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LibJS: Add support for arrow functions

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This commit is contained in:
Jack Karamanian 2020-03-30 08:26:09 -05:00 • committed by Andreas Kling
parent f90da71d28
commit 098f1cd0ca
5 changed files with 144 additions and 1 deletions
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85
Libraries/LibJS/Parser.cpp
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@ -223,6 +223,78 @@ NonnullRefPtr<Statement> Parser::parse_statement()
return statement;
}
RefPtr<FunctionExpression> Parser::try_parse_arrow_function_expression(bool expect_parens)
{
save_state();
Vector<FlyString> parameters;
bool parse_failed = false;
while (true) {
if (match(TokenType::Comma)) {
consume(TokenType::Comma);
} else if (match(TokenType::Identifier)) {
auto token = consume(TokenType::Identifier);
parameters.append(token.value());
} else if (match(TokenType::ParenClose)) {
if (expect_parens) {
consume(TokenType::ParenClose);
if (match(TokenType::Arrow)) {
consume(TokenType::Arrow);
} else {
parse_failed = true;
}
break;
}
parse_failed = true;
break;
} else if (match(TokenType::Arrow)) {
if (!expect_parens) {
consume(TokenType::Arrow);
break;
}
parse_failed = true;
break;
} else {
parse_failed = true;
break;
}
}
if (parse_failed) {
load_state();
return nullptr;
}
auto function_body_result = [this]() -> RefPtr<BlockStatement> {
if (match(TokenType::CurlyOpen)) {
// Parse a function body with statements
return parse_block_statement();
}
if (match_expression()) {
// Parse a function body which returns a single expression
// FIXME: We synthesize a block with a return statement
// for arrow function bodies which are a single expression.
// Esprima generates a single "ArrowFunctionExpression"
// with a "body" property.
auto return_expression = parse_expression(0);
auto return_block = create_ast_node<BlockStatement>();
return_block->append<ReturnStatement>(move(return_expression));
return return_block;
}
// Invalid arrow function body
return nullptr;
}();
if (!function_body_result.is_null()) {
auto body = function_body_result.release_nonnull();
return create_ast_node<FunctionExpression>("", move(body), move(parameters));
}
load_state();
return nullptr;
}
NonnullRefPtr<Expression> Parser::parse_primary_expression()
{
if (match_unary_prefixed_expression())
@ -231,12 +303,23 @@ NonnullRefPtr<Expression> Parser::parse_primary_expression()
switch (m_parser_state.m_current_token.type()) {
case TokenType::ParenOpen: {
consume(TokenType::ParenOpen);
if (match(TokenType::ParenClose) || match(TokenType::Identifier)) {
auto arrow_function_result = try_parse_arrow_function_expression(true);
if (!arrow_function_result.is_null()) {
return arrow_function_result.release_nonnull();
}
}
auto expression = parse_expression(0);
consume(TokenType::ParenClose);
return expression;
}
case TokenType::Identifier:
case TokenType::Identifier: {
auto arrow_function_result = try_parse_arrow_function_expression(false);
if (!arrow_function_result.is_null()) {
return arrow_function_result.release_nonnull();
}
return create_ast_node<Identifier>(consume().value());
}
case TokenType::NumericLiteral:
return create_ast_node<NumericLiteral>(consume().double_value());
case TokenType::BoolLiteral: