/* * Copyright (c) 2020, Stephan Unverwerth * Copyright (c) 2020-2021, Linus Groh * Copyright (c) 2021-2022, David Tuin * Copyright (c) 2021, Ali Mohammad Pur * Copyright (c) 2021, Idan Horowitz * * SPDX-License-Identifier: BSD-2-Clause */ #include "Parser.h" #include #include #include #include #include #include #include #include namespace JS { class ScopePusher { private: ScopePusher(Parser& parser, ScopeNode* node, bool is_top_level) : m_parser(parser) , m_is_top_level(is_top_level) { m_parent_scope = exchange(m_parser.m_state.current_scope_pusher, this); VERIFY(node || (m_parent_scope && !is_top_level)); if (!node) m_node = m_parent_scope->m_node; else m_node = node; VERIFY(m_node); if (!is_top_level) m_top_level_scope = m_parent_scope->m_top_level_scope; else m_top_level_scope = this; } public: static ScopePusher function_scope(Parser& parser, FunctionBody& function_body, Vector const& parameters) { ScopePusher scope_pusher(parser, &function_body, true); scope_pusher.m_function_parameters = parameters; for (auto& parameter : parameters) { parameter.binding.visit( [&](FlyString const& name) { scope_pusher.m_forbidden_lexical_names.set(name); }, [&](NonnullRefPtr const& binding_pattern) { binding_pattern->for_each_bound_name([&](auto const& name) { scope_pusher.m_forbidden_lexical_names.set(name); }); }); } return scope_pusher; } static ScopePusher program_scope(Parser& parser, Program& program) { return ScopePusher(parser, &program, true); } static ScopePusher block_scope(Parser& parser, ScopeNode& node) { return ScopePusher(parser, &node, false); } static ScopePusher for_loop_scope(Parser& parser, RefPtr const& init) { ScopePusher scope_pusher(parser, nullptr, false); if (init && is(*init)) { auto& variable_declaration = static_cast(*init); if (variable_declaration.declaration_kind() != DeclarationKind::Var) { variable_declaration.for_each_bound_name([&](auto const& name) { scope_pusher.m_forbidden_var_names.set(name); }); } } return scope_pusher; } static ScopePusher catch_scope(Parser& parser, RefPtr const& pattern, FlyString const& parameter) { ScopePusher scope_pusher(parser, nullptr, false); if (pattern) { pattern->for_each_bound_name([&](auto const& name) { scope_pusher.m_forbidden_var_names.set(name); }); } else if (!parameter.is_empty()) { scope_pusher.m_var_names.set(parameter); } return scope_pusher; } static ScopePusher static_init_block_scope(Parser& parser, ScopeNode& node) { return ScopePusher(parser, &node, true); } static ScopePusher class_field_scope(Parser& parser) { return ScopePusher(parser, nullptr, false); } void add_declaration(NonnullRefPtr declaration) { if (declaration->is_lexical_declaration()) { declaration->for_each_bound_name([&](auto const& name) { if (m_var_names.contains(name) || m_forbidden_lexical_names.contains(name) || m_function_names.contains(name)) throw_identifier_declared(name, declaration); if (m_lexical_names.set(name) != AK::HashSetResult::InsertedNewEntry) throw_identifier_declared(name, declaration); }); m_node->add_lexical_declaration(move(declaration)); } else if (!declaration->is_function_declaration()) { declaration->for_each_bound_name([&](auto const& name) { ScopePusher* pusher = this; while (true) { if (pusher->m_lexical_names.contains(name) || pusher->m_function_names.contains(name) || pusher->m_forbidden_var_names.contains(name)) throw_identifier_declared(name, declaration); pusher->m_var_names.set(name); if (pusher->m_is_top_level) break; VERIFY(pusher->m_parent_scope != nullptr); pusher = pusher->m_parent_scope; } VERIFY(pusher->m_is_top_level && pusher->m_node); pusher->m_node->add_var_scoped_declaration(declaration); }); VERIFY(m_top_level_scope); m_top_level_scope->m_node->add_var_scoped_declaration(move(declaration)); } else { if (m_is_top_level && m_parser.m_program_type == Program::Type::Script) { declaration->for_each_bound_name([&](auto const& name) { m_var_names.set(name); }); m_node->add_var_scoped_declaration(move(declaration)); } else { VERIFY(is(*declaration)); auto& function_declaration = static_cast(*declaration); auto& function_name = function_declaration.name(); if (m_var_names.contains(function_name) || m_lexical_names.contains(function_name)) throw_identifier_declared(function_name, declaration); if (function_declaration.kind() != FunctionKind::Normal || m_parser.m_state.strict_mode) { if (m_function_names.contains(function_name)) throw_identifier_declared(function_name, declaration); m_lexical_names.set(function_name); m_node->add_lexical_declaration(move(declaration)); return; } m_function_names.set(function_name); if (!m_lexical_names.contains(function_name)) m_functions_to_hoist.append(static_ptr_cast(declaration)); m_node->add_lexical_declaration(move(declaration)); } } } ScopePusher const* last_function_scope() const { for (auto scope_ptr = this; scope_ptr; scope_ptr = scope_ptr->m_parent_scope) { if (scope_ptr->m_function_parameters.has_value()) return scope_ptr; } return nullptr; } Vector const& function_parameters() const { return *m_function_parameters; } ScopePusher* parent_scope() { return m_parent_scope; } ScopePusher const* parent_scope() const { return m_parent_scope; } [[nodiscard]] bool has_declaration(StringView name) const { return m_lexical_names.contains(name) || m_var_names.contains(name) || !m_functions_to_hoist.find_if([&name](auto& function) { return function->name() == name; }).is_end(); } bool contains_direct_call_to_eval() const { return m_contains_direct_call_to_eval; } bool contains_access_to_arguments_object() const { return m_contains_access_to_arguments_object; } void set_contains_direct_call_to_eval() { m_contains_direct_call_to_eval = true; } void set_contains_access_to_arguments_object() { m_contains_access_to_arguments_object = true; } ~ScopePusher() { VERIFY(m_is_top_level || m_parent_scope); if (!m_contains_access_to_arguments_object) { for (auto& it : m_identifier_and_argument_index_associations) { for (auto& identifier : it.value) { if (!has_declaration(identifier.string())) identifier.set_lexically_bound_function_argument_index(it.key); } } } for (size_t i = 0; i < m_functions_to_hoist.size(); i++) { auto const& function_declaration = m_functions_to_hoist[i]; if (m_lexical_names.contains(function_declaration.name()) || m_forbidden_var_names.contains(function_declaration.name())) continue; if (m_is_top_level) m_node->add_hoisted_function(move(m_functions_to_hoist[i])); else m_parent_scope->m_functions_to_hoist.append(move(m_functions_to_hoist[i])); } if (m_parent_scope && !m_function_parameters.has_value()) { m_parent_scope->m_contains_access_to_arguments_object |= m_contains_access_to_arguments_object; m_parent_scope->m_contains_direct_call_to_eval |= m_contains_direct_call_to_eval; } VERIFY(m_parser.m_state.current_scope_pusher == this); m_parser.m_state.current_scope_pusher = m_parent_scope; } void associate_identifier_with_argument_index(NonnullRefPtr identifier, size_t index) { m_identifier_and_argument_index_associations.ensure(index).append(move(identifier)); } void set_contains_await_expression() { m_contains_await_expression = true; } bool contains_await_expression() const { return m_contains_await_expression; } private: void throw_identifier_declared(FlyString const& name, NonnullRefPtr const& declaration) { m_parser.syntax_error(String::formatted("Identifier '{}' already declared", name), declaration->source_range().start); } Parser& m_parser; ScopeNode* m_node { nullptr }; bool m_is_top_level { false }; ScopePusher* m_parent_scope { nullptr }; ScopePusher* m_top_level_scope { nullptr }; HashTable m_lexical_names; HashTable m_var_names; HashTable m_function_names; HashTable m_forbidden_lexical_names; HashTable m_forbidden_var_names; NonnullRefPtrVector m_functions_to_hoist; Optional> m_function_parameters; HashMap> m_identifier_and_argument_index_associations; bool m_contains_access_to_arguments_object { false }; bool m_contains_direct_call_to_eval { false }; bool m_contains_await_expression { false }; }; class OperatorPrecedenceTable { public: constexpr OperatorPrecedenceTable() : m_token_precedence() { for (size_t i = 0; i < array_size(m_operator_precedence); ++i) { auto& op = m_operator_precedence[i]; m_token_precedence[static_cast(op.token)] = op.precedence; } } constexpr int get(TokenType token) const { int p = m_token_precedence[static_cast(token)]; if (p == 0) { warnln("Internal Error: No precedence for operator {}", Token::name(token)); VERIFY_NOT_REACHED(); return -1; } return p; } private: int m_token_precedence[cs_num_of_js_tokens]; struct OperatorPrecedence { TokenType token; int precedence; }; // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence static constexpr const OperatorPrecedence m_operator_precedence[] = { { TokenType::Period, 20 }, { TokenType::BracketOpen, 20 }, { TokenType::ParenOpen, 20 }, { TokenType::QuestionMarkPeriod, 20 }, { TokenType::New, 19 }, { TokenType::PlusPlus, 18 }, { TokenType::MinusMinus, 18 }, { TokenType::ExclamationMark, 17 }, { TokenType::Tilde, 17 }, { TokenType::Typeof, 17 }, { TokenType::Void, 17 }, { TokenType::Delete, 17 }, { TokenType::Await, 17 }, { TokenType::DoubleAsterisk, 16 }, { TokenType::Asterisk, 15 }, { TokenType::Slash, 15 }, { TokenType::Percent, 15 }, { TokenType::Plus, 14 }, { TokenType::Minus, 14 }, { TokenType::ShiftLeft, 13 }, { TokenType::ShiftRight, 13 }, { TokenType::UnsignedShiftRight, 13 }, { TokenType::LessThan, 12 }, { TokenType::LessThanEquals, 12 }, { TokenType::GreaterThan, 12 }, { TokenType::GreaterThanEquals, 12 }, { TokenType::In, 12 }, { TokenType::Instanceof, 12 }, { TokenType::EqualsEquals, 11 }, { TokenType::ExclamationMarkEquals, 11 }, { TokenType::EqualsEqualsEquals, 11 }, { TokenType::ExclamationMarkEqualsEquals, 11 }, { TokenType::Ampersand, 10 }, { TokenType::Caret, 9 }, { TokenType::Pipe, 8 }, { TokenType::DoubleQuestionMark, 7 }, { TokenType::DoubleAmpersand, 6 }, { TokenType::DoublePipe, 5 }, { TokenType::QuestionMark, 4 }, { TokenType::Equals, 3 }, { TokenType::PlusEquals, 3 }, { TokenType::MinusEquals, 3 }, { TokenType::DoubleAsteriskEquals, 3 }, { TokenType::AsteriskEquals, 3 }, { TokenType::SlashEquals, 3 }, { TokenType::PercentEquals, 3 }, { TokenType::ShiftLeftEquals, 3 }, { TokenType::ShiftRightEquals, 3 }, { TokenType::UnsignedShiftRightEquals, 3 }, { TokenType::AmpersandEquals, 3 }, { TokenType::CaretEquals, 3 }, { TokenType::PipeEquals, 3 }, { TokenType::DoubleAmpersandEquals, 3 }, { TokenType::DoublePipeEquals, 3 }, { TokenType::DoubleQuestionMarkEquals, 3 }, { TokenType::Yield, 2 }, { TokenType::Comma, 1 }, }; }; constexpr OperatorPrecedenceTable g_operator_precedence; Parser::ParserState::ParserState(Lexer l, Program::Type program_type) : lexer(move(l)) { if (program_type == Program::Type::Module) lexer.disallow_html_comments(); current_token = lexer.next(); } Parser::Parser(Lexer lexer, Program::Type program_type) : m_state(move(lexer), program_type) , m_program_type(program_type) { } Associativity Parser::operator_associativity(TokenType type) const { switch (type) { case TokenType::Period: case TokenType::BracketOpen: case TokenType::ParenOpen: case TokenType::QuestionMarkPeriod: case TokenType::Asterisk: case TokenType::Slash: case TokenType::Percent: case TokenType::Plus: case TokenType::Minus: case TokenType::ShiftLeft: case TokenType::ShiftRight: case TokenType::UnsignedShiftRight: case TokenType::LessThan: case TokenType::LessThanEquals: case TokenType::GreaterThan: case TokenType::GreaterThanEquals: case TokenType::In: case TokenType::Instanceof: case TokenType::EqualsEquals: case TokenType::ExclamationMarkEquals: case TokenType::EqualsEqualsEquals: case TokenType::ExclamationMarkEqualsEquals: case TokenType::Typeof: case TokenType::Void: case TokenType::Delete: case TokenType::Await: case TokenType::Ampersand: case TokenType::Caret: case TokenType::Pipe: case TokenType::DoubleQuestionMark: case