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v8/src/scanner.cc

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// Copyright 2006-2008 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.
#include "v8.h"
#include "ast.h"
#include "handles.h"
#include "scanner.h"
namespace v8 {
namespace internal {
// ----------------------------------------------------------------------------
// Character predicates
unibrow::Predicate<IdentifierStart, 128> Scanner::kIsIdentifierStart;
unibrow::Predicate<IdentifierPart, 128> Scanner::kIsIdentifierPart;
unibrow::Predicate<unibrow::LineTerminator, 128> Scanner::kIsLineTerminator;
unibrow::Predicate<unibrow::WhiteSpace, 128> Scanner::kIsWhiteSpace;
StaticResource<Scanner::Utf8Decoder> Scanner::utf8_decoder_;
// ----------------------------------------------------------------------------
// UTF8Buffer
UTF8Buffer::UTF8Buffer() : buffer_(kInitialCapacity) { }
UTF8Buffer::~UTF8Buffer() {}
void UTF8Buffer::AddCharSlow(uc32 c) {
ASSERT(static_cast<unsigned>(c) > unibrow::Utf8::kMaxOneByteChar);
int length = unibrow::Utf8::Length(c);
Vector<char> block = buffer_.AddBlock(length, '\0');
#ifdef DEBUG
int written_length = unibrow::Utf8::Encode(block.start(), c);
CHECK_EQ(length, written_length);
#else
unibrow::Utf8::Encode(block.start(), c);
#endif
}
// ----------------------------------------------------------------------------
// UTF16Buffer
UTF16Buffer::UTF16Buffer()
: pos_(0), end_(Scanner::kNoEndPosition) { }
// CharacterStreamUTF16Buffer
CharacterStreamUTF16Buffer::CharacterStreamUTF16Buffer()
: pushback_buffer_(0), last_(0), stream_(NULL) { }
void CharacterStreamUTF16Buffer::Initialize(Handle<String> data,
unibrow::CharacterStream* input,
int start_position,
int end_position) {
stream_ = input;
if (start_position > 0) {
SeekForward(start_position);
}
end_ = end_position != Scanner::kNoEndPosition ? end_position : kMaxInt;
}
void CharacterStreamUTF16Buffer::PushBack(uc32 ch) {
pushback_buffer()->Add(last_);
last_ = ch;
pos_--;
}
uc32 CharacterStreamUTF16Buffer::Advance() {
ASSERT(end_ != Scanner::kNoEndPosition);
ASSERT(end_ >= 0);
// NOTE: It is of importance to Persian / Farsi resources that we do
// *not* strip format control characters in the scanner; see
//
// https://bugzilla.mozilla.org/show_bug.cgi?id=274152
//
// So, even though ECMA-262, section 7.1, page 11, dictates that we
// must remove Unicode format-control characters, we do not. This is
// in line with how IE and SpiderMonkey handles it.
if (!pushback_buffer()->is_empty()) {
pos_++;
return last_ = pushback_buffer()->RemoveLast();
} else if (stream_->has_more() && pos_ < end_) {
pos_++;
uc32 next = stream_->GetNext();
return last_ = next;
} else {
// Note: currently the following increment is necessary to avoid a
// test-parser problem!
pos_++;
return last_ = static_cast<uc32>(-1);
}
}
void CharacterStreamUTF16Buffer::SeekForward(int pos) {
pos_ = pos;
ASSERT(pushback_buffer()->is_empty());
stream_->Seek(pos);
}
// ExternalStringUTF16Buffer
template <typename StringType, typename CharType>
ExternalStringUTF16Buffer<StringType, CharType>::ExternalStringUTF16Buffer()
: raw_data_(NULL) { }
template <typename StringType, typename CharType>
void ExternalStringUTF16Buffer<StringType, CharType>::Initialize(
Handle<StringType> data,
int start_position,
int end_position) {
ASSERT(!data.is_null());
raw_data_ = data->resource()->data();
ASSERT(end_position <= data->length());
if (start_position > 0) {
SeekForward(start_position);
}
end_ =
end_position != Scanner::kNoEndPosition ? end_position : data->length();
}
template <typename StringType, typename CharType>
uc32 ExternalStringUTF16Buffer<StringType, CharType>::Advance() {
if (pos_ < end_) {
return raw_data_[pos_++];
} else {
// note: currently the following increment is necessary to avoid a
// test-parser problem!
pos_++;
return static_cast<uc32>(-1);
}
}
template <typename StringType, typename CharType>
void ExternalStringUTF16Buffer<StringType, CharType>::PushBack(uc32 ch) {
pos_--;
ASSERT(pos_ >= Scanner::kCharacterLookaheadBufferSize);
ASSERT(raw_data_[pos_ - Scanner::kCharacterLookaheadBufferSize] == ch);
}
template <typename StringType, typename CharType>
void ExternalStringUTF16Buffer<StringType, CharType>::SeekForward(int pos) {
pos_ = pos;
}
// ----------------------------------------------------------------------------
// Keyword Matcher
KeywordMatcher::FirstState KeywordMatcher::first_states_[] = {
{ "break", KEYWORD_PREFIX, Token::BREAK },
{ NULL, C, Token::ILLEGAL },
{ NULL, D, Token::ILLEGAL },
{ "else", KEYWORD_PREFIX, Token::ELSE },
{ NULL, F, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ NULL, I, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ NULL, N, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ "return", KEYWORD_PREFIX, Token::RETURN },
{ "switch", KEYWORD_PREFIX, Token::SWITCH },
{ NULL, T, Token::ILLEGAL },
{ NULL, UNMATCHABLE, Token::ILLEGAL },
{ NULL, V, Token::ILLEGAL },
{ NULL, W, Token::ILLEGAL }
};
void KeywordMatcher::Step(uc32 input) {
switch (state_) {
case INITIAL: {
// matching the first character is the only state with significant fanout.
// Match only lower-case letters in range 'b'..'w'.
unsigned int offset = input - kFirstCharRangeMin;
if (offset < kFirstCharRangeLength) {
state_ = first_states_[offset].state;
if (state_ == KEYWORD_PREFIX) {
keyword_ = first_states_[offset].keyword;
counter_ = 1;
keyword_token_ = first_states_[offset].token;
}
return;
}
break;
}
case KEYWORD_PREFIX:
if (keyword_[counter_] == input) {
ASSERT_NE(input, '\0');
counter_++;
if (keyword_[counter_] == '\0') {
state_ = KEYWORD_MATCHED;
token_ = keyword_token_;
}
return;
}
break;
case KEYWORD_MATCHED:
token_ = Token::IDENTIFIER;
break;
case C:
if (MatchState(input, 'a', CA)) return;
if (MatchState(input, 'o', CO)) return;
break;
case CA:
if (MatchKeywordStart(input, "case", 2, Token::CASE)) return;
if (MatchKeywordStart(input, "catch", 2, Token::CATCH)) return;
break;
case CO:
if (MatchState(input, 'n', CON)) return;
break;
case CON:
if (MatchKeywordStart(input, "const", 3, Token::CONST)) return;
if (MatchKeywordStart(input, "continue", 3, Token::CONTINUE)) return;
break;
case D:
if (MatchState(input, 'e', DE)) return;
if (MatchKeyword(input, 'o', KEYWORD_MATCHED, Token::DO)) return;
break;
case DE:
if (MatchKeywordStart(input, "debugger", 2, Token::DEBUGGER)) return;
if (MatchKeywordStart(input, "default", 2, Token::DEFAULT)) return;
if (MatchKeywordStart(input, "delete", 2, Token::DELETE)) return;
break;
case F:
if (MatchKeywordStart(input, "false", 1, Token::FALSE_LITERAL)) return;
if (MatchKeywordStart(input, "finally", 1, Token::FINALLY)) return;
if (MatchKeywordStart(input, "for", 1, Token::FOR)) return;
if (MatchKeywordStart(input, "function", 1, Token::FUNCTION)) return;
break;
case I:
if (MatchKeyword(input, 'f', KEYWORD_MATCHED, Token::IF)) return;
if (MatchKeyword(input, 'n', IN, Token::IN)) return;
break;
case IN:
token_ = Token::IDENTIFIER;
if (MatchKeywordStart(input, "instanceof", 2, Token::INSTANCEOF)) {
return;
}
break;
case N:
if (MatchKeywordStart(input, "native", 1, Token::NATIVE)) return;
if (MatchKeywordStart(input, "new", 1, Token::NEW)) return;
if (MatchKeywordStart(input, "null", 1, Token::NULL_LITERAL)) return;
break;
case T:
if (MatchState(input, 'h', TH)) return;
if (MatchState(input, 'r', TR)) return;
if (MatchKeywordStart(input, "typeof", 1, Token::TYPEOF)) return;
break;
case TH:
if (MatchKeywordStart(input, "this", 2, Token::THIS)) return;
if (MatchKeywordStart(input, "throw", 2, Token::THROW)) return;
break;
case TR:
if (MatchKeywordStart(input, "true", 2, Token::TRUE_LITERAL)) return;
if (MatchKeyword(input, 'y', KEYWORD_MATCHED, Token::TRY)) return;
break;
case V:
if (MatchKeywordStart(input, "var", 1, Token::VAR)) return;
if (MatchKeywordStart(input, "void", 1, Token::VOID)) return;
break;
case W:
if (MatchKeywordStart(input, "while", 1, Token::WHILE)) return;
if (MatchKeywordStart(input, "with", 1, Token::WITH)) return;
break;
default:
UNREACHABLE();
}
// On fallthrough, it's a failure.
state_ = UNMATCHABLE;
}
// ----------------------------------------------------------------------------
// Scanner::LiteralScope
Scanner::LiteralScope::LiteralScope(Scanner* self)
: scanner_(self), complete_(false) {
self->StartLiteral();
}
Scanner::LiteralScope::~LiteralScope() {
if (!complete_) scanner_->DropLiteral();
}
void Scanner::LiteralScope::Complete() {
scanner_->TerminateLiteral();
complete_ = true;
}
// ----------------------------------------------------------------------------
// Scanner
Scanner::Scanner(ParserMode pre)
: is_pre_parsing_(pre == PREPARSE), stack_overflow_(false) { }
void Scanner::Initialize(Handle<String> source,
ParserLanguage language) {
Init(source, NULL, 0, source->length(), language);
}
void Scanner::Initialize(Handle<String> source,
unibrow::CharacterStream* stream,
ParserLanguage language) {
Init(source, stream, 0, kNoEndPosition, language);
}
void Scanner::Initialize(Handle<String> source,
int start_position,
int end_position,
ParserLanguage language) {
Init(source, NULL, start_position, end_position, language);
}
void Scanner::Init(Handle<String> source,
unibrow::CharacterStream* stream,
int start_position,
int end_position,
ParserLanguage language) {
// Either initialize the scanner from a character stream or from a
// string.
ASSERT(source.is_null() || stream == NULL);
// Initialize the source buffer.
if (!source.is_null() && StringShape(*source).IsExternalTwoByte()) {
two_byte_string_buffer_.Initialize(
Handle<ExternalTwoByteString>::cast(source),
start_position,
end_position);
source_ = &two_byte_string_buffer_;
} else if (!source.is_null() && StringShape(*source).IsExternalAscii()) {
ascii_string_buffer_.Initialize(
Handle<ExternalAsciiString>::cast(source),
start_position,
end_position);
source_ = &ascii_string_buffer_;
} else {
if (!source.is_null()) {
safe_string_input_buffer_.Reset(source.location());
stream = &safe_string_input_buffer_;
}
char_stream_buffer_.Initialize(source,
stream,
start_position,
end_position);
source_ = &char_stream_buffer_;
}
is_parsing_json_ = (language == JSON);
// Set c0_ (one character ahead)
ASSERT(kCharacterLookaheadBufferSize == 1);
Advance();
// Initialize current_ to not refer to a literal.
current_.literal_chars = Vector<const char>();
// Reset literal buffer.
literal_buffer_.Reset();
// Skip initial whitespace allowing HTML comment ends just like
// after a newline and scan first token.
has_line_terminator_before_next_ = true;
SkipWhiteSpace();
Scan();
}
Token::Value Scanner::Next() {
// BUG 1215673: Find a thread safe way to set a stack limit in
// pre-parse mode. Otherwise, we cannot safely pre-parse from other
// threads.
current_ = next_;
// Check for stack-overflow before returning any tokens.
StackLimitCheck check;
if (check.HasOverflowed()) {
stack_overflow_ = true;
next_.token = Token::ILLEGAL;
} else {
has_line_terminator_before_next_ = false;
Scan();
}
return current_.token;
}
void Scanner::StartLiteral() {
literal_buffer_.StartLiteral();
}
void Scanner::AddChar(uc32 c) {
literal_buffer_.AddChar(c);
}
void Scanner::TerminateLiteral() {
next_.literal_chars = literal_buffer_.EndLiteral();
}
void Scanner::DropLiteral() {
literal_buffer_.DropLiteral();
}
void Scanner::AddCharAdvance() {
AddChar(c0_);
Advance();
}
static inline bool IsByteOrderMark(uc32 c) {
// The Unicode value U+FFFE is guaranteed never to be assigned as a
// Unicode character; this implies that in a Unicode context the
// 0xFF, 0xFE byte pattern can only be interpreted as the U+FEFF
// character expressed in little-endian byte order (since it could
// not be a U+FFFE character expressed in big-endian byte
// order). Nevertheless, we check for it to be compatible with
// Spidermonkey.
return c == 0xFEFF || c == 0xFFFE;
}
bool Scanner::SkipJsonWhiteSpace() {
int start_position = source_pos();
// JSON WhiteSpace is tab, carrige-return, newline and space.
while (c0_ == ' ' || c0_ == '\n' || c0_ == '\r' || c0_ == '\t') {
Advance();
}
return source_pos() != start_position;
}
bool Scanner::SkipJavaScriptWhiteSpace() {
int start_position = source_pos();
while (true) {
// We treat byte-order marks (BOMs) as whitespace for better
// compatibility with Spidermonkey and other JavaScript engines.
while (kIsWhiteSpace.get(c0_) || IsByteOrderMark(c0_)) {
// IsWhiteSpace() includes line terminators!
if (kIsLineTerminator.get(c0_)) {
// Ignore line terminators, but remember them. This is necessary
// for automatic semicolon insertion.
has_line_terminator_before_next_ = true;
}
Advance();
}
// If there is an HTML comment end '-->' at the beginning of a
// line (with only whitespace in front of it), we treat the rest
// of the line as a comment. This is in line with the way
// SpiderMonkey handles it.
if (c0_ == '-' && has_line_terminator_before_next_) {
Advance();
if (c0_ == '-') {
Advance();
if (c0_ == '>') {
// Treat the rest of the line as a comment.
SkipSingleLineComment();
// Continue skipping white space after the comment.
continue;
}
PushBack('-'); // undo Advance()
}
PushBack('-'); // undo Advance()
}
// Return whether or not we skipped any characters.
return source_pos() != start_position;
}
}
Token::Value Scanner::SkipSingleLineComment() {
Advance();
// The line terminator at the end of the line is not considered
// to be part of the single-line comment; it is recognized
// separately by the lexical grammar and becomes part of the
// stream of input elements for the syntactic grammar (see
// ECMA-262, section 7.4, page 12).
while (c0_ >= 0 && !kIsLineTerminator.get(c0_)) {
Advance();
}
return Token::WHITESPACE;
}
Token::Value Scanner::SkipMultiLineComment() {
ASSERT(c0_ == '*');
Advance();
while (c0_ >= 0) {
char ch = c0_;
Advance();
// If we have reached the end of the multi-line comment, we
// consume the '/' and insert a whitespace. This way all
// multi-line comments are treated as whitespace - even the ones
// containing line terminators. This contradicts ECMA-262, section
// 7.4, page 12, that says that multi-line comments containing
// line terminators should be treated as a line terminator, but it
// matches the behaviour of SpiderMonkey and KJS.
if (ch == '*' && c0_ == '/') {
c0_ = ' ';
return Token::WHITESPACE;
}
}
// Unterminated multi-line comment.
return Token::ILLEGAL;
}
Token::Value Scanner::ScanHtmlComment() {
// Check for <!-- comments.
ASSERT(c0_ == '!');
Advance();
if (c0_ == '-') {
Advance();
if (c0_ == '-') return SkipSingleLineComment();
PushBack('-'); // undo Advance()
}
PushBack('!'); // undo Advance()
ASSERT(c0_ == '!');
return Token::LT;
}
void Scanner::ScanJson() {
next_.literal_chars = Vector<const char>();
Token::Value token;
has_line_terminator_before_next_ = false;
do {
// Remember the position of the next token
next_.location.beg_pos = source_pos();
switch (c0_) {
case '\t':
case '\r':
case '\n':
case ' ':
Advance();
token = Token::WHITESPACE;
break;
case '{':
Advance();
token = Token::LBRACE;
break;
case '}':
Advance();
token = Token::RBRACE;
break;
case '[':
Advance();
token = Token::LBRACK;
break;
case ']':
Advance();
token = Token::RBRACK;
break;
case ':':
Advance();
token = Token::COLON;
break;
case ',':
Advance();
token = Token::COMMA;
break;
case '"':
token = ScanJsonString();
break;
case '-':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
token = ScanJsonNumber();
break;
case 't':
token = ScanJsonIdentifier("true", Token::TRUE_LITERAL);
break;
case 'f':
token = ScanJsonIdentifier("false", Token::FALSE_LITERAL);
break;
case 'n':
token = ScanJsonIdentifier("null", Token::NULL_LITERAL);
break;
default:
if (c0_ < 0) {
Advance();
token = Token::EOS;
} else {
Advance();
token = Select(Token::ILLEGAL);
}
}
} while (token == Token::WHITESPACE);
next_.location.end_pos = source_pos();
next_.token = token;
}
Token::Value Scanner::ScanJsonString() {
ASSERT_EQ('"', c0_);
Advance();
LiteralScope literal(this);
while (c0_ != '"' && c0_ > 0) {
// Check for control character (0x00-0x1f) or unterminated string (<0).
if (c0_ < 0x20) return Token::ILLEGAL;
if (c0_ != '\\') {
AddCharAdvance();
} else {
Advance();
switch (c0_) {
case '"':
case '\\':
case '/':
AddChar(c0_);
break;
case 'b':
AddChar('\x08');
break;
case 'f':
AddChar('\x0c');
break;
case 'n':
AddChar('\x0a');
break;
case 'r':
AddChar('\x0d');
break;
case 't':
AddChar('\x09');
break;
case 'u': {
uc32 value = 0;
for (int i = 0; i < 4; i++) {
Advance();
int digit = HexValue(c0_);
if (digit < 0) {
return Token::ILLEGAL;
}
value = value * 16 + digit;
}
AddChar(value);
break;
}
default:
return Token::ILLEGAL;
}
Advance();
}
}
if (c0_ != '"') {
return Token::ILLEGAL;
}
literal.Complete();
Advance();
return Token::STRING;
}
Token::Value Scanner::ScanJsonNumber() {
LiteralScope literal(this);
if (c0_ == '-') AddCharAdvance();
if (c0_ == '0') {
AddCharAdvance();
// Prefix zero is only allowed if it's the only digit before
// a decimal point or exponent.
if ('0' <= c0_ && c0_ <= '9') return Token::ILLEGAL;
} else {
if (c0_ < '1' || c0_ > '9') return Token::ILLEGAL;
do {
AddCharAdvance();
} while (c0_ >= '0' && c0_ <= '9');
}
if (c0_ == '.') {
AddCharAdvance();
if (c0_ < '0' || c0_ > '9') return Token::ILLEGAL;
do {
AddCharAdvance();
} while (c0_ >= '0' && c0_ <= '9');
}
if (AsciiAlphaToLower(c0_) == 'e') {
AddCharAdvance();
if (c0_ == '-' || c0_ == '+') AddCharAdvance();
if (c0_ < '0' || c0_ > '9') return Token::ILLEGAL;
do {
AddCharAdvance();
} while (c0_ >= '0' && c0_ <= '9');
}
literal.Complete();
return Token::NUMBER;
}
Token::Value Scanner::ScanJsonIdentifier(const char* text,
Token::Value token) {
LiteralScope literal(this);
while (*text != '\0') {
if (c0_ != *text) return Token::ILLEGAL;
Advance();
text++;
}
if (kIsIdentifierPart.get(c0_)) return Token::ILLEGAL;
literal.Complete();
return token;
}
void Scanner::ScanJavaScript() {
next_.literal_chars = Vector<const char>();
Token::Value token;
do {
// Remember the position of the next token
next_.location.beg_pos = source_pos();
switch (c0_) {
case ' ':
case '\t':
Advance();
token = Token::WHITESPACE;
break;
case '\n':
Advance();
has_line_terminator_before_next_ = true;
token = Token::WHITESPACE;
break;
case '"': case '\'':
token = ScanString();
break;
case '<':
// < <= << <<= <!--
Advance();
if (c0_ == '=') {
token = Select(Token::LTE);
} else if (c0_ == '<') {
token = Select('=', Token::ASSIGN_SHL, Token::SHL);
} else if (c0_ == '!') {
token = ScanHtmlComment();
} else {
token = Token::LT;
}
break;
case '>':
// > >= >> >>= >>> >>>=
Advance();
if (c0_ == '=') {
token = Select(Token::GTE);
} else if (c0_ == '>') {
// >> >>= >>> >>>=
Advance();
if (c0_ == '=') {
token = Select(Token::ASSIGN_SAR);
} else if (c0_ == '>') {
token = Select('=', Token::ASSIGN_SHR, Token::SHR);
} else {
token = Token::SAR;
}
} else {
token = Token::GT;
}
break;
case '=':
// = == ===
Advance();
if (c0_ == '=') {
token = Select('=', Token::EQ_STRICT, Token::EQ);
} else {
token = Token::ASSIGN;
}
break;
case '!':
// ! != !==
Advance();
if (c0_ == '=') {
token = Select('=', Token::NE_STRICT, Token::NE);
} else {
token = Token::NOT;
}
break;
case '+':
// + ++ +=
Advance();
if (c0_ == '+') {
token = Select(Token::INC);
} else if (c0_ == '=') {
token = Select(Token::ASSIGN_ADD);
} else {
token = Token::ADD;
}
break;
case '-':
// - -- --> -=
Advance();
if (c0_ == '-') {
Advance();
if (c0_ == '>' && has_line_terminator_before_next_) {
// For compatibility with SpiderMonkey, we skip lines that
// start with an HTML comment end '-->'.
token = SkipSingleLineComment();
} else {
token = Token::DEC;
}
} else if (c0_ == '=') {
token = Select(Token::ASSIGN_SUB);
} else {
token = Token::SUB;
}
break;
case '*':
// * *=
token = Select('=', Token::ASSIGN_MUL, Token::MUL);
break;
case '%':
// % %=
token = Select('=', Token::ASSIGN_MOD, Token::MOD);
break;
case '/':
// / // /* /=
Advance();
if (c0_ == '/') {
token = SkipSingleLineComment();
} else if (c0_ == '*') {
token = SkipMultiLineComment();
} else if (c0_ == '=') {
token = Select(Token::ASSIGN_DIV);
} else {
token = Token::DIV;
}
break;
case '&':
// & && &=
Advance();
if (c0_ == '&') {
token = Select(Token::AND);
} else if (c0_ == '=') {
token = Select(Token::ASSIGN_BIT_AND);
} else {
token = Token::BIT_AND;
}
break;
case '|':
// | || |=
Advance();
if (c0_ == '|') {
token = Select(Token::OR);
} else if (c0_ == '=') {
token = Select(Token::ASSIGN_BIT_OR);
} else {
token = Token::BIT_OR;
}
break;
case '^':
// ^ ^=
token = Select('=', Token::ASSIGN_BIT_XOR, Token::BIT_XOR);
break;
case '.':
// . Number
Advance();
if (IsDecimalDigit(c0_)) {
token = ScanNumber(true);
} else {
token = Token::PERIOD;
}
break;
case ':':
token = Select(Token::COLON);
break;
case ';':
token = Select(Token::SEMICOLON);
break;
case ',':
token = Select(Token::COMMA);
break;
case '(':
token = Select(Token::LPAREN);
break;
case ')':
token = Select(Token::RPAREN);
break;
case '[':
token = Select(Token::LBRACK);
break;
case ']':
token = Select(Token::RBRACK);
break;
case '{':
token = Select(Token::LBRACE);
break;
case '}':
token = Select(Token::RBRACE);
break;
case '?':
token = Select(Token::CONDITIONAL);
break;
case '~':
token = Select(Token::BIT_NOT);
break;
default:
if (kIsIdentifierStart.get(c0_)) {
token = ScanIdentifier();
} else if (IsDecimalDigit(c0_)) {
token = ScanNumber(false);
} else if (SkipWhiteSpace()) {
token = Token::WHITESPACE;
} else if (c0_ < 0) {
token = Token::EOS;
} else {
token = Select(Token::ILLEGAL);
}
break;
}
// Continue scanning for tokens as long as we're just skipping
// whitespace.
} while (token == Token::WHITESPACE);
next_.location.end_pos = source_pos();
next_.token = token;
}
void Scanner::SeekForward(int pos) {
source_->SeekForward(pos - 1);
Advance();
// This function is only called to seek to the location
// of the end of a function (at the "}" token). It doesn't matter
// whether there was a line terminator in the part we skip.
has_line_terminator_before_next_ = false;
Scan();
}
uc32 Scanner::ScanHexEscape(uc32 c, int length) {
ASSERT(length <= 4); // prevent overflow
uc32 digits[4];
uc32 x = 0;
for (int i = 0; i < length; i++) {
digits[i] = c0_;
int d = HexValue(c0_);
if (d < 0) {
// According to ECMA-262, 3rd, 7.8.4, page 18, these hex escapes
// should be illegal, but other JS VMs just return the
// non-escaped version of the original character.
// Push back digits read, except the last one (in c0_).
for (int j = i-1; j >= 0; j--) {
PushBack(digits[j]);
}
// Notice: No handling of error - treat it as "\u"->"u".
return c;
}
x = x * 16 + d;
Advance();
}
return x;
}
// Octal escapes of the forms '\0xx' and '\xxx' are not a part of
// ECMA-262. Other JS VMs support them.
uc32 Scanner::ScanOctalEscape(uc32 c, int length) {
uc32 x = c - '0';
for (int i = 0; i < length; i++) {
int d = c0_ - '0';
if (d < 0 || d > 7) break;
int nx = x * 8 + d;
if (nx >= 256) break;
x = nx;
Advance();
}
return x;
}
void Scanner::ScanEscape() {
uc32 c = c0_;
Advance();
// Skip escaped newlines.
if (kIsLineTerminator.get(c)) {
// Allow CR+LF newlines in multiline string literals.
if (IsCarriageReturn(c) && IsLineFeed(c0_)) Advance();
// Allow LF+CR newlines in multiline string literals.
if (IsLineFeed(c) && IsCarriageReturn(c0_)) Advance();
return;
}
switch (c) {
case '\'': // fall through
case '"' : // fall through
case '\\': break;
case 'b' : c = '\b'; break;
case 'f' : c = '\f'; break;
case 'n' : c = '\n'; break;
case 'r' : c = '\r'; break;
case 't' : c = '\t'; break;
case 'u' : c = ScanHexEscape(c, 4); break;
case 'v' : c = '\v'; break;
case 'x' : c = ScanHexEscape(c, 2); break;
case '0' : // fall through
case '1' : // fall through
case '2' : // fall through
case '3' : // fall through
case '4' : // fall through
case '5' : // fall through
case '6' : // fall through
case '7' : c = ScanOctalEscape(c, 2); break;
}
// According to ECMA-262, 3rd, 7.8.4 (p 18ff) these
// should be illegal, but they are commonly handled
// as non-escaped characters by JS VMs.
AddChar(c);
}
Token::Value Scanner::ScanString() {
uc32 quote = c0_;
Advance(); // consume quote
LiteralScope literal(this);
while (c0_ != quote && c0_ >= 0 && !kIsLineTerminator.get(c0_)) {
uc32 c = c0_;
Advance();
if (c == '\\') {
if (c0_ < 0) return Token::ILLEGAL;
ScanEscape();
} else {
AddChar(c);
}
}
if (c0_ != quote) return Token::ILLEGAL;
literal.Complete();
Advance(); // consume quote
return Token::STRING;
}
Token::Value Scanner::Select(Token::Value tok) {
Advance();
return tok;
}
Token::Value Scanner::Select(uc32 next, Token::Value then, Token::Value else_) {
Advance();
if (c0_ == next) {
Advance();
return then;
} else {
return else_;
}
}
// Returns true if any decimal digits were scanned, returns false otherwise.
void Scanner::ScanDecimalDigits() {
while (IsDecimalDigit(c0_))
AddCharAdvance();
}
Token::Value Scanner::ScanNumber(bool seen_period) {
ASSERT(IsDecimalDigit(c0_)); // the first digit of the number or the fraction
enum { DECIMAL, HEX, OCTAL } kind = DECIMAL;
LiteralScope literal(this);
if (seen_period) {
// we have already seen a decimal point of the float
AddChar('.');
ScanDecimalDigits(); // we know we have at least one digit
} else {
// if the first character is '0' we must check for octals and hex
if (c0_ == '0') {
AddCharAdvance();
// either 0, 0exxx, 0Exxx, 0.xxx, an octal number, or a hex number
if (c0_ == 'x' || c0_ == 'X') {
// hex number
kind = HEX;
AddCharAdvance();
if (!IsHexDigit(c0_)) {
// we must have at least one hex digit after 'x'/'X'
return Token::ILLEGAL;
}
while (IsHexDigit(c0_)) {
AddCharAdvance();
}
} else if ('0' <= c0_ && c0_ <= '7') {
// (possible) octal number
kind = OCTAL;
while (true) {
if (c0_ == '8' || c0_ == '9') {
kind = DECIMAL;
break;
}
if (c0_ < '0' || '7' < c0_) break;
AddCharAdvance();
}
}
}
// Parse decimal digits and allow trailing fractional part.
if (kind == DECIMAL) {
ScanDecimalDigits(); // optional
if (c0_ == '.') {
AddCharAdvance();
ScanDecimalDigits(); // optional
}
}
}
// scan exponent, if any
if (c0_ == 'e' || c0_ == 'E') {
ASSERT(kind != HEX); // 'e'/'E' must be scanned as part of the hex number
if (kind == OCTAL) return Token::ILLEGAL; // no exponent for octals allowed
// scan exponent
AddCharAdvance();
if (c0_ == '+' || c0_ == '-')
AddCharAdvance();
if (!IsDecimalDigit(c0_)) {
// we must have at least one decimal digit after 'e'/'E'
return Token::ILLEGAL;
}
ScanDecimalDigits();
}
// The source character immediately following a numeric literal must
// not be an identifier start or a decimal digit; see ECMA-262
// section 7.8.3, page 17 (note that we read only one decimal digit
// if the value is 0).
if (IsDecimalDigit(c0_) || kIsIdentifierStart.get(c0_))
return Token::ILLEGAL;
literal.Complete();
return Token::NUMBER;
}
uc32 Scanner::ScanIdentifierUnicodeEscape() {
Advance();
if (c0_ != 'u') return unibrow::Utf8::kBadChar;
Advance();
uc32 c = ScanHexEscape('u', 4);
// We do not allow a unicode escape sequence to start another
// unicode escape sequence.
if (c == '\\') return unibrow::Utf8::kBadChar;
return c;
}
Token::Value Scanner::ScanIdentifier() {
ASSERT(kIsIdentifierStart.get(c0_));
LiteralScope literal(this);
KeywordMatcher keyword_match;
// Scan identifier start character.
if (c0_ == '\\') {
uc32 c = ScanIdentifierUnicodeEscape();
// Only allow legal identifier start characters.
if (!kIsIdentifierStart.get(c)) return Token::ILLEGAL;
AddChar(c);
keyword_match.Fail();
} else {
AddChar(c0_);
keyword_match.AddChar(c0_);
Advance();
}
// Scan the rest of the identifier characters.
while (kIsIdentifierPart.get(c0_)) {
if (c0_ == '\\') {
uc32 c = ScanIdentifierUnicodeEscape();
// Only allow legal identifier part characters.
if (!kIsIdentifierPart.get(c)) return Token::ILLEGAL;
AddChar(c);
keyword_match.Fail();
} else {
AddChar(c0_);
keyword_match.AddChar(c0_);
Advance();
}
}
literal.Complete();
return keyword_match.token();
}
bool Scanner::IsIdentifier(unibrow::CharacterStream* buffer) {
// Checks whether the buffer contains an identifier (no escape).
if (!buffer->has_more()) return false;
if (!kIsIdentifierStart.get(buffer->GetNext())) return false;
while (buffer->has_more()) {
if (!kIsIdentifierPart.get(buffer->GetNext())) return false;
}
return true;
}
bool Scanner::ScanRegExpPattern(bool seen_equal) {
// Scan: ('/' | '/=') RegularExpressionBody '/' RegularExpressionFlags
bool in_character_class = false;
// Previous token is either '/' or '/=', in the second case, the
// pattern starts at =.
next_.location.beg_pos = source_pos() - (seen_equal ? 2 : 1);
next_.location.end_pos = source_pos() - (seen_equal ? 1 : 0);
// Scan regular expression body: According to ECMA-262, 3rd, 7.8.5,
// the scanner should pass uninterpreted bodies to the RegExp
// constructor.
LiteralScope literal(this);
if (seen_equal)
AddChar('=');
while (c0_ != '/' || in_character_class) {
if (kIsLineTerminator.get(c0_) || c0_ < 0) return false;
if (c0_ == '\\') { // escaped character
AddCharAdvance();
if (kIsLineTerminator.get(c0_) || c0_ < 0) return false;
AddCharAdvance();
} else { // unescaped character
if (c0_ == '[') in_character_class = true;
if (c0_ == ']') in_character_class = false;
AddCharAdvance();
}
}
Advance(); // consume '/'
literal.Complete();
return true;
}
bool Scanner::ScanRegExpFlags() {
// Scan regular expression flags.
LiteralScope literal(this);
while (kIsIdentifierPart.get(c0_)) {
if (c0_ == '\\') {
uc32 c = ScanIdentifierUnicodeEscape();
if (c != static_cast<uc32>(unibrow::Utf8::kBadChar)) {
// We allow any escaped character, unlike the restriction on
// IdentifierPart when it is used to build an IdentifierName.
AddChar(c);
continue;
}
}
AddCharAdvance();
}
literal.Complete();
next_.location.end_pos = source_pos() - 1;
return true;
}
} } // namespace v8::internal
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