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// Copyright 2011 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
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_JSON_PARSER_H_
#define V8_JSON_PARSER_H_
#include "v8.h"
#include "char-predicates-inl.h"
#include "v8conversions.h"
#include "messages.h"
#include "spaces-inl.h"
#include "token.h"
namespace v8 {
namespace internal {
// A simple json parser.
template <bool seq_ascii>
class JsonParser BASE_EMBEDDED {
public:
static Handle<Object> Parse(Handle<String> source) {
return JsonParser().ParseJson(source);
}
static const int kEndOfString = -1;
private:
// Parse a string containing a single JSON value.
Handle<Object> ParseJson(Handle<String> source);
inline void Advance() {
position_++;
if (position_ >= source_length_) {
c0_ = kEndOfString;
} else if (seq_ascii) {
c0_ = seq_source_->SeqAsciiStringGet(position_);
} else {
c0_ = source_->Get(position_);
}
}
// The JSON lexical grammar is specified in the ECMAScript 5 standard,
// section 15.12.1.1. The only allowed whitespace characters between tokens
// are tab, carriage-return, newline and space.
inline void AdvanceSkipWhitespace() {
do {
Advance();
} while (c0_ == '\t' || c0_ == '\r' || c0_ == '\n' || c0_ == ' ');
}
inline void SkipWhitespace() {
while (c0_ == '\t' || c0_ == '\r' || c0_ == '\n' || c0_ == ' ') {
Advance();
}
}
inline uc32 AdvanceGetChar() {
Advance();
return c0_;
}
// Checks that current charater is c.
// If so, then consume c and skip whitespace.
inline bool MatchSkipWhiteSpace(uc32 c) {
if (c0_ == c) {
AdvanceSkipWhitespace();
return true;
}
return false;
}
// A JSON string (production JSONString) is subset of valid JavaScript string
// literals. The string must only be double-quoted (not single-quoted), and
// the only allowed backslash-escapes are ", /, \, b, f, n, r, t and
// four-digit hex escapes (uXXXX). Any other use of backslashes is invalid.
Handle<String> ParseJsonString() {
return ScanJsonString<false>();
}
Handle<String> ParseJsonSymbol() {
return ScanJsonString<true>();
}
template <bool is_symbol>
Handle<String> ScanJsonString();
// Creates a new string and copies prefix[start..end] into the beginning
// of it. Then scans the rest of the string, adding characters after the
// prefix. Called by ScanJsonString when reaching a '\' or non-ASCII char.
template <typename StringType, typename SinkChar>
Handle<String> SlowScanJsonString(Handle<String> prefix, int start, int end);
// A JSON number (production JSONNumber) is a subset of the valid JavaScript
// decimal number literals.
// It includes an optional minus sign, must have at least one
// digit before and after a decimal point, may not have prefixed zeros (unless
// the integer part is zero), and may include an exponent part (e.g., "e-10").
// Hexadecimal and octal numbers are not allowed.
Handle<Object> ParseJsonNumber();
// Parse a single JSON value from input (grammar production JSONValue).
// A JSON value is either a (double-quoted) string literal, a number literal,
// one of "true", "false", or "null", or an object or array literal.
Handle<Object> ParseJsonValue();
// Parse a JSON object literal (grammar production JSONObject).
// An object literal is a squiggly-braced and comma separated sequence
// (possibly empty) of key/value pairs, where the key is a JSON string
// literal, the value is a JSON value, and the two are separated by a colon.
// A JSON array doesn't allow numbers and identifiers as keys, like a
// JavaScript array.
Handle<Object> ParseJsonObject();
// Parses a JSON array literal (grammar production JSONArray). An array
// literal is a square-bracketed and comma separated sequence (possibly empty)
// of JSON values.
// A JSON array doesn't allow leaving out values from the sequence, nor does
// it allow a terminal comma, like a JavaScript array does.
Handle<Object> ParseJsonArray();
// Mark that a parsing error has happened at the current token, and
// return a null handle. Primarily for readability.
inline Handle<Object> ReportUnexpectedCharacter() {
return Handle<Object>::null();
}
inline Isolate* isolate() { return isolate_; }
static const int kInitialSpecialStringLength = 1024;
private:
Handle<String> source_;
int source_length_;
Handle<SeqAsciiString> seq_source_;
Isolate* isolate_;
uc32 c0_;
int position_;
};
template <bool seq_ascii>
Handle<Object> JsonParser<seq_ascii>::ParseJson(Handle<String> source) {
isolate_ = source->map()->GetHeap()->isolate();
FlattenString(source);
source_ = source;
source_length_ = source_->length();
// Optimized fast case where we only have ASCII characters.
if (seq_ascii) {
seq_source_ = Handle<SeqAsciiString>::cast(source_);
}
// Set initial position right before the string.
position_ = -1;
// Advance to the first character (possibly EOS)
AdvanceSkipWhitespace();
Handle<Object> result = ParseJsonValue();
if (result.is_null() || c0_ != kEndOfString) {
// Parse failed. Current character is the unexpected token.
const char* message;
Factory* factory = isolate()->factory();
Handle<JSArray> array;
switch (c0_) {
case kEndOfString:
message = "unexpected_eos";
array = factory->NewJSArray(0);
break;
case '-':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
message = "unexpected_token_number";
array = factory->NewJSArray(0);
break;
case '"':
message = "unexpected_token_string";
array = factory->NewJSArray(0);
break;
default:
message = "unexpected_token";
Handle<Object> name = LookupSingleCharacterStringFromCode(c0_);
Handle<FixedArray> element = factory->NewFixedArray(1);
element->set(0, *name);
array = factory->NewJSArrayWithElements(element);
break;
}
MessageLocation location(factory->NewScript(source),
position_,
position_ + 1);
Handle<Object> result = factory->NewSyntaxError(message, array);
isolate()->Throw(*result, &location);
return Handle<Object>::null();
}
return result;
}
// Parse any JSON value.
template <bool seq_ascii>
Handle<Object> JsonParser<seq_ascii>::ParseJsonValue() {
switch (c0_) {
case '"':
return ParseJsonString();
case '-':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
return ParseJsonNumber();
case 'f':
if (AdvanceGetChar() == 'a' && AdvanceGetChar() == 'l' &&
AdvanceGetChar() == 's' && AdvanceGetChar() == 'e') {
AdvanceSkipWhitespace();
return isolate()->factory()->false_value();
} else {
return ReportUnexpectedCharacter();
}
case 't':
if (AdvanceGetChar() == 'r' && AdvanceGetChar() == 'u' &&
AdvanceGetChar() == 'e') {
AdvanceSkipWhitespace();
return isolate()->factory()->true_value();
} else {
return ReportUnexpectedCharacter();
}
case 'n':
if (AdvanceGetChar() == 'u' && AdvanceGetChar() == 'l' &&
AdvanceGetChar() == 'l') {
AdvanceSkipWhitespace();
return isolate()->factory()->null_value();
} else {
return ReportUnexpectedCharacter();
}
case '{':
return ParseJsonObject();
case '[':
return ParseJsonArray();
default:
return ReportUnexpectedCharacter();
}
}
// Parse a JSON object. Position must be right at '{'.
template <bool seq_ascii>
Handle<Object> JsonParser<seq_ascii>::ParseJsonObject() {
Handle<JSFunction> object_constructor(
isolate()->global_context()->object_function());
Handle<JSObject> json_object =
isolate()->factory()->NewJSObject(object_constructor);
ASSERT_EQ(c0_, '{');
AdvanceSkipWhitespace();
if (c0_ != '}') {
do {
if (c0_ != '"') return ReportUnexpectedCharacter();
Handle<String> key = ParseJsonSymbol();
if (key.is_null() || c0_ != ':') return ReportUnexpectedCharacter();
AdvanceSkipWhitespace();
Handle<Object> value = ParseJsonValue();
if (value.is_null()) return ReportUnexpectedCharacter();
uint32_t index;
if (key->AsArrayIndex(&index)) {
JSObject::SetOwnElement(json_object, index, value, kNonStrictMode);
} else if (key->Equals(isolate()->heap()->Proto_symbol())) {
SetPrototype(json_object, value);
} else {
JSObject::SetLocalPropertyIgnoreAttributes(
json_object, key, value, NONE);
}
} while (MatchSkipWhiteSpace(','));
if (c0_ != '}') {
return ReportUnexpectedCharacter();
}
}
AdvanceSkipWhitespace();
return json_object;
}
// Parse a JSON array. Position must be right at '['.
template <bool seq_ascii>
Handle<Object> JsonParser<seq_ascii>::ParseJsonArray() {
ZoneScope zone_scope(isolate(), DELETE_ON_EXIT);
ZoneList<Handle<Object> > elements(4);
ASSERT_EQ(c0_, '[');
AdvanceSkipWhitespace();
if (c0_ != ']') {
do {
Handle<Object> element = ParseJsonValue();
if (element.is_null()) return ReportUnexpectedCharacter();
elements.Add(element);
} while (MatchSkipWhiteSpace(','));
if (c0_ != ']') {
return ReportUnexpectedCharacter();
}
}
AdvanceSkipWhitespace();
// Allocate a fixed array with all the elements.
Handle<FixedArray> fast_elements =
isolate()->factory()->NewFixedArray(elements.length());
for (int i = 0, n = elements.length(); i < n; i++) {
fast_elements->set(i, *elements[i]);
}
return isolate()->factory()->NewJSArrayWithElements(fast_elements);
}
template <bool seq_ascii>
Handle<Object> JsonParser<seq_ascii>::ParseJsonNumber() {
bool negative = false;
int beg_pos = position_;
if (c0_ == '-') {
Advance();
negative = true;
}
if (c0_ == '0') {
Advance();
// Prefix zero is only allowed if it's the only digit before
// a decimal point or exponent.
if ('0' <= c0_ && c0_ <= '9') return ReportUnexpectedCharacter();
} else {
int i = 0;
int digits = 0;
if (c0_ < '1' || c0_ > '9') return ReportUnexpectedCharacter();
do {
i = i * 10 + c0_ - '0';
digits++;
Advance();
} while (c0_ >= '0' && c0_ <= '9');
if (c0_ != '.' && c0_ != 'e' && c0_ != 'E' && digits < 10) {
SkipWhitespace();
return Handle<Smi>(Smi::FromInt((negative ? -i : i)), isolate());
}
}
if (c0_ == '.') {
Advance();
if (c0_ < '0' || c0_ > '9') return ReportUnexpectedCharacter();
do {
Advance();
} while (c0_ >= '0' && c0_ <= '9');
}
if (AsciiAlphaToLower(c0_) == 'e') {
Advance();
if (c0_ == '-' || c0_ == '+') Advance();
if (c0_ < '0' || c0_ > '9') return ReportUnexpectedCharacter();
do {
Advance();
} while (c0_ >= '0' && c0_ <= '9');
}
int length = position_ - beg_pos;
double number;
if (seq_ascii) {
Vector<const char> chars(seq_source_->GetChars() + beg_pos, length);
number = StringToDouble(isolate()->unicode_cache(),
chars,
NO_FLAGS, // Hex, octal or trailing junk.
OS::nan_value());
} else {
Vector<char> buffer = Vector<char>::New(length);
String::WriteToFlat(*source_, buffer.start(), beg_pos, position_);
Vector<const char> result =
Vector<const char>(reinterpret_cast<const char*>(buffer.start()),
length);
number = StringToDouble(isolate()->unicode_cache(),
result,
NO_FLAGS, // Hex, octal or trailing junk.
0.0);
buffer.Dispose();
}
SkipWhitespace();
return isolate()->factory()->NewNumber(number);
}
template <typename StringType>
inline void SeqStringSet(Handle<StringType> seq_str, int i, uc32 c);
template <>
inline void SeqStringSet(Handle<SeqTwoByteString> seq_str, int i, uc32 c) {
seq_str->SeqTwoByteStringSet(i, c);
}
template <>
inline void SeqStringSet(Handle<SeqAsciiString> seq_str, int i, uc32 c) {
seq_str->SeqAsciiStringSet(i, c);
}
template <typename StringType>
inline Handle<StringType> NewRawString(Factory* factory, int length);
template <>
inline Handle<SeqTwoByteString> NewRawString(Factory* factory, int length) {
return factory->NewRawTwoByteString(length, NOT_TENURED);
}
template <>
inline Handle<SeqAsciiString> NewRawString(Factory* factory, int length) {
return factory->NewRawAsciiString(length, NOT_TENURED);
}
// Scans the rest of a JSON string starting from position_ and writes
// prefix[start..end] along with the scanned characters into a
// sequential string of type StringType.
template <bool seq_ascii>
template <typename StringType, typename SinkChar>
Handle<String> JsonParser<seq_ascii>::SlowScanJsonString(
Handle<String> prefix, int start, int end) {
int count = end - start;
int max_length = count + source_length_ - position_;
int length = Min(max_length, Max(kInitialSpecialStringLength, 2 * count));
Handle<StringType> seq_str = NewRawString<StringType>(isolate()->factory(),
length);
// Copy prefix into seq_str.
SinkChar* dest = seq_str->GetChars();
String::WriteToFlat(*prefix, dest, start, end);
while (c0_ != '"') {
// Check for control character (0x00-0x1f) or unterminated string (<0).
if (c0_ < 0x20) return Handle<String>::null();
if (count >= length) {
// We need to create a longer sequential string for the result.
return SlowScanJsonString<StringType, SinkChar>(seq_str, 0, count);
}
if (c0_ != '\\') {
// If the sink can contain UC16 characters, or source_ contains only
// ASCII characters, there's no need to test whether we can store the
// character. Otherwise check whether the UC16 source character can fit
// in the ASCII sink.
if (sizeof(SinkChar) == kUC16Size ||
seq_ascii ||
c0_ <= kMaxAsciiCharCode) {
SeqStringSet(seq_str, count++, c0_);
Advance();
} else {
// StringType is SeqAsciiString and we just read a non-ASCII char.
return SlowScanJsonString<SeqTwoByteString, uc16>(seq_str, 0, count);
}
} else {
Advance(); // Advance past the \.
switch (c0_) {
case '"':
case '\\':
case '/':
SeqStringSet(seq_str, count++, c0_);
break;
case 'b':
SeqStringSet(seq_str, count++, '\x08');
break;
case 'f':
SeqStringSet(seq_str, count++, '\x0c');
break;
case 'n':
SeqStringSet(seq_str, count++, '\x0a');
break;
case 'r':
SeqStringSet(seq_str, count++, '\x0d');
break;
case 't':
SeqStringSet(seq_str, count++, '\x09');
break;
case 'u': {
uc32 value = 0;
for (int i = 0; i < 4; i++) {
Advance();
int digit = HexValue(c0_);
if (digit < 0) {
return Handle<String>::null();
}
value = value * 16 + digit;
}
if (sizeof(SinkChar) == kUC16Size || value <= kMaxAsciiCharCode) {
SeqStringSet(seq_str, count++, value);
break;
} else {
// StringType is SeqAsciiString and we just read a non-ASCII char.
position_ -= 6; // Rewind position_ to \ in \uxxxx.
Advance();
return SlowScanJsonString<SeqTwoByteString, uc16>(seq_str,
0,
count);
}
}
default:
return Handle<String>::null();
}
Advance();
}
}
// Shrink seq_string length to count.
if (isolate()->heap()->InNewSpace(*seq_str)) {
isolate()->heap()->new_space()->
template ShrinkStringAtAllocationBoundary<StringType>(
*seq_str, count);
} else {
int string_size = StringType::SizeFor(count);
int allocated_string_size = StringType::SizeFor(length);
int delta = allocated_string_size - string_size;
Address start_filler_object = seq_str->address() + string_size;
seq_str->set_length(count);
isolate()->heap()->CreateFillerObjectAt(start_filler_object, delta);
}
ASSERT_EQ('"', c0_);
// Advance past the last '"'.
AdvanceSkipWhitespace();
return seq_str;
}
template <bool seq_ascii>
template <bool is_symbol>
Handle<String> JsonParser<seq_ascii>::ScanJsonString() {
ASSERT_EQ('"', c0_);
Advance();
if (c0_ == '"') {
AdvanceSkipWhitespace();
return Handle<String>(isolate()->heap()->empty_string());
}
int beg_pos = position_;
// Fast case for ASCII only without escape characters.
do {
// Check for control character (0x00-0x1f) or unterminated string (<0).
if (c0_ < 0x20) return Handle<String>::null();
if (c0_ != '\\') {
if (seq_ascii || c0_ <= kMaxAsciiCharCode) {
Advance();
} else {
return SlowScanJsonString<SeqTwoByteString, uc16>(source_,
beg_pos,
position_);
}
} else {
return SlowScanJsonString<SeqAsciiString, char>(source_,
beg_pos,
position_);
}
} while (c0_ != '"');
int length = position_ - beg_pos;
Handle<String> result;
if (seq_ascii && is_symbol) {
result = isolate()->factory()->LookupAsciiSymbol(seq_source_,
beg_pos,
length);
} else {
result = isolate()->factory()->NewRawAsciiString(length);
char* dest = SeqAsciiString::cast(*result)->GetChars();
String::WriteToFlat(*source_, dest, beg_pos, position_);
}
ASSERT_EQ('"', c0_);
// Advance past the last '"'.
AdvanceSkipWhitespace();
return result;
}
} } // namespace v8::internal
#endif // V8_JSON_PARSER_H_