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LibJS: Parse slashes after reserved identifiers correctly

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Previously we were unable to parse code like `yield/2` because `/2`
was parsed as a regex. At the same time `for (a in / b/)` was parsed
as a division.

This is solved by defaulting to division in the lexer, but calling
`force_slash_as_regex()` from the parser whenever an IdentifierName
is parsed as a ReservedWord.
This commit is contained in:
Simon Wanner 2023-05-28 00:08:52 +02:00 • committed by Andreas Kling
parent b0bd1e5eb5
commit a2efecac03
6 changed files with 65 additions and 25 deletions
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42
Userland/Libraries/LibJS/Parser.cpp
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@ -1458,11 +1458,11 @@ Parser::PrimaryExpressionParseResult Parser::parse_primary_expression()
case TokenType::BigIntLiteral:
return { create_ast_node<BigIntLiteral>({ m_source_code, rule_start.position(), position() }, consume().value()) };
case TokenType::BoolLiteral:
return { create_ast_node<BooleanLiteral>({ m_source_code, rule_start.position(), position() }, consume().bool_value()) };
return { create_ast_node<BooleanLiteral>({ m_source_code, rule_start.position(), position() }, consume_and_allow_division().bool_value()) };
case TokenType::StringLiteral:
return { parse_string_literal(consume()) };
case TokenType::NullLiteral:
consume();
consume_and_allow_division();
return { create_ast_node<NullLiteral>({ m_source_code, rule_start.position(), position() }) };
case TokenType::CurlyOpen:
return { parse_object_expression() };
@ -2168,7 +2168,7 @@ Parser::ExpressionResult Parser::parse_secondary_expression(NonnullRefPtr<Expres
expected("IdentifierName");
}
return create_ast_node<MemberExpression>({ m_source_code, rule_start.position(), position() }, move(lhs), create_ast_node<Identifier>({ m_source_code, rule_start.position(), position() }, consume().DeprecatedFlyString_value()));
return create_ast_node<MemberExpression>({ m_source_code, rule_start.position(), position() }, move(lhs), create_ast_node<Identifier>({ m_source_code, rule_start.position(), position() }, consume_and_allow_division().DeprecatedFlyString_value()));
case TokenType::BracketOpen: {
consume(TokenType::BracketOpen);
auto expression = create_ast_node<MemberExpression>({ m_source_code, rule_start.position(), position() }, move(lhs), parse_expression(0), true);
@ -4010,6 +4010,18 @@ bool Parser::done() const
}
Token Parser::consume()
{
auto old_token = m_state.current_token;
m_state.current_token = m_state.lexer.next();
// If an IdentifierName is not parsed as an Identifier a slash after it should not be a division
if (old_token.is_identifier_name() && (m_state.current_token.type() == TokenType::Slash || m_state.current_token.type() == TokenType::SlashEquals)) {
m_state.current_token = m_state.lexer.force_slash_as_regex();
}
return old_token;
}
Token Parser::consume_and_allow_division()
{
auto old_token = m_state.current_token;
m_state.current_token = m_state.lexer.next();
@ -4057,26 +4069,26 @@ Token Parser::consume_identifier()
if (match(TokenType::Let)) {
if (m_state.strict_mode)
syntax_error("'let' is not allowed as an identifier in strict mode");
return consume();
return consume_and_allow_division();
}
if (match(TokenType::Yield)) {
if (m_state.strict_mode || m_state.in_generator_function_context)
syntax_error("Identifier must not be a reserved word in strict mode ('yield')");
return consume();
return consume_and_allow_division();
}
if (match(TokenType::Await)) {
if (m_program_type == Program::Type::Module || m_state.await_expression_is_valid || m_state.in_class_static_init_block)
syntax_error("Identifier must not be a reserved word in modules ('await')");
return consume();
return consume_and_allow_division();
}
if (match(TokenType::Async))
return consume();
return consume_and_allow_division();
expected("Identifier");
return consume();
return consume_and_allow_division();
}
// https://tc39.es/ecma262/#prod-IdentifierReference
@ -4092,33 +4104,33 @@ Token Parser::consume_identifier_reference()
if (m_program_type == Program::Type::Module && name == "await"sv)
syntax_error("'await' is not allowed as an identifier in module");
return consume();
return consume_and_allow_division();
}
// See note in Parser::parse_identifier().
if (match(TokenType::Let)) {
if (m_state.strict_mode)
syntax_error("'let' is not allowed as an identifier in strict mode");
return consume();
return consume_and_allow_division();
}
if (match(TokenType::Yield)) {
if (m_state.strict_mode)
syntax_error("Identifier reference may not be 'yield' in strict mode");
return consume();
return consume_and_allow_division();
}
if (match(TokenType::Await)) {
if (m_program_type == Program::Type::Module)
syntax_error("'await' is not allowed as an identifier in module");
return consume();
return consume_and_allow_division();
}
if (match(TokenType::Async))
return consume();
return consume_and_allow_division();
expected(Token::name(TokenType::Identifier));
return consume();
return consume_and_allow_division();
}
Token Parser::consume(TokenType expected_type)
@ -4126,7 +4138,7 @@ Token Parser::consume(TokenType expected_type)
if (!match(expected_type)) {
expected(Token::name(expected_type));
}
auto token = consume();
auto token = expected_type == TokenType::Identifier ? consume_and_allow_division() : consume();
if (expected_type == TokenType::Identifier) {
if (m_state.strict_mode && is_strict_reserved_word(token.value()))
syntax_error(DeprecatedString::formatted("Identifier must not be a reserved word in strict mode ('{}')", token.value()));