TokenType::DoubleAmpersand: case TokenType::DoublePipe: case TokenType::Comma: return Associativity::Left; default: return Associativity::Right; } } bool Parser::parse_directive(ScopeNode& body) { bool found_use_strict = false; while (!done() && match(TokenType::StringLiteral)) { // It cannot be a labelled function since we hit a string literal. auto statement = parse_statement(AllowLabelledFunction::No); body.append(statement); VERIFY(is(*statement)); auto& expression = static_cast(*statement).expression(); if (!is(expression)) break; auto& string_literal = static_cast(expression); if (string_literal.is_use_strict_directive()) { found_use_strict = true; if (m_state.string_legacy_octal_escape_sequence_in_scope) syntax_error("Octal escape sequence in string literal not allowed in strict mode"); break; } } m_state.string_legacy_octal_escape_sequence_in_scope = false; return found_use_strict; } NonnullRefPtr Parser::parse_program(bool starts_in_strict_mode) { auto rule_start = push_start(); auto program = adopt_ref(*new Program({ m_filename, rule_start.position(), position() }, m_program_type)); ScopePusher program_scope = ScopePusher::program_scope(*this, *program); if (m_program_type == Program::Type::Script) parse_script(program, starts_in_strict_mode); else parse_module(program); program->source_range().end = position(); return program; } void Parser::parse_script(Program& program, bool starts_in_strict_mode) { bool strict_before = m_state.strict_mode; if (starts_in_strict_mode) m_state.strict_mode = true; bool has_use_strict = parse_directive(program); if (m_state.strict_mode || has_use_strict) { program.set_strict_mode(); m_state.strict_mode = true; } parse_statement_list(program, AllowLabelledFunction::Yes); if (!done()) { expected("statement or declaration"); consume(); } m_state.strict_mode = strict_before; } void Parser::parse_module(Program& program) { TemporaryChange strict_mode_rollback(m_state.strict_mode, true); TemporaryChange await_expression_valid_rollback(m_state.await_expression_is_valid, true); // Since strict mode is already enabled we skip any directive parsing. while (!done()) { parse_statement_list(program, AllowLabelledFunction::Yes); if (done()) break; if (match_export_or_import()) { VERIFY(m_state.current_token.type() == TokenType::Export || m_state.current_token.type() == TokenType::Import); if (m_state.current_token.type() == TokenType::Export) program.append_export(parse_export_statement(program)); else program.append_import(parse_import_statement(program)); } else { expected("statement or declaration"); consume(); } } VERIFY(m_state.current_scope_pusher); if (m_state.current_scope_pusher->contains_await_expression()) program.set_has_top_level_await(); for (auto& export_statement : program.exports()) { if (export_statement.has_statement()) continue; for (auto& entry : export_statement.entries()) { if (entry.kind == ExportStatement::ExportEntry::Kind::ModuleRequest) return; auto const& exported_name = entry.local_or_import_name; bool found = false; program.for_each_lexically_declared_name([&](auto const& name) { if (name == exported_name) { found = true; return IterationDecision::Break; } return IterationDecision::Continue; }); if (found) continue; program.for_each_var_declared_name([&](auto const& name) { if (name == exported_name) { found = true; return IterationDecision::Break; } return IterationDecision::Continue; }); if (!found) syntax_error(String::formatted("'{}' is not declared", exported_name)); } } } NonnullRefPtr Parser::parse_declaration() { auto rule_start = push_start(); if (m_state.current_token.type() == TokenType::Async && next_token().type() == TokenType::Function) return parse_function_node(); switch (m_state.current_token.type()) { case TokenType::Class: return parse_class_declaration(); case TokenType::Function: return parse_function_node(); case TokenType::Let: case TokenType::Const: return parse_variable_declaration(); default: expected("declaration"); consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); } } NonnullRefPtr Parser::parse_statement(AllowLabelledFunction allow_labelled_function) { auto rule_start = push_start(); auto type = m_state.current_token.type(); switch (type) { case TokenType::CurlyOpen: return parse_block_statement(); case TokenType::Return: return parse_return_statement(); case TokenType::Var: { auto declaration = parse_variable_declaration(); m_state.current_scope_pusher->add_declaration(declaration); return declaration; } case TokenType::For: return parse_for_statement(); case TokenType::If: return parse_if_statement(); case TokenType::Throw: return parse_throw_statement(); case TokenType::Try: return parse_try_statement(); case TokenType::Break: return parse_break_statement(); case TokenType::Continue: return parse_continue_statement(); case TokenType::Switch: return parse_switch_statement(); case TokenType::Do: return parse_do_while_statement(); case TokenType::While: return parse_while_statement(); case TokenType::With: if (m_state.strict_mode) syntax_error("'with' statement not allowed in strict mode"); return parse_with_statement(); case TokenType::Debugger: return parse_debugger_statement(); case TokenType::Semicolon: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); case TokenType::Slash: case TokenType::SlashEquals: m_state.current_token = m_state.lexer.force_slash_as_regex(); [[fallthrough]]; default: if (match_invalid_escaped_keyword()) syntax_error("Keyword must not contain escaped characters"); if (match_identifier_name()) { auto result = try_parse_labelled_statement(allow_labelled_function); if (!result.is_null()) return result.release_nonnull(); } if (match_expression()) { if (match(TokenType::Async)) { auto lookahead_token = next_token(); if (lookahead_token.type() == TokenType::Function && !lookahead_token.trivia_contains_line_terminator()) syntax_error("Async function declaration not allowed in single-statement context"); } else if (match(TokenType::Function) || match(TokenType::Class)) { syntax_error(String::formatted("{} declaration not allowed in single-statement context", m_state.current_token.name())); } else if (match(TokenType::Let) && next_token().type() == TokenType::BracketOpen) { syntax_error(String::formatted("let followed by [ is not allowed in single-statement context")); } auto expr = parse_expression(0); consume_or_insert_semicolon(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(expr)); } expected("statement"); consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); } } bool Parser::match_invalid_escaped_keyword() const { if (m_state.current_token.type() != TokenType::EscapedKeyword) return false; auto token_value = m_state.current_token.value(); if (token_value == "await"sv) return m_program_type == Program::Type::Module || m_state.await_expression_is_valid; if (token_value == "async"sv) return false; if (token_value == "yield"sv) return m_state.in_generator_function_context; if (m_state.strict_mode) return true; return token_value != "let"sv; } static constexpr AK::Array strict_reserved_words = { "implements", "interface", "let", "package", "private", "protected", "public", "static", "yield" }; static bool is_strict_reserved_word(StringView str) { return any_of(strict_reserved_words, [&str](StringView word) { return word == str; }); } static bool is_simple_parameter_list(Vector const& parameters) { return all_of(parameters, [](FunctionNode::Parameter const& parameter) { return !parameter.is_rest && parameter.default_value.is_null() && parameter.binding.has(); }); } RefPtr Parser::try_parse_arrow_function_expression(bool expect_parens, bool is_async) { if (is_async) VERIFY(match(TokenType::Async)); if (!expect_parens && !is_async) { // NOTE: This is a fast path where we try to fail early in case this can't possibly // be a match. The idea is to avoid the expensive parser state save/load mechanism. // The logic is duplicated below in the "real" !expect_parens branch. if (!match_identifier() && !match(TokenType::Yield) && !match(TokenType::Await)) return nullptr; auto token = next_token(); if (token.trivia_contains_line_terminator()) return nullptr; if (token.type() != TokenType::Arrow) return nullptr; } save_state(); auto rule_start = (expect_parens && !is_async) // Someone has consumed the opening parenthesis for us! Start there. ? RulePosition { *this, m_rule_starts.last() } // We've not encountered one yet, so the rule start is actually here. : push_start(); ArmedScopeGuard state_rollback_guard = [&] { load_state(); }; auto function_kind = FunctionKind::Normal; if (is_async) { consume(TokenType::Async); function_kind = FunctionKind::Async; if (m_state.current_token.trivia_contains_line_terminator()) return nullptr; // Since we have async it can be followed by paren open in the expect_parens case // so we also consume that token. if (expect_parens) { VERIFY(match(TokenType::ParenOpen)); consume(TokenType::ParenOpen); } } Vector parameters; i32 function_length = -1; if (expect_parens) { // We have parens around the function parameters and can re-use the same parsing // logic used for regular functions: multiple parameters, default values, rest // parameter, maybe a trailing comma. If we have a new syntax error afterwards we // check if it's about a wrong token (something like duplicate parameter name must // not abort), know parsing failed and rollback the parser state. auto previous_syntax_errors = m_state.errors.size(); TemporaryChange in_async_context(m_state.await_expression_is_valid, is_async || m_state.await_expression_is_valid); parameters = parse_formal_parameters(function_length, FunctionNodeParseOptions::IsArrowFunction | (is_async ? FunctionNodeParseOptions::IsAsyncFunction : 0)); if (m_state.errors.size() > previous_syntax_errors && m_state.errors[previous_syntax_errors].message.starts_with("Unexpected token")) return nullptr; if (!match(TokenType::ParenClose)) return nullptr; consume(); } else { // No parens - this must be an identifier followed by arrow. That's it. if (!match_identifier() && !match(TokenType::Yield) && !match(TokenType::Await)) return nullptr; auto token = consume_identifier_reference(); if (m_state.strict_mode && token.value().is_one_of("arguments"sv, "eval"sv)) syntax_error("BindingIdentifier may not be 'arguments' or 'eval' in strict mode"); if (is_async && token.value() == "await"sv) syntax_error("'await' is a reserved identifier in async functions"); parameters.append({ FlyString { token.value() }, {} }); } // If there's a newline between the closing paren and arrow it's not a valid arrow function, // ASI should kick in instead (it'll then fail with "Unexpected token Arrow") if (m_state.current_token.trivia_contains_line_terminator()) return nullptr; if (!match(TokenType::Arrow)) return nullptr; consume(); if (function_length == -1) function_length = parameters.size(); auto old_labels_in_scope = move(m_state.labels_in_scope); ScopeGuard guard([&]() { m_state.labels_in_scope = move(old_labels_in_scope); }); bool contains_direct_call_to_eval = false; auto function_body_result = [&]() -> RefPtr { TemporaryChange change(m_state.in_arrow_function_context, true); TemporaryChange async_context_change(m_state.await_expression_is_valid, is_async); TemporaryChange in_class_static_init_block_change(m_state.in_class_static_init_block, false); if (match(TokenType::CurlyOpen)) { // Parse a function body with statements consume(TokenType::CurlyOpen); auto body = parse_function_body(parameters, function_kind, contains_direct_call_to_eval); consume(TokenType::CurlyClose); return body; } 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_block = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); ScopePusher function_scope = ScopePusher::function_scope(*this, return_block, parameters); auto return_expression = parse_expression(2); return_block->append({ m_filename, rule_start.position(), position() }, move(return_expression)); if (m_state.strict_mode) return_block->set_strict_mode(); contains_direct_call_to_eval = function_scope.contains_direct_call_to_eval(); return return_block; } // Invalid arrow function body return nullptr; }(); if (function_body_result.is_null()) return nullptr; state_rollback_guard.disarm(); discard_saved_state(); auto body = function_body_result.release_nonnull(); if (body->in_strict_mode()) { for (auto& parameter : parameters) { parameter.binding.visit( [&](FlyString const& name) { check_identifier_name_for_assignment_validity(name, true); }, [&](auto const&) {}); } } auto function_start_offset = rule_start.position().offset; auto function_end_offset = position().offset - m_state.current_token.trivia().length(); auto source_text = String { m_state.lexer.source().substring_view(function_start_offset, function_end_offset - function_start_offset) }; return create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, "", move(source_text), move(body), move(parameters), function_length, function_kind, body->in_strict_mode(), /* might_need_arguments_object */ false, contains_direct_call_to_eval, /* is_arrow_function */ true); } RefPtr Parser::try_parse_labelled_statement(AllowLabelledFunction allow_function) { { // NOTE: This is a fast path where we try to fail early to avoid the expensive save_state+load_state. if (next_token().type() != TokenType::Colon) return {}; } save_state(); auto rule_start = push_start(); ArmedScopeGuard state_rollback_guard = [&] { load_state(); }; if (m_state.current_token.value() == "yield"sv && (m_state.strict_mode || m_state.in_generator_function_context)) { return {}; } if (m_state.current_token.value() == "await"sv && (m_program_type == Program::Type::Module || m_state.await_expression_is_valid || m_state.in_class_static_init_block)) { return {}; } auto identifier = [&] { if (m_state.current_token.value() == "await"sv) { return consume().value(); } return consume_identifier_reference().value(); }(); if (!match(TokenType::Colon)) return {}; consume(TokenType::Colon); if (!match_statement()) return {}; state_rollback_guard.disarm(); discard_saved_state(); if (m_state.strict_mode && identifier == "let"sv) { syntax_error("Strict mode reserved word 'let' is not allowed in label", rule_start.position()); return {}; } if (match(TokenType::Function) && (allow_function == AllowLabelledFunction::No || m_state.strict_mode)) { syntax_error("Not allowed to declare a function here"); return {}; } if (m_state.labels_in_scope.contains(identifier)) syntax_error(String::formatted("Label '{}' has already been declared", identifier)); RefPtr labelled_item; auto is_iteration_statement = false; if (match(TokenType::Function)) { m_state.labels_in_scope.set(identifier, {}); auto function_declaration = parse_function_node(); VERIFY(m_state.current_scope_pusher); m_state.current_scope_pusher->add_declaration(function_declaration); if (function_declaration->kind() == FunctionKind::Generator) syntax_error("Generator functions cannot be defined in labelled statements"); if (function_declaration->kind() == FunctionKind::Async) syntax_error("Async functions cannot be defined in labelled statements"); labelled_item = move(function_declaration); } else { m_state.labels_in_scope.set(identifier, {}); labelled_item = parse_statement(allow_function); // Extract the innermost statement from a potentially nested chain of LabelledStatements. auto statement = labelled_item; while (is(*statement)) statement = static_cast(*statement).labelled_item(); if (is(*statement)) is_iteration_statement = true; } if (!is_iteration_statement) { if (auto entry = m_state.labels_in_scope.find(identifier); entry != m_state.labels_in_scope.end() && entry->value.has_value()) syntax_error("labelled continue statement cannot use non iterating statement", m_state.labels_in_scope.get(identifier).value()); } m_state.labels_in_scope.remove(identifier); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, identifier, labelled_item.release_nonnull()); } RefPtr Parser::try_parse_new_target_expression() { // Optimization which skips the save/load state. if (next_token().type() != TokenType::Period) return {}; save_state(); auto rule_start = push_start(); ArmedScopeGuard state_rollback_guard = [&] { load_state(); }; consume(TokenType::New); consume(TokenType::Period); if (!match(TokenType::Identifier)) return {}; // The string 'target' cannot have escapes so we check original value. if (consume().original_value() != "target"sv) return {}; state_rollback_guard.disarm(); discard_saved_state(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, MetaProperty::Type::NewTarget); } RefPtr Parser::try_parse_import_meta_expression() { // Optimization which skips the save/load state. if (next_token().type() != TokenType::Period) return {}; save_state(); auto rule_start = push_start(); ArmedScopeGuard state_rollback_guard = [&] { load_state(); }; consume(TokenType::Import); consume(TokenType::Period); if (!match(TokenType::Identifier)) return {}; // The string 'meta' cannot have escapes so we check original value. if (consume().original_value() != "meta"sv) return {}; state_rollback_guard.disarm(); discard_saved_state(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, MetaProperty::Type::ImportMeta); } NonnullRefPtr Parser::parse_import_call() { auto rule_start = push_start(); // We use the extended definition: // ImportCall[Yield, Await]: // import(AssignmentExpression[+In, ?Yield, ?Await] ,opt) // import(AssignmentExpression[+In, ?Yield, ?Await] ,AssignmentExpression[+In, ?Yield, ?Await] ,opt) // From https://tc39.es/proposal-import-assertions/#sec-evaluate-import-call consume(TokenType::Import); consume(TokenType::ParenOpen); auto argument = parse_expression(2); RefPtr options; if (match(TokenType::Comma)) { consume(TokenType::Comma); if (!match(TokenType::ParenClose)) { options = parse_expression(2); // Second optional comma if (match(TokenType::Comma)) consume(TokenType::Comma); } } consume(TokenType::ParenClose); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(argument), move(options)); } NonnullRefPtr Parser::parse_class_declaration() { auto rule_start = push_start(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, parse_class_expression(true)); } NonnullRefPtr Parser::parse_class_expression(bool expect_class_name) { auto rule_start = push_start(); // Classes are always in strict mode. TemporaryChange strict_mode_rollback(m_state.strict_mode, true); consume(TokenType::Class); NonnullRefPtrVector elements; RefPtr super_class; RefPtr constructor; HashTable found_private_names; String class_name = expect_class_name || match_identifier() || match(TokenType::Yield) || match(TokenType::Await) ? consume_identifier_reference().value().to_string() : ""; check_identifier_name_for_assignment_validity(class_name, true); if (m_state.in_class_static_init_block && class_name == "await"sv) syntax_error("Identifier must not be a reserved word in modules ('await')"); if (match(TokenType::Extends)) { consume(); auto [expression, should_continue_parsing] = parse_primary_expression(); // Basically a (much) simplified parse_secondary_expression(). for (;;) { if (match(TokenType::TemplateLiteralStart)) { auto template_literal = parse_template_literal(true); expression = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(expression), move(template_literal)); continue; } if (match(TokenType::BracketOpen) || match(TokenType::Period) || match(TokenType::ParenOpen)) { auto precedence = g_operator_precedence.get(m_state.current_token.type()); expression = parse_secondary_expression(move(expression), precedence); continue; } break; } super_class = move(expression); (void)should_continue_parsing; } consume(TokenType::CurlyOpen); HashTable referenced_private_names; HashTable* outer_referenced_private_names = m_state.referenced_private_names; m_state.referenced_private_names = &referenced_private_names; ScopeGuard restore_private_name_table = [&] { m_state.referenced_private_names = outer_referenced_private_names; }; while (!done() && !match(TokenType::CurlyClose)) { RefPtr property_key; bool is_static = false; bool is_constructor = false; bool is_generator = false; bool is_async = false; auto method_kind = ClassMethod::Kind::Method; if (match(TokenType::Semicolon)) { consume(); continue; } auto function_start = position(); if (match(TokenType::Async)) { auto lookahead_token = next_token(); if (lookahead_token.type() != TokenType::Semicolon && lookahead_token.type() != TokenType::CurlyClose && !lookahead_token.trivia_contains_line_terminator()) { consume(); is_async = true; } } if (match(TokenType::Asterisk)) { consume(); is_generator = true; } StringView name; if (match_property_key() || match(TokenType::PrivateIdentifier)) { if (!is_generator && !is_async && m_state.current_token.original_value() == "static"sv) { if (match(TokenType::Identifier)) { consume(); is_static = true; function_start = position(); if (match(TokenType::Async)) { consume(); is_async = true; } if (match(TokenType::Asterisk)) { consume(); is_generator = true; } } } if (match(TokenType::Identifier)) { auto identifier_name = m_state.current_token.original_value(); if (identifier_name == "get"sv) { method_kind = ClassMethod::Kind::Getter; consume(); } else if (identifier_name == "set"sv) { method_kind = ClassMethod::Kind::Setter; consume(); } } if (match_property_key() || match(TokenType::PrivateIdentifier)) { switch (m_state.current_token.type()) { case TokenType::Identifier: name = consume().value(); property_key = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, name); break; case TokenType::PrivateIdentifier: name = consume().value(); if (name == "#constructor") syntax_error("Private property with name '#constructor' is not allowed"); if (method_kind != ClassMethod::Kind::Method) { // It is a Syntax Error if PrivateBoundIdentifiers of ClassElementList contains any duplicate entries, // unless the name is used once for a getter and once for a setter and in no other entries, // and the getter and setter are either both static or both non-static. for (auto& element : elements) { auto private_name = element.private_bound_identifier(); if (!private_name.has_value() || private_name.value() != name) continue; if (element.class_element_kind() != ClassElement::ElementKind::Method || element.is_static() != is_static) { syntax_error(String::formatted("Duplicate private field or method named '{}'", name)); break; } VERIFY(is(element)); auto& class_method_element = static_cast(element); if (class_method_element.kind() == ClassMethod::Kind::Method || class_method_element.kind() == method_kind) { syntax_error(String::formatted("Duplicate private field or method named '{}'", name)); break; } } found_private_names.set(name); } else if (found_private_names.set(name) != AK::HashSetResult::InsertedNewEntry) { syntax_error(String::formatted("Duplicate private field or method named '{}'", name)); } property_key = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, name); break; case TokenType::StringLiteral: { auto string_literal = parse_string_literal(consume()); name = string_literal->value(); property_key = move(string_literal); break; } default: property_key = parse_property_key(); break; } // https://tc39.es/ecma262/#sec-class-definitions-static-semantics-early-errors // ClassElement : static MethodDefinition // It is a Syntax Error if PropName of MethodDefinition is "prototype". if (is_static && name == "prototype"sv) syntax_error("Classes may not have a static property named 'prototype'"); } else if ((match(TokenType::ParenOpen) || match(TokenType::Equals) || match(TokenType::Semicolon) || match(TokenType::CurlyClose)) && (is_static || is_async || method_kind != ClassMethod::Kind::Method)) { switch (method_kind) { case ClassMethod::Kind::Method: if (is_async) { name = "async"; is_async = false; } else { VERIFY(is_static); name = "static"; is_static = false; } break; case ClassMethod::Kind::Getter: name = "get"; method_kind = ClassMethod::Kind::Method; break; case ClassMethod::Kind::Setter: name = "set"; method_kind = ClassMethod::Kind::Method; break; } property_key = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, name); } else if (match(TokenType::CurlyOpen) && is_static) { auto static_start = push_start(); consume(TokenType::CurlyOpen); auto static_init_block = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); TemporaryChange break_context_rollback(m_state.in_break_context, false); TemporaryChange continue_context_rollback(m_state.in_continue_context, false); TemporaryChange function_context_rollback(m_state.in_function_context, false); TemporaryChange generator_function_context_rollback(m_state.in_generator_function_context, false); TemporaryChange async_function_context_rollback(m_state.await_expression_is_valid, false); TemporaryChange class_field_initializer_rollback(m_state.in_class_field_initializer, true); TemporaryChange class_static_init_block_rollback(m_state.in_class_static_init_block, true); TemporaryChange super_property_access_rollback(m_state.allow_super_property_lookup, true); ScopePusher static_init_scope = ScopePusher::static_init_block_scope(*this, *static_init_block); parse_statement_list(static_init_block); consume(TokenType::CurlyClose); elements.append(create_ast_node({ m_state.current_token.filename(), static_start.position(), position() }, move(static_init_block), static_init_scope.contains_direct_call_to_eval())); continue; } else { expected("property key"); } // Constructor may be a StringLiteral or an Identifier. if (!is_static && name == "constructor"sv) { if (method_kind != ClassMethod::Kind::Method) syntax_error("Class constructor may not be an accessor"); if (!constructor.is_null()) syntax_error("Classes may not have more than one constructor"); if (is_generator) syntax_error("Class constructor may not be a generator"); if (is_async) syntax_error("Class constructor may not be async"); is_constructor = true; } } if (match(TokenType::ParenOpen)) { u8 parse_options = FunctionNodeParseOptions::AllowSuperPropertyLookup; if (!super_class.is_null() && !is_static && is_constructor) parse_options |= FunctionNodeParseOptions::AllowSuperConstructorCall; if (method_kind == ClassMethod::Kind::Getter) parse_options |= FunctionNodeParseOptions::IsGetterFunction; if (method_kind == ClassMethod::Kind::Setter) parse_options |= FunctionNodeParseOptions::IsSetterFunction; if (is_generator) parse_options |= FunctionNodeParseOptions::IsGeneratorFunction; if (is_async) parse_options |= FunctionNodeParseOptions::IsAsyncFunction; auto function = parse_function_node(parse_options, function_start); if (is_constructor) { constructor = move(function); } else if (!property_key.is_null()) { elements.append(create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, property_key.release_nonnull(), move(function), method_kind, is_static)); } else { syntax_error("No key for class method"); } } else if (is_generator || is_async) { expected("ParenOpen"); consume(); } else if (property_key.is_null()) { expected("property key"); consume(); } else { if (name == "constructor"sv) syntax_error("Class cannot have field named 'constructor'"); RefPtr initializer; bool contains_direct_call_to_eval = false; if (match(TokenType::Equals)) { consume(); TemporaryChange super_property_access_rollback(m_state.allow_super_property_lookup, true); TemporaryChange field_initializer_rollback(m_state.in_class_field_initializer, true); auto class_field_scope = ScopePusher::class_field_scope(*this); initializer = parse_expression(2); contains_direct_call_to_eval = class_field_scope.contains_direct_call_to_eval(); } elements.append(create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, property_key.release_nonnull(), move(initializer), contains_direct_call_to_eval, is_static)); consume_or_insert_semicolon(); } } consume(TokenType::CurlyClose); if (constructor.is_null()) { auto constructor_body = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); if (!super_class.is_null()) { // Set constructor to the result of parsing the source text // constructor(... args){ super (...args);} auto super_call = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, Vector { CallExpression::Argument { create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, "args"), true } }); // NOTE: While the JS approximation above doesn't do `return super(...args)`, the // abstract closure is expected to capture and return the result, so we do need a // return statement here to create the correct completion. constructor_body->append(create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(super_call))); constructor = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, class_name, "", move(constructor_body), Vector { FunctionNode::Parameter { FlyString { "args" }, nullptr, true } }, 0, FunctionKind::Normal, /* is_strict_mode */ true, /* might_need_arguments_object */ false, /* contains_direct_call_to_eval */ false); } else { constructor = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, class_name, "", move(constructor_body), Vector {}, 0, FunctionKind::Normal, /* is_strict_mode */ true, /* might_need_arguments_object */ false, /* contains_direct_call_to_eval */ false); } } // We could be in a subclass defined within the main class so must move all non declared private names to outer. for (auto& private_name : referenced_private_names) { if (found_private_names.contains(private_name)) continue; if (outer_referenced_private_names) outer_referenced_private_names->set(private_name); else // FIXME: Make these error appear in the appropriate places. syntax_error(String::formatted("Reference to undeclared private field or method '{}'", private_name)); } auto function_start_offset = rule_start.position().offset; auto function_end_offset = position().offset - m_state.current_token.trivia().length(); auto