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v8/src/json-stringifier.h

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// 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
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_JSON_STRINGIFIER_H_
#define V8_JSON_STRINGIFIER_H_
#include "v8.h"
#include "v8utils.h"
#include "v8conversions.h"
namespace v8 {
namespace internal {
class BasicJsonStringifier BASE_EMBEDDED {
public:
explicit BasicJsonStringifier(Isolate* isolate);
MaybeObject* Stringify(Handle<Object> object);
private:
static const int kInitialPartLength = 32;
static const int kMaxPartLength = 16 * 1024;
static const int kPartLengthGrowthFactor = 2;
enum Result { UNCHANGED, SUCCESS, BAILOUT, CIRCULAR, STACK_OVERFLOW };
template <bool is_ascii> void Extend();
void ChangeEncoding();
void ShrinkCurrentPart();
template <bool is_ascii, typename Char>
INLINE(void Append_(Char c));
template <bool is_ascii, typename Char>
INLINE(void Append_(const Char* chars));
INLINE(void Append(char c)) {
if (is_ascii_) {
Append_<true>(c);
} else {
Append_<false>(c);
}
}
INLINE(void Append(const char* chars)) {
if (is_ascii_) {
Append_<true>(chars);
} else {
Append_<false>(chars);
}
}
Handle<Object> GetProperty(Handle<JSObject> object,
Handle<String> key);
bool MayHaveToJsonFunction(Handle<JSObject> object);
INLINE(Result Serialize(Handle<Object> object)) {
return Serialize_<false>(object);
}
INLINE(Result SerializeDeferred(Handle<Object> object,
bool deferred_comma,
Handle<String> deferred_key)) {
ASSERT(!deferred_key.is_null());
return Serialize_<true>(object, deferred_comma, deferred_key);
}
template <bool deferred_key>
Result Serialize_(Handle<Object> object,
bool comma = false,
Handle<String> key = Handle<String>::null());
void SerializeDeferredKey(bool deferred_comma, Handle<String> deferred_key) {
if (deferred_comma) Append(',');
SerializeString(deferred_key);
Append(':');
}
Result SerializeSmi(Smi* object);
Result SerializeDouble(double number);
INLINE(Result SerializeHeapNumber(Handle<HeapNumber> object)) {
return SerializeDouble(object->value());
}
INLINE(Result SerializeArray(Handle<JSArray> object));
INLINE(Result SerializeObject(Handle<JSObject> object));
void SerializeString(Handle<String> object);
template <typename SrcChar, typename DestChar>
INLINE(void SerializeStringUnchecked_(const SrcChar* src,
DestChar* dest,
int length));
template <bool is_ascii, typename Char>
INLINE(void SerializeString_(Vector<const Char> vector,
Handle<String> string));
template <typename Char>
INLINE(bool DoNotEscape(Char c));
template <typename Char>
INLINE(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()));
}
INLINE(void set_accumulator(Handle<String> string)) {
return accumulator_store_->set_value(*string);
}
Isolate* isolate_;
// 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_symbol_;
Handle<JSArray> stack_;
int current_index_;
int part_length_;
bool is_ascii_;
static const int kJsonEscapeTableEntrySize = 8;
static const char* const JsonEscapeTable;
};
// Translation table to escape ASCII 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 ";
BasicJsonStringifier::BasicJsonStringifier(Isolate* isolate)
: isolate_(isolate), current_index_(0), is_ascii_(true) {
accumulator_store_ = Handle<JSValue>::cast(
isolate_->factory()->ToObject(isolate_->factory()->empty_string()));
part_length_ = kInitialPartLength;
current_part_ =
isolate_->factory()->NewRawAsciiString(kInitialPartLength);
