/
parser.go
650 lines (584 loc) · 14.6 KB
/
parser.go
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
package zygo
import (
"errors"
"fmt"
"io"
"math"
"strconv"
"strings"
"sync"
)
var NaN float64
func init() {
NaN = math.NaN()
}
type Parser struct {
lexer *Lexer
env *Zlisp
Done chan bool
reqStop chan bool
AddInput chan io.RuneScanner
ReqReset chan io.RuneScanner
ParsedOutput chan []ParserReply
mut sync.Mutex
stopped bool
sendMe []ParserReply
FlagSendNeedInput bool
inBacktick bool
}
type ParserReply struct {
Expr []Sexp
Err error
}
func (env *Zlisp) NewParser() *Parser {
p := &Parser{
env: env,
Done: make(chan bool),
reqStop: make(chan bool),
ReqReset: make(chan io.RuneScanner),
AddInput: make(chan io.RuneScanner),
ParsedOutput: make(chan []ParserReply),
sendMe: make([]ParserReply, 0, 1),
}
p.lexer = NewLexer(p)
return p
}
func (p *Parser) Stop() error {
p.mut.Lock()
defer p.mut.Unlock()
if p.stopped {
return nil
}
p.stopped = true
close(p.reqStop)
<-p.Done
return nil
}
// Starts launches a background goroutine that runs an
// infinite parsing loop.
func (p *Parser) Start() {
go func() {
defer close(p.Done)
expressions := make([]Sexp, 0, SliceDefaultCap)
// maybe we already have input, be optimistic!
// no need to call p.GetMoreInput() before staring
// our loop.
for {
expr, err := p.ParseExpression(0)
if err != nil || expr == SexpEnd {
if err == ParserHaltRequested {
return
}
err = p.GetMoreInput(expressions, err)
if err == ParserHaltRequested {
return
}
// GetMoreInput will have delivered what we gave them. Reset since we
// don't own that memory any more.
expressions = make([]Sexp, 0, SliceDefaultCap)
} else {
// INVAR: err == nil && expr is not SexpEnd
expressions = append(expressions, expr)
}
}
}()
}
var ParserHaltRequested = fmt.Errorf("parser halt requested")
var ResetRequested = fmt.Errorf("parser reset requested")
var ErrMoreInputNeeded = fmt.Errorf("parser needs more input")
// This function should *return* when it has more input
// for the parser/lexer, which will call it when they get wedged.
//
// Listeners on p.ParsedOutput should know the Convention: sending
// a length 0 []ParserReply on p.ParsedOutput channel means: we need more
// input! They should send some in on p.AddInput channel; or request
// a reset and simultaneously give us new input with p.ReqReset channel.
func (p *Parser) GetMoreInput(deliverThese []Sexp, errorToReport error) error {
if len(deliverThese) == 0 && errorToReport == nil {
p.FlagSendNeedInput = true
} else {
p.sendMe = append(p.sendMe,
ParserReply{
Expr: deliverThese,
Err: errorToReport,
})
}
for {
select {
case <-p.reqStop:
return ParserHaltRequested
case input := <-p.AddInput:
p.lexer.AddNextStream(input)
p.FlagSendNeedInput = false
return nil
case input := <-p.ReqReset:
p.lexer.Reset()
p.lexer.AddNextStream(input)
p.FlagSendNeedInput = false
return ResetRequested
case p.HaveStuffToSend() <- p.sendMe:
p.sendMe = make([]ParserReply, 0, 1)
p.FlagSendNeedInput = false
}
}
}
func (p *Parser) HaveStuffToSend() chan []ParserReply {
if len(p.sendMe) > 0 || p.FlagSendNeedInput {
return p.ParsedOutput
}
return nil
}
func (p *Parser) Reset() {
select {
case p.ReqReset <- nil:
case <-p.reqStop:
}
}
func (p *Parser) NewInput(s io.RuneScanner) {
select {
case p.AddInput <- s:
case <-p.reqStop:
}
}
func (p *Parser) ResetAddNewInput(s io.RuneScanner) {
select {
case p.ReqReset <- s:
case <-p.reqStop:
}
}
var UnexpectedEnd error = errors.New("Unexpected end of input")
const SliceDefaultCap = 10
func (parser *Parser) ParseList(depth int) (sx Sexp, err error) {
lexer := parser.lexer
var tok Token
tokFilled:
for {
tok, err = lexer.PeekNextToken()
//Q("\n ParseList(depth=%d) got lexer.PeekNextToken() -> tok='%v' err='%v'\n", depth, tok, err)
if err != nil {
return SexpNull, err
}
if tok.typ != TokenEnd {
break tokFilled
}
// instead of returning UnexpectedEnd, we:
err = parser.GetMoreInput(nil, ErrMoreInputNeeded)
//Q("\n ParseList(depth=%d) got back from parser.GetMoreInput(): '%v'\n", depth, err)
switch err {
case ParserHaltRequested:
return SexpNull, err
case ResetRequested:
return SexpEnd, err
}
// have to still fill tok, so
// loop to the top to PeekNextToken
}
if tok.typ == TokenRParen {
_, _ = lexer.GetNextToken()
return SexpNull, nil
}
var start = &SexpPair{}
expr, err := parser.ParseExpression(depth + 1)
if err != nil {
return SexpNull, err
}
start.Head = expr
tok, err = lexer.PeekNextToken()
if err != nil {
return SexpNull, err
}
// backslash '\' replaces dot '.' in zygo
if tok.typ == TokenBackslash {
// eat up the backslash
_, _ = lexer.GetNextToken()
expr, err = parser.ParseExpression(depth + 1)
if err != nil {
return SexpNull, err
}
// eat up the end paren
tok, err = lexer.GetNextToken()
if err != nil {
return SexpNull, err
}
// make sure it was actually an end paren
if tok.typ != TokenRParen {
return SexpNull, errors.New("extra value in dotted pair")
}
start.Tail = expr
return start, nil
}
expr, err = parser.ParseList(depth + 1)
if err != nil {
return start, err
}
start.Tail = expr
return start, nil
}
func (parser *Parser) ParseArray(depth int) (Sexp, error) {
lexer := parser.lexer
arr := make([]Sexp, 0, SliceDefaultCap)
var tok Token
var err error
for {
getTok:
for {
tok, err = lexer.PeekNextToken()
if err != nil {
return SexpEnd, err
}
if tok.typ == TokenComma {
// pop off the ,
_, _ = lexer.GetNextToken()
continue getTok
}
if tok.typ != TokenEnd {
break getTok
} else {
//instead of return SexpEnd, UnexpectedEnd
// we ask for more, and then loop
err = parser.GetMoreInput(nil, ErrMoreInputNeeded)
switch err {
case ParserHaltRequested:
return SexpNull, err
case ResetRequested:
return SexpEnd, err
}
}
}
if tok.typ == TokenRSquare {
// pop off the ]
_, _ = lexer.GetNextToken()
break
}
expr, err := parser.ParseExpression(depth + 1)
if err != nil {
return SexpNull, err
}
arr = append(arr, expr)
}
return &SexpArray{Val: arr, Env: parser.env}, nil
}
func (parser *Parser) ParseExpression(depth int) (res Sexp, err error) {
defer func() {
if res != nil {
//Q("returning from ParseExpression at depth=%v with res='%s'\n", depth, res.SexpString(nil))
} else {
//Q("returning from ParseExpression at depth=%v, res = nil", depth)
}
}()
lexer := parser.lexer
env := parser.env
//getAnother:
tok, err := lexer.GetNextToken()
if err != nil {
return SexpEnd, err
}
switch tok.typ {
case TokenLParen:
exp, err := parser.ParseList(depth + 1)
return exp, err
case TokenLSquare:
exp, err := parser.ParseArray(depth + 1)
return exp, err
case TokenLCurly:
exp, err := parser.ParseInfix(depth + 1)
return exp, err
case TokenQuote:
expr, err := parser.ParseExpression(depth + 1)
if err != nil {
return SexpNull, err
}
return MakeList([]Sexp{env.MakeSymbol("quote"), expr}), nil
case TokenCaret:
// '^' is now our syntax-quote symbol, not TokenBacktick, to allow go-style `string literals`.
