[json] move json parser and stringifier into own compilation units.

src/json-parser.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_JSON_PARSER_H_
 #define V8_JSON_PARSER_H_
 
-#include "src/char-predicates.h"
-#include "src/conversions.h"
-#include "src/debug/debug.h"
 #include "src/factory.h"
-#include "src/field-type.h"
-#include "src/messages.h"
-#include "src/parsing/scanner.h"
-#include "src/parsing/token.h"
-#include "src/transitions.h"
+#include "src/objects.h"
 
 namespace v8 {
 namespace internal {
 
 enum ParseElementResult { kElementFound, kElementNotFound, kNullHandle };
 
 
 // A simple json parser.
 template <bool seq_one_byte>
 class JsonParser BASE_EMBEDDED {
  public:
   MUST_USE_RESULT static MaybeHandle<Object> Parse(Handle<String> source) {
     return JsonParser(source).ParseJson();
   }
 
   static const int kEndOfString = -1;
 
  private:
-  explicit JsonParser(Handle<String> source)
-      : source_(source),
-        source_length_(source->length()),
-        isolate_(source->map()->GetHeap()->isolate()),
-        factory_(isolate_->factory()),
-        zone_(isolate_->allocator()),
-        object_constructor_(isolate_->native_context()->object_function(),
-                            isolate_),
-        position_(-1) {
-    source_ = String::Flatten(source_);
-    pretenure_ = (source_length_ >= kPretenureTreshold) ? TENURED : NOT_TENURED;
-
-    // Optimized fast case where we only have Latin1 characters.
-    if (seq_one_byte) {
-      seq_source_ = Handle<SeqOneByteString>::cast(source_);
-    }
-  }
+  explicit JsonParser(Handle<String> source);
 
   // Parse a string containing a single JSON value.
   MaybeHandle<Object> ParseJson();
 
-  inline void Advance() {
-    position_++;
-    if (position_ >= source_length_) {
-      c0_ = kEndOfString;
-    } else if (seq_one_byte) {
-      c0_ = seq_source_->SeqOneByteStringGet(position_);
-    } else {
-      c0_ = source_->Get(position_);
-    }
-  }
+  INLINE(void Advance());
 
   // The JSON lexical grammar is specified in the ECMAScript 5 standard,
   // section 15.12.1.1. The only allowed whitespace characters between tokens
   // are tab, carriage-return, newline and space.
 
-  inline void AdvanceSkipWhitespace() {
-    do {
-      Advance();
-    } while (c0_ == ' ' || c0_ == '\t' || c0_ == '\n' || c0_ == '\r');
-  }
-
-  inline void SkipWhitespace() {
-    while (c0_ == ' ' || c0_ == '\t' || c0_ == '\n' || c0_ == '\r') {
-      Advance();
-    }
-  }
-
-  inline uc32 AdvanceGetChar() {
-    Advance();
-    return c0_;
-  }
+  INLINE(void AdvanceSkipWhitespace());
+  INLINE(void SkipWhitespace());
+  INLINE(uc32 AdvanceGetChar());
 
   // Checks that current charater is c.
   // If so, then consume c and skip whitespace.
-  inline bool MatchSkipWhiteSpace(uc32 c) {
-    if (c0_ == c) {
-      AdvanceSkipWhitespace();
-      return true;
-    }
-    return false;
-  }
+  INLINE(bool MatchSkipWhiteSpace(uc32 c));
 
   // A JSON string (production JSONString) is subset of valid JavaScript string
   // literals. The string must only be double-quoted (not single-quoted), and
   // the only allowed backslash-escapes are ", /, \, b, f, n, r, t and
   // four-digit hex escapes (uXXXX). Any other use of backslashes is invalid.
   Handle<String> ParseJsonString() {
     return ScanJsonString<false>();
   }
 
-  bool ParseJsonString(Handle<String> expected) {
-    int length = expected->length();
-    if (source_->length() - position_ - 1 > length) {
-      DisallowHeapAllocation no_gc;
-      String::FlatContent content = expected->GetFlatContent();
-      if (content.IsOneByte()) {
-        DCHECK_EQ('"', c0_);
-        const uint8_t* input_chars = seq_source_->GetChars() + position_ + 1;
-        const uint8_t* expected_chars = content.ToOneByteVector().start();
-        for (int i = 0; i < length; i++) {
-          uint8_t c0 = input_chars[i];
-          if (c0 != expected_chars[i] || c0 == '"' || c0 < 0x20 || c0 == '\\') {
-            return false;
-          }
-        }
-        if (input_chars[length] == '"') {
-          position_ = position_ + length + 1;
-          AdvanceSkipWhitespace();
-          return true;
-        }
-      }
-    }
-    return false;
-  }
+  bool ParseJsonString(Handle<String> expected);
 
   Handle<String> ParseJsonInternalizedString() {
     Handle<String> result = ScanJsonString<true>();
     if (result.is_null()) return result;
     return factory()->InternalizeString(result);
   }
 
   template <bool is_internalized>
   Handle<String> ScanJsonString();
   // Creates a new string and copies prefix[start..end] into the beginning
@@ skipping 41 matching lines @@
     return Handle<Object>::null();
   }
 
   inline Isolate* isolate() { return isolate_; }
   inline Factory* factory() { return factory_; }
   inline Handle<JSFunction> object_constructor() { return object_constructor_; }
 
   static const int kInitialSpecialStringLength = 32;
   static const int kPretenureTreshold = 100 * 1024;
 
-
  private:
   Zone* zone() { return &zone_; }
 
   void CommitStateToJsonObject(Handle<JSObject> json_object, Handle<Map> map,
                                ZoneList<Handle<Object> >* properties);
 
   Handle<String> source_;
   int source_length_;
   Handle<SeqOneByteString> seq_source_;
 
   PretenureFlag pretenure_;
   Isolate* isolate_;
   Factory* factory_;
   Zone zone_;
   Handle<JSFunction> object_constructor_;
   uc32 c0_;
   int position_;
 };
 
-template <bool seq_one_byte>
-MaybeHandle<Object> JsonParser<seq_one_byte>::ParseJson() {
-  // Advance to the first character (possibly EOS)
-  AdvanceSkipWhitespace();
-  Handle<Object> result = ParseJsonValue();
-  if (result.is_null() || c0_ != kEndOfString) {
-    // Some exception (for example stack overflow) is already pending.
-    if (isolate_->has_pending_exception()) return Handle<Object>::null();
-
-    // Parse failed. Current character is the unexpected token.
-    Factory* factory = this->factory();
-    MessageTemplate::Template message;
-    Handle<Object> arg1 = Handle<Smi>(Smi::FromInt(position_), isolate());
-    Handle<Object> arg2;
-
-    switch (c0_) {
-      case kEndOfString:
-        message = MessageTemplate::kJsonParseUnexpectedEOS;
-        break;
-      case '-':
-      case '0':
-      case '1':
-      case '2':
-      case '3':
-      case '4':
-      case '5':
-      case '6':
-      case '7':
-      case '8':
-      case '9':
-        message = MessageTemplate::kJsonParseUnexpectedTokenNumber;
-        break;
-      case '"':
-        message = MessageTemplate::kJsonParseUnexpectedTokenString;
-        break;
-      default:
-        message = MessageTemplate::kJsonParseUnexpectedToken;
-        arg2 = arg1;
-        arg1 = factory->LookupSingleCharacterStringFromCode(c0_);
-        break;
-    }
-
-    Handle<Script> script(factory->NewScript(source_));
-    // We should sent compile error event because we compile JSON object in
-    // separated source file.
-    isolate()->debug()->OnCompileError(script);
-    MessageLocation location(script, position_, position_ + 1);
-    Handle<Object> error = factory->NewSyntaxError(message, arg1, arg2);
-    return isolate()->template Throw<Object>(error, &location);
-  }
-  return result;
-}
-
-
-// Parse any JSON value.
-template <bool seq_one_byte>
-Handle<Object> JsonParser<seq_one_byte>::ParseJsonValue() {
-  StackLimitCheck stack_check(isolate_);
-  if (stack_check.HasOverflowed()) {
-    isolate_->StackOverflow();
-    return Handle<Object>::null();
-  }
-
-  if (stack_check.InterruptRequested()) {
-    ExecutionAccess access(isolate_);
-    // Avoid blocking GC in long running parser (v8:3974).
-    isolate_->stack_guard()->HandleGCInterrupt();
-  }
-
-  if (c0_ == '"') return ParseJsonString();
-  if ((c0_ >= '0' && c0_ <= '9') || c0_ == '-') return ParseJsonNumber();
-  if (c0_ == '{') return ParseJsonObject();
-  if (c0_ == '[') return ParseJsonArray();
-  if (c0_ == 'f') {
-    if (AdvanceGetChar() == 'a' && AdvanceGetChar() == 'l' &&
-        AdvanceGetChar() == 's' && AdvanceGetChar() == 'e') {
-      AdvanceSkipWhitespace();
-      return factory()->false_value();
-    }
-    return ReportUnexpectedCharacter();
-  }
-  if (c0_ == 't') {
-    if (AdvanceGetChar() == 'r' && AdvanceGetChar() == 'u' &&
-        AdvanceGetChar() == 'e') {
-      AdvanceSkipWhitespace();
-      return factory()->true_value();
-    }
-    return ReportUnexpectedCharacter();
-  }
-  if (c0_ == 'n') {
-    if (AdvanceGetChar() == 'u' && AdvanceGetChar() == 'l' &&
-        AdvanceGetChar() == 'l') {
-      AdvanceSkipWhitespace();
-      return factory()->null_value();
-    }
-    return ReportUnexpectedCharacter();
-  }
-  return ReportUnexpectedCharacter();
-}
-
-
-template <bool seq_one_byte>
-ParseElementResult JsonParser<seq_one_byte>::ParseElement(
-    Handle<JSObject> json_object) {
-  uint32_t index = 0;
-  // Maybe an array index, try to parse it.
-  if (c0_ == '0') {
-    // With a leading zero, the string has to be "0" only to be an index.
-    Advance();
-  } else {
-    do {
-      int d = c0_ - '0';
-      if (index > 429496729U - ((d + 3) >> 3)) break;
-      index = (index * 10) + d;
-      Advance();
-    } while (IsDecimalDigit(c0_));
-  }
-
-  if (c0_ == '"') {
-    // Successfully parsed index, parse and store element.
-    AdvanceSkipWhitespace();
-
-    if (c0_ == ':') {
-      AdvanceSkipWhitespace();
-      Handle<Object> value = ParseJsonValue();
-      if (!value.is_null()) {
-        JSObject::SetOwnElementIgnoreAttributes(json_object, index, value, NONE)
-            .Assert();
-        return kElementFound;
-      } else {
-        return kNullHandle;
-      }
-    }
-  }
-  return kElementNotFound;
-}
-
-// Parse a JSON object. Position must be right at '{'.
-template <bool seq_one_byte>
-Handle<Object> JsonParser<seq_one_byte>::ParseJsonObject() {
-  HandleScope scope(isolate());
-  Handle<JSObject> json_object =
-      factory()->NewJSObject(object_constructor(), pretenure_);
-  Handle<Map> map(json_object->map());
-  int descriptor = 0;
-  ZoneList<Handle<Object> > properties(8, zone());
-  DCHECK_EQ(c0_, '{');
-
-  bool transitioning = true;
-
-  AdvanceSkipWhitespace();
-  if (c0_ != '}') {
-    do {
-      if (c0_ != '"') return ReportUnexpectedCharacter();
-
-      int start_position = position_;
-      Advance();
-
-      if (IsDecimalDigit(c0_)) {
-        ParseElementResult element_result = ParseElement(json_object);
-        if (element_result == kNullHandle) return Handle<Object>::null();
-        if (element_result == kElementFound) continue;
-      }
-      // Not an index, fallback to the slow path.
-
-      position_ = start_position;
-#ifdef DEBUG
-      c0_ = '"';
-#endif
-
-      Handle<String> key;
-      Handle<Object> value;
-
-      // Try to follow existing transitions as long as possible. Once we stop
-      // transitioning, no transition can be found anymore.
-      DCHECK(transitioning);
-      // First check whether there is a single expected transition. If so, try
-      // to parse it first.
-      bool follow_expected = false;
-      Handle<Map> target;
-      if (seq_one_byte) {
-        key = TransitionArray::ExpectedTransitionKey(map);
-        follow_expected = !key.is_null() && ParseJsonString(key);
-      }
-      // If the expected transition hits, follow it.
-      if (follow_expected) {
-        target = TransitionArray::ExpectedTransitionTarget(map);
-      } else {
-        // If the expected transition failed, parse an internalized string and
-        // try to find a matching transition.
-        key = ParseJsonInternalizedString();
-        if (key.is_null()) return ReportUnexpectedCharacter();
-
-        target = TransitionArray::FindTransitionToField(map, key);
-        // If a transition was found, follow it and continue.
-        transitioning = !target.is_null();
-      }
-      if (c0_ != ':') return ReportUnexpectedCharacter();
-
-      AdvanceSkipWhitespace();
-      value = ParseJsonValue();
-      if (value.is_null()) return ReportUnexpectedCharacter();
-
-      if (transitioning) {
-        PropertyDetails details =
-            target->instance_descriptors()->GetDetails(descriptor);
-        Representation expected_representation = details.representation();
-
-        if (value->FitsRepresentation(expected_representation)) {
-          if (expected_representation.IsHeapObject() &&
-              !target->instance_descriptors()
-                   ->GetFieldType(descriptor)
-                   ->NowContains(value)) {
-            Handle<FieldType> value_type(
-                value->OptimalType(isolate(), expected_representation));
-            Map::GeneralizeFieldType(target, descriptor,
-                                     expected_representation, value_type);
-          }
-          DCHECK(target->instance_descriptors()
-                     ->GetFieldType(descriptor)
-                     ->NowContains(value));
-          properties.Add(value, zone());
-          map = target;
-          descriptor++;
-          continue;
-        } else {
-          transitioning = false;
-        }
-      }
-
-      DCHECK(!transitioning);
-
-      // Commit the intermediate state to the object and stop transitioning.
-      CommitStateToJsonObject(json_object, map, &properties);
-
-      JSObject::DefinePropertyOrElementIgnoreAttributes(json_object, key, value)
-          .Check();
-    } while (transitioning && MatchSkipWhiteSpace(','));
-
-    // If we transitioned until the very end, transition the map now.
-    if (transitioning) {
-      CommitStateToJsonObject(json_object, map, &properties);
-    } else {
-      while (MatchSkipWhiteSpace(',')) {
-        HandleScope local_scope(isolate());
-        if (c0_ != '"') return ReportUnexpectedCharacter();
-
-        int start_position = position_;
-        Advance();
-
-        if (IsDecimalDigit(c0_)) {
-          ParseElementResult element_result = ParseElement(json_object);
-          if (element_result == kNullHandle) return Handle<Object>::null();
-          if (element_result == kElementFound) continue;
-        }
-        // Not an index, fallback to the slow path.
-
-        position_ = start_position;
-#ifdef DEBUG
-        c0_ = '"';
-#endif
-
-        Handle<String> key;
-        Handle<Object> value;
-
-        key = ParseJsonInternalizedString();
-        if (key.is_null() || c0_ != ':') return ReportUnexpectedCharacter();
-
-        AdvanceSkipWhitespace();
-        value = ParseJsonValue();
-        if (value.is_null()) return ReportUnexpectedCharacter();
-
-        JSObject::DefinePropertyOrElementIgnoreAttributes(json_object, key,
-                                                          value).Check();
-      }
-    }
-
-    if (c0_ != '}') {
-      return ReportUnexpectedCharacter();
-    }
-  }
-  AdvanceSkipWhitespace();
-  return scope.CloseAndEscape(json_object);
-}
-
-
-template <bool seq_one_byte>
-void JsonParser<seq_one_byte>::CommitStateToJsonObject(
-    Handle<JSObject> json_object, Handle<Map> map,
-    ZoneList<Handle<Object> >* properties) {
-  JSObject::AllocateStorageForMap(json_object, map);
-  DCHECK(!json_object->map()->is_dictionary_map());
-
-  DisallowHeapAllocation no_gc;
-
-  int length = properties->length();
-  for (int i = 0; i < length; i++) {
-    Handle<Object> value = (*properties)[i];
-    json_object->WriteToField(i, *value);
-  }
-}
-
-
-// Parse a JSON array. Position must be right at '['.
-template <bool seq_one_byte>
-Handle<Object> JsonParser<seq_one_byte>::ParseJsonArray() {
-  HandleScope scope(isolate());
-  ZoneList<Handle<Object> > elements(4, zone());
-  DCHECK_EQ(c0_, '[');
-
-  AdvanceSkipWhitespace();
-  if (c0_ != ']') {
-    do {
-      Handle<Object> element = ParseJsonValue();
-      if (element.is_null()) return ReportUnexpectedCharacter();
-      elements.Add(element, zone());
-    } while (MatchSkipWhiteSpace(','));
-    if (c0_ != ']') {
-      return ReportUnexpectedCharacter();
-    }
-  }
-  AdvanceSkipWhitespace();
-  // Allocate a fixed array with all the elements.
-  Handle<FixedArray> fast_elements =
-      factory()->NewFixedArray(elements.length(), pretenure_);
-  for (int i = 0, n = elements.length(); i < n; i++) {
-    fast_elements->set(i, *elements[i]);
-  }
-  Handle<Object> json_array = factory()->NewJSArrayWithElements(
-      fast_elements, FAST_ELEMENTS, pretenure_);
-  return scope.CloseAndEscape(json_array);
-}
-
-
-template <bool seq_one_byte>
-Handle<Object> JsonParser<seq_one_byte>::ParseJsonNumber() {
-  bool negative = false;
-  int beg_pos = position_;
-  if (c0_ == '-') {
-    Advance();
-    negative = true;
-  }
-  if (c0_ == '0') {
-    Advance();
-    // Prefix zero is only allowed if it's the only digit before
-    // a decimal point or exponent.
-    if (IsDecimalDigit(c0_)) return ReportUnexpectedCharacter();
-  } else {
-    int i = 0;
-    int digits = 0;
-    if (c0_ < '1' || c0_ > '9') return ReportUnexpectedCharacter();
-    do {
-      i = i * 10 + c0_ - '0';
-      digits++;
-      Advance();
-    } while (IsDecimalDigit(c0_));
-    if (c0_ != '.' && c0_ != 'e' && c0_ != 'E' && digits < 10) {
-      SkipWhitespace();
-      return Handle<Smi>(Smi::FromInt((negative ? -i : i)), isolate());
-    }
-  }
-  if (c0_ == '.') {
-    Advance();
-    if (!IsDecimalDigit(c0_)) return ReportUnexpectedCharacter();
-    do {
-      Advance();
-    } while (IsDecimalDigit(c0_));
-  }
-  if (AsciiAlphaToLower(c0_) == 'e') {
-    Advance();
-    if (c0_ == '-' || c0_ == '+') Advance();
-    if (!IsDecimalDigit(c0_)) return ReportUnexpectedCharacter();
-    do {
-      Advance();
-    } while (IsDecimalDigit(c0_));
-  }
-  int length = position_ - beg_pos;
-  double number;
-  if (seq_one_byte) {
-    Vector<const uint8_t> chars(seq_source_->GetChars() +  beg_pos, length);
-    number = StringToDouble(isolate()->unicode_cache(), chars,
-                            NO_FLAGS,  // Hex, octal or trailing junk.
-                            std::numeric_limits<double>::quiet_NaN());
-  } else {
-    Vector<uint8_t> buffer = Vector<uint8_t>::New(length);
-    String::WriteToFlat(*source_, buffer.start(), beg_pos, position_);
-    Vector<const uint8_t> result =
-        Vector<const uint8_t>(buffer.start(), length);
-    number = StringToDouble(isolate()->unicode_cache(),
-                            result,
-                            NO_FLAGS,  // Hex, octal or trailing junk.
-                            0.0);
-    buffer.Dispose();
-  }
-  SkipWhitespace();
-  return factory()->NewNumber(number, pretenure_);
-}
-
-
-template <typename StringType>
-inline void SeqStringSet(Handle<StringType> seq_str, int i, uc32 c);
-
-template <>
-inline void SeqStringSet(Handle<SeqTwoByteString> seq_str, int i, uc32 c) {
-  seq_str->SeqTwoByteStringSet(i, c);
-}
-
-template <>
-inline void SeqStringSet(Handle<SeqOneByteString> seq_str, int i, uc32 c) {
-  seq_str->SeqOneByteStringSet(i, c);
-}
-
-template <typename StringType>
-inline Handle<StringType> NewRawString(Factory* factory,
-                                       int length,
-                                       PretenureFlag pretenure);
-
-template <>
-inline Handle<SeqTwoByteString> NewRawString(Factory* factory,
-                                             int length,
-                                             PretenureFlag pretenure) {
-  return factory->NewRawTwoByteString(length, pretenure).ToHandleChecked();
-}
-
-template <>
-inline Handle<SeqOneByteString> NewRawString(Factory* factory,
-                                           int length,
-                                           PretenureFlag pretenure) {
-  return factory->NewRawOneByteString(length, pretenure).ToHandleChecked();
-}
-
-
-// Scans the rest of a JSON string starting from position_ and writes
-// prefix[start..end] along with the scanned characters into a
-// sequential string of type StringType.
-template <bool seq_one_byte>
-template <typename StringType, typename SinkChar>
-Handle<String> JsonParser<seq_one_byte>::SlowScanJsonString(
-    Handle<String> prefix, int start, int end) {
-  int count = end - start;
-  int max_length = count + source_length_ - position_;
-  int length = Min(max_length, Max(kInitialSpecialStringLength, 2 * count));
-  Handle<StringType> seq_string =
-      NewRawString<StringType>(factory(), length, pretenure_);
-  // Copy prefix into seq_str.
-  SinkChar* dest = seq_string->GetChars();
-  String::WriteToFlat(*prefix, dest, start, end);
-
-  while (c0_ != '"') {
-    // Check for control character (0x00-0x1f) or unterminated string (<0).
-    if (c0_ < 0x20) return Handle<String>::null();
-    if (count >= length) {
-      // We need to create a longer sequential string for the result.
-      return SlowScanJsonString<StringType, SinkChar>(seq_string, 0, count);
-    }
-    if (c0_ != '\\') {
-      // If the sink can contain UC16 characters, or source_ contains only
-      // Latin1 characters, there's no need to test whether we can store the
-      // character. Otherwise check whether the UC16 source character can fit
-      // in the Latin1 sink.
-      if (sizeof(SinkChar) == kUC16Size || seq_one_byte ||
-          c0_ <= String::kMaxOneByteCharCode) {
-        SeqStringSet(seq_string, count++, c0_);
-        Advance();
-      } else {
-        // StringType is SeqOneByteString and we just read a non-Latin1 char.
-        return SlowScanJsonString<SeqTwoByteString, uc16>(seq_string, 0, count);
-      }
-    } else {
-      Advance();  // Advance past the \.
-      switch (c0_) {
-        case '"':
-        case '\\':
-        case '/':
-          SeqStringSet(seq_string, count++, c0_);
-          break;
-        case 'b':
-          SeqStringSet(seq_string, count++, '\x08');
-          break;
-        case 'f':
-          SeqStringSet(seq_string, count++, '\x0c');
-          break;
-        case 'n':
-          SeqStringSet(seq_string, count++, '\x0a');
-          break;
-        case 'r':
-          SeqStringSet(seq_string, count++, '\x0d');
-          break;
-        case 't':
-          SeqStringSet(seq_string, count++, '\x09');
-          break;
-        case 'u': {
-          uc32 value = 0;
-          for (int i = 0; i < 4; i++) {
-            Advance();
-            int digit = HexValue(c0_);
-            if (digit < 0) {
-              return Handle<String>::null();
-            }
-            value = value * 16 + digit;
-          }
-          if (sizeof(SinkChar) == kUC16Size ||
-              value <= String::kMaxOneByteCharCode) {
-            SeqStringSet(seq_string, count++, value);
-            break;
-          } else {
-            // StringType is SeqOneByteString and we just read a non-Latin1
-            // char.
-            position_ -= 6;  // Rewind position_ to \ in \uxxxx.
-            Advance();
-            return SlowScanJsonString<SeqTwoByteString, uc16>(seq_string,
-                                                              0,
-                                                              count);
-          }
-        }
-        default:
-          return Handle<String>::null();
-      }
-      Advance();
-    }
-  }
-
-  DCHECK_EQ('"', c0_);
-  // Advance past the last '"'.
-  AdvanceSkipWhitespace();
-
-  // Shrink seq_string length to count and return.
-  return SeqString::Truncate(seq_string, count);
-}
-
-
-template <bool seq_one_byte>
-template <bool is_internalized>
-Handle<String> JsonParser<seq_one_byte>::ScanJsonString() {
-  DCHECK_EQ('"', c0_);
-  Advance();
-  if (c0_ == '"') {
-    AdvanceSkipWhitespace();
-    return factory()->empty_string();
-  }
-
-  if (seq_one_byte && is_internalized) {
-    // Fast path for existing internalized strings.  If the the string being
-    // parsed is not a known internalized string, contains backslashes or
-    // unexpectedly reaches the end of string, return with an empty handle.
-    uint32_t running_hash = isolate()->heap()->HashSeed();
-    int position = position_;
-    uc32 c0 = c0_;
-    do {
-      if (c0 == '\\') {
-        c0_ = c0;
-        int beg_pos = position_;
-        position_ = position;
-        return SlowScanJsonString<SeqOneByteString, uint8_t>(source_,
-                                                             beg_pos,
-                                                             position_);
-      }
-      if (c0 < 0x20) return Handle<String>::null();
-      running_hash = StringHasher::AddCharacterCore(running_hash,
-                                                    static_cast<uint16_t>(c0));
-      position++;
-      if (position >= source_length_) return Handle<String>::null();
-      c0 = seq_source_->SeqOneByteStringGet(position);
-    } while (c0 != '"');
-    int length = position - position_;
-    uint32_t hash = (length <= String::kMaxHashCalcLength)
-                        ? StringHasher::GetHashCore(running_hash)
-                        : static_cast<uint32_t>(length);
-    Vector<const uint8_t> string_vector(
-        seq_source_->GetChars() + position_, length);
-    StringTable* string_table = isolate()->heap()->string_table();
-    uint32_t capacity = string_table->Capacity();
-    uint32_t entry = StringTable::FirstProbe(hash, capacity);
-    uint32_t count = 1;
-    Handle<String> result;
-    while (true) {
-      Object* element = string_table->KeyAt(entry);
-      if (element == isolate()->heap()->undefined_value()) {
-        // Lookup failure.
-        result = factory()->InternalizeOneByteString(
-            seq_source_, position_, length);
-        break;
-      }
-      if (element != isolate()->heap()->the_hole_value() &&
-          String::cast(element)->IsOneByteEqualTo(string_vector)) {
-        result = Handle<String>(String::cast(element), isolate());
-#ifdef DEBUG
-        uint32_t hash_field =
-            (hash << String::kHashShift) | String::kIsNotArrayIndexMask;
-        DCHECK_EQ(static_cast<int>(result->Hash()),
-                  static_cast<int>(hash_field >> String::kHashShift));
-#endif
-        break;
-      }
-      entry = StringTable::NextProbe(entry, count++, capacity);
-    }
-    position_ = position;
-    // Advance past the last '"'.
-    AdvanceSkipWhitespace();
-    return result;
-  }
-
-  int beg_pos = position_;
-  // Fast case for Latin1 only without escape characters.
-  do {
-    // Check for control character (0x00-0x1f) or unterminated string (<0).
-    if (c0_ < 0x20) return Handle<String>::null();
-    if (c0_ != '\\') {
-      if (seq_one_byte || c0_ <= String::kMaxOneByteCharCode) {
-        Advance();
-      } else {
-        return SlowScanJsonString<SeqTwoByteString, uc16>(source_,
-                                                          beg_pos,
-                                                          position_);
-      }
-    } else {
-      return SlowScanJsonString<SeqOneByteString, uint8_t>(source_,
-                                                           beg_pos,
-                                                           position_);
-    }
-  } while (c0_ != '"');
-  int length = position_ - beg_pos;
-  Handle<String> result =
-      factory()->NewRawOneByteString(length, pretenure_).ToHandleChecked();
-  uint8_t* dest = SeqOneByteString::cast(*result)->GetChars();
-  String::WriteToFlat(*source_, dest, beg_pos, position_);
-
-  DCHECK_EQ('"', c0_);
-  // Advance past the last '"'.
-  AdvanceSkipWhitespace();
-  return result;
-}
-
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_JSON_PARSER_H_