tojson_symbol_ = isolate_->factory()->LookupAsciiSymbol("toJSON");
stack_ = isolate_->factory()->NewJSArray(8);
}
MaybeObject* BasicJsonStringifier::Stringify(Handle<Object> object) {
switch (Serialize(object)) {
case SUCCESS:
ShrinkCurrentPart();
return *isolate_->factory()->NewConsString(accumulator(), current_part_);
case UNCHANGED:
return isolate_->heap()->undefined_value();
case CIRCULAR:
return isolate_->Throw(*isolate_->factory()->NewTypeError(
"circular_structure", HandleVector<Object>(NULL, 0)));
case STACK_OVERFLOW:
return isolate_->StackOverflow();
default:
return Smi::FromInt(0);
}
}
template <bool is_ascii, typename Char>
void BasicJsonStringifier::Append_(Char c) {
if (is_ascii) {
SeqAsciiString::cast(*current_part_)->SeqAsciiStringSet(
current_index_++, c);
} else {
SeqTwoByteString::cast(*current_part_)->SeqTwoByteStringSet(
current_index_++, c);
}
if (current_index_ == part_length_) Extend<is_ascii>();
}
template <bool is_ascii, typename Char>
void BasicJsonStringifier::Append_(const Char* chars) {
for ( ; *chars != '\0'; chars++) Append_<is_ascii, Char>(*chars);
}
Handle<Object> BasicJsonStringifier::GetProperty(Handle<JSObject> object,
Handle<String> key) {
LookupResult lookup(isolate_);
object->LocalLookupRealNamedProperty(*key, &lookup);
if (!lookup.IsProperty()) return isolate_->factory()->undefined_value();
switch (lookup.type()) {
case NORMAL: {
Object* value = lookup.holder()->GetNormalizedProperty(&lookup);
ASSERT(!value->IsTheHole());
return Handle<Object>(value);
}
case FIELD: {
Object* value = lookup.holder()->FastPropertyAt(lookup.GetFieldIndex());
ASSERT(!value->IsTheHole());
return Handle<Object>(value);
}
case CONSTANT_FUNCTION:
return Handle<Object>(lookup.GetConstantFunction());
case CALLBACKS:
case HANDLER:
case INTERCEPTOR:
return Handle<Object>::null();
case TRANSITION:
case NONEXISTENT:
UNREACHABLE();
break;
}
return Handle<Object>::null();
}
bool BasicJsonStringifier::MayHaveToJsonFunction(Handle<JSObject> object) {
LookupResult lookup(isolate_);
object->LookupRealNamedProperty(*tojson_symbol_, &lookup);
if (!lookup.IsProperty()) return false;
Object* value;
switch (lookup.type()) {
case NORMAL:
value = lookup.holder()->GetNormalizedProperty(&lookup);
break;
case FIELD:
value = lookup.holder()->FastPropertyAt(lookup.GetFieldIndex());
break;
default:
return true;
}
ASSERT(!value->IsTheHole());
return value->IsSpecFunction();
}
BasicJsonStringifier::Result BasicJsonStringifier::StackPush(
Handle<Object> object) {
StackLimitCheck check(isolate_);
if (check.HasOverflowed()) return STACK_OVERFLOW;
int length = Smi::cast(stack_->length())->value();
FixedArray* elements = FixedArray::cast(stack_->elements());
for (int i = 0; i < length; i++) {
if (elements->get(i) == *object) {
return CIRCULAR;
}
}
stack_->EnsureSize(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_key>
BasicJsonStringifier::Result BasicJsonStringifier::Serialize_(
Handle<Object> object, bool comma, Handle<String> key) {
if (object->IsJSObject()) {
// We don't deal with custom toJSON functions.
if (MayHaveToJsonFunction(Handle<JSObject>::cast(object))) return BAILOUT;
if (object->IsJSFunction()) {
return UNCHANGED;
} else if (object->IsJSArray()) {
if (deferred_key) SerializeDeferredKey(comma, key);
return SerializeArray(Handle<JSArray>::cast(object));
} else if (object->IsJSValue()) {
// JSValue with a custom prototype.
if (object->GetPrototype()->IsJSReceiver()) return BAILOUT;
// Unpack value wrapper and fall through.