expr, err := parser.ParseExpression(depth + 1)
if err != nil {
return SexpNull, err
}
return MakeList([]Sexp{env.MakeSymbol("syntaxQuote"), expr}), nil
case TokenTilde:
expr, err := parser.ParseExpression(depth + 1)
if err != nil {
return SexpNull, err
}
return MakeList([]Sexp{env.MakeSymbol("unquote"), expr}), nil
case TokenTildeAt:
expr, err := parser.ParseExpression(depth + 1)
if err != nil {
return SexpNull, err
}
return MakeList([]Sexp{env.MakeSymbol("unquote-splicing"), expr}), nil
case TokenFreshAssign:
return env.MakeSymbol(tok.str), nil
case TokenColonOperator:
return env.MakeSymbol(tok.str), nil
case TokenDollar:
return env.MakeSymbol(tok.str), nil
case TokenBool:
return &SexpBool{Val: tok.str == "true"}, nil
case TokenUint64:
// truncate off the "ULL" suffix
inp := tok.str[:len(tok.str)-3]
// handle hex 0x and octacl 0o
n := len(inp)
base := 10
if n > 2 {
switch inp[:2] {
case "0o":
base = 8
inp = inp[2:]
case "0x":
base = 16
inp = inp[2:]
}
}
u, err := strconv.ParseUint(inp, base, 64)
//fmt.Printf("debug: parsed inp='%s' into u=%v\n", inp, u)
if err != nil {
return SexpNull, err
}
return &SexpUint64{Val: u}, nil
case TokenDecimal:
i, err := strconv.ParseInt(tok.str, 10, SexpIntSize)
if err != nil {
return SexpNull, err
}
return &SexpInt{Val: i}, nil
case TokenHex:
i, err := strconv.ParseInt(tok.str, 16, SexpIntSize)
if err != nil {
return SexpNull, err
}
return &SexpInt{Val: i}, nil
case TokenOct:
i, err := strconv.ParseInt(tok.str, 8, SexpIntSize)
if err != nil {
return SexpNull, err
}
return &SexpInt{Val: i}, nil
case TokenBinary:
i, err := strconv.ParseInt(tok.str, 2, SexpIntSize)
if err != nil {
return SexpNull, err
}
return &SexpInt{Val: i}, nil
case TokenChar:
return &SexpChar{Val: rune(tok.str[0])}, nil
case TokenString:
return &SexpStr{S: tok.str}, nil
case TokenBeginBacktickString:
parser.inBacktick = true
return parser.ParseBacktickString(&tok)
case TokenBacktickString:
parser.inBacktick = false
return &SexpStr{S: tok.str, backtick: true}, nil
case TokenFloat:
var f float64
if tok.str == "NaN" {
f = NaN
} else {
f, err = strconv.ParseFloat(tok.str, SexpFloatSize)
if err != nil {
return SexpNull, err
}
}
r := &SexpFloat{Val: f}
if strings.Contains(tok.str, "e") || strings.Contains(tok.str, "E") {
r.Scientific = true
}
return r, nil
case TokenEnd:
return SexpEnd, nil
case TokenSymbol:
return env.MakeSymbol(tok.str), nil
case TokenSymbolColon:
sym := env.MakeSymbol(tok.str)
sym.colonTail = true
return sym, nil
case TokenDot:
sym := env.MakeSymbol(tok.str)
sym.isDot = true
return sym, nil
case TokenDotSymbol:
sym := env.MakeSymbol(tok.str)
sym.isDot = true
return sym, nil
case TokenComment:
//Q("parser making SexpComment from '%s'", tok.str)
return &SexpComment{Comment: tok.str}, nil
// parser skips comments
//goto getAnother
case TokenBeginBlockComment:
// parser skips comments
return parser.ParseBlockComment(&tok)
//parser.ParseBlockComment(&tok)
//goto getAnother
case TokenComma:
return &SexpComma{}, nil
case TokenSemicolon:
return &SexpSemicolon{}, nil
}
return SexpNull, fmt.Errorf("Invalid syntax, don't know what to do with %v '%v'", tok.typ, tok)
}
// ParseTokens is the main service the Parser provides.
// Currently returns first error encountered, ignoring
// any expressions after that.
func (p *Parser) ParseTokens() ([]Sexp, error) {
select {
case out := <-p.ParsedOutput:
Q("ParseTokens got p.ParsedOutput out: '%#v'", out)
r := make([]Sexp, 0)
for _, k := range out {
r = append(r, k.Expr...)
Q("\n ParseTokens k.Expr = '%v'\n\n", (&SexpArray{Val: k.Expr, Env: p.env}).SexpString(nil))
if k.Err != nil {
return r, k.Err
}
}
return r, nil
case <-p.reqStop:
return nil, ErrShuttingDown
}
}
var ErrShuttingDown error = fmt.Errorf("lexer shutting down")
func (parser *Parser) ParseBlockComment(start *Token) (sx Sexp, err error) {
defer func() {
if sx != nil {
//Q("returning from ParseBlockComment with sx ='%v', err='%v'",
// sx.SexpString(), err)
}
}()
lexer := parser.lexer
var tok Token
var block = &SexpComment{Block: true, Comment: start.str}
for {
tokFilled:
for {
tok, err = lexer.PeekNextToken()
if err != nil {
return SexpNull, err
}
if tok.typ != TokenEnd {
break tokFilled
}
err = parser.GetMoreInput(nil, ErrMoreInputNeeded)
switch err {
case ParserHaltRequested:
return SexpNull, err
case ResetRequested:
return SexpEnd, err
}
// have to still fill tok, so
// loop to the top to PeekNextToken
}
// consume it
//cons, err := lexer.GetNextToken()
_, err := lexer.GetNextToken()
if err != nil {
return nil, err
}
//Q("parse block comment is consuming '%v'", cons)
switch tok.typ {
case TokenEndBlockComment:
block.Comment += tok.str
return block, nil
case TokenComment:
block.Comment += tok.str
default:
panic("internal error: inside a block comment, we should only see TokenComment and TokenEndBlockComment tokens")
}
}
//return block, nil
}
func (parser *Parser) ParseBacktickString(start *Token) (sx Sexp, err error) {
defer func() {
if sx != nil {
//Q("returning from ParseBlockComment with sx ='%v', err='%v'",
// sx.SexpString(), err)
}
}()
lexer := parser.lexer
var tok Token
for {
tokFilled:
for {
tok, err = lexer.PeekNextToken()
if err != nil {
return SexpNull, err
}
if tok.typ != TokenEnd {
break tokFilled
}
err = parser.GetMoreInput(nil, ErrMoreInputNeeded)
switch err {
case ParserHaltRequested:
return SexpNull, err
case ResetRequested:
return SexpEnd, err
}
// have to still fill tok, so
// loop to the top to PeekNextToken
}
// consume it
//cons, err := lexer.GetNextToken()
_, err := lexer.GetNextToken()
if err != nil {
return nil, err
}
//P("parse backtick string is consuming '%v'", cons)
switch tok.typ {
case TokenBacktickString:
return &SexpStr{S: tok.str, backtick: true}, nil
default:
panic("internal error: inside a backtick string, we should only see TokenBacktickString token")
}
}
}
func (parser *Parser) ParseInfix(depth int) (Sexp, error) {
lexer := parser.lexer
arr := make([]Sexp, 0, SliceDefaultCap)
var err error
var tok Token
for {
getTok:
for {
tok, err = lexer.PeekNextToken()
if err != nil {
return SexpEnd, err
}
if tok.typ != TokenEnd {
break getTok
} else {
//instead of return SexpEnd, UnexpectedEnd
// we ask for more, and then loop
err = parser.GetMoreInput(nil, ErrMoreInputNeeded)
switch err {
case ParserHaltRequested:
return SexpNull, err
case ResetRequested:
return SexpEnd, err
}
}
}
if tok.typ == TokenRCurly {
// pop off the }
_, _ = lexer.GetNextToken()
break
}
Q("debug: ParseInfix(depth=%v) calling ParseExpression", depth)
expr, err := parser.ParseExpression(depth + 1)
if err != nil {
return SexpNull, err
}
Q("debug2: ParseInfix(depth=%v) appending expr = '%v'", depth, expr.SexpString(nil))
arr = append(arr, expr)
}
var list SexpPair
list.Head = parser.env.MakeSymbol("infix")
list.Tail = SexpNull
if len(arr) > 0 {
list.Tail = Cons(&SexpArray{Val: arr, Infix: true, Env: parser.env}, SexpNull)
}
return &list, nil
//return &SexpArray{Val: arr, Infix: true, Env: env}, nil
}