source_text = String { m_state.lexer.source().substring_view(function_start_offset, function_end_offset - function_start_offset) }; return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(class_name), move(source_text), move(constructor), move(super_class), move(elements)); } Parser::PrimaryExpressionParseResult Parser::parse_primary_expression() { auto rule_start = push_start(); if (match_unary_prefixed_expression()) return { parse_unary_prefixed_expression() }; auto try_arrow_function_parse_or_fail = [this](Position const& position, bool expect_paren, bool is_async = false) -> RefPtr { if (try_parse_arrow_function_expression_failed_at_position(position)) return nullptr; auto arrow_function = try_parse_arrow_function_expression(expect_paren, is_async); if (arrow_function) return arrow_function; set_try_parse_arrow_function_expression_failed_at_position(position, true); return nullptr; }; switch (m_state.current_token.type()) { case TokenType::ParenOpen: { auto paren_position = position(); consume(TokenType::ParenOpen); if ((match(TokenType::ParenClose) || match_identifier() || match(TokenType::TripleDot) || match(TokenType::CurlyOpen) || match(TokenType::BracketOpen))) { if (auto arrow_function_result = try_arrow_function_parse_or_fail(paren_position, true)) return { arrow_function_result.release_nonnull(), false }; } auto expression = parse_expression(0); consume(TokenType::ParenClose); if (is(*expression)) { auto& function = static_cast(*expression); if (function.kind() == FunctionKind::Generator && function.name() == "yield"sv) syntax_error("function is not allowed to be called 'yield' in this context", function.source_range().start); if (function.kind() == FunctionKind::Async && function.name() == "await"sv) syntax_error("function is not allowed to be called 'await' in this context", function.source_range().start); } return { move(expression) }; } case TokenType::This: consume(); return { create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }) }; case TokenType::Class: return { parse_class_expression(false) }; case TokenType::Super: consume(); if (!m_state.allow_super_property_lookup) syntax_error("'super' keyword unexpected here"); return { create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }) }; case TokenType::EscapedKeyword: if (match_invalid_escaped_keyword()) syntax_error("Keyword must not contain escaped characters"); [[fallthrough]]; case TokenType::Identifier: { read_as_identifier:; if (auto arrow_function_result = try_arrow_function_parse_or_fail(position(), false)) return { arrow_function_result.release_nonnull(), false }; auto string = m_state.current_token.value(); // This could be 'eval' or 'arguments' and thus needs a custom check (`eval[1] = true`) if (m_state.strict_mode && (string == "let" || is_strict_reserved_word(string))) syntax_error(String::formatted("Identifier must not be a reserved word in strict mode ('{}')", string)); return { parse_identifier() }; } case TokenType::NumericLiteral: return { create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, consume_and_validate_numeric_literal().double_value()) }; case TokenType::BigIntLiteral: return { create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, consume().value()) }; case TokenType::BoolLiteral: return { create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, consume().bool_value()) }; case TokenType::StringLiteral: return { parse_string_literal(consume()) }; case TokenType::NullLiteral: consume(); return { create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }) }; case TokenType::CurlyOpen: return { parse_object_expression() }; case TokenType::Async: { auto lookahead_token = next_token(); // No valid async function (arrow or not) can have a line terminator after the async since asi would kick in. if (lookahead_token.trivia_contains_line_terminator()) goto read_as_identifier; if (lookahead_token.type() == TokenType::Function) return { parse_function_node() }; if (lookahead_token.type() == TokenType::ParenOpen) { if (auto arrow_function_result = try_arrow_function_parse_or_fail(position(), true, true)) return { arrow_function_result.release_nonnull(), false }; } else if (lookahead_token.is_identifier_name()) { if (auto arrow_function_result = try_arrow_function_parse_or_fail(position(), false, true)) return { arrow_function_result.release_nonnull(), false }; } goto read_as_identifier; } case TokenType::Function: return { parse_function_node() }; case TokenType::BracketOpen: return { parse_array_expression() }; case TokenType::RegexLiteral: return { parse_regexp_literal() }; case TokenType::TemplateLiteralStart: return { parse_template_literal(false) }; case TokenType::New: { auto new_start = position(); auto new_target_result = try_parse_new_target_expression(); if (!new_target_result.is_null()) { if (!m_state.in_function_context && !m_state.in_class_static_init_block) syntax_error("'new.target' not allowed outside of a function", new_start); return { new_target_result.release_nonnull() }; } return { parse_new_expression() }; } case TokenType::Import: { auto lookahead_token = next_token(); if (lookahead_token.type() == TokenType::ParenOpen) return { parse_import_call() }; if (lookahead_token.type() == TokenType::Period) { if (auto import_meta = try_parse_import_meta_expression()) { if (m_program_type != Program::Type::Module) syntax_error("import.meta is only allowed in modules"); return { import_meta.release_nonnull() }; } } else { consume(); expected("import.meta or import call"); } break; } case TokenType::Yield: if (!m_state.in_generator_function_context) goto read_as_identifier; return { parse_yield_expression(), false }; case TokenType::Await: if (!m_state.await_expression_is_valid) goto read_as_identifier; return { parse_await_expression() }; case TokenType::PrivateIdentifier: if (next_token().type() != TokenType::In) syntax_error("Cannot have a private identifier in expression if not followed by 'in'"); