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json-parser.cc
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json-parser.cc
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// Copyright 2016 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.
#include "src/json/json-parser.h"
#include "src/common/message-template.h"
#include "src/debug/debug.h"
#include "src/numbers/conversions.h"
#include "src/numbers/hash-seed-inl.h"
#include "src/objects/field-type.h"
#include "src/objects/hash-table-inl.h"
#include "src/objects/objects-inl.h"
#include "src/objects/property-descriptor.h"
#include "src/strings/char-predicates-inl.h"
#include "src/strings/string-hasher.h"
namespace v8 {
namespace internal {
namespace {
constexpr JsonToken GetOneCharJsonToken(uint8_t c) {
// clang-format off
return
c == '"' ? JsonToken::STRING :
IsDecimalDigit(c) ? JsonToken::NUMBER :
c == '-' ? JsonToken::NUMBER :
c == '[' ? JsonToken::LBRACK :
c == '{' ? JsonToken::LBRACE :
c == ']' ? JsonToken::RBRACK :
c == '}' ? JsonToken::RBRACE :
c == 't' ? JsonToken::TRUE_LITERAL :
c == 'f' ? JsonToken::FALSE_LITERAL :
c == 'n' ? JsonToken::NULL_LITERAL :
c == ' ' ? JsonToken::WHITESPACE :
c == '\t' ? JsonToken::WHITESPACE :
c == '\r' ? JsonToken::WHITESPACE :
c == '\n' ? JsonToken::WHITESPACE :
c == ':' ? JsonToken::COLON :
c == ',' ? JsonToken::COMMA :
JsonToken::ILLEGAL;
// clang-format on
}
// Table of one-character tokens, by character (0x00..0xFF only).
static const constexpr JsonToken one_char_json_tokens[256] = {
#define CALL_GET_SCAN_FLAGS(N) GetOneCharJsonToken(N),
INT_0_TO_127_LIST(CALL_GET_SCAN_FLAGS)
#undef CALL_GET_SCAN_FLAGS
#define CALL_GET_SCAN_FLAGS(N) GetOneCharJsonToken(128 + N),
INT_0_TO_127_LIST(CALL_GET_SCAN_FLAGS)
#undef CALL_GET_SCAN_FLAGS
};
enum class EscapeKind : uint8_t {
kIllegal,
kSelf,
kBackspace,
kTab,
kNewLine,
kFormFeed,
kCarriageReturn,
kUnicode
};
using EscapeKindField = base::BitField8<EscapeKind, 0, 3>;
using MayTerminateStringField = EscapeKindField::Next<bool, 1>;
using NumberPartField = MayTerminateStringField::Next<bool, 1>;
constexpr bool MayTerminateJsonString(uint8_t flags) {
return MayTerminateStringField::decode(flags);
}
constexpr EscapeKind GetEscapeKind(uint8_t flags) {
return EscapeKindField::decode(flags);
}
constexpr bool IsNumberPart(uint8_t flags) {
return NumberPartField::decode(flags);
}
constexpr uint8_t GetJsonScanFlags(uint8_t c) {
// clang-format off
return (c == 'b' ? EscapeKindField::encode(EscapeKind::kBackspace)
: c == 't' ? EscapeKindField::encode(EscapeKind::kTab)
: c == 'n' ? EscapeKindField::encode(EscapeKind::kNewLine)
: c == 'f' ? EscapeKindField::encode(EscapeKind::kFormFeed)
: c == 'r' ? EscapeKindField::encode(EscapeKind::kCarriageReturn)
: c == 'u' ? EscapeKindField::encode(EscapeKind::kUnicode)
: c == '"' ? EscapeKindField::encode(EscapeKind::kSelf)
: c == '\\' ? EscapeKindField::encode(EscapeKind::kSelf)
: c == '/' ? EscapeKindField::encode(EscapeKind::kSelf)
: EscapeKindField::encode(EscapeKind::kIllegal)) |
(c < 0x20 ? MayTerminateStringField::encode(true)
: c == '"' ? MayTerminateStringField::encode(true)
: c == '\\' ? MayTerminateStringField::encode(true)
: MayTerminateStringField::encode(false)) |
NumberPartField::encode(c == '.' ||
c == 'e' ||
c == 'E' ||
IsDecimalDigit(c) ||
c == '-' ||
c == '+');
// clang-format on
}
// Table of one-character scan flags, by character (0x00..0xFF only).
static const constexpr uint8_t character_json_scan_flags[256] = {
#define CALL_GET_SCAN_FLAGS(N) GetJsonScanFlags(N),
INT_0_TO_127_LIST(CALL_GET_SCAN_FLAGS)
#undef CALL_GET_SCAN_FLAGS
#define CALL_GET_SCAN_FLAGS(N) GetJsonScanFlags(128 + N),
INT_0_TO_127_LIST(CALL_GET_SCAN_FLAGS)
#undef CALL_GET_SCAN_FLAGS
};
} // namespace
MaybeHandle<Object> JsonParseInternalizer::Internalize(Isolate* isolate,
Handle<Object> object,
Handle<Object> reviver) {
DCHECK(reviver->IsCallable());
JsonParseInternalizer internalizer(isolate,
Handle<JSReceiver>::cast(reviver));
Handle<JSObject> holder =
isolate->factory()->NewJSObject(isolate->object_function());
Handle<String> name = isolate->factory()->empty_string();
JSObject::AddProperty(isolate, holder, name, object, NONE);
return internalizer.InternalizeJsonProperty(holder, name);
}
MaybeHandle<Object> JsonParseInternalizer::InternalizeJsonProperty(
Handle<JSReceiver> holder, Handle<String> name) {
HandleScope outer_scope(isolate_);
Handle<Object> value;
ASSIGN_RETURN_ON_EXCEPTION(
isolate_, value, Object::GetPropertyOrElement(isolate_, holder, name),
Object);
if (value->IsJSReceiver()) {
Handle<JSReceiver> object = Handle<JSReceiver>::cast(value);
Maybe<bool> is_array = Object::IsArray(object);
if (is_array.IsNothing()) return MaybeHandle<Object>();
if (is_array.FromJust()) {
Handle<Object> length_object;
ASSIGN_RETURN_ON_EXCEPTION(
isolate_, length_object,
Object::GetLengthFromArrayLike(isolate_, object), Object);
double length = length_object->Number();
for (double i = 0; i < length; i++) {
HandleScope inner_scope(isolate_);
Handle<Object> index = isolate_->factory()->NewNumber(i);
Handle<String> name = isolate_->factory()->NumberToString(index);
if (!RecurseAndApply(object, name)) return MaybeHandle<Object>();
}
} else {
Handle<FixedArray> contents;
ASSIGN_RETURN_ON_EXCEPTION(
isolate_, contents,
KeyAccumulator::GetKeys(object, KeyCollectionMode::kOwnOnly,
ENUMERABLE_STRINGS,
GetKeysConversion::kConvertToString),
Object);
for (int i = 0; i < contents->length(); i++) {
HandleScope inner_scope(isolate_);
Handle<String> name(String::cast(contents->get(i)), isolate_);
if (!RecurseAndApply(object, name)) return MaybeHandle<Object>();
}
}
}
Handle<Object> argv[] = {name, value};
Handle<Object> result;
ASSIGN_RETURN_ON_EXCEPTION(
isolate_, result, Execution::Call(isolate_, reviver_, holder, 2, argv),
Object);
return outer_scope.CloseAndEscape(result);
}
bool JsonParseInternalizer::RecurseAndApply(Handle<JSReceiver> holder,
Handle<String> name) {
STACK_CHECK(isolate_, false);
Handle<Object> result;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate_, result, InternalizeJsonProperty(holder, name), false);
Maybe<bool> change_result = Nothing<bool>();
if (result->IsUndefined(isolate_)) {
change_result = JSReceiver::DeletePropertyOrElement(holder, name,
LanguageMode::kSloppy);
} else {
PropertyDescriptor desc;
desc.set_value(result);
desc.set_configurable(true);
desc.set_enumerable(true);
desc.set_writable(true);
change_result = JSReceiver::DefineOwnProperty(isolate_, holder, name, &desc,
Just(kDontThrow));
}
MAYBE_RETURN(change_result, false);
return true;
}
template <typename Char>
JsonParser<Char>::JsonParser(Isolate* isolate, Handle<String> source)
: isolate_(isolate),
hash_seed_(HashSeed(isolate)),
object_constructor_(isolate_->object_function()),
original_source_(source) {
size_t start = 0;
size_t length = source->length();
if (source->IsSlicedString()) {
SlicedString string = SlicedString::cast(*source);
start = string.offset();
String parent = string.parent();
if (parent.IsThinString()) parent = ThinString::cast(parent).actual();
source_ = handle(parent, isolate);
} else {
source_ = String::Flatten(isolate, source);
}
if (StringShape(*source_).IsExternal()) {
chars_ =
static_cast<const Char*>(SeqExternalString::cast(*source_).GetChars());
chars_may_relocate_ = false;
} else {
DisallowHeapAllocation no_gc;
isolate->heap()->AddGCEpilogueCallback(UpdatePointersCallback,
v8::kGCTypeAll, this);
chars_ = SeqString::cast(*source_).GetChars(no_gc);
chars_may_relocate_ = true;
}
cursor_ = chars_ + start;
end_ = cursor_ + length;
}
template <typename Char>
void JsonParser<Char>::ReportUnexpectedToken(JsonToken token) {
// Some exception (for example stack overflow) is already pending.
if (isolate_->has_pending_exception()) return;
// Parse failed. Current character is the unexpected token.
Factory* factory = this->factory();
MessageTemplate message;
int offset = original_source_->IsSlicedString()
? SlicedString::cast(*original_source_).offset()
: 0;
int pos = position() - offset;
Handle<Object> arg1 = Handle<Smi>(Smi::FromInt(pos), isolate());
Handle<Object> arg2;
switch (token) {
case JsonToken::EOS:
message = MessageTemplate::kJsonParseUnexpectedEOS;
break;
case JsonToken::NUMBER:
message = MessageTemplate::kJsonParseUnexpectedTokenNumber;
break;
case JsonToken::STRING:
message = MessageTemplate::kJsonParseUnexpectedTokenString;
break;
default:
message = MessageTemplate::kJsonParseUnexpectedToken;
arg2 = arg1;
arg1 = factory->LookupSingleCharacterStringFromCode(*cursor_);
break;
}
Handle<Script> script(factory->NewScript(original_source_));
if (isolate()->NeedsSourcePositionsForProfiling()) {
Script::InitLineEnds(isolate(), script);
}
// We should sent compile error event because we compile JSON object in
// separated source file.
isolate()->debug()->OnCompileError(script);
MessageLocation location(script, pos, pos + 1);
Handle<Object> error = factory->NewSyntaxError(message, arg1, arg2);
isolate()->Throw(*error, &location);
// Move the cursor to the end so we won't be able to proceed parsing.
cursor_ = end_;
}
template <typename Char>
void JsonParser<Char>::ReportUnexpectedCharacter(uc32 c) {
JsonToken token = JsonToken::ILLEGAL;
if (c == kEndOfString) {
token = JsonToken::EOS;
} else if (c <= unibrow::Latin1::kMaxChar) {
token = one_char_json_tokens[c];
}
return ReportUnexpectedToken(token);
}
template <typename Char>
JsonParser<Char>::~JsonParser() {
if (StringShape(*source_).IsExternal()) {
// Check that the string shape hasn't changed. Otherwise our GC hooks are
// broken.
SeqExternalString::cast(*source_);
} else {
// Check that the string shape hasn't changed. Otherwise our GC hooks are
// broken.
SeqString::cast(*source_);
isolate()->heap()->RemoveGCEpilogueCallback(UpdatePointersCallback, this);
}
}
template <typename Char>
MaybeHandle<Object> JsonParser<Char>::ParseJson() {
MaybeHandle<Object> result = ParseJsonValue();
if (!Check(JsonToken::EOS)) ReportUnexpectedToken(peek());
if (isolate_->has_pending_exception()) return MaybeHandle<Object>();
return result;
}
MaybeHandle<Object> InternalizeJsonProperty(Handle<JSObject> holder,
Handle<String> key);
template <typename Char>
void JsonParser<Char>::SkipWhitespace() {
next_ = JsonToken::EOS;
cursor_ = std::find_if(cursor_, end_, [this](Char c) {
JsonToken current = V8_LIKELY(c <= unibrow::Latin1::kMaxChar)
? one_char_json_tokens[c]
: JsonToken::ILLEGAL;
bool result = current != JsonToken::WHITESPACE;
if (result) next_ = current;
return result;
});
}
template <typename Char>
uc32 JsonParser<Char>::ScanUnicodeCharacter() {
uc32 value = 0;
for (int i = 0; i < 4; i++) {
int digit = HexValue(NextCharacter());
if (V8_UNLIKELY(digit < 0)) return -1;
value = value * 16 + digit;
}
return value;
}
// Parse any JSON value.
template <typename Char>
JsonString JsonParser<Char>::ScanJsonPropertyKey(JsonContinuation* cont) {
{
DisallowHeapAllocation no_gc;
const Char* start = cursor_;
uc32 first = CurrentCharacter();
if (first == '\\' && NextCharacter() == 'u') first = ScanUnicodeCharacter();
if (IsDecimalDigit(first)) {
if (first == '0') {
if (NextCharacter() == '"') {
advance();
// Record element information.
cont->elements++;
DCHECK_LE(0, cont->max_index);
return JsonString(0);
}
} else {
uint32_t index = first - '0';
while (true) {
cursor_ = std::find_if(cursor_ + 1, end_, [&index](Char c) {
return !TryAddArrayIndexChar(&index, c);
});
if (CurrentCharacter() == '"') {
advance();
// Record element information.
cont->elements++;
cont->max_index = Max(cont->max_index, index);
return JsonString(index);
}
if (CurrentCharacter() == '\\' && NextCharacter() == 'u') {
if (TryAddArrayIndexChar(&index, ScanUnicodeCharacter())) continue;
}
break;
}
}
}
// Reset cursor_ to start if the key is not an index.
cursor_ = start;
}
return ScanJsonString(true);
}
namespace {
Handle<Map> ParentOfDescriptorOwner(Isolate* isolate, Handle<Map> maybe_root,
Handle<Map> source, int descriptor) {
if (descriptor == 0) {
DCHECK_EQ(0, maybe_root->NumberOfOwnDescriptors());
return maybe_root;
}
return handle(source->FindFieldOwner(isolate, InternalIndex(descriptor - 1)),
isolate);
}
} // namespace
template <typename Char>
Handle<Object> JsonParser<Char>::BuildJsonObject(
const JsonContinuation& cont,
const std::vector<JsonProperty>& property_stack, Handle<Map> feedback) {
size_t start = cont.index;
int length = static_cast<int>(property_stack.size() - start);
int named_length = length - cont.elements;
Handle<Map> initial_map = factory()->ObjectLiteralMapFromCache(
isolate_->native_context(), named_length);
Handle<Map> map = initial_map;
Handle<FixedArrayBase> elements = factory()->empty_fixed_array();
// First store the elements.
if (cont.elements > 0) {
// Store as dictionary elements if that would use less memory.
if (ShouldConvertToSlowElements(cont.elements, cont.max_index + 1)) {
Handle<NumberDictionary> elms =
NumberDictionary::New(isolate_, cont.elements);
for (int i = 0; i < length; i++) {
const JsonProperty& property = property_stack[start + i];
if (!property.string.is_index()) continue;
uint32_t index = property.string.index();
Handle<Object> value = property.value;
elms = NumberDictionary::Set(isolate_, elms, index, value);
}
map = Map::AsElementsKind(isolate_, map, DICTIONARY_ELEMENTS);
elements = elms;
} else {
Handle<FixedArray> elms =
factory()->NewFixedArrayWithHoles(cont.max_index + 1);
DisallowHeapAllocation no_gc;
WriteBarrierMode mode = elms->GetWriteBarrierMode(no_gc);
DCHECK_EQ(HOLEY_ELEMENTS, map->elements_kind());
for (int i = 0; i < length; i++) {
const JsonProperty& property = property_stack[start + i];
if (!property.string.is_index()) continue;
uint32_t index = property.string.index();
Handle<Object> value = property.value;
elms->set(static_cast<int>(index), *value, mode);
}
elements = elms;
}
}
int feedback_descriptors =
(feedback.is_null() ||
feedback->elements_kind() != map->elements_kind() ||
feedback->instance_size() != map->instance_size())
? 0
: feedback->NumberOfOwnDescriptors();
int i;
int descriptor = 0;
int new_mutable_double = 0;
for (i = 0; i < length; i++) {
const JsonProperty& property = property_stack[start + i];
if (property.string.is_index()) continue;
Handle<String> expected;
Handle<Map> target;
InternalIndex descriptor_index(descriptor);
if (descriptor < feedback_descriptors) {
expected = handle(String::cast(feedback->instance_descriptors().GetKey(
descriptor_index)),
isolate_);
} else {
DisallowHeapAllocation no_gc;
TransitionsAccessor transitions(isolate(), *map, &no_gc);
expected = transitions.ExpectedTransitionKey();
if (!expected.is_null()) {
// Directly read out the target while reading out the key, otherwise it
// might die while building the string below.
target = TransitionsAccessor(isolate(), *map, &no_gc)
.ExpectedTransitionTarget();
}
}
Handle<String> key = MakeString(property.string, expected);
if (key.is_identical_to(expected)) {
if (descriptor < feedback_descriptors) target = feedback;
} else {
if (descriptor < feedback_descriptors) {
map = ParentOfDescriptorOwner(isolate_, map, feedback, descriptor);
feedback_descriptors = 0;
}
if (!TransitionsAccessor(isolate(), map)
.FindTransitionToField(key)
.ToHandle(&target)) {
break;
}
}
Handle<Object> value = property.value;
PropertyDetails details =
target->instance_descriptors().GetDetails(descriptor_index);
Representation expected_representation = details.representation();
if (!value->FitsRepresentation(expected_representation)) {
Representation representation = value->OptimalRepresentation(isolate());
representation = representation.generalize(expected_representation);
if (!expected_representation.CanBeInPlaceChangedTo(representation)) {
map = ParentOfDescriptorOwner(isolate_, map, target, descriptor);
break;
}
Handle<FieldType> value_type =
value->OptimalType(isolate(), representation);
Map::GeneralizeField(isolate(), target, descriptor_index,
details.constness(), representation, value_type);
} else if (expected_representation.IsHeapObject() &&
!target->instance_descriptors()
.GetFieldType(descriptor_index)
.NowContains(value)) {
Handle<FieldType> value_type =
value->OptimalType(isolate(), expected_representation);
Map::GeneralizeField(isolate(), target, descriptor_index,
details.constness(), expected_representation,
value_type);
} else if (!FLAG_unbox_double_fields &&
expected_representation.IsDouble() && value->IsSmi()) {
new_mutable_double++;
}
DCHECK(target->instance_descriptors()
.GetFieldType(descriptor_index)
.NowContains(value));
map = target;
descriptor++;
}
// Fast path: Write all transitioned named properties.
if (i == length && descriptor < feedback_descriptors) {
map = ParentOfDescriptorOwner(isolate_, map, map, descriptor);
}
// Preallocate all mutable heap numbers so we don't need to allocate while
// setting up the object. Otherwise verification of that object may fail.
Handle<ByteArray> mutable_double_buffer;
// Allocate enough space so we can double-align the payload.
const int kMutableDoubleSize = sizeof(double) * 2;
STATIC_ASSERT(HeapNumber::kSize <= kMutableDoubleSize);
if (new_mutable_double > 0) {
mutable_double_buffer =
factory()->NewByteArray(kMutableDoubleSize * new_mutable_double);
}
Handle<JSObject> object = initial_map->is_dictionary_map()
? factory()->NewSlowJSObjectFromMap(map)
: factory()->NewJSObjectFromMap(map);
object->set_elements(*elements);
{
descriptor = 0;
DisallowHeapAllocation no_gc;
WriteBarrierMode mode = object->GetWriteBarrierMode(no_gc);
Address mutable_double_address =
mutable_double_buffer.is_null()
? 0
: reinterpret_cast<Address>(
mutable_double_buffer->GetDataStartAddress());
Address filler_address = mutable_double_address;
if (kTaggedSize != kDoubleSize) {
if (IsAligned(mutable_double_address, kDoubleAlignment)) {
mutable_double_address += kTaggedSize;
} else {
filler_address += HeapNumber::kSize;
}
}
for (int j = 0; j < i; j++) {
const JsonProperty& property = property_stack[start + j];
if (property.string.is_index()) continue;
InternalIndex descriptor_index(descriptor);
PropertyDetails details =
map->instance_descriptors().GetDetails(descriptor_index);
Object value = *property.value;
FieldIndex index = FieldIndex::ForDescriptor(*map, descriptor_index);
descriptor++;
if (details.representation().IsDouble()) {
if (object->IsUnboxedDoubleField(index)) {
uint64_t bits;
if (value.IsSmi()) {
bits = bit_cast<uint64_t>(static_cast<double>(Smi::ToInt(value)));
} else {
DCHECK(value.IsHeapNumber());
bits = HeapNumber::cast(value).value_as_bits();
}
object->RawFastDoublePropertyAsBitsAtPut(index, bits);
continue;
}
if (value.IsSmi()) {
if (kTaggedSize != kDoubleSize) {
// Write alignment filler.
HeapObject filler = HeapObject::FromAddress(filler_address);
filler.set_map_after_allocation(
*factory()->one_pointer_filler_map());
filler_address += kMutableDoubleSize;
}
uint64_t bits =
bit_cast<uint64_t>(static_cast<double>(Smi::ToInt(value)));
// Allocate simple heapnumber with immortal map, with non-pointer
// payload, so we can skip notifying object layout change.
HeapObject hn = HeapObject::FromAddress(mutable_double_address);
hn.set_map_after_allocation(*factory()->heap_number_map());
HeapNumber::cast(hn).set_value_as_bits(bits);
value = hn;
mutable_double_address += kMutableDoubleSize;
} else {
DCHECK(value.IsHeapNumber());
HeapObject::cast(value).synchronized_set_map(
*factory()->heap_number_map());
}
}
object->RawFastInobjectPropertyAtPut(index, value, mode);
}
// Make all mutable HeapNumbers alive.
if (!mutable_double_buffer.is_null()) {
#ifdef DEBUG
Address end =
reinterpret_cast<Address>(mutable_double_buffer->GetDataEndAddress());
if (kTaggedSize != kDoubleSize) {
DCHECK_EQ(Min(filler_address, mutable_double_address), end);
DCHECK_GE(filler_address, end);
DCHECK_GE(mutable_double_address, end);
} else {
DCHECK_EQ(mutable_double_address, end);
}
#endif
mutable_double_buffer->set_length(0);
}
}
// Slow path: define remaining named properties.
for (; i < length; i++) {
HandleScope scope(isolate_);
const JsonProperty& property = property_stack[start + i];
if (property.string.is_index()) continue;
Handle<String> key = MakeString(property.string);
#ifdef DEBUG
uint32_t index;
DCHECK(!key->AsArrayIndex(&index));
#endif
Handle<Object> value = property.value;
LookupIterator it(isolate_, object, key, object, LookupIterator::OWN);
JSObject::DefineOwnPropertyIgnoreAttributes(&it, value, NONE).Check();
}
return object;
}
template <typename Char>
Handle<Object> JsonParser<Char>::BuildJsonArray(
const JsonContinuation& cont,
const std::vector<Handle<Object>>& element_stack) {
size_t start = cont.index;
int length = static_cast<int>(element_stack.size() - start);
ElementsKind kind = PACKED_SMI_ELEMENTS;
for (size_t i = start; i < element_stack.size(); i++) {
Object value = *element_stack[i];
if (value.IsHeapObject()) {
if (HeapObject::cast(value).IsHeapNumber()) {
kind = PACKED_DOUBLE_ELEMENTS;
} else {
kind = PACKED_ELEMENTS;
break;
}
}
}
Handle<JSArray> array = factory()->NewJSArray(kind, length, length);
if (kind == PACKED_DOUBLE_ELEMENTS) {
DisallowHeapAllocation no_gc;
FixedDoubleArray elements = FixedDoubleArray::cast(array->elements());
for (int i = 0; i < length; i++) {
elements.set(i, element_stack[start + i]->Number());
}
} else {
DisallowHeapAllocation no_gc;
FixedArray elements = FixedArray::cast(array->elements());
WriteBarrierMode mode = kind == PACKED_SMI_ELEMENTS
? SKIP_WRITE_BARRIER
: elements.GetWriteBarrierMode(no_gc);
for (int i = 0; i < length; i++) {
elements.set(i, *element_stack[start + i], mode);
}
}
return array;
}
// Parse any JSON value.
template <typename Char>
MaybeHandle<Object> JsonParser<Char>::ParseJsonValue() {
std::vector<JsonContinuation> cont_stack;
std::vector<JsonProperty> property_stack;
std::vector<Handle<Object>> element_stack;
cont_stack.reserve(16);
property_stack.reserve(16);
element_stack.reserve(16);
JsonContinuation cont(isolate_, JsonContinuation::kReturn, 0);
Handle<Object> value;
while (true) {
// Produce a json value.
//
// Iterate until a value is produced. Starting but not immediately finishing
// objects and arrays will cause the loop to continue until a first member
// is completed.
while (true) {
SkipWhitespace();
// The switch is immediately followed by 'break' so we can use 'break' to
// break out of the loop, and 'continue' to continue the loop.
switch (peek()) {
case JsonToken::STRING:
Consume(JsonToken::STRING);
value = MakeString(ScanJsonString(false));
break;
case JsonToken::NUMBER:
value = ParseJsonNumber();
break;
case JsonToken::LBRACE: {
Consume(JsonToken::LBRACE);
if (Check(JsonToken::RBRACE)) {
// TODO(verwaest): Directly use the map instead.
value = factory()->NewJSObject(object_constructor_);
break;
}
// Start parsing an object with properties.
cont_stack.emplace_back(std::move(cont));
cont = JsonContinuation(isolate_, JsonContinuation::kObjectProperty,
property_stack.size());
// Parse the property key.
ExpectNext(JsonToken::STRING);
property_stack.emplace_back(ScanJsonPropertyKey(&cont));
ExpectNext(JsonToken::COLON);
// Continue to start producing the first property value.
continue;
}
case JsonToken::LBRACK:
Consume(JsonToken::LBRACK);
if (Check(JsonToken::RBRACK)) {
value = factory()->NewJSArray(0, PACKED_SMI_ELEMENTS);
break;
}
// Start parsing an array with elements.
cont_stack.emplace_back(std::move(cont));
cont = JsonContinuation(isolate_, JsonContinuation::kArrayElement,
element_stack.size());
// Continue to start producing the first array element.
continue;
case JsonToken::TRUE_LITERAL:
ScanLiteral("true");
value = factory()->true_value();
break;
case JsonToken::FALSE_LITERAL:
ScanLiteral("false");
value = factory()->false_value();
break;
case JsonToken::NULL_LITERAL:
ScanLiteral("null");
value = factory()->null_value();
break;
case JsonToken::COLON:
case JsonToken::COMMA:
case JsonToken::ILLEGAL:
case JsonToken::RBRACE:
case JsonToken::RBRACK:
case JsonToken::EOS:
ReportUnexpectedCharacter(CurrentCharacter());
// Pop the continuation stack to correctly tear down handle scopes.
while (!cont_stack.empty()) {
cont = std::move(cont_stack.back());
cont_stack.pop_back();
}
return MaybeHandle<Object>();
case JsonToken::WHITESPACE:
UNREACHABLE();
}
// Done producing a value, consume it.
break;
}
// Consume a produced json value.
//
// Iterate as long as values are produced (arrays or object literals are
// finished).
while (true) {
// The switch is immediately followed by 'break' so we can use 'break' to
// break out of the loop, and 'continue' to continue the loop.
switch (cont.type()) {
case JsonContinuation::kReturn:
return cont.scope.CloseAndEscape(value);
case JsonContinuation::kObjectProperty: {
// Store the previous property value into its property info.
property_stack.back().value = value;
if (V8_LIKELY(Check(JsonToken::COMMA))) {
// Parse the property key.
ExpectNext(JsonToken::STRING);
property_stack.emplace_back(ScanJsonPropertyKey(&cont));
ExpectNext(JsonToken::COLON);
// Break to start producing the subsequent property value.
break;
}
Handle<Map> feedback;
if (cont_stack.size() > 0 &&
cont_stack.back().type() == JsonContinuation::kArrayElement &&
cont_stack.back().index < element_stack.size() &&
element_stack.back()->IsJSObject()) {
Map maybe_feedback = JSObject::cast(*element_stack.back()).map();
// Don't consume feedback from objects with a map that's detached
// from the transition tree.
if (!maybe_feedback.IsDetached(isolate_)) {
feedback = handle(maybe_feedback, isolate_);
if (feedback->is_deprecated()) {
feedback = Map::Update(isolate_, feedback);
}
}
}
value = BuildJsonObject(cont, property_stack, feedback);
property_stack.resize(cont.index);
Expect(JsonToken::RBRACE);
// Return the object.
value = cont.scope.CloseAndEscape(value);
// Pop the continuation.
cont = std::move(cont_stack.back());
cont_stack.pop_back();
// Consume to produced object.
continue;
}
case JsonContinuation::kArrayElement: {
// Store the previous element on the stack.
element_stack.emplace_back(value);
// Break to start producing the subsequent element value.
if (V8_LIKELY(Check(JsonToken::COMMA))) break;
value = BuildJsonArray(cont, element_stack);
element_stack.resize(cont.index);
Expect(JsonToken::RBRACK);
// Return the array.
value = cont.scope.CloseAndEscape(value);
// Pop the continuation.
cont = std::move(cont_stack.back());
cont_stack.pop_back();
// Consume the produced array.
continue;
}
}
// Done consuming a value. Produce next value.
break;
}
}
}
template <typename Char>
void JsonParser<Char>::AdvanceToNonDecimal() {
cursor_ =
std::find_if(cursor_, end_, [](Char c) { return !IsDecimalDigit(c); });
}
template <typename Char>
Handle<Object> JsonParser<Char>::ParseJsonNumber() {
double number;
int sign = 1;
{
const Char* start = cursor_;
DisallowHeapAllocation no_gc;
uc32 c = *cursor_;
if (c == '-') {
sign = -1;
c = NextCharacter();
}
if (c == '0') {
// Prefix zero is only allowed if it's the only digit before
// a decimal point or exponent.
c = NextCharacter();
if (base::IsInRange(c, 0,
static_cast<int32_t>(unibrow::Latin1::kMaxChar)) &&
IsNumberPart(character_json_scan_flags[c])) {
if (V8_UNLIKELY(IsDecimalDigit(c))) {
AllowHeapAllocation allow_before_exception;
ReportUnexpectedToken(JsonToken::NUMBER);
return handle(Smi::FromInt(0), isolate_);
}
} else if (sign > 0) {
return handle(Smi::FromInt(0), isolate_);
}
} else {
const Char* smi_start = cursor_;
AdvanceToNonDecimal();
if (V8_UNLIKELY(smi_start == cursor_)) {
AllowHeapAllocation allow_before_exception;
ReportUnexpectedCharacter(CurrentCharacter());
return handle(Smi::FromInt(0), isolate_);
}
uc32 c = CurrentCharacter();
STATIC_ASSERT(Smi::IsValid(-999999999));
STATIC_ASSERT(Smi::IsValid(999999999));
const int kMaxSmiLength = 9;
if ((cursor_ - smi_start) <= kMaxSmiLength &&
(!base::IsInRange(c, 0,
static_cast<int32_t>(unibrow::Latin1::kMaxChar)) ||
!IsNumberPart(character_json_scan_flags[c]))) {
// Smi.
int32_t i = 0;
for (; smi_start != cursor_; smi_start++) {
DCHECK(IsDecimalDigit(*smi_start));
i = (i * 10) + ((*smi_start) - '0');
}
// TODO(verwaest): Cache?
return handle(Smi::FromInt(i * sign), isolate_);
}
}
if (CurrentCharacter() == '.') {
uc32 c = NextCharacter();
if (!IsDecimalDigit(c)) {
AllowHeapAllocation allow_before_exception;
ReportUnexpectedCharacter(c);
return handle(Smi::FromInt(0), isolate_);
}
AdvanceToNonDecimal();
}
if (AsciiAlphaToLower(CurrentCharacter()) == 'e') {
uc32 c = NextCharacter();
if (c == '-' || c == '+') c = NextCharacter();
if (!IsDecimalDigit(c)) {
AllowHeapAllocation allow_before_exception;
ReportUnexpectedCharacter(c);
return handle(Smi::FromInt(0), isolate_);
}
AdvanceToNonDecimal();
}
Vector<const Char> chars(start, cursor_ - start);
number = StringToDouble(chars,
NO_FLAGS, // Hex, octal or trailing junk.
std::numeric_limits<double>::quiet_NaN());
DCHECK(!std::isnan(number));
}
return factory()->NewNumber(number);
}
namespace {
template <typename Char>
bool Matches(const Vector<const Char>& chars, Handle<String> string) {
DCHECK(!string.is_null());
if (chars.length() != string->length()) return false;
DisallowHeapAllocation no_gc;
if (string->IsOneByteRepresentation()) {
const uint8_t* string_data = string->GetChars<uint8_t>(no_gc);
return CompareChars(chars.begin(), string_data, chars.length()) == 0;
}
const uint16_t* string_data = string->GetChars<uint16_t>(no_gc);
return CompareChars(chars.begin(), string_data, chars.length()) == 0;
}
} // namespace