// 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/conversions.h"
#include "src/lookup.h"
#include "src/messages.h"
#include "src/string-builder.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:
enum Result { UNCHANGED, SUCCESS, EXCEPTION };
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);
// 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) builder_.AppendCharacter(',');
SerializeString(Handle<String>::cast(deferred_key));
builder_.AppendCharacter(':');
}
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 start,
uint32_t length);
void SerializeString(Handle<String> object);
template <typename SrcChar, typename DestChar>
INLINE(static void SerializeStringUnchecked_(
Vector<const SrcChar> src,
IncrementalStringBuilder::NoExtend<DestChar>* dest));
template <typename SrcChar, typename DestChar>
INLINE(void SerializeString_(Handle<String> string));
template <typename Char>
INLINE(static bool DoNotEscape(Char c));
Result StackPush(Handle<Object> object);
void StackPop();
Factory* factory() { return isolate_->factory(); }
Isolate* isolate_;
IncrementalStringBuilder builder_;
Handle<String> tojson_string_;
Handle<JSArray> stack_;
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), builder_(isolate) {
tojson_string_ = factory()->toJSON_string();
stack_ = factory()->NewJSArray(8);
}
MaybeHandle<Object> BasicJsonStringifier::Stringify(Handle<Object> object) {
Result result = SerializeObject(object);
if (result == UNCHANGED) return factory()->undefined_value();
if (result == SUCCESS) return builder_.Finish();
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());
Handle<SeqString> result;
if (object->IsOneByteRepresentationUnderneath()) {
result = isolate->factory()
->NewRawOneByteString(worst_case_length)
.ToHandleChecked();
IncrementalStringBuilder::NoExtendString<uint8_t> no_extend(
result, worst_case_length);
no_extend.Append('\"');
SerializeStringUnchecked_(object->GetFlatContent().ToOneByteVector(),
&no_extend);
no_extend.Append('\"');
return no_extend.Finalize();
} else {
result = isolate->factory()
->NewRawTwoByteString(worst_case_length)
.ToHandleChecked();
IncrementalStringBuilder::NoExtendString<uc16> no_extend(result,
worst_case_length);
no_extend.Append('\"');
SerializeStringUnchecked_(object->GetFlatContent().ToUC16Vector(),
&no_extend);
no_extend.Append('\"');
return no_extend.Finalize();
}
}
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 =
factory()->NewTypeError(MessageTemplate::kCircularStructure);
isolate_->Throw(*error);
return EXCEPTION;
}
}
}
JSArray::SetLength(stack_, length + 1);
FixedArray::cast(stack_->elements())->set(length, *object);
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);
builder_.AppendCString("false");
return SUCCESS;
case Oddball::kTrue:
if (deferred_string_key) SerializeDeferredKey(comma, key);
builder_.AppendCString("true");
return SUCCESS;
case Oddball::kNull:
if (deferred_string_key) SerializeDeferredKey(comma, key);
builder_.AppendCString("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));
default:
if (object->IsString()) {
if (deferred_string_key) SerializeDeferredKey(comma, key);
SerializeString(Handle<String>::cast(object));
return SUCCESS;
} else if (object->IsJSObject()) {
if (object->IsCallable()) return UNCHANGED;
// 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<JSFunction> fun = isolate_->json_serialize_adapter();
Handle<Object> argv[] = { key, object };
Handle<Object> result;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, result, Execution::Call(isolate_, fun, object, 2, argv),
EXCEPTION);
if (result->IsUndefined()) return UNCHANGED;
if (deferred_key) {
if (key->IsSmi()) key = factory()->NumberToString(key);
SerializeDeferredKey(deferred_comma, key);
}
builder_.AppendString(Handle<String>::cast(result));
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, Object::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, Object::ToNumber(object),
EXCEPTION);
if (value->IsSmi()) return SerializeSmi(Smi::cast(*value));
SerializeHeapNumber(Handle<HeapNumber>::cast(value));
} else if (class_name == isolate_->heap()->Boolean_string()) {
Object* value = JSValue::cast(*object)->value();
DCHECK(value->IsBoolean());
builder_.AppendCString(value->IsTrue() ? "true" : "false");
} else {
// ES6 24.3.2.1 step 10.c, serialize as an ordinary JSObject.
CHECK(!object->IsAccessCheckNeeded());
CHECK(!object->IsJSGlobalProxy());
return SerializeJSObject(object);
}
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeSmi(Smi* object) {
static const int kBufferSize = 100;
char chars[kBufferSize];
Vector<char> buffer(chars, kBufferSize);
builder_.AppendCString(IntToCString(object->value(), buffer));
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeDouble(
double number) {
if (std::isinf(number) || std::isnan(number)) {
builder_.AppendCString("null");
return SUCCESS;
}
static const int kBufferSize = 100;
char chars[kBufferSize];
Vector<char> buffer(chars, kBufferSize);
builder_.AppendCString(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()->ToArrayLength(&length));
builder_.AppendCharacter('[');
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) builder_.AppendCharacter(',');
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) builder_.AppendCharacter(',');
SerializeDouble(elements->get_scalar(i));
}
break;
}
case FAST_ELEMENTS: {
Handle<Object> old_length(object->length(), isolate_);
for (uint32_t i = 0; i < length; i++) {
if (object->length() != *old_length ||
object->GetElementsKind() != FAST_ELEMENTS) {
Result result = SerializeJSArraySlow(object, i, length);
if (result != SUCCESS) return result;
break;
}
if (i > 0) builder_.AppendCharacter(',');
Result result = SerializeElement(
isolate_,
Handle<Object>(FixedArray::cast(object->elements())->get(i),
isolate_),
i);
if (result == SUCCESS) continue;
if (result == UNCHANGED) {
builder_.AppendCString("null");
} else {
return result;
}
}
break;
}
// The FAST_HOLEY_* cases could be handled in a faster way. They resemble
// the non-holey cases except that a lookup is necessary for holes.
default: {
Result result = SerializeJSArraySlow(object, 0, length);
if (result != SUCCESS) return result;
break;
}
}
builder_.AppendCharacter(']');
StackPop();
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeJSArraySlow(
Handle<JSArray> object, uint32_t start, uint32_t length) {
for (uint32_t i = start; i < length; i++) {
if (i > 0) builder_.AppendCharacter(',');
Handle<Object> element;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, element,
Object::GetElement(isolate_, object, i),
EXCEPTION);
if (element->IsUndefined()) {
builder_.AppendCString("null");
} else {
Result result = SerializeElement(isolate_, element, i);
if (result == SUCCESS) continue;
if (result == UNCHANGED) {
builder_.AppendCString("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->IsJSGlobalObject());
builder_.AppendCharacter('{');
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() == DATA && *map == object->map()) {
FieldIndex field_index = FieldIndex::ForDescriptor(*map, i);
Isolate* isolate = object->GetIsolate();
if (object->IsUnboxedDoubleField(field_index)) {
double value = object->RawFastDoublePropertyAt(field_index);
property = isolate->factory()->NewHeapNumber(value);
} else {
property = handle(object->RawFastPropertyAt(field_index), 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, ENUMERABLE_STRINGS),
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_));
if (key->IsSmi()) {
maybe_property = Object::GetElement(
isolate_, object, Smi::cast(key)->value());
} 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;
}
}
builder_.AppendCharacter('}');
StackPop();
return SUCCESS;
}
template <typename SrcChar, typename DestChar>
void BasicJsonStringifier::SerializeStringUnchecked_(
Vector<const SrcChar> src,
IncrementalStringBuilder::NoExtend<DestChar>* 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(DestChar) >= sizeof(SrcChar));
for (int i = 0; i < src.length(); i++) {
SrcChar c = src[i];
if (DoNotEscape(c)) {
dest->Append(c);
} else {
dest->AppendCString(&JsonEscapeTable[c * kJsonEscapeTableEntrySize]);
}
}
}
template <typename SrcChar, typename DestChar>
void BasicJsonStringifier::SerializeString_(Handle<String> string) {
int length = string->length();
builder_.Append<uint8_t, DestChar>('"');
// 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.
int worst_case_length = length << 3;
if (builder_.CurrentPartCanFit(worst_case_length)) {
DisallowHeapAllocation no_gc;
Vector<const SrcChar> vector = string->GetCharVector<SrcChar>();
IncrementalStringBuilder::NoExtendBuilder<DestChar> no_extend(
&builder_, worst_case_length);
SerializeStringUnchecked_(vector, &no_extend);
} else {
FlatStringReader reader(isolate_, string);
for (int i = 0; i < reader.length(); i++) {
SrcChar c = reader.Get<SrcChar>(i);
if (DoNotEscape(c)) {
builder_.Append<SrcChar, DestChar>(c);
} else {
builder_.AppendCString(&JsonEscapeTable[c * kJsonEscapeTableEntrySize]);
}
}
}
builder_.Append<uint8_t, DestChar>('"');
}
template <>
bool BasicJsonStringifier::DoNotEscape(uint8_t c) {
return c >= '#' && c <= '~' && c != '\\';
}
template <>
bool BasicJsonStringifier::DoNotEscape(uint16_t c) {
return c >= '#' && c != '\\' && c != 0x7f;
}
void BasicJsonStringifier::SerializeString(Handle<String> object) {
object = String::Flatten(object);
if (builder_.CurrentEncoding() == String::ONE_BYTE_ENCODING) {
if (object->IsOneByteRepresentationUnderneath()) {
SerializeString_<uint8_t, uint8_t>(object);
} else {
builder_.ChangeEncoding();
SerializeString(object);
}
} else {
if (object->IsOneByteRepresentationUnderneath()) {
SerializeString_<uint8_t, uc16>(object);
} else {
SerializeString_<uc16, uc16>(object);
}
}
}
} // namespace internal
} // namespace v8
#endif // V8_JSON_STRINGIFIER_H_