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
|
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef frontend_ParseContext_h
#define frontend_ParseContext_h
#include "ds/Nestable.h"
#include "frontend/BytecodeCompiler.h"
#include "frontend/ErrorReporter.h"
#include "frontend/SharedContext.h"
namespace js {
namespace frontend {
class ParserBase;
// A data structure for tracking used names per parsing session in order to
// compute which bindings are closed over. Scripts and scopes are numbered
// monotonically in textual order and name uses are tracked by lists of
// (script id, scope id) pairs of their use sites.
//
// Intuitively, in a pair (P,S), P tracks the most nested function that has a
// use of u, and S tracks the most nested scope that is still being parsed.
//
// P is used to answer the question "is u used by a nested function?"
// S is used to answer the question "is u used in any scopes currently being
// parsed?"
//
// The algorithm:
//
// Let Used by a map of names to lists.
//
// 1. Number all scopes in monotonic increasing order in textual order.
// 2. Number all scripts in monotonic increasing order in textual order.
// 3. When an identifier u is used in scope numbered S in script numbered P,
// and u is found in Used,
// a. Append (P,S) to Used[u].
// b. Otherwise, assign the the list [(P,S)] to Used[u].
// 4. When we finish parsing a scope S in script P, for each declared name d in
// Declared(S):
// a. If d is found in Used, mark d as closed over if there is a value
// (P_d, S_d) in Used[d] such that P_d > P and S_d > S.
// b. Remove all values (P_d, S_d) in Used[d] such that S_d are >= S.
//
// Steps 1 and 2 are implemented by UsedNameTracker::next{Script,Scope}Id.
// Step 3 is implemented by UsedNameTracker::noteUsedInScope.
// Step 4 is implemented by UsedNameTracker::noteBoundInScope and
// Parser::propagateFreeNamesAndMarkClosedOverBindings.
class UsedNameTracker
{
public:
struct Use
{
uint32_t scriptId;
uint32_t scopeId;
};
class UsedNameInfo
{
friend class UsedNameTracker;
Vector<Use, 6> uses_;
void resetToScope(uint32_t scriptId, uint32_t scopeId);
public:
explicit UsedNameInfo(JSContext* cx)
: uses_(cx)
{ }
UsedNameInfo(UsedNameInfo&& other)
: uses_(std::move(other.uses_))
{ }
bool noteUsedInScope(uint32_t scriptId, uint32_t scopeId) {
if (uses_.empty() || uses_.back().scopeId < scopeId)
return uses_.append(Use { scriptId, scopeId });
return true;
}
void noteBoundInScope(uint32_t scriptId, uint32_t scopeId, bool* closedOver) {
*closedOver = false;
while (!uses_.empty()) {
Use& innermost = uses_.back();
if (innermost.scopeId < scopeId)
break;
if (innermost.scriptId > scriptId)
*closedOver = true;
uses_.popBack();
}
}
bool isUsedInScript(uint32_t scriptId) const {
return !uses_.empty() && uses_.back().scriptId >= scriptId;
}
};
using UsedNameMap = HashMap<JSAtom*,
UsedNameInfo,
DefaultHasher<JSAtom*>>;
private:
// The map of names to chains of uses.
UsedNameMap map_;
// Monotonically increasing id for all nested scripts.
uint32_t scriptCounter_;
// Monotonically increasing id for all nested scopes.
uint32_t scopeCounter_;
public:
explicit UsedNameTracker(JSContext* cx)
: map_(cx),
scriptCounter_(0),
scopeCounter_(0)
{ }
uint32_t nextScriptId() {
MOZ_ASSERT(scriptCounter_ != UINT32_MAX,
"ParseContext::Scope::init should have prevented wraparound");
return scriptCounter_++;
}
uint32_t nextScopeId() {
MOZ_ASSERT(scopeCounter_ != UINT32_MAX);
return scopeCounter_++;
}
UsedNameMap::Ptr lookup(JSAtom* name) const {
return map_.lookup(name);
}
MOZ_MUST_USE bool noteUse(JSContext* cx, JSAtom* name,
uint32_t scriptId, uint32_t scopeId);
struct RewindToken
{
private:
friend class UsedNameTracker;
uint32_t scriptId;
uint32_t scopeId;
};
RewindToken getRewindToken() const {
RewindToken token;
token.scriptId = scriptCounter_;
token.scopeId = scopeCounter_;
return token;
}
// Resets state so that scriptId and scopeId are the innermost script and
// scope, respectively. Used for rewinding state on syntax parse failure.
void rewind(RewindToken token);
// Resets state to beginning of compilation.
void reset() {
map_.clear();
RewindToken token;
token.scriptId = 0;
token.scopeId = 0;
rewind(token);
}
};
/*
* The struct ParseContext stores information about the current parsing context,
* which is part of the parser state (see the field Parser::pc). The current
* parsing context is either the global context, or the function currently being
* parsed. When the parser encounters a function definition, it creates a new
* ParseContext, makes it the new current context.
*/
class ParseContext : public Nestable<ParseContext>
{
public:
// The intra-function statement stack.
//
// Used for early error checking that depend on the nesting structure of
// statements, such as continue/break targets, labels, and unbraced
// lexical declarations.
class Statement : public Nestable<Statement>
{
StatementKind kind_;
public:
using Nestable<Statement>::enclosing;
using Nestable<Statement>::findNearest;
Statement(ParseContext* pc, StatementKind kind)
: Nestable<Statement>(&pc->innermostStatement_),
kind_(kind)
{ }
template <typename T> inline bool is() const;
template <typename T> inline T& as();
StatementKind kind() const {
return kind_;
}
void refineForKind(StatementKind newForKind) {
MOZ_ASSERT(kind_ == StatementKind::ForLoop);
MOZ_ASSERT(newForKind == StatementKind::ForInLoop ||
newForKind == StatementKind::ForOfLoop);
kind_ = newForKind;
}
};
class LabelStatement : public Statement
{
RootedAtom label_;
public:
LabelStatement(ParseContext* pc, JSAtom* label)
: Statement(pc, StatementKind::Label),
label_(pc->sc_->context, label)
{ }
HandleAtom label() const {
return label_;
}
};
struct ClassStatement : public Statement
{
FunctionBox* constructorBox;
explicit ClassStatement(ParseContext* pc)
: Statement(pc, StatementKind::Class),
constructorBox(nullptr)
{ }
};
// The intra-function scope stack.
//
// Tracks declared and used names within a scope.
class Scope : public Nestable<Scope>
{
// Names declared in this scope. Corresponds to the union of
// VarDeclaredNames and LexicallyDeclaredNames in the ES spec.
//
// A 'var' declared name is a member of the declared name set of every
// scope in its scope contour.
//
// A lexically declared name is a member only of the declared name set of
// the scope in which it is declared.
PooledMapPtr<DeclaredNameMap> declared_;
// FunctionBoxes in this scope that need to be considered for Annex
// B.3.3 semantics. This is checked on Scope exit, as by then we have
// all the declared names and would know if Annex B.3.3 is applicable.
PooledVectorPtr<FunctionBoxVector> possibleAnnexBFunctionBoxes_;
// Monotonically increasing id.
uint32_t id_;
bool maybeReportOOM(ParseContext* pc, bool result) {
if (!result)
ReportOutOfMemory(pc->sc()->context);
return result;
}
public:
using DeclaredNamePtr = DeclaredNameMap::Ptr;
using AddDeclaredNamePtr = DeclaredNameMap::AddPtr;
using Nestable<Scope>::enclosing;
explicit inline Scope(ParserBase* parser);
explicit inline Scope(JSContext* cx, ParseContext* pc, UsedNameTracker& usedNames);
void dump(ParseContext* pc);
uint32_t id() const {
return id_;
}
MOZ_MUST_USE bool init(ParseContext* pc) {
if (id_ == UINT32_MAX) {
pc->errorReporter_.reportErrorNoOffset(JSMSG_NEED_DIET, js_script_str);
return false;
}
return declared_.acquire(pc->sc()->context);
}
bool isEmpty() const {
return declared_->all().empty();
}
DeclaredNamePtr lookupDeclaredName(JSAtom* name) {
return declared_->lookup(name);
}
AddDeclaredNamePtr lookupDeclaredNameForAdd(JSAtom* name) {
return declared_->lookupForAdd(name);
}
MOZ_MUST_USE bool addDeclaredName(ParseContext* pc, AddDeclaredNamePtr& p, JSAtom* name,
DeclarationKind kind, uint32_t pos)
{
return maybeReportOOM(pc, declared_->add(p, name, DeclaredNameInfo(kind, pos)));
}
// Add a FunctionBox as a possible candidate for Annex B.3.3 semantics.
MOZ_MUST_USE bool addPossibleAnnexBFunctionBox(ParseContext* pc, FunctionBox* funbox);
// Check if the candidate function boxes for Annex B.3.3 should in
// fact get Annex B semantics. Checked on Scope exit.
MOZ_MUST_USE bool propagateAndMarkAnnexBFunctionBoxes(ParseContext* pc);
// Add and remove catch parameter names. Used to implement the odd
// semantics of catch bodies.
bool addCatchParameters(ParseContext* pc, Scope& catchParamScope);
void removeCatchParameters(ParseContext* pc, Scope& catchParamScope);
void useAsVarScope(ParseContext* pc) {
MOZ_ASSERT(!pc->varScope_);
pc->varScope_ = this;
}
// An iterator for the set of names a scope binds: the set of all
// declared names for 'var' scopes, and the set of lexically declared
// names for non-'var' scopes.
class BindingIter
{
friend class Scope;
DeclaredNameMap::Range declaredRange_;
mozilla::DebugOnly<uint32_t> count_;
bool isVarScope_;
BindingIter(Scope& scope, bool isVarScope)
: declaredRange_(scope.declared_->all()),
count_(0),
isVarScope_(isVarScope)
{
settle();
}
void settle() {
// Both var and lexically declared names are binding in a var
// scope.
if (isVarScope_)
return;
// Otherwise, pop only lexically declared names are
// binding. Pop the range until we find such a name.
while (!declaredRange_.empty()) {
if (BindingKindIsLexical(kind()))
break;
declaredRange_.popFront();
}
}
public:
bool done() const {
return declaredRange_.empty();
}
explicit operator bool() const {
return !done();
}
JSAtom* name() {
MOZ_ASSERT(!done());
return declaredRange_.front().key();
}
DeclarationKind declarationKind() {
MOZ_ASSERT(!done());
return declaredRange_.front().value()->kind();
}
BindingKind kind() {
return DeclarationKindToBindingKind(declarationKind());
}
bool closedOver() {
MOZ_ASSERT(!done());
return declaredRange_.front().value()->closedOver();
}
void setClosedOver() {
MOZ_ASSERT(!done());
return declaredRange_.front().value()->setClosedOver();
}
void operator++(int) {
MOZ_ASSERT(!done());
MOZ_ASSERT(count_ != UINT32_MAX);
declaredRange_.popFront();
settle();
}
};
inline BindingIter bindings(ParseContext* pc);
};
class VarScope : public Scope
{
public:
explicit inline VarScope(ParserBase* parser);
explicit inline VarScope(JSContext* cx, ParseContext* pc, UsedNameTracker& usedNames);
};
private:
// Trace logging of parsing time.
AutoFrontendTraceLog traceLog_;
// Context shared between parsing and bytecode generation.
SharedContext* sc_;
// A mechanism used for error reporting.
ErrorReporter& errorReporter_;
// The innermost statement, i.e., top of the statement stack.
Statement* innermostStatement_;
// The innermost scope, i.e., top of the scope stack.
//
// The outermost scope in the stack is usually varScope_. In the case of
// functions, the outermost scope is functionScope_, which may be
// varScope_. See comment above functionScope_.
Scope* innermostScope_;
// If isFunctionBox() and the function is a named lambda, the DeclEnv
// scope for named lambdas.
mozilla::Maybe<Scope> namedLambdaScope_;
// If isFunctionBox(), the scope for the function. If there are no
// parameter expressions, this is scope for the entire function. If there
// are parameter expressions, this holds the special function names
// ('.this', 'arguments') and the formal parameters.
mozilla::Maybe<Scope> functionScope_;
// The body-level scope. This always exists, but not necessarily at the
// beginning of parsing the script in the case of functions with parameter
// expressions.
Scope* varScope_;
// Simple formal parameter names, in order of appearance. Only used when
// isFunctionBox().
PooledVectorPtr<AtomVector> positionalFormalParameterNames_;
// Closed over binding names, in order of appearance. Null-delimited
// between scopes. Only used when syntax parsing.
PooledVectorPtr<AtomVector> closedOverBindingsForLazy_;
public:
// All inner functions in this context. Only used when syntax parsing.
Rooted<GCVector<JSFunction*, 8>> innerFunctionsForLazy;
// In a function context, points to a Directive struct that can be updated
// to reflect new directives encountered in the Directive Prologue that
// require reparsing the function. In global/module/generator-tail contexts,
// we don't need to reparse when encountering a DirectivePrologue so this
// pointer may be nullptr.
Directives* newDirectives;
// lastYieldOffset stores the offset of the last yield that was parsed.
// NoYieldOffset is its initial value.
static const uint32_t NoYieldOffset = UINT32_MAX;
uint32_t lastYieldOffset;
// lastAwaitOffset stores the offset of the last await that was parsed.
// NoAwaitOffset is its initial value.
static const uint32_t NoAwaitOffset = UINT32_MAX;
uint32_t lastAwaitOffset;
private:
// Monotonically increasing id.
uint32_t scriptId_;
// Set when compiling a function using Parser::standaloneFunctionBody via
// the Function or Generator constructor.
bool isStandaloneFunctionBody_;
// Set when encountering a super.property inside a method. We need to mark
// the nearest super scope as needing a home object.
bool superScopeNeedsHomeObject_;
public:
ParseContext(JSContext* cx, ParseContext*& parent, SharedContext* sc,
ErrorReporter& errorReporter, UsedNameTracker& usedNames,
Directives* newDirectives, bool isFull);
MOZ_MUST_USE bool init();
SharedContext* sc() {
return sc_;
}
// `true` if we are in the body of a function definition.
bool isFunctionBox() const {
return sc_->isFunctionBox();
}
FunctionBox* functionBox() {
return sc_->asFunctionBox();
}
Statement* innermostStatement() {
return innermostStatement_;
}
Scope* innermostScope() {
// There is always at least one scope: the 'var' scope.
MOZ_ASSERT(innermostScope_);
return innermostScope_;
}
Scope& namedLambdaScope() {
MOZ_ASSERT(functionBox()->function()->isNamedLambda());
return *namedLambdaScope_;
}
Scope& functionScope() {
MOZ_ASSERT(isFunctionBox());
return *functionScope_;
}
Scope& varScope() {
MOZ_ASSERT(varScope_);
return *varScope_;
}
bool isFunctionExtraBodyVarScopeInnermost() {
return isFunctionBox() && functionBox()->hasParameterExprs &&
innermostScope() == varScope_;
}
template <typename Predicate /* (Statement*) -> bool */>
Statement* findInnermostStatement(Predicate predicate) {
return Statement::findNearest(innermostStatement_, predicate);
}
template <typename T, typename Predicate /* (Statement*) -> bool */>
T* findInnermostStatement(Predicate predicate) {
return Statement::findNearest<T>(innermostStatement_, predicate);
}
template <typename T>
T* findInnermostStatement() {
return Statement::findNearest<T>(innermostStatement_);
}
AtomVector& positionalFormalParameterNames() {
return *positionalFormalParameterNames_;
}
AtomVector& closedOverBindingsForLazy() {
return *closedOverBindingsForLazy_;
}
enum class BreakStatementError {
// Unlabeled break must be inside loop or switch.
ToughBreak,
LabelNotFound,
};
// Return Err(true) if we have encountered at least one loop,
// Err(false) otherwise.
MOZ_MUST_USE inline JS::Result<Ok, BreakStatementError> checkBreakStatement(PropertyName* label);
enum class ContinueStatementError {
NotInALoop,
LabelNotFound,
};
MOZ_MUST_USE inline JS::Result<Ok, ContinueStatementError> checkContinueStatement(PropertyName* label);
// True if we are at the topmost level of a entire script or function body.
// For example, while parsing this code we would encounter f1 and f2 at
// body level, but we would not encounter f3 or f4 at body level:
//
// function f1() { function f2() { } }
// if (cond) { function f3() { if (cond) { function f4() { } } } }
//
bool atBodyLevel() {
return !innermostStatement_;
}
bool atGlobalLevel() {
return atBodyLevel() && sc_->isGlobalContext();
}
// True if we are at the topmost level of a module only.
bool atModuleLevel() {
return atBodyLevel() && sc_->isModuleContext();
}
void setIsStandaloneFunctionBody() {
isStandaloneFunctionBody_ = true;
}
bool isStandaloneFunctionBody() const {
return isStandaloneFunctionBody_;
}
void setSuperScopeNeedsHomeObject() {
MOZ_ASSERT(sc_->allowSuperProperty());
superScopeNeedsHomeObject_ = true;
}
bool superScopeNeedsHomeObject() const {
return superScopeNeedsHomeObject_;
}
bool useAsmOrInsideUseAsm() const {
return sc_->isFunctionBox() && sc_->asFunctionBox()->useAsmOrInsideUseAsm();
}
// A generator is marked as a generator before its body is parsed.
GeneratorKind generatorKind() const {
return sc_->isFunctionBox()
? sc_->asFunctionBox()->generatorKind()
: GeneratorKind::NotGenerator;
}
bool isGenerator() const {
return generatorKind() == GeneratorKind::Generator;
}
bool isAsync() const {
return sc_->isFunctionBox() && sc_->asFunctionBox()->isAsync();
}
bool needsDotGeneratorName() const {
return isGenerator() || isAsync();
}
FunctionAsyncKind asyncKind() const {
return isAsync() ? FunctionAsyncKind::AsyncFunction : FunctionAsyncKind::SyncFunction;
}
bool isArrowFunction() const {
return sc_->isFunctionBox() && sc_->asFunctionBox()->function()->isArrow();
}
bool isMethod() const {
return sc_->isFunctionBox() && sc_->asFunctionBox()->function()->isMethod();
}
bool isGetterOrSetter() const {
return sc_->isFunctionBox() && (sc_->asFunctionBox()->function()->isGetter() ||
sc_->asFunctionBox()->function()->isSetter());
}
uint32_t scriptId() const {
return scriptId_;
}
bool annexBAppliesToLexicalFunctionInInnermostScope(FunctionBox* funbox);
bool tryDeclareVar(HandlePropertyName name, DeclarationKind kind, uint32_t beginPos,
mozilla::Maybe<DeclarationKind>* redeclaredKind, uint32_t* prevPos);
private:
mozilla::Maybe<DeclarationKind> isVarRedeclaredInInnermostScope(HandlePropertyName name,
DeclarationKind kind);
mozilla::Maybe<DeclarationKind> isVarRedeclaredInEval(HandlePropertyName name,
DeclarationKind kind);
enum DryRunOption { NotDryRun, DryRunInnermostScopeOnly };
template <DryRunOption dryRunOption>
bool tryDeclareVarHelper(HandlePropertyName name, DeclarationKind kind, uint32_t beginPos,
mozilla::Maybe<DeclarationKind>* redeclaredKind, uint32_t* prevPos);
};
} // namespace frontend
} // namespace js
#endif // frontend_ParseContext_h
|