return
print(indent + "(" + t + ",", end="")
if t in listNodes:
print()
print(indent + ".[")
for y in a:
printAST(y, indent + "..")
print(indent + ".]")
print(indent + ")")
elif t in tagNodes:
print()
printAST(a, indent + "..")
print(indent + ")")
elif t.startswith("Infix"):
(op, lhs, rhs) = a
print(" " + op + ":")
printAST(lhs, indent + "..")
printAST(rhs, indent + "..")
print(indent + ")")
elif t.startswith("Prefix"):
(op, expr) = a
print(" " + op + ":")
printAST(expr, indent + "..")
print(indent + ")")
elif t.startswith("Postfix"):
(expr, op) = a
print(" " + op + ":")
printAST(expr, indent + "..")
print(indent + ")")
elif t == "Optional":
if a == None:
print(" None)")
else:
print()
printAST(a, indent + "..")
print(indent + ")")
else:
print(" '" + str(a) + "'", end="")
print(")")
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
#### Compiler: BNF rules
#### #### #### #### #### #### #### #### #### #### #### #### #### #### #### ####
# Extract the lexeme out of a token
def lexeme(token):
(lex, line, column, first) = token
return lex
stack = [] # Global parser state used for parsing disjuncts and conjuncts
# For error messages
shortest = []
error = []
def parseError(a, r):
global shortest, error
if len(r) < len(shortest):
error = a
shortest = r
return (False, a, r)
def match(name, s, rule, select=None):
"""
Handy routine for rules that simply call other rules
It parses s using the given rule and returns a node (name, (t, a), r)
where name is the type of the AST node and (t, a) the result of
parsing given the rule and r is remaining tokens.
If t is a "Concat" rule (sequence of other rules), then you can
select a subset using the select argument.
Otherwise, if select is not None, the result of the rule is
directly returned without adding a new AST node.
:param name: the type of the AST node
:param s: list of tokens
:param rule: rule to parse s with
:param select: subset of rules to select
:return: AST node with selected rules
"""
(t, a, r) = rule.parse(s)
if not t:
return parseError([name] + a, r)
if isinstance(select, list) and t == "Concat":
if len(select) == 1:
return (name, a[select[0]], r)
return (name, [ a[i] for i in select ], r)
if select is not None:
return (t, a, r)
return (name, (t, a), r)
# BNF rule
class Rule:
# s is a list of tokens. Returns (t, a, r) where
# t: type of the AST node (or False if not recognized)
# a: contents of the AST node (or error message if t = False)
# r: remainder of 's' that was not parsed
# Must be redefined in child class
def parse(self, s):
return parseError(["Rule.parse undefined"], s)
class GModule(Rule):
def parse(self, s):
return match("GModule", s, Concat([
tok("----"), tok("MODULE"), Name(), tok("----"),
Optional(Concat([ tok("EXTENDS"), CommaList(Name()) ]), [1]),
AtLeast(GUnit(), 0), tok("====")
]), [ 2, 4, 5 ])
# This rule recognizes a list of other rules: rule1 & rule2 & rule3 & ...
class Concat(Rule):
def __init__(self, what):
self.what = what
def parse(self, s):
rem = s
result = []
for x in self.what:
(t, a, r) = x.parse(rem)
if not t:
return parseError(["Concat"] + a, r)
result = result + [(t, a)]
rem = r
return ("Concat", result, rem)
# This rule recognizes a list of at least count rules
class AtLeast(Rule):
def __init__(self, rule, count):
self.rule = rule
self.count = count
def parse(self, s):
rem = s
result = []
c = self.count
while True:
(t, a, r) = self.rule.parse(rem)
if not t:
if c > 0:
return parseError(["AtLeast" + str(self.count)] + a, r)
else:
return ("AtLeast" + str(self.count), result, rem)
result = result + [(t, a)]
rem = r
c -= 1
# Recognizes an optional rule, i.e., 'rule?'
# 'select' can be used similarly as in Rule.match()
class Optional(Rule):
def __init__(self, rule, select=None):
self.rule = rule
self.select = select
def parse(self, s):
(t, a, r) = self.rule.parse(s)
if not t:
return ("Optional", None, s)
elif t == "Concat" and isinstance(self.select, list):
if len(self.select) == 1:
return ("Optional", a[self.select[0]], r)
return ("Optional", [ a[i] for i in self.select ], r)
else:
return ("Optional", (t, a), r)
class tok(Rule):
def __init__(self, what):
self.what = what
def parse(self, s):
if s == []:
return parseError(["tok: no more tokens"], s)
if lexeme(s[0]) == self.what:
return ("tok", s[0], s[1:])
return parseError([("tok: no match with '" + self.what + "'",
stringToken(s[0]))], s)
class Tok(Rule):
def __init__(self, what, name):
self.what = what
self.name = name
def parse(self, s):
if s == []:
return parseError(["Tok: no more tokens"], s)
if lexeme(s[0]) in self.what:
return ("Tok", s[0], s[1:])
return parseError(["Tok: no match with " + self.name], s)
class Name(Rule):
def __init__(self):
pass
def parse(self, s):
if s == []:
return parseError(["Name"], s)
lex = lexeme(s[0])
if lex.startswith("WF_"):
return parseError([("Name WF_", s[0])], s)
if lex.startswith("SF_"):
return parseError([("Name SF_", s[0])], s)
hasletter = False
for c in lex:
if not isnamechar(c):
return parseError([("Name with bad character", s[0])], s)
if isletter(c):
hasletter = True
if hasletter:
return ("Name", s[0], s[1:])
return parseError([("Name with no letter", s[0])], s)
class Identifier(Rule):
def __init__(self):
pass
def parse(self, s):
(t, a, r) = Name().parse(s)
if t != "Name":
return parseError(["Identifier: not a Name"] + a, s)
lex = lexeme(a)
if lex in ReservedWords:
return parseError([("Identifier: Name Reserved", a)], s)
return ("Identifier", a, r)
# Sometimes it is convenient to give certain rules names.
# A Tag node simply inserts another AST node with the given name
class Tag(Rule):
def __init__(self, name, rule, select=None):
self.name = name
self.rule = rule
self.select = select
def parse(self, s):
return match(self.name, s, self.rule, self.select)
class Number(Rule):
def __init__(self):
pass
def parse(self, s):
if s == []:
return parseError(["Number"], s)
lex = lexeme(s[0])
for c in lex:
if not isnumeral(c):
return parseError([("Number", s[0])], s)
return ("Number", lex, s[1:])
class String(Rule):
def __init__(self):
pass
def parse(self, s):
if s == []:
return parseError(["String"], s)
lex = lexeme(s[0])
if lex[0] == '"' and lex[-1] == '"':
return ("String", lex, s[1:])
return parseError([("String", s[0])], s)
class SeparatorList(Rule):
def __init__(self, what, sep, optional):
self.what = what # expression to match
self.sep = sep # separator token
self.optional = optional # empty list allowed
def parse(self, s):
(t, a, r) = self.what.parse(s)
if not t:
return ("SeparatorList", [], s) if self.optional \
else (False, ["SeparatorList"] + a, r)
rem = r
result = [(t, a)]
while True:
if lexeme(rem[0]) != self.sep:
return ("SeparatorList", result, rem)
(t, a, r) = self.what.parse(rem[1:])
if not t:
return ("SeparatorList", result, rem)
result = result + [(t, a)]
rem = r
class CommaList(Rule):
def __init__(self, what):