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LibJS: Parse FunctionExpressions

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FunctionExpression is mostly like FunctionDeclaration, except the name
is optional. Share the parsing logic in parse_function_node<NodeType>.

This allows us to do nice things like:

    document.addEventListener("DOMContentLoaded", function() {
        alert("Hello friends!");
    });
This commit is contained in:
Andreas Kling 2020-03-19 11:52:56 +01:00
parent b1b4c9844e
commit 07679e347c
3 changed files with 21 additions and 5 deletions
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18
Libraries/LibJS/Parser.cpp
View file

@ -187,7 +187,7 @@ NonnullRefPtr<Statement> Parser::parse_statement()
switch (m_current_token.type()) {
case TokenType::Function:
return parse_function_declaration();
return parse_function_node<FunctionDeclaration>();
case TokenType::CurlyOpen:
return parse_block_statement();
case TokenType::Return:
@ -231,6 +231,8 @@ NonnullRefPtr<Expression> Parser::parse_primary_expression()
return create_ast_node<UndefinedLiteral>();
case TokenType::CurlyOpen:
return parse_object_expression();
case TokenType::Function:
return parse_function_node<FunctionExpression>();
default:
m_has_errors = true;
expected("primary expression (missing switch case)");
@ -416,10 +418,17 @@ NonnullRefPtr<BlockStatement> Parser::parse_block_statement()
return block;
}
NonnullRefPtr<FunctionDeclaration> Parser::parse_function_declaration()
template<typename FunctionNodeType>
NonnullRefPtr<FunctionNodeType> Parser::parse_function_node()
{
consume(TokenType::Function);
auto name = consume(TokenType::Identifier).value();
String name;
if (FunctionNodeType::must_have_name()) {
name = consume(TokenType::Identifier).value();
} else {
if (match(TokenType::Identifier))
name = consume(TokenType::Identifier).value();
}
consume(TokenType::ParenOpen);
Vector<String> parameters;
while (match(TokenType::Identifier)) {
@ -432,7 +441,7 @@ NonnullRefPtr<FunctionDeclaration> Parser::parse_function_declaration()
}
consume(TokenType::ParenClose);
auto body = parse_block_statement();
return create_ast_node<FunctionDeclaration>(name, move(body), move(parameters));
return create_ast_node<FunctionNodeType>(name, move(body), move(parameters));
}
NonnullRefPtr<VariableDeclaration> Parser::parse_variable_declaration()
@ -526,6 +535,7 @@ bool Parser::match_expression() const
|| type == TokenType::CurlyOpen
|| type == TokenType::BracketOpen
|| type == TokenType::ParenOpen
|| type == TokenType::Function
|| match_unary_prefixed_expression();
}