Unify code for fast and slow path of JSON.stringify.

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5153 matching lines @@
   ASSERT(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(String, source, 0);
   Handle<String> string = FlattenGetString(source);
   String::FlatContent content = string->GetFlatContent();
   ASSERT(content.IsFlat());
   return content.IsAscii() ? *URIUnescape::Unescape<uint8_t>(isolate, source)
                            : *URIUnescape::Unescape<uc16>(isolate, source);
 }
 
 
-static const unsigned int kQuoteTableLength = 128u;
-
-static const int kJsonQuotesCharactersPerEntry = 8;
-static const char* const JsonQuotes =
-    "\\u0000  \\u0001  \\u0002  \\u0003  "
-    "\\u0004  \\u0005  \\u0006  \\u0007  "
-    "\\b      \\t      \\n      \\u000b  "
-    "\\f      \\r      \\u000e  \\u000f  "
-    "\\u0010  \\u0011  \\u0012  \\u0013  "
-    "\\u0014  \\u0015  \\u0016  \\u0017  "
-    "\\u0018  \\u0019  \\u001a  \\u001b  "
-    "\\u001c  \\u001d  \\u001e  \\u001f  "
-    "        !       \\\"      #       "
-    "$       %       &       '       "
-    "(       )       *       +       "
-    ",       -       .       /       "
-    "0       1       2       3       "
-    "4       5       6       7       "
-    "8       9       :       ;       "
-    "<       =       >       ?       "
-    "@       A       B       C       "
-    "D       E       F       G       "
-    "H       I       J       K       "
-    "L       M       N       O       "
-    "P       Q       R       S       "
-    "T       U       V       W       "
-    "X       Y       Z       [       "
-    "\\\\      ]       ^       _       "
-    "`       a       b       c       "
-    "d       e       f       g       "
-    "h       i       j       k       "
-    "l       m       n       o       "
-    "p       q       r       s       "
-    "t       u       v       w       "
-    "x       y       z       {       "
-    "|       }       ~       \177       ";
-
-
-// For a string that is less than 32k characters it should always be
-// possible to allocate it in new space.
-static const int kMaxGuaranteedNewSpaceString = 32 * 1024;
-
-
-// Doing JSON quoting cannot make the string more than this many times larger.
-static const int kJsonQuoteWorstCaseBlowup = 6;
-
-static const int kSpaceForQuotesAndComma = 3;
-static const int kSpaceForBrackets = 2;
-
-// Covers the entire ASCII range (all other characters are unchanged by JSON
-// quoting).
-static const byte JsonQuoteLengths[kQuoteTableLength] = {
-    6, 6, 6, 6, 6, 6, 6, 6,
-    2, 2, 2, 6, 2, 2, 6, 6,
-    6, 6, 6, 6, 6, 6, 6, 6,
-    6, 6, 6, 6, 6, 6, 6, 6,
-    1, 1, 2, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 2, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1,
-};
-
-
-template <typename StringType>
-MaybeObject* AllocateRawString(Isolate* isolate, int length);
-
-
-template <>
-MaybeObject* AllocateRawString<SeqTwoByteString>(Isolate* isolate, int length) {
-  return isolate->heap()->AllocateRawTwoByteString(length);
-}
-
-
-template <>
-MaybeObject* AllocateRawString<SeqOneByteString>(Isolate* isolate, int length) {
-  return isolate->heap()->AllocateRawOneByteString(length);
-}
-
-
-template <typename Char, typename StringType, bool comma>
-static MaybeObject* SlowQuoteJsonString(Isolate* isolate,
-                                        Vector<const Char> characters) {
-  int length = characters.length();
-  const Char* read_cursor = characters.start();
-  const Char* end = read_cursor + length;
-  const int kSpaceForQuotes = 2 + (comma ? 1 :0);
-  int quoted_length = kSpaceForQuotes;
-  while (read_cursor < end) {
-    Char c = *(read_cursor++);
-    if (static_cast<unsigned>(c) >= kQuoteTableLength) {
-      quoted_length++;
-    } else {
-      quoted_length += JsonQuoteLengths[static_cast<unsigned>(c)];
-    }
-  }
-  MaybeObject* new_alloc = AllocateRawString<StringType>(isolate,
-                                                         quoted_length);
-  Object* new_object;
-  if (!new_alloc->ToObject(&new_object)) {
-    return new_alloc;
-  }
-  StringType* new_string = StringType::cast(new_object);
-
-  Char* write_cursor = reinterpret_cast<Char*>(
-      new_string->address() + SeqString::kHeaderSize);
-  if (comma) *(write_cursor++) = ',';
-  *(write_cursor++) = '"';
-
-  read_cursor = characters.start();
-  while (read_cursor < end) {
-    Char c = *(read_cursor++);
-    if (static_cast<unsigned>(c) >= kQuoteTableLength) {
-      *(write_cursor++) = c;
-    } else {
-      int len = JsonQuoteLengths[static_cast<unsigned>(c)];
-      const char* replacement = JsonQuotes +
-          static_cast<unsigned>(c) * kJsonQuotesCharactersPerEntry;
-      for (int i = 0; i < len; i++) {
-        *write_cursor++ = *replacement++;
-      }
-    }
-  }
-  *(write_cursor++) = '"';
-  return new_string;
-}
-
-
-template <typename SinkChar, typename SourceChar>
-static inline SinkChar* WriteQuoteJsonString(
-    Isolate* isolate,
-    SinkChar* write_cursor,
-    Vector<const SourceChar> characters) {
-  // SinkChar is only char if SourceChar is guaranteed to be char.
-  ASSERT(sizeof(SinkChar) >= sizeof(SourceChar));
-  const SourceChar* read_cursor = characters.start();
-  const SourceChar* end = read_cursor + characters.length();
-  *(write_cursor++) = '"';
-  while (read_cursor < end) {
-    SourceChar c = *(read_cursor++);
-    if (static_cast<unsigned>(c) >= kQuoteTableLength) {
-      *(write_cursor++) = static_cast<SinkChar>(c);
-    } else {
-      int len = JsonQuoteLengths[static_cast<unsigned>(c)];
-      const char* replacement = JsonQuotes +
-          static_cast<unsigned>(c) * kJsonQuotesCharactersPerEntry;
-      write_cursor[0] = replacement[0];
-      if (len > 1) {
-        write_cursor[1] = replacement[1];
-        if (len > 2) {
-          ASSERT(len == 6);
-          write_cursor[2] = replacement[2];
-          write_cursor[3] = replacement[3];
-          write_cursor[4] = replacement[4];
-          write_cursor[5] = replacement[5];
-        }
-      }
-      write_cursor += len;
-    }
-  }
-  *(write_cursor++) = '"';
-  return write_cursor;
-}
-
-
-template <typename Char, typename StringType, bool comma>
-static MaybeObject* QuoteJsonString(Isolate* isolate,
-                                    Vector<const Char> characters) {
-  int length = characters.length();
-  isolate->counters()->quote_json_char_count()->Increment(length);
-  int worst_case_length =
-        length * kJsonQuoteWorstCaseBlowup + kSpaceForQuotesAndComma;
-  if (worst_case_length > kMaxGuaranteedNewSpaceString) {
-    return SlowQuoteJsonString<Char, StringType, comma>(isolate, characters);
-  }
-
-  MaybeObject* new_alloc = AllocateRawString<StringType>(isolate,
-                                                         worst_case_length);
-  Object* new_object;
-  if (!new_alloc->ToObject(&new_object)) {
-    return new_alloc;
-  }
-  if (!isolate->heap()->new_space()->Contains(new_object)) {
-    // Even if our string is small enough to fit in new space we still have to
-    // handle it being allocated in old space as may happen in the third
-    // attempt.  See CALL_AND_RETRY in heap-inl.h and similar code in
-    // CEntryStub::GenerateCore.
-    return SlowQuoteJsonString<Char, StringType, comma>(isolate, characters);
-  }
-  StringType* new_string = StringType::cast(new_object);
-  ASSERT(isolate->heap()->new_space()->Contains(new_string));
-
-  Char* write_cursor = reinterpret_cast<Char*>(
-      new_string->address() + SeqString::kHeaderSize);
-  if (comma) *(write_cursor++) = ',';
-  write_cursor = WriteQuoteJsonString<Char, Char>(isolate,
-                                                  write_cursor,
-                                                  characters);
-  int final_length = static_cast<int>(
-      write_cursor - reinterpret_cast<Char*>(
-          new_string->address() + SeqString::kHeaderSize));
-  isolate->heap()->new_space()->
-      template ShrinkStringAtAllocationBoundary<StringType>(
-          new_string, final_length);
-  return new_string;
-}
-
-
 RUNTIME_FUNCTION(MaybeObject*, Runtime_QuoteJSONString) {
-  NoHandleAllocation ha(isolate);
-  CONVERT_ARG_CHECKED(String, str, 0);
-  if (!str->IsFlat()) {
-    MaybeObject* try_flatten = str->TryFlatten();
-    Object* flat;
-    if (!try_flatten->ToObject(&flat)) {
-      return try_flatten;
-    }
-    str = String::cast(flat);
-    ASSERT(str->IsFlat());
-  }
-  String::FlatContent flat = str->GetFlatContent();
-  ASSERT(flat.IsFlat());
-  if (flat.IsTwoByte()) {
-    return QuoteJsonString<uc16, SeqTwoByteString, false>(isolate,
-                                                          flat.ToUC16Vector());
-  } else {
-    return QuoteJsonString<uint8_t, SeqOneByteString, false>(
-        isolate,
-        flat.ToOneByteVector());
-  }
+  HandleScope scope(isolate);
+  CONVERT_ARG_HANDLE_CHECKED(String, string, 0);
+  ASSERT(args.length() == 1);
+  return BasicJsonStringifier::StringifyString(isolate, string);
 }
 
 
-RUNTIME_FUNCTION(MaybeObject*, Runtime_QuoteJSONStringComma) {
-  NoHandleAllocation ha(isolate);
-  CONVERT_ARG_CHECKED(String, str, 0);
-  if (!str->IsFlat()) {
-    MaybeObject* try_flatten = str->TryFlatten();
-    Object* flat;
-    if (!try_flatten->ToObject(&flat)) {
-      return try_flatten;
-    }
-    str = String::cast(flat);
-    ASSERT(str->IsFlat());
-  }
-  String::FlatContent flat = str->GetFlatContent();
-  if (flat.IsTwoByte()) {
-    return QuoteJsonString<uc16, SeqTwoByteString, true>(isolate,
-                                                         flat.ToUC16Vector());
-  } else {
-    return QuoteJsonString<uint8_t, SeqOneByteString, true>(
-        isolate,
-        flat.ToOneByteVector());
-  }
-}
-
-
-template <typename Char, typename StringType>
-static MaybeObject* QuoteJsonStringArray(Isolate* isolate,
-                                         FixedArray* array,
-                                         int worst_case_length) {
-  int length = array->length();
-
-  MaybeObject* new_alloc = AllocateRawString<StringType>(isolate,
-                                                         worst_case_length);
-  Object* new_object;
-  if (!new_alloc->ToObject(&new_object)) {
-    return new_alloc;
-  }
-  if (!isolate->heap()->new_space()->Contains(new_object)) {
-    // Even if our string is small enough to fit in new space we still have to
-    // handle it being allocated in old space as may happen in the third
-    // attempt.  See CALL_AND_RETRY in heap-inl.h and similar code in
-    // CEntryStub::GenerateCore.
-    return isolate->heap()->undefined_value();
-  }
-  AssertNoAllocation no_gc;
-  StringType* new_string = StringType::cast(new_object);
-  ASSERT(isolate->heap()->new_space()->Contains(new_string));
-
-  Char* write_cursor = reinterpret_cast<Char*>(
-      new_string->address() + SeqString::kHeaderSize);
-  *(write_cursor++) = '[';
-  for (int i = 0; i < length; i++) {
-    if (i != 0) *(write_cursor++) = ',';
-    String* str = String::cast(array->get(i));
-    String::FlatContent content = str->GetFlatContent();
-    ASSERT(content.IsFlat());
-    if (content.IsTwoByte()) {
-      write_cursor = WriteQuoteJsonString<Char, uc16>(isolate,
-                                                      write_cursor,
-                                                      content.ToUC16Vector());
-    } else {
-      write_cursor =
-          WriteQuoteJsonString<Char, uint8_t>(isolate,
-                                              write_cursor,
-                                              content.ToOneByteVector());
-    }
-  }
-  *(write_cursor++) = ']';
-
-  int final_length = static_cast<int>(
-      write_cursor - reinterpret_cast<Char*>(
-          new_string->address() + SeqString::kHeaderSize));
-  isolate->heap()->new_space()->
-      template ShrinkStringAtAllocationBoundary<StringType>(
-          new_string, final_length);
-  return new_string;
-}
-
-
-RUNTIME_FUNCTION(MaybeObject*, Runtime_QuoteJSONStringArray) {
-  NoHandleAllocation ha(isolate);
-  ASSERT(args.length() == 1);
-  CONVERT_ARG_CHECKED(JSArray, array, 0);
-
-  if (!array->HasFastObjectElements()) {
-    return isolate->heap()->undefined_value();
-  }
-  FixedArray* elements = FixedArray::cast(array->elements());
-  int n = elements->length();
-  bool ascii = true;
-  int total_length = 0;
-
-  for (int i = 0; i < n; i++) {
-    Object* elt = elements->get(i);
-    if (!elt->IsString()) return isolate->heap()->undefined_value();
-    String* element = String::cast(elt);
-    if (!element->IsFlat()) return isolate->heap()->undefined_value();
-    total_length += element->length();
-    if (ascii && element->IsTwoByteRepresentation()) {
-      ascii = false;
-    }
-  }
-
-  int worst_case_length =
-      kSpaceForBrackets + n * kSpaceForQuotesAndComma
-      + total_length * kJsonQuoteWorstCaseBlowup;
-
-  if (worst_case_length > kMaxGuaranteedNewSpaceString) {
-    return isolate->heap()->undefined_value();
-  }
-
-  if (ascii) {
-    return QuoteJsonStringArray<char, SeqOneByteString>(isolate,
-                                                      elements,
-                                                      worst_case_length);
-  } else {
-    return QuoteJsonStringArray<uc16, SeqTwoByteString>(isolate,
-                                                        elements,
-                                                        worst_case_length);
-  }
-}
-
-
 RUNTIME_FUNCTION(MaybeObject*, Runtime_BasicJSONStringify) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   BasicJsonStringifier stringifier(isolate);
   return stringifier.Stringify(Handle<Object>(args[0], isolate));
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_StringParseInt) {
   NoHandleAllocation ha(isolate);
@@ skipping 7859 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal