// Copyright 2012 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_STRINGIFIER_H_
#define V8_JSON_STRINGIFIER_H_
#include "src/v8.h"
#include "src/conversions.h"
#include "src/utils.h"
namespace v8 {
namespace internal {
class BasicJsonStringifier BASE_EMBEDDED {
public:
explicit BasicJsonStringifier(Isolate* isolate);
MUST_USE_RESULT MaybeHandle<Object> Stringify(Handle<Object> object);
MUST_USE_RESULT INLINE(static MaybeHandle<Object> StringifyString(
Isolate* isolate,
Handle<String> object));
private:
static const int kInitialPartLength = 32;
static const int kMaxPartLength = 16 * 1024;
static const int kPartLengthGrowthFactor = 2;
enum Result { UNCHANGED, SUCCESS, EXCEPTION };
void Accumulate();
void Extend();
void ChangeEncoding();
INLINE(void ShrinkCurrentPart());
template <bool is_one_byte, typename Char>
INLINE(void Append_(Char c));
template <bool is_one_byte, typename Char>
INLINE(void Append_(const Char* chars));
INLINE(void Append(uint8_t c)) {
if (is_one_byte_) {
Append_<true>(c);
} else {
Append_<false>(c);
}
}
INLINE(void AppendOneByte(const char* chars)) {
if (is_one_byte_) {
Append_<true>(reinterpret_cast<const uint8_t*>(chars));
} else {
Append_<false>(reinterpret_cast<const uint8_t*>(chars));
}
}
MUST_USE_RESULT MaybeHandle<Object> ApplyToJsonFunction(
Handle<Object> object,
Handle<Object> key);
Result SerializeGeneric(Handle<Object> object,
Handle<Object> key,
bool deferred_comma,
bool deferred_key);
template <typename ResultType, typename Char>
INLINE(static Handle<String> StringifyString_(Isolate* isolate,
Vector<Char> vector,
Handle<String> result));
// Entry point to serialize the object.
INLINE(Result SerializeObject(Handle<Object> obj)) {
return Serialize_<false>(obj, false, factory_->empty_string());
}
// Serialize an array element.
// The index may serve as argument for the toJSON function.
INLINE(Result SerializeElement(Isolate* isolate,
Handle<Object> object,
int i)) {
return Serialize_<false>(object,
false,
Handle<Object>(Smi::FromInt(i), isolate));
}
// Serialize a object property.
// The key may or may not be serialized depending on the property.
// The key may also serve as argument for the toJSON function.
INLINE(Result SerializeProperty(Handle<Object> object,
bool deferred_comma,
Handle<String> deferred_key)) {
DCHECK(!deferred_key.is_null());
return Serialize_<true>(object, deferred_comma, deferred_key);
}
template <bool deferred_string_key>
Result Serialize_(Handle<Object> object, bool comma, Handle<Object> key);
void SerializeDeferredKey(bool deferred_comma, Handle<Object> deferred_key) {
if (deferred_comma) Append(',');
SerializeString(Handle<String>::cast(deferred_key));
Append(':');
}
Result SerializeSmi(Smi* object);
Result SerializeDouble(double number);
INLINE(Result SerializeHeapNumber(Handle<HeapNumber> object)) {
return SerializeDouble(object->value());
}
Result SerializeJSValue(Handle<JSValue> object);
INLINE(Result SerializeJSArray(Handle<JSArray> object));
INLINE(Result SerializeJSObject(Handle<JSObject> object));
Result SerializeJSArraySlow(Handle<JSArray> object, uint32_t length);
void SerializeString(Handle<String> object);
template <typename SrcChar, typename DestChar>
INLINE(static int SerializeStringUnchecked_(const SrcChar* src,
DestChar* dest,
int length));
template <bool is_one_byte, typename Char>
INLINE(void SerializeString_(Handle<String> string));
template <typename Char>
INLINE(static bool DoNotEscape(Char c));
template <typename Char>
INLINE(static Vector<const Char> GetCharVector(Handle<String> string));
Result StackPush(Handle<Object> object);
void StackPop();
INLINE(Handle<String> accumulator()) {
return Handle<String>(String::cast(accumulator_store_->value()), isolate_);
}
INLINE(void set_accumulator(Handle<String> string)) {
return accumulator_store_->set_value(*string);
}
Isolate* isolate_;
Factory* factory_;
// We use a value wrapper for the string accumulator to keep the
// (indirect) handle to it in the outermost handle scope.
Handle<JSValue> accumulator_store_;
Handle<String> current_part_;
Handle<String> tojson_string_;
Handle<JSArray> stack_;
int current_index_;
int part_length_;
bool is_one_byte_;
bool overflowed_;
static const int kJsonEscapeTableEntrySize = 8;
static const char* const JsonEscapeTable;
};
// Translation table to escape Latin1 characters.
// Table entries start at a multiple of 8 and are null-terminated.
const char* const BasicJsonStringifier::JsonEscapeTable =
"\\u0000\0 \\u0001\0 \\u0002\0 \\u0003\0 "
"\\u0004\0 \\u0005\0 \\u0006\0 \\u0007\0 "
"\\b\0 \\t\0 \\n\0 \\u000b\0 "
"\\f\0 \\r\0 \\u000e\0 \\u000f\0 "
"\\u0010\0 \\u0011\0 \\u0012\0 \\u0013\0 "
"\\u0014\0 \\u0015\0 \\u0016\0 \\u0017\0 "
"\\u0018\0 \\u0019\0 \\u001a\0 \\u001b\0 "
"\\u001c\0 \\u001d\0 \\u001e\0 \\u001f\0 "
" \0 !\0 \\\"\0 #\0 "
"$\0 %\0 &\0 '\0 "
"(\0 )\0 *\0 +\0 "
",\0 -\0 .\0 /\0 "
"0\0 1\0 2\0 3\0 "
"4\0 5\0 6\0 7\0 "
"8\0 9\0 :\0 ;\0 "
"<\0 =\0 >\0 ?\0 "
"@\0 A\0 B\0 C\0 "
"D\0 E\0 F\0 G\0 "
"H\0 I\0 J\0 K\0 "
"L\0 M\0 N\0 O\0 "
"P\0 Q\0 R\0 S\0 "
"T\0 U\0 V\0 W\0 "
"X\0 Y\0 Z\0 [\0 "
"\\\\\0 ]\0 ^\0 _\0 "
"`\0 a\0 b\0 c\0 "
"d\0 e\0 f\0 g\0 "
"h\0 i\0 j\0 k\0 "
"l\0 m\0 n\0 o\0 "
"p\0 q\0 r\0 s\0 "
"t\0 u\0 v\0 w\0 "
"x\0 y\0 z\0 {\0 "
"|\0 }\0 ~\0 \177\0 "
"\200\0 \201\0 \202\0 \203\0 "
"\204\0 \205\0 \206\0 \207\0 "
"\210\0 \211\0 \212\0 \213\0 "
"\214\0 \215\0 \216\0 \217\0 "
"\220\0 \221\0 \222\0 \223\0 "
"\224\0 \225\0 \226\0 \227\0 "
"\230\0 \231\0 \232\0 \233\0 "
"\234\0 \235\0 \236\0 \237\0 "
"\240\0 \241\0 \242\0 \243\0 "
"\244\0 \245\0 \246\0 \247\0 "
"\250\0 \251\0 \252\0 \253\0 "
"\254\0 \255\0 \256\0 \257\0 "
"\260\0 \261\0 \262\0 \263\0 "
"\264\0 \265\0 \266\0 \267\0 "
"\270\0 \271\0 \272\0 \273\0 "
"\274\0 \275\0 \276\0 \277\0 "
"\300\0 \301\0 \302\0 \303\0 "
"\304\0 \305\0 \306\0 \307\0 "
"\310\0 \311\0 \312\0 \313\0 "
"\314\0 \315\0 \316\0 \317\0 "
"\320\0 \321\0 \322\0 \323\0 "
"\324\0 \325\0 \326\0 \327\0 "
"\330\0 \331\0 \332\0 \333\0 "
"\334\0 \335\0 \336\0 \337\0 "
"\340\0 \341\0 \342\0 \343\0 "
"\344\0 \345\0 \346\0 \347\0 "
"\350\0 \351\0 \352\0 \353\0 "
"\354\0 \355\0 \356\0 \357\0 "
"\360\0 \361\0 \362\0 \363\0 "
"\364\0 \365\0 \366\0 \367\0 "
"\370\0 \371\0 \372\0 \373\0 "
"\374\0 \375\0 \376\0 \377\0 ";
BasicJsonStringifier::BasicJsonStringifier(Isolate* isolate)
: isolate_(isolate),
current_index_(0),
is_one_byte_(true),
overflowed_(false) {
factory_ = isolate_->factory();
accumulator_store_ = Handle<JSValue>::cast(
Object::ToObject(isolate, factory_->empty_string()).ToHandleChecked());
part_length_ = kInitialPartLength;
current_part_ = factory_->NewRawOneByteString(part_length_).ToHandleChecked();
tojson_string_ = factory_->toJSON_string();
stack_ = factory_->NewJSArray(8);
}
MaybeHandle<Object> BasicJsonStringifier::Stringify(Handle<Object> object) {
Result result = SerializeObject(object);
if (result == UNCHANGED) return isolate_->factory()->undefined_value();
if (result == SUCCESS) {
ShrinkCurrentPart();
Accumulate();
if (overflowed_) {
THROW_NEW_ERROR(isolate_, NewInvalidStringLengthError(), Object);
}
return accumulator();
}
DCHECK(result == EXCEPTION);
return MaybeHandle<Object>();
}
MaybeHandle<Object> BasicJsonStringifier::StringifyString(
Isolate* isolate, Handle<String> object) {
static const int kJsonQuoteWorstCaseBlowup = 6;
static const int kSpaceForQuotes = 2;
int worst_case_length =
object->length() * kJsonQuoteWorstCaseBlowup + kSpaceForQuotes;
if (worst_case_length > 32 * KB) { // Slow path if too large.
BasicJsonStringifier stringifier(isolate);
return stringifier.Stringify(object);
}
object = String::Flatten(object);
DCHECK(object->IsFlat());
if (object->IsOneByteRepresentationUnderneath()) {
Handle<String> result = isolate->factory()->NewRawOneByteString(
worst_case_length).ToHandleChecked();
DisallowHeapAllocation no_gc;
return StringifyString_<SeqOneByteString>(
isolate,
object->GetFlatContent().ToOneByteVector(),
result);
} else {
Handle<String> result = isolate->factory()->NewRawTwoByteString(
worst_case_length).ToHandleChecked();
DisallowHeapAllocation no_gc;
return StringifyString_<SeqTwoByteString>(
isolate,
object->GetFlatContent().ToUC16Vector(),
result);
}
}
template <typename ResultType, typename Char>
Handle<String> BasicJsonStringifier::StringifyString_(Isolate* isolate,
Vector<Char> vector,
Handle<String> result) {
DisallowHeapAllocation no_gc;
int final_size = 0;
ResultType* dest = ResultType::cast(*result);
dest->Set(final_size++, '\"');
final_size += SerializeStringUnchecked_(vector.start(),
dest->GetChars() + 1,
vector.length());
dest->Set(final_size++, '\"');
return SeqString::Truncate(Handle<SeqString>::cast(result), final_size);
}
template <bool is_one_byte, typename Char>
void BasicJsonStringifier::Append_(Char c) {
if (is_one_byte) {
SeqOneByteString::cast(*current_part_)->SeqOneByteStringSet(
current_index_++, c);
} else {
SeqTwoByteString::cast(*current_part_)->SeqTwoByteStringSet(
current_index_++, c);
}
if (current_index_ == part_length_) Extend();
}
template <bool is_one_byte, typename Char>
void BasicJsonStringifier::Append_(const Char* chars) {
for (; *chars != '\0'; chars++) Append_<is_one_byte, Char>(*chars);
}
MaybeHandle<Object> BasicJsonStringifier::ApplyToJsonFunction(
Handle<Object> object, Handle<Object> key) {
LookupIterator it(object, tojson_string_,
LookupIterator::PROTOTYPE_CHAIN_SKIP_INTERCEPTOR);
Handle<Object> fun;
ASSIGN_RETURN_ON_EXCEPTION(isolate_, fun, Object::GetProperty(&it), Object);
if (!fun->IsJSFunction()) return object;
// Call toJSON function.
if (key->IsSmi()) key = factory_->NumberToString(key);
Handle<Object> argv[] = { key };
HandleScope scope(isolate_);
ASSIGN_RETURN_ON_EXCEPTION(
isolate_, object,
Execution::Call(isolate_, fun, object, 1, argv),
Object);
return scope.CloseAndEscape(object);
}
BasicJsonStringifier::Result BasicJsonStringifier::StackPush(
Handle<Object> object) {
StackLimitCheck check(isolate_);
if (check.HasOverflowed()) {
isolate_->StackOverflow();
return EXCEPTION;
}
int length = Smi::cast(stack_->length())->value();
{
DisallowHeapAllocation no_allocation;
FixedArray* elements = FixedArray::cast(stack_->elements());
for (int i = 0; i < length; i++) {
if (elements->get(i) == *object) {
AllowHeapAllocation allow_to_return_error;
Handle<Object> error;
MaybeHandle<Object> maybe_error = factory_->NewTypeError(
"circular_structure", HandleVector<Object>(NULL, 0));
if (maybe_error.ToHandle(&error)) isolate_->Throw(*error);
return EXCEPTION;
}
}
}
JSArray::EnsureSize(stack_, length + 1);
FixedArray::cast(stack_->elements())->set(length, *object);
stack_->set_length(Smi::FromInt(length + 1));
return SUCCESS;
}
void BasicJsonStringifier::StackPop() {
int length = Smi::cast(stack_->length())->value();
stack_->set_length(Smi::FromInt(length - 1));
}
template <bool deferred_string_key>
BasicJsonStringifier::Result BasicJsonStringifier::Serialize_(
Handle<Object> object, bool comma, Handle<Object> key) {
if (object->IsJSObject()) {
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, object,
ApplyToJsonFunction(object, key),
EXCEPTION);
}
if (object->IsSmi()) {
if (deferred_string_key) SerializeDeferredKey(comma, key);
return SerializeSmi(Smi::cast(*object));
}
switch (HeapObject::cast(*object)->map()->instance_type()) {
case HEAP_NUMBER_TYPE:
case MUTABLE_HEAP_NUMBER_TYPE:
if (deferred_string_key) SerializeDeferredKey(comma, key);
return SerializeHeapNumber(Handle<HeapNumber>::cast(object));
case ODDBALL_TYPE:
switch (Oddball::cast(*object)->kind()) {
case Oddball::kFalse:
if (deferred_string_key) SerializeDeferredKey(comma, key);
AppendOneByte("false");
return SUCCESS;
case Oddball::kTrue:
if (deferred_string_key) SerializeDeferredKey(comma, key);
AppendOneByte("true");
return SUCCESS;
case Oddball::kNull:
if (deferred_string_key) SerializeDeferredKey(comma, key);
AppendOneByte("null");
return SUCCESS;
default:
return UNCHANGED;
}
case JS_ARRAY_TYPE:
if (object->IsAccessCheckNeeded()) break;
if (deferred_string_key) SerializeDeferredKey(comma, key);
return SerializeJSArray(Handle<JSArray>::cast(object));
case JS_VALUE_TYPE:
if (deferred_string_key) SerializeDeferredKey(comma, key);
return SerializeJSValue(Handle<JSValue>::cast(object));
case JS_FUNCTION_TYPE:
return UNCHANGED;
default:
if (object->IsString()) {
if (deferred_string_key) SerializeDeferredKey(comma, key);
SerializeString(Handle<String>::cast(object));
return SUCCESS;
} else if (object->IsJSObject()) {
// Go to slow path for global proxy and objects requiring access checks.
if (object->IsAccessCheckNeeded() || object->IsJSGlobalProxy()) break;
if (deferred_string_key) SerializeDeferredKey(comma, key);
return SerializeJSObject(Handle<JSObject>::cast(object));
}
}
return SerializeGeneric(object, key, comma, deferred_string_key);
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeGeneric(
Handle<Object> object,
Handle<Object> key,
bool deferred_comma,
bool deferred_key) {
Handle<JSObject> builtins(isolate_->native_context()->builtins(), isolate_);
Handle<JSFunction> builtin = Handle<JSFunction>::cast(Object::GetProperty(
isolate_, builtins, "JSONSerializeAdapter").ToHandleChecked());
Handle<Object> argv[] = { key, object };
Handle<Object> result;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, result,
Execution::Call(isolate_, builtin, object, 2, argv),
EXCEPTION);
if (result->IsUndefined()) return UNCHANGED;
if (deferred_key) {
if (key->IsSmi()) key = factory_->NumberToString(key);
SerializeDeferredKey(deferred_comma, key);
}
Handle<String> result_string = Handle<String>::cast(result);
// Shrink current part, attach it to the accumulator, also attach the result
// string to the accumulator, and allocate a new part.
ShrinkCurrentPart(); // Shrink.
part_length_ = kInitialPartLength; // Allocate conservatively.
Extend(); // Attach current part and allocate new part.
// Attach result string to the accumulator.
Handle<String> cons;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, cons,
factory_->NewConsString(accumulator(), result_string),
EXCEPTION);
set_accumulator(cons);
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeJSValue(
Handle<JSValue> object) {
String* class_name = object->class_name();
if (class_name == isolate_->heap()->String_string()) {
Handle<Object> value;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, value, Execution::ToString(isolate_, object), EXCEPTION);
SerializeString(Handle<String>::cast(value));
} else if (class_name == isolate_->heap()->Number_string()) {
Handle<Object> value;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, value, Execution::ToNumber(isolate_, object), EXCEPTION);
if (value->IsSmi()) return SerializeSmi(Smi::cast(*value));
SerializeHeapNumber(Handle<HeapNumber>::cast(value));
} else {
DCHECK(class_name == isolate_->heap()->Boolean_string());
Object* value = JSValue::cast(*object)->value();
DCHECK(value->IsBoolean());
AppendOneByte(value->IsTrue() ? "true" : "false");
}
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeSmi(Smi* object) {
static const int kBufferSize = 100;
char chars[kBufferSize];
Vector<char> buffer(chars, kBufferSize);
AppendOneByte(IntToCString(object->value(), buffer));
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeDouble(
double number) {
if (std::isinf(number) || std::isnan(number)) {
AppendOneByte("null");
return SUCCESS;
}
static const int kBufferSize = 100;
char chars[kBufferSize];
Vector<char> buffer(chars, kBufferSize);
AppendOneByte(DoubleToCString(number, buffer));
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeJSArray(
Handle<JSArray> object) {
HandleScope handle_scope(isolate_);
Result stack_push = StackPush(object);
if (stack_push != SUCCESS) return stack_push;
uint32_t length = 0;
CHECK(object->length()->ToArrayIndex(&length));
Append('[');
switch (object->GetElementsKind()) {
case FAST_SMI_ELEMENTS: {
Handle<FixedArray> elements(
FixedArray::cast(object->elements()), isolate_);
for (uint32_t i = 0; i < length; i++) {
if (i > 0) Append(',');
SerializeSmi(Smi::cast(elements->get(i)));
}
break;
}
case FAST_DOUBLE_ELEMENTS: {
// Empty array is FixedArray but not FixedDoubleArray.
if (length == 0) break;
Handle<FixedDoubleArray> elements(
FixedDoubleArray::cast(object->elements()), isolate_);
for (uint32_t i = 0; i < length; i++) {
if (i > 0) Append(',');
SerializeDouble(elements->get_scalar(i));
}
break;
}
case FAST_ELEMENTS: {
Handle<FixedArray> elements(
FixedArray::cast(object->elements()), isolate_);
for (uint32_t i = 0; i < length; i++) {
if (i > 0) Append(',');
Result result =
SerializeElement(isolate_,
Handle<Object>(elements->get(i), isolate_),
i);
if (result == SUCCESS) continue;
if (result == UNCHANGED) {
AppendOneByte("null");
} else {
return result;
}
}
break;
}
// TODO(yangguo): The FAST_HOLEY_* cases could be handled in a faster way.
// They resemble the non-holey cases except that a prototype chain lookup
// is necessary for holes.
default: {
Result result = SerializeJSArraySlow(object, length);
if (result != SUCCESS) return result;
break;
}
}
Append(']');
StackPop();
current_part_ = handle_scope.CloseAndEscape(current_part_);
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeJSArraySlow(
Handle<JSArray> object, uint32_t length) {
for (uint32_t i = 0; i < length; i++) {
if (i > 0) Append(',');
Handle<Object> element;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, element,
Object::GetElement(isolate_, object, i),
EXCEPTION);
if (element->IsUndefined()) {
AppendOneByte("null");
} else {
Result result = SerializeElement(isolate_, element, i);
if (result == SUCCESS) continue;
if (result == UNCHANGED) {
AppendOneByte("null");
} else {
return result;
}
}
}
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeJSObject(
Handle<JSObject> object) {
HandleScope handle_scope(isolate_);
Result stack_push = StackPush(object);
if (stack_push != SUCCESS) return stack_push;
DCHECK(!object->IsJSGlobalProxy() && !object->IsGlobalObject());
Append('{');
bool comma = false;
if (object->HasFastProperties() &&
!object->HasIndexedInterceptor() &&
!object->HasNamedInterceptor() &&
object->elements()->length() == 0) {
Handle<Map> map(object->map());
for (int i = 0; i < map->NumberOfOwnDescriptors(); i++) {
Handle<Name> name(map->instance_descriptors()->GetKey(i), isolate_);
// TODO(rossberg): Should this throw?
if (!name->IsString()) continue;
Handle<String> key = Handle<String>::cast(name);
PropertyDetails details = map->instance_descriptors()->GetDetails(i);
if (details.IsDontEnum()) continue;
Handle<Object> property;
if (details.type() == FIELD && *map == object->map()) {
property = Handle<Object>(object->RawFastPropertyAt(
FieldIndex::ForDescriptor(*map, i)), isolate_);
} else {
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, property,
Object::GetPropertyOrElement(object, key),
EXCEPTION);
}
Result result = SerializeProperty(property, comma, key);
if (!comma && result == SUCCESS) comma = true;
if (result == EXCEPTION) return result;
}
} else {
Handle<FixedArray> contents;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, contents,
JSReceiver::GetKeys(object, JSReceiver::OWN_ONLY),
EXCEPTION);
for (int i = 0; i < contents->length(); i++) {
Object* key = contents->get(i);
Handle<String> key_handle;
MaybeHandle<Object> maybe_property;
if (key->IsString()) {
key_handle = Handle<String>(String::cast(key), isolate_);
maybe_property = Object::GetPropertyOrElement(object, key_handle);
} else {
DCHECK(key->IsNumber());
key_handle = factory_->NumberToString(Handle<Object>(key, isolate_));
uint32_t index;
if (key->IsSmi()) {
maybe_property = Object::GetElement(
isolate_, object, Smi::cast(key)->value());
} else if (key_handle->AsArrayIndex(&index)) {
maybe_property = Object::GetElement(isolate_, object, index);
} else {
maybe_property = Object::GetPropertyOrElement(object, key_handle);
}
}
Handle<Object> property;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, property, maybe_property, EXCEPTION);
Result result = SerializeProperty(property, comma, key_handle);
if (!comma && result == SUCCESS) comma = true;
if (result == EXCEPTION) return result;
}
}
Append('}');
StackPop();
current_part_ = handle_scope.CloseAndEscape(current_part_);
return SUCCESS;
}
void BasicJsonStringifier::ShrinkCurrentPart() {
DCHECK(current_index_ < part_length_);
current_part_ = SeqString::Truncate(Handle<SeqString>::cast(current_part_),
current_index_);
}
void BasicJsonStringifier::Accumulate() {
if (accumulator()->length() + current_part_->length() > String::kMaxLength) {
// Screw it. Simply set the flag and carry on. Throw exception at the end.
set_accumulator(factory_->empty_string());
overflowed_ = true;
} else {
set_accumulator(factory_->NewConsString(accumulator(),
current_part_).ToHandleChecked());
}
}
void BasicJsonStringifier::Extend() {
Accumulate();
if (part_length_ <= kMaxPartLength / kPartLengthGrowthFactor) {
part_length_ *= kPartLengthGrowthFactor;
}
if (is_one_byte_) {
current_part_ =
factory_->NewRawOneByteString(part_length_).ToHandleChecked();
} else {
current_part_ =
factory_->NewRawTwoByteString(part_length_).ToHandleChecked();
}
DCHECK(!current_part_.is_null());
current_index_ = 0;
}
void BasicJsonStringifier::ChangeEncoding() {
ShrinkCurrentPart();
Accumulate();
current_part_ =
factory_->NewRawTwoByteString(part_length_).ToHandleChecked();
DCHECK(!current_part_.is_null());
current_index_ = 0;
is_one_byte_ = false;
}
template <typename SrcChar, typename DestChar>
int BasicJsonStringifier::SerializeStringUnchecked_(const SrcChar* src,
DestChar* dest,
int length) {
DestChar* dest_start = dest;
// Assert that uc16 character is not truncated down to 8 bit.
// The <uc16, char> version of this method must not be called.
DCHECK(sizeof(*dest) >= sizeof(*src));
for (int i = 0; i < length; i++) {
SrcChar c = src[i];
if (DoNotEscape(c)) {
*(dest++) = static_cast<DestChar>(c);
} else {
const uint8_t* chars = reinterpret_cast<const uint8_t*>(
&JsonEscapeTable[c * kJsonEscapeTableEntrySize]);
while (*chars != '\0') *(dest++) = *(chars++);
}
}
return static_cast<int>(dest - dest_start);
}
template <bool is_one_byte, typename Char>
void BasicJsonStringifier::SerializeString_(Handle<String> string) {
int length = string->length();
Append_<is_one_byte, char>('"');
// We make a rough estimate to find out if the current string can be
// serialized without allocating a new string part. The worst case length of
// an escaped character is 6. Shifting the remainin string length right by 3
// is a more pessimistic estimate, but faster to calculate.
if (((part_length_ - current_index_) >> 3) > length) {
DisallowHeapAllocation no_gc;
Vector<const Char> vector = GetCharVector<Char>(string);
if (is_one_byte) {
current_index_ += SerializeStringUnchecked_(
vector.start(),
SeqOneByteString::cast(*current_part_)->GetChars() + current_index_,
length);
} else {
current_index_ += SerializeStringUnchecked_(
vector.start(),
SeqTwoByteString::cast(*current_part_)->GetChars() + current_index_,
length);
}
} else {
String* string_location = NULL;
Vector<const Char> vector(NULL, 0);
for (int i = 0; i < length; i++) {
// If GC moved the string, we need to refresh the vector.
if (*string != string_location) {
DisallowHeapAllocation no_gc;
// This does not actually prevent the string from being relocated later.
vector = GetCharVector<Char>(string);
string_location = *string;
}
Char c = vector[i];
if (DoNotEscape(c)) {
Append_<is_one_byte, Char>(c);
} else {
Append_<is_one_byte, uint8_t>(reinterpret_cast<const uint8_t*>(
&JsonEscapeTable[c * kJsonEscapeTableEntrySize]));
}
}
}
Append_<is_one_byte, uint8_t>('"');
}
template <>
bool BasicJsonStringifier::DoNotEscape(uint8_t c) {
return c >= '#' && c <= '~' && c != '\\';
}
template <>
bool BasicJsonStringifier::DoNotEscape(uint16_t c) {
return c >= '#' && c != '\\' && c != 0x7f;
}
template <>
Vector<const uint8_t> BasicJsonStringifier::GetCharVector(
Handle<String> string) {
String::FlatContent flat = string->GetFlatContent();
DCHECK(flat.IsOneByte());
return flat.ToOneByteVector();
}
template <>
Vector<const uc16> BasicJsonStringifier::GetCharVector(Handle<String> string) {
String::FlatContent flat = string->GetFlatContent();
DCHECK(flat.IsTwoByte());
return flat.ToUC16Vector();
}
void BasicJsonStringifier::SerializeString(Handle<String> object) {
object = String::Flatten(object);
if (is_one_byte_) {
if (object->IsOneByteRepresentationUnderneath()) {
SerializeString_<true, uint8_t>(object);
} else {
ChangeEncoding();
SerializeString(object);
}
} else {
if (object->IsOneByteRepresentationUnderneath()) {
SerializeString_<false, uint8_t>(object);
} else {
SerializeString_<false, uc16>(object);
}
}
}
} } // namespace v8::internal
#endif // V8_JSON_STRINGIFIER_H_