1// Copyright 2011 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef V8_JSON_PARSER_H_
6#define V8_JSON_PARSER_H_
7
8#include "src/v8.h"
9
10#include "src/char-predicates-inl.h"
11#include "src/conversions.h"
12#include "src/messages.h"
13#include "src/spaces-inl.h"
14#include "src/token.h"
15
16namespace v8 {
17namespace internal {
18
19// A simple json parser.
20template <bool seq_ascii>
21class JsonParser BASE_EMBEDDED {
22 public:
23  MUST_USE_RESULT static MaybeHandle<Object> Parse(Handle<String> source) {
24    return JsonParser(source).ParseJson();
25  }
26
27  static const int kEndOfString = -1;
28
29 private:
30  explicit JsonParser(Handle<String> source)
31      : source_(source),
32        source_length_(source->length()),
33        isolate_(source->map()->GetHeap()->isolate()),
34        factory_(isolate_->factory()),
35        zone_(isolate_),
36        object_constructor_(isolate_->native_context()->object_function(),
37                            isolate_),
38        position_(-1) {
39    source_ = String::Flatten(source_);
40    pretenure_ = (source_length_ >= kPretenureTreshold) ? TENURED : NOT_TENURED;
41
42    // Optimized fast case where we only have ASCII characters.
43    if (seq_ascii) {
44      seq_source_ = Handle<SeqOneByteString>::cast(source_);
45    }
46  }
47
48  // Parse a string containing a single JSON value.
49  MaybeHandle<Object> ParseJson();
50
51  inline void Advance() {
52    position_++;
53    if (position_ >= source_length_) {
54      c0_ = kEndOfString;
55    } else if (seq_ascii) {
56      c0_ = seq_source_->SeqOneByteStringGet(position_);
57    } else {
58      c0_ = source_->Get(position_);
59    }
60  }
61
62  // The JSON lexical grammar is specified in the ECMAScript 5 standard,
63  // section 15.12.1.1. The only allowed whitespace characters between tokens
64  // are tab, carriage-return, newline and space.
65
66  inline void AdvanceSkipWhitespace() {
67    do {
68      Advance();
69    } while (c0_ == ' ' || c0_ == '\t' || c0_ == '\n' || c0_ == '\r');
70  }
71
72  inline void SkipWhitespace() {
73    while (c0_ == ' ' || c0_ == '\t' || c0_ == '\n' || c0_ == '\r') {
74      Advance();
75    }
76  }
77
78  inline uc32 AdvanceGetChar() {
79    Advance();
80    return c0_;
81  }
82
83  // Checks that current charater is c.
84  // If so, then consume c and skip whitespace.
85  inline bool MatchSkipWhiteSpace(uc32 c) {
86    if (c0_ == c) {
87      AdvanceSkipWhitespace();
88      return true;
89    }
90    return false;
91  }
92
93  // A JSON string (production JSONString) is subset of valid JavaScript string
94  // literals. The string must only be double-quoted (not single-quoted), and
95  // the only allowed backslash-escapes are ", /, \, b, f, n, r, t and
96  // four-digit hex escapes (uXXXX). Any other use of backslashes is invalid.
97  Handle<String> ParseJsonString() {
98    return ScanJsonString<false>();
99  }
100
101  bool ParseJsonString(Handle<String> expected) {
102    int length = expected->length();
103    if (source_->length() - position_ - 1 > length) {
104      DisallowHeapAllocation no_gc;
105      String::FlatContent content = expected->GetFlatContent();
106      if (content.IsAscii()) {
107        ASSERT_EQ('"', c0_);
108        const uint8_t* input_chars = seq_source_->GetChars() + position_ + 1;
109        const uint8_t* expected_chars = content.ToOneByteVector().start();
110        for (int i = 0; i < length; i++) {
111          uint8_t c0 = input_chars[i];
112          if (c0 != expected_chars[i] ||
113              c0 == '"' || c0 < 0x20 || c0 == '\\') {
114            return false;
115          }
116        }
117        if (input_chars[length] == '"') {
118          position_ = position_ + length + 1;
119          AdvanceSkipWhitespace();
120          return true;
121        }
122      }
123    }
124    return false;
125  }
126
127  Handle<String> ParseJsonInternalizedString() {
128    return ScanJsonString<true>();
129  }
130
131  template <bool is_internalized>
132  Handle<String> ScanJsonString();
133  // Creates a new string and copies prefix[start..end] into the beginning
134  // of it. Then scans the rest of the string, adding characters after the
135  // prefix. Called by ScanJsonString when reaching a '\' or non-ASCII char.
136  template <typename StringType, typename SinkChar>
137  Handle<String> SlowScanJsonString(Handle<String> prefix, int start, int end);
138
139  // A JSON number (production JSONNumber) is a subset of the valid JavaScript
140  // decimal number literals.
141  // It includes an optional minus sign, must have at least one
142  // digit before and after a decimal point, may not have prefixed zeros (unless
143  // the integer part is zero), and may include an exponent part (e.g., "e-10").
144  // Hexadecimal and octal numbers are not allowed.
145  Handle<Object> ParseJsonNumber();
146
147  // Parse a single JSON value from input (grammar production JSONValue).
148  // A JSON value is either a (double-quoted) string literal, a number literal,
149  // one of "true", "false", or "null", or an object or array literal.
150  Handle<Object> ParseJsonValue();
151
152  // Parse a JSON object literal (grammar production JSONObject).
153  // An object literal is a squiggly-braced and comma separated sequence
154  // (possibly empty) of key/value pairs, where the key is a JSON string
155  // literal, the value is a JSON value, and the two are separated by a colon.
156  // A JSON array doesn't allow numbers and identifiers as keys, like a
157  // JavaScript array.
158  Handle<Object> ParseJsonObject();
159
160  // Parses a JSON array literal (grammar production JSONArray). An array
161  // literal is a square-bracketed and comma separated sequence (possibly empty)
162  // of JSON values.
163  // A JSON array doesn't allow leaving out values from the sequence, nor does
164  // it allow a terminal comma, like a JavaScript array does.
165  Handle<Object> ParseJsonArray();
166
167
168  // Mark that a parsing error has happened at the current token, and
169  // return a null handle. Primarily for readability.
170  inline Handle<Object> ReportUnexpectedCharacter() {
171    return Handle<Object>::null();
172  }
173
174  inline Isolate* isolate() { return isolate_; }
175  inline Factory* factory() { return factory_; }
176  inline Handle<JSFunction> object_constructor() { return object_constructor_; }
177
178  static const int kInitialSpecialStringLength = 1024;
179  static const int kPretenureTreshold = 100 * 1024;
180
181
182 private:
183  Zone* zone() { return &zone_; }
184
185  Handle<String> source_;
186  int source_length_;
187  Handle<SeqOneByteString> seq_source_;
188
189  PretenureFlag pretenure_;
190  Isolate* isolate_;
191  Factory* factory_;
192  Zone zone_;
193  Handle<JSFunction> object_constructor_;
194  uc32 c0_;
195  int position_;
196};
197
198template <bool seq_ascii>
199MaybeHandle<Object> JsonParser<seq_ascii>::ParseJson() {
200  // Advance to the first character (possibly EOS)
201  AdvanceSkipWhitespace();
202  Handle<Object> result = ParseJsonValue();
203  if (result.is_null() || c0_ != kEndOfString) {
204    // Some exception (for example stack overflow) is already pending.
205    if (isolate_->has_pending_exception()) return Handle<Object>::null();
206
207    // Parse failed. Current character is the unexpected token.
208    const char* message;
209    Factory* factory = this->factory();
210    Handle<JSArray> array;
211
212    switch (c0_) {
213      case kEndOfString:
214        message = "unexpected_eos";
215        array = factory->NewJSArray(0);
216        break;
217      case '-':
218      case '0':
219      case '1':
220      case '2':
221      case '3':
222      case '4':
223      case '5':
224      case '6':
225      case '7':
226      case '8':
227      case '9':
228        message = "unexpected_token_number";
229        array = factory->NewJSArray(0);
230        break;
231      case '"':
232        message = "unexpected_token_string";
233        array = factory->NewJSArray(0);
234        break;
235      default:
236        message = "unexpected_token";
237        Handle<Object> name = factory->LookupSingleCharacterStringFromCode(c0_);
238        Handle<FixedArray> element = factory->NewFixedArray(1);
239        element->set(0, *name);
240        array = factory->NewJSArrayWithElements(element);
241        break;
242    }
243
244    MessageLocation location(factory->NewScript(source_),
245                             position_,
246                             position_ + 1);
247    Handle<Object> error = factory->NewSyntaxError(message, array);
248    return isolate()->template Throw<Object>(error, &location);
249  }
250  return result;
251}
252
253
254// Parse any JSON value.
255template <bool seq_ascii>
256Handle<Object> JsonParser<seq_ascii>::ParseJsonValue() {
257  StackLimitCheck stack_check(isolate_);
258  if (stack_check.HasOverflowed()) {
259    isolate_->StackOverflow();
260    return Handle<Object>::null();
261  }
262
263  if (c0_ == '"') return ParseJsonString();
264  if ((c0_ >= '0' && c0_ <= '9') || c0_ == '-') return ParseJsonNumber();
265  if (c0_ == '{') return ParseJsonObject();
266  if (c0_ == '[') return ParseJsonArray();
267  if (c0_ == 'f') {
268    if (AdvanceGetChar() == 'a' && AdvanceGetChar() == 'l' &&
269        AdvanceGetChar() == 's' && AdvanceGetChar() == 'e') {
270      AdvanceSkipWhitespace();
271      return factory()->false_value();
272    }
273    return ReportUnexpectedCharacter();
274  }
275  if (c0_ == 't') {
276    if (AdvanceGetChar() == 'r' && AdvanceGetChar() == 'u' &&
277        AdvanceGetChar() == 'e') {
278      AdvanceSkipWhitespace();
279      return factory()->true_value();
280    }
281    return ReportUnexpectedCharacter();
282  }
283  if (c0_ == 'n') {
284    if (AdvanceGetChar() == 'u' && AdvanceGetChar() == 'l' &&
285        AdvanceGetChar() == 'l') {
286      AdvanceSkipWhitespace();
287      return factory()->null_value();
288    }
289    return ReportUnexpectedCharacter();
290  }
291  return ReportUnexpectedCharacter();
292}
293
294
295// Parse a JSON object. Position must be right at '{'.
296template <bool seq_ascii>
297Handle<Object> JsonParser<seq_ascii>::ParseJsonObject() {
298  HandleScope scope(isolate());
299  Handle<JSObject> json_object =
300      factory()->NewJSObject(object_constructor(), pretenure_);
301  Handle<Map> map(json_object->map());
302  ZoneList<Handle<Object> > properties(8, zone());
303  ASSERT_EQ(c0_, '{');
304
305  bool transitioning = true;
306
307  AdvanceSkipWhitespace();
308  if (c0_ != '}') {
309    do {
310      if (c0_ != '"') return ReportUnexpectedCharacter();
311
312      int start_position = position_;
313      Advance();
314
315      uint32_t index = 0;
316      if (c0_ >= '0' && c0_ <= '9') {
317        // Maybe an array index, try to parse it.
318        if (c0_ == '0') {
319          // With a leading zero, the string has to be "0" only to be an index.
320          Advance();
321        } else {
322          do {
323            int d = c0_ - '0';
324            if (index > 429496729U - ((d > 5) ? 1 : 0)) break;
325            index = (index * 10) + d;
326            Advance();
327          } while (c0_ >= '0' && c0_ <= '9');
328        }
329
330        if (c0_ == '"') {
331          // Successfully parsed index, parse and store element.
332          AdvanceSkipWhitespace();
333
334          if (c0_ != ':') return ReportUnexpectedCharacter();
335          AdvanceSkipWhitespace();
336          Handle<Object> value = ParseJsonValue();
337          if (value.is_null()) return ReportUnexpectedCharacter();
338
339          JSObject::SetOwnElement(json_object, index, value, SLOPPY).Assert();
340          continue;
341        }
342        // Not an index, fallback to the slow path.
343      }
344
345      position_ = start_position;
346#ifdef DEBUG
347      c0_ = '"';
348#endif
349
350      Handle<String> key;
351      Handle<Object> value;
352
353      // Try to follow existing transitions as long as possible. Once we stop
354      // transitioning, no transition can be found anymore.
355      if (transitioning) {
356        // First check whether there is a single expected transition. If so, try
357        // to parse it first.
358        bool follow_expected = false;
359        Handle<Map> target;
360        if (seq_ascii) {
361          key = JSObject::ExpectedTransitionKey(map);
362          follow_expected = !key.is_null() && ParseJsonString(key);
363        }
364        // If the expected transition hits, follow it.
365        if (follow_expected) {
366          target = JSObject::ExpectedTransitionTarget(map);
367        } else {
368          // If the expected transition failed, parse an internalized string and
369          // try to find a matching transition.
370          key = ParseJsonInternalizedString();
371          if (key.is_null()) return ReportUnexpectedCharacter();
372
373          target = JSObject::FindTransitionToField(map, key);
374          // If a transition was found, follow it and continue.
375          transitioning = !target.is_null();
376        }
377        if (c0_ != ':') return ReportUnexpectedCharacter();
378
379        AdvanceSkipWhitespace();
380        value = ParseJsonValue();
381        if (value.is_null()) return ReportUnexpectedCharacter();
382
383        if (transitioning) {
384          int descriptor = map->NumberOfOwnDescriptors();
385          PropertyDetails details =
386              target->instance_descriptors()->GetDetails(descriptor);
387          Representation expected_representation = details.representation();
388
389          if (value->FitsRepresentation(expected_representation)) {
390            // If the target representation is double and the value is already
391            // double, use the existing box.
392            if (value->IsSmi() && expected_representation.IsDouble()) {
393              value = factory()->NewHeapNumber(
394                  Handle<Smi>::cast(value)->value());
395            } else if (expected_representation.IsHeapObject() &&
396                       !target->instance_descriptors()->GetFieldType(
397                           descriptor)->NowContains(value)) {
398              Handle<HeapType> value_type(value->OptimalType(
399                      isolate(), expected_representation));
400              Map::GeneralizeFieldType(target, descriptor, value_type);
401            }
402            ASSERT(target->instance_descriptors()->GetFieldType(
403                    descriptor)->NowContains(value));
404            properties.Add(value, zone());
405            map = target;
406            continue;
407          } else {
408            transitioning = false;
409          }
410        }
411
412        // Commit the intermediate state to the object and stop transitioning.
413        JSObject::AllocateStorageForMap(json_object, map);
414        int length = properties.length();
415        for (int i = 0; i < length; i++) {
416          Handle<Object> value = properties[i];
417          FieldIndex index = FieldIndex::ForPropertyIndex(*map, i);
418          json_object->FastPropertyAtPut(index, *value);
419        }
420      } else {
421        key = ParseJsonInternalizedString();
422        if (key.is_null() || c0_ != ':') return ReportUnexpectedCharacter();
423
424        AdvanceSkipWhitespace();
425        value = ParseJsonValue();
426        if (value.is_null()) return ReportUnexpectedCharacter();
427      }
428
429      JSObject::SetOwnPropertyIgnoreAttributes(
430          json_object, key, value, NONE).Assert();
431    } while (MatchSkipWhiteSpace(','));
432    if (c0_ != '}') {
433      return ReportUnexpectedCharacter();
434    }
435
436    // If we transitioned until the very end, transition the map now.
437    if (transitioning) {
438      JSObject::AllocateStorageForMap(json_object, map);
439      int length = properties.length();
440      for (int i = 0; i < length; i++) {
441        Handle<Object> value = properties[i];
442        FieldIndex index = FieldIndex::ForPropertyIndex(*map, i);
443        json_object->FastPropertyAtPut(index, *value);
444      }
445    }
446  }
447  AdvanceSkipWhitespace();
448  return scope.CloseAndEscape(json_object);
449}
450
451// Parse a JSON array. Position must be right at '['.
452template <bool seq_ascii>
453Handle<Object> JsonParser<seq_ascii>::ParseJsonArray() {
454  HandleScope scope(isolate());
455  ZoneList<Handle<Object> > elements(4, zone());
456  ASSERT_EQ(c0_, '[');
457
458  AdvanceSkipWhitespace();
459  if (c0_ != ']') {
460    do {
461      Handle<Object> element = ParseJsonValue();
462      if (element.is_null()) return ReportUnexpectedCharacter();
463      elements.Add(element, zone());
464    } while (MatchSkipWhiteSpace(','));
465    if (c0_ != ']') {
466      return ReportUnexpectedCharacter();
467    }
468  }
469  AdvanceSkipWhitespace();
470  // Allocate a fixed array with all the elements.
471  Handle<FixedArray> fast_elements =
472      factory()->NewFixedArray(elements.length(), pretenure_);
473  for (int i = 0, n = elements.length(); i < n; i++) {
474    fast_elements->set(i, *elements[i]);
475  }
476  Handle<Object> json_array = factory()->NewJSArrayWithElements(
477      fast_elements, FAST_ELEMENTS, pretenure_);
478  return scope.CloseAndEscape(json_array);
479}
480
481
482template <bool seq_ascii>
483Handle<Object> JsonParser<seq_ascii>::ParseJsonNumber() {
484  bool negative = false;
485  int beg_pos = position_;
486  if (c0_ == '-') {
487    Advance();
488    negative = true;
489  }
490  if (c0_ == '0') {
491    Advance();
492    // Prefix zero is only allowed if it's the only digit before
493    // a decimal point or exponent.
494    if ('0' <= c0_ && c0_ <= '9') return ReportUnexpectedCharacter();
495  } else {
496    int i = 0;
497    int digits = 0;
498    if (c0_ < '1' || c0_ > '9') return ReportUnexpectedCharacter();
499    do {
500      i = i * 10 + c0_ - '0';
501      digits++;
502      Advance();
503    } while (c0_ >= '0' && c0_ <= '9');
504    if (c0_ != '.' && c0_ != 'e' && c0_ != 'E' && digits < 10) {
505      SkipWhitespace();
506      return Handle<Smi>(Smi::FromInt((negative ? -i : i)), isolate());
507    }
508  }
509  if (c0_ == '.') {
510    Advance();
511    if (c0_ < '0' || c0_ > '9') return ReportUnexpectedCharacter();
512    do {
513      Advance();
514    } while (c0_ >= '0' && c0_ <= '9');
515  }
516  if (AsciiAlphaToLower(c0_) == 'e') {
517    Advance();
518    if (c0_ == '-' || c0_ == '+') Advance();
519    if (c0_ < '0' || c0_ > '9') return ReportUnexpectedCharacter();
520    do {
521      Advance();
522    } while (c0_ >= '0' && c0_ <= '9');
523  }
524  int length = position_ - beg_pos;
525  double number;
526  if (seq_ascii) {
527    Vector<const uint8_t> chars(seq_source_->GetChars() +  beg_pos, length);
528    number = StringToDouble(isolate()->unicode_cache(),
529                            chars,
530                            NO_FLAGS,  // Hex, octal or trailing junk.
531                            OS::nan_value());
532  } else {
533    Vector<uint8_t> buffer = Vector<uint8_t>::New(length);
534    String::WriteToFlat(*source_, buffer.start(), beg_pos, position_);
535    Vector<const uint8_t> result =
536        Vector<const uint8_t>(buffer.start(), length);
537    number = StringToDouble(isolate()->unicode_cache(),
538                            result,
539                            NO_FLAGS,  // Hex, octal or trailing junk.
540                            0.0);
541    buffer.Dispose();
542  }
543  SkipWhitespace();
544  return factory()->NewNumber(number, pretenure_);
545}
546
547
548template <typename StringType>
549inline void SeqStringSet(Handle<StringType> seq_str, int i, uc32 c);
550
551template <>
552inline void SeqStringSet(Handle<SeqTwoByteString> seq_str, int i, uc32 c) {
553  seq_str->SeqTwoByteStringSet(i, c);
554}
555
556template <>
557inline void SeqStringSet(Handle<SeqOneByteString> seq_str, int i, uc32 c) {
558  seq_str->SeqOneByteStringSet(i, c);
559}
560
561template <typename StringType>
562inline Handle<StringType> NewRawString(Factory* factory,
563                                       int length,
564                                       PretenureFlag pretenure);
565
566template <>
567inline Handle<SeqTwoByteString> NewRawString(Factory* factory,
568                                             int length,
569                                             PretenureFlag pretenure) {
570  return factory->NewRawTwoByteString(length, pretenure).ToHandleChecked();
571}
572
573template <>
574inline Handle<SeqOneByteString> NewRawString(Factory* factory,
575                                           int length,
576                                           PretenureFlag pretenure) {
577  return factory->NewRawOneByteString(length, pretenure).ToHandleChecked();
578}
579
580
581// Scans the rest of a JSON string starting from position_ and writes
582// prefix[start..end] along with the scanned characters into a
583// sequential string of type StringType.
584template <bool seq_ascii>
585template <typename StringType, typename SinkChar>
586Handle<String> JsonParser<seq_ascii>::SlowScanJsonString(
587    Handle<String> prefix, int start, int end) {
588  int count = end - start;
589  int max_length = count + source_length_ - position_;
590  int length = Min(max_length, Max(kInitialSpecialStringLength, 2 * count));
591  Handle<StringType> seq_string =
592      NewRawString<StringType>(factory(), length, pretenure_);
593  // Copy prefix into seq_str.
594  SinkChar* dest = seq_string->GetChars();
595  String::WriteToFlat(*prefix, dest, start, end);
596
597  while (c0_ != '"') {
598    // Check for control character (0x00-0x1f) or unterminated string (<0).
599    if (c0_ < 0x20) return Handle<String>::null();
600    if (count >= length) {
601      // We need to create a longer sequential string for the result.
602      return SlowScanJsonString<StringType, SinkChar>(seq_string, 0, count);
603    }
604    if (c0_ != '\\') {
605      // If the sink can contain UC16 characters, or source_ contains only
606      // ASCII characters, there's no need to test whether we can store the
607      // character. Otherwise check whether the UC16 source character can fit
608      // in the ASCII sink.
609      if (sizeof(SinkChar) == kUC16Size ||
610          seq_ascii ||
611          c0_ <= String::kMaxOneByteCharCode) {
612        SeqStringSet(seq_string, count++, c0_);
613        Advance();
614      } else {
615        // StringType is SeqOneByteString and we just read a non-ASCII char.
616        return SlowScanJsonString<SeqTwoByteString, uc16>(seq_string, 0, count);
617      }
618    } else {
619      Advance();  // Advance past the \.
620      switch (c0_) {
621        case '"':
622        case '\\':
623        case '/':
624          SeqStringSet(seq_string, count++, c0_);
625          break;
626        case 'b':
627          SeqStringSet(seq_string, count++, '\x08');
628          break;
629        case 'f':
630          SeqStringSet(seq_string, count++, '\x0c');
631          break;
632        case 'n':
633          SeqStringSet(seq_string, count++, '\x0a');
634          break;
635        case 'r':
636          SeqStringSet(seq_string, count++, '\x0d');
637          break;
638        case 't':
639          SeqStringSet(seq_string, count++, '\x09');
640          break;
641        case 'u': {
642          uc32 value = 0;
643          for (int i = 0; i < 4; i++) {
644            Advance();
645            int digit = HexValue(c0_);
646            if (digit < 0) {
647              return Handle<String>::null();
648            }
649            value = value * 16 + digit;
650          }
651          if (sizeof(SinkChar) == kUC16Size ||
652              value <= String::kMaxOneByteCharCode) {
653            SeqStringSet(seq_string, count++, value);
654            break;
655          } else {
656            // StringType is SeqOneByteString and we just read a non-ASCII char.
657            position_ -= 6;  // Rewind position_ to \ in \uxxxx.
658            Advance();
659            return SlowScanJsonString<SeqTwoByteString, uc16>(seq_string,
660                                                              0,
661                                                              count);
662          }
663        }
664        default:
665          return Handle<String>::null();
666      }
667      Advance();
668    }
669  }
670
671  ASSERT_EQ('"', c0_);
672  // Advance past the last '"'.
673  AdvanceSkipWhitespace();
674
675  // Shrink seq_string length to count and return.
676  return SeqString::Truncate(seq_string, count);
677}
678
679
680template <bool seq_ascii>
681template <bool is_internalized>
682Handle<String> JsonParser<seq_ascii>::ScanJsonString() {
683  ASSERT_EQ('"', c0_);
684  Advance();
685  if (c0_ == '"') {
686    AdvanceSkipWhitespace();
687    return factory()->empty_string();
688  }
689
690  if (seq_ascii && is_internalized) {
691    // Fast path for existing internalized strings.  If the the string being
692    // parsed is not a known internalized string, contains backslashes or
693    // unexpectedly reaches the end of string, return with an empty handle.
694    uint32_t running_hash = isolate()->heap()->HashSeed();
695    int position = position_;
696    uc32 c0 = c0_;
697    do {
698      if (c0 == '\\') {
699        c0_ = c0;
700        int beg_pos = position_;
701        position_ = position;
702        return SlowScanJsonString<SeqOneByteString, uint8_t>(source_,
703                                                             beg_pos,
704                                                             position_);
705      }
706      if (c0 < 0x20) return Handle<String>::null();
707      if (static_cast<uint32_t>(c0) >
708          unibrow::Utf16::kMaxNonSurrogateCharCode) {
709        running_hash =
710            StringHasher::AddCharacterCore(running_hash,
711                                           unibrow::Utf16::LeadSurrogate(c0));
712        running_hash =
713            StringHasher::AddCharacterCore(running_hash,
714                                           unibrow::Utf16::TrailSurrogate(c0));
715      } else {
716        running_hash = StringHasher::AddCharacterCore(running_hash, c0);
717      }
718      position++;
719      if (position >= source_length_) return Handle<String>::null();
720      c0 = seq_source_->SeqOneByteStringGet(position);
721    } while (c0 != '"');
722    int length = position - position_;
723    uint32_t hash = (length <= String::kMaxHashCalcLength)
724        ? StringHasher::GetHashCore(running_hash) : length;
725    Vector<const uint8_t> string_vector(
726        seq_source_->GetChars() + position_, length);
727    StringTable* string_table = isolate()->heap()->string_table();
728    uint32_t capacity = string_table->Capacity();
729    uint32_t entry = StringTable::FirstProbe(hash, capacity);
730    uint32_t count = 1;
731    Handle<String> result;
732    while (true) {
733      Object* element = string_table->KeyAt(entry);
734      if (element == isolate()->heap()->undefined_value()) {
735        // Lookup failure.
736        result = factory()->InternalizeOneByteString(
737            seq_source_, position_, length);
738        break;
739      }
740      if (element != isolate()->heap()->the_hole_value() &&
741          String::cast(element)->IsOneByteEqualTo(string_vector)) {
742        result = Handle<String>(String::cast(element), isolate());
743#ifdef DEBUG
744        uint32_t hash_field =
745            (hash << String::kHashShift) | String::kIsNotArrayIndexMask;
746        ASSERT_EQ(static_cast<int>(result->Hash()),
747                  static_cast<int>(hash_field >> String::kHashShift));
748#endif
749        break;
750      }
751      entry = StringTable::NextProbe(entry, count++, capacity);
752    }
753    position_ = position;
754    // Advance past the last '"'.
755    AdvanceSkipWhitespace();
756    return result;
757  }
758
759  int beg_pos = position_;
760  // Fast case for ASCII only without escape characters.
761  do {
762    // Check for control character (0x00-0x1f) or unterminated string (<0).
763    if (c0_ < 0x20) return Handle<String>::null();
764    if (c0_ != '\\') {
765      if (seq_ascii || c0_ <= String::kMaxOneByteCharCode) {
766        Advance();
767      } else {
768        return SlowScanJsonString<SeqTwoByteString, uc16>(source_,
769                                                          beg_pos,
770                                                          position_);
771      }
772    } else {
773      return SlowScanJsonString<SeqOneByteString, uint8_t>(source_,
774                                                           beg_pos,
775                                                           position_);
776    }
777  } while (c0_ != '"');
778  int length = position_ - beg_pos;
779  Handle<String> result =
780      factory()->NewRawOneByteString(length, pretenure_).ToHandleChecked();
781  uint8_t* dest = SeqOneByteString::cast(*result)->GetChars();
782  String::WriteToFlat(*source_, dest, beg_pos, position_);
783
784  ASSERT_EQ('"', c0_);
785  // Advance past the last '"'.
786  AdvanceSkipWhitespace();
787  return result;
788}
789
790} }  // namespace v8::internal
791
792#endif  // V8_JSON_PARSER_H_
793