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LibJS: Implement parsing and executing for-await-of loops

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davidot 2021-11-23 16:09:28 +01:00 • committed by Linus Groh
parent b3699029e2
commit e69276e704
5 changed files with 242 additions and 7 deletions
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34
Userland/Libraries/LibJS/Parser.cpp
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@ -3142,15 +3142,34 @@ NonnullRefPtr<IfStatement> Parser::parse_if_statement()
NonnullRefPtr<Statement> Parser::parse_for_statement()
{
auto rule_start = push_start();
auto is_await_loop = IsForAwaitLoop::No;
auto match_of = [&](Token const& token) {
return token.type() == TokenType::Identifier && token.original_value() == "of"sv;
};
auto match_for_in_of = [&] {
return match(TokenType::In) || match_of(m_state.current_token);
auto match_for_in_of = [&]() {
bool is_of = match_of(m_state.current_token);
if (is_await_loop == IsForAwaitLoop::Yes) {
if (!is_of)
syntax_error("for await loop is only valid with 'of'");
else if (!m_state.in_async_function_context)
syntax_error("for await loop is only valid in async function or generator");
return true;
}
return match(TokenType::In) || is_of;
};
consume(TokenType::For);
if (match(TokenType::Await)) {
consume();
if (!m_state.in_async_function_context)
syntax_error("for-await-of is only allowed in async function context");
is_await_loop = IsForAwaitLoop::Yes;
}
consume(TokenType::ParenOpen);
Optional<ScopePusher> scope_pusher;
@ -3172,7 +3191,7 @@ NonnullRefPtr<Statement> Parser::parse_for_statement()
init = move(declaration);
if (match_for_in_of())
return parse_for_in_of_statement(*init);
return parse_for_in_of_statement(*init, is_await_loop);
if (static_cast<VariableDeclaration&>(*init).declaration_kind() == DeclarationKind::Const) {
for (auto& variable : static_cast<VariableDeclaration&>(*init).declarations()) {
if (!variable.init())
@ -3185,9 +3204,10 @@ NonnullRefPtr<Statement> Parser::parse_for_statement()
init = parse_expression(0, Associativity::Right, { TokenType::In });
if (match_for_in_of()) {
if (starts_with_async_of && match_of(m_state.current_token))
if (is_await_loop != IsForAwaitLoop::Yes
&& starts_with_async_of && match_of(m_state.current_token))
syntax_error("for-of loop may not start with async of");
return parse_for_in_of_statement(*init);
return parse_for_in_of_statement(*init, is_await_loop);
}
} else {
syntax_error("Unexpected token in for loop");
@ -3215,7 +3235,7 @@ NonnullRefPtr<Statement> Parser::parse_for_statement()
return create_ast_node<ForStatement>({ m_state.current_token.filename(), rule_start.position(), position() }, move(init), move(test), move(update), move(body));
}
NonnullRefPtr<Statement> Parser::parse_for_in_of_statement(NonnullRefPtr<ASTNode> lhs)
NonnullRefPtr<Statement> Parser::parse_for_in_of_statement(NonnullRefPtr<ASTNode> lhs, IsForAwaitLoop is_for_await_loop)
{
Variant<NonnullRefPtr<ASTNode>, NonnullRefPtr<BindingPattern>> for_declaration = lhs;
auto rule_start = push_start();
@ -3272,6 +3292,8 @@ NonnullRefPtr<Statement> Parser::parse_for_in_of_statement(NonnullRefPtr<ASTNode
auto body = parse_statement();
if (is_in)
return create_ast_node<ForInStatement>({ m_state.current_token.filename(), rule_start.position(), position() }, move(for_declaration), move(rhs), move(body));
if (is_for_await_loop == IsForAwaitLoop::Yes)
return create_ast_node<ForAwaitOfStatement>({ m_state.current_token.filename(), rule_start.position(), position() }, move(for_declaration), move(rhs), move(body));
return create_ast_node<ForOfStatement>({ m_state.current_token.filename(), rule_start.position(), position() }, move(for_declaration), move(rhs), move(body));
}