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LibJS: Implement 'new.target'

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This adds a new MetaProperty AST node which will be used for
'new.target' and 'import.meta' meta properties. The parser now
distinguishes between "in function context" and "in arrow function
context" (which is required for this).
When encountering TokenType::New we will attempt to parse it as meta
property and resort to regular new expression parsing if that fails,
much like the parsing of labelled statements.
This commit is contained in:
Linus Groh 2020-11-02 21:27:42 +00:00 • committed by Andreas Kling
parent e07a39c816
commit 39a1c9d827
6 changed files with 109 additions and 10 deletions
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40
Libraries/LibJS/Parser.cpp
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@ -401,7 +401,7 @@ RefPtr<FunctionExpression> Parser::try_parse_arrow_function_expression(bool expe
bool is_strict = false;
auto function_body_result = [&]() -> RefPtr<BlockStatement> {
TemporaryChange change(m_parser_state.m_in_function_context, true);
TemporaryChange change(m_parser_state.m_in_arrow_function_context, true);
if (match(TokenType::CurlyOpen)) {
// Parse a function body with statements
return parse_block_statement(is_strict);
@ -454,6 +454,26 @@ RefPtr<Statement> Parser::try_parse_labelled_statement()
return statement;
}
RefPtr<MetaProperty> Parser::try_parse_new_target_expression()
{
save_state();
ArmedScopeGuard state_rollback_guard = [&] {
load_state();
};
consume(TokenType::New);
if (!match(TokenType::Period))
return {};
consume();
if (!match(TokenType::Identifier))
return {};
if (consume().value() != "target")
return {};
state_rollback_guard.disarm();
return create_ast_node<MetaProperty>(MetaProperty::Type::NewTarget);
}
NonnullRefPtr<ClassDeclaration> Parser::parse_class_declaration()
{
return create_ast_node<ClassDeclaration>(parse_class_expression(true));
@ -593,9 +613,8 @@ NonnullRefPtr<Expression> Parser::parse_primary_expression()
consume(TokenType::ParenOpen);
if (match(TokenType::ParenClose) || match(TokenType::Identifier) || match(TokenType::TripleDot)) {
auto arrow_function_result = try_parse_arrow_function_expression(true);
if (!arrow_function_result.is_null()) {
if (!arrow_function_result.is_null())
return arrow_function_result.release_nonnull();
}
}
auto expression = parse_expression(0);
consume(TokenType::ParenClose);
@ -613,9 +632,8 @@ NonnullRefPtr<Expression> Parser::parse_primary_expression()
return create_ast_node<SuperExpression>();
case TokenType::Identifier: {
auto arrow_function_result = try_parse_arrow_function_expression(false);
if (!arrow_function_result.is_null()) {
if (!arrow_function_result.is_null())
return arrow_function_result.release_nonnull();
}
return create_ast_node<Identifier>(consume().value());
}
case TokenType::NumericLiteral:
@ -639,8 +657,16 @@ NonnullRefPtr<Expression> Parser::parse_primary_expression()
return parse_regexp_literal();
case TokenType::TemplateLiteralStart:
return parse_template_literal(false);
case TokenType::New:
case TokenType::New: {
auto new_start = position();
auto new_target_result = try_parse_new_target_expression();
if (!new_target_result.is_null()) {
if (!m_parser_state.m_in_function_context)
syntax_error("'new.target' not allowed outside of a function", new_start);
return new_target_result.release_nonnull();
}
return parse_new_expression();
}
default:
expected("primary expression");
consume();
@ -1191,7 +1217,7 @@ NonnullRefPtr<NewExpression> Parser::parse_new_expression()
NonnullRefPtr<ReturnStatement> Parser::parse_return_statement()
{
if (!m_parser_state.m_in_function_context)
if (!m_parser_state.m_in_function_context && !m_parser_state.m_in_arrow_function_context)
syntax_error("'return' not allowed outside of a function");
consume(TokenType::Return);