object = Handle<Object>(JSValue::cast(*object)->value());
} else {
if (deferred_key) SerializeDeferredKey(comma, key);
return SerializeObject(Handle<JSObject>::cast(object));
}
}
if (object->IsString()) {
if (deferred_key) SerializeDeferredKey(comma, key);
SerializeString(Handle<String>::cast(object));
return SUCCESS;
} else if (object->IsSmi()) {
if (deferred_key) SerializeDeferredKey(comma, key);
return SerializeSmi(Smi::cast(*object));
} else if (object->IsHeapNumber()) {
if (deferred_key) SerializeDeferredKey(comma, key);
return SerializeHeapNumber(Handle<HeapNumber>::cast(object));
} else if (object->IsOddball()) {
switch (Oddball::cast(*object)->kind()) {
case Oddball::kFalse:
if (deferred_key) SerializeDeferredKey(comma, key);
Append("false");
return SUCCESS;
case Oddball::kTrue:
if (deferred_key) SerializeDeferredKey(comma, key);
Append("true");
return SUCCESS;
case Oddball::kNull:
if (deferred_key) SerializeDeferredKey(comma, key);
Append("null");
return SUCCESS;
}
}
return UNCHANGED;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeSmi(Smi* object) {
static const int kBufferSize = 100;
char chars[kBufferSize];
Vector<char> buffer(chars, kBufferSize);
Append(IntToCString(object->value(), buffer));
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeDouble(
double number) {
if (isinf(number) || isnan(number)) {
Append("null");
return SUCCESS;
}
static const int kBufferSize = 100;
char chars[kBufferSize];
Vector<char> buffer(chars, kBufferSize);
Append(DoubleToCString(number, buffer));
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeArray(
Handle<JSArray> object) {
HandleScope handle_scope(isolate_);
Result stack_push = StackPush(object);
if (stack_push != SUCCESS) return stack_push;
int length = Smi::cast(object->length())->value();
Append('[');
switch (object->GetElementsKind()) {
case FAST_SMI_ELEMENTS: {
Handle<FixedArray> elements = Handle<FixedArray>(
FixedArray::cast(object->elements()));
for (int i = 0; i < length; i++) {
if (i > 0) Append(',');
SerializeSmi(Smi::cast(elements->get(i)));
}
break;
}
case FAST_DOUBLE_ELEMENTS: {
Handle<FixedDoubleArray> elements = Handle<FixedDoubleArray>(
FixedDoubleArray::cast(object->elements()));
for (int i = 0; i < length; i++) {
if (i > 0) Append(',');
SerializeDouble(elements->get_scalar(i));
}
break;
}
case FAST_ELEMENTS: {
Handle<FixedArray> elements = Handle<FixedArray>(
FixedArray::cast(object->elements()));
for (int i = 0; i < length; i++) {
if (i > 0) Append(',');
Result result = Serialize(Handle<Object>(elements->get(i)));
if (result == SUCCESS) continue;
if (result == UNCHANGED) {
Append("null");
} else {
return result;
}
}
break;
}
default:
return BAILOUT;
}
Append(']');
StackPop();
current_part_ = handle_scope.CloseAndEscape(current_part_);
return SUCCESS;
}
BasicJsonStringifier::Result BasicJsonStringifier::SerializeObject(
Handle<JSObject> object) {
HandleScope handle_scope(isolate_);
Result stack_push = StackPush(object);
if (stack_push != SUCCESS) return stack_push;
if (object->IsJSGlobalProxy()) return BAILOUT;
bool threw = false;
Handle<FixedArray> contents =
GetKeysInFixedArrayFor(object, LOCAL_ONLY, &threw);
if (threw) return BAILOUT;
Append('{');
bool comma = false;
for (int i = 0; i < contents->length(); i++) {
Object* key = contents->get(i);
Handle<String> key_handle;
Handle<Object> property;
if (key->IsString()) {
key_handle = Handle<String>(String::cast(key));
property = GetProperty(object, key_handle);
} else {
ASSERT(key->IsNumber());
key_handle = isolate_->factory()->NumberToString(Handle<Object>(key));
uint32_t index;
if (key->IsSmi()) {
property = Object::GetElement(object, Smi::cast(key)->value());
} else if (key_handle->AsArrayIndex(&index)) {
property = Object::GetElement(object, index);
} else {
property = GetProperty(object, key_handle);
}
}
if (property.is_null()) return BAILOUT;
Result result = SerializeDeferred(property, comma, key_handle);
if (!comma && result == SUCCESS) comma = true;
if (result >= BAILOUT) return result;
}
Append('}');
StackPop();
current_part_ = handle_scope.CloseAndEscape(current_part_);
return SUCCESS;
}
void BasicJsonStringifier::ShrinkCurrentPart() {
ASSERT(current_index_ < part_length_);
if (current_index_ == 0) {
current_part_ = isolate_->factory()->empty_string();
return;
}
int string_size, allocated_string_size;
if (is_ascii_) {
allocated_string_size = SeqAsciiString::SizeFor(part_length_);
string_size = SeqAsciiString::SizeFor(current_index_);
} else {
allocated_string_size = SeqTwoByteString::SizeFor(part_length_);
string_size = SeqTwoByteString::SizeFor(current_index_);
}
int delta = allocated_string_size - string_size;
current_part_->set_length(current_index_);
// String sizes are pointer size aligned, so that we can use filler objects
// that are a multiple of pointer size.
Address end_of_string = current_part_->address() + string_size;
isolate_->heap()->CreateFillerObjectAt(end_of_string, delta);
if (Marking::IsBlack(Marking::MarkBitFrom(*current_part_))) {
MemoryChunk::IncrementLiveBytesFromMutator(
current_part_->address(), -delta);
}
}
template <bool is_ascii>
void BasicJsonStringifier::Extend() {
set_accumulator(
isolate_->factory()->NewConsString(accumulator(), current_part_));
if (part_length_ <= kMaxPartLength / kPartLengthGrowthFactor) {
part_length_ *= kPartLengthGrowthFactor;
}
if (is_ascii) {
current_part_ =
isolate_->factory()->NewRawAsciiString(part_length_);
} else {
current_part_ =
isolate_->factory()->NewRawTwoByteString(part_length_);
}
current_index_ = 0;
}
void BasicJsonStringifier::ChangeEncoding() {
ShrinkCurrentPart();
set_accumulator(
isolate_->factory()->NewConsString(accumulator(), current_part_));
current_part_ =
isolate_->factory()->NewRawTwoByteString(part_length_);
current_index_ = 0;
is_ascii_ = false;
}
template <typename SrcChar, typename DestChar>
void BasicJsonStringifier::SerializeStringUnchecked_(const SrcChar* src,
DestChar* dest,
int length) {
dest += current_index_;
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.
ASSERT(sizeof(*dest) >= sizeof(*src));
*(dest++) = '"';
for (int i = 0; i < length; i++) {
SrcChar c = src[i];
if (DoNotEscape(c)) {
*(dest++) = static_cast<DestChar>(c);
} else {
const char* chars = &JsonEscapeTable[c * kJsonEscapeTableEntrySize];
while (*chars != '\0') *(dest++) = *(chars++);
}
}
*(dest++) = '"';
current_index_ += static_cast<int>(dest - dest_start);
}
template <bool is_ascii, typename Char>
void BasicJsonStringifier::SerializeString_(Vector<const Char> vector,
Handle<String> string) {
int length = vector.length();
// 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 left by 3 is a more pessimistic
// estimate than multiplying by 6, but faster to calculate.
static const int kEnclosingQuotesLength = 2;
if (current_index_ + (length << 3) + kEnclosingQuotesLength < part_length_) {
if (is_ascii) {
SerializeStringUnchecked_(
vector.start(),
SeqAsciiString::cast(*current_part_)->GetChars(),
length);
} else {
SerializeStringUnchecked_(
vector.start(),
SeqTwoByteString::cast(*current_part_)->GetChars(),
length);
}
} else {
Append_<is_ascii, char>('"');
String* string_location = *string;
for (int i = 0; i < length; i++) {
Char c = vector[i];
if (DoNotEscape(c)) {
Append_<is_ascii, Char>(c);
} else {
Append_<is_ascii, char>(
&JsonEscapeTable[c * kJsonEscapeTableEntrySize]);
}
// If GC moved the string, we need to refresh the vector.
if (*string != string_location) {
vector = GetCharVector<Char>(string);
string_location = *string;
}
}
Append_<is_ascii, char>('"');
}
}
template <>
bool BasicJsonStringifier::DoNotEscape(char c) {
return c >= '#' && c <= '~' && c != '\\';
}
template <>
bool BasicJsonStringifier::DoNotEscape(uc16 c) {
return (c >= 0x80) || (c >= '#' && c <= '~' && c != '\\');
}
template <>
Vector<const char> BasicJsonStringifier::GetCharVector(Handle<String> string) {
String::FlatContent flat = string->GetFlatContent();
ASSERT(flat.IsAscii());
return flat.ToAsciiVector();
}
template <>
Vector<const uc16> BasicJsonStringifier::GetCharVector(Handle<String> string) {
String::FlatContent flat = string->GetFlatContent();
ASSERT(flat.IsTwoByte());
return flat.ToUC16Vector();
}
void BasicJsonStringifier::SerializeString(Handle<String> object) {
FlattenString(object);
String::FlatContent flat = object->GetFlatContent();
if (is_ascii_) {
if (flat.IsAscii()) {
SerializeString_<true, char>(flat.ToAsciiVector(), object);
} else {
ChangeEncoding();
SerializeString(object);
}
} else {
if (flat.IsAscii()) {
SerializeString_<false, char>(flat.ToAsciiVector(), object);
} else {
SerializeString_<false, uc16>(flat.ToUC16Vector(), object);
}
}
}
} } // namespace v8::internal
#endif // V8_JSON_STRINGIFIER_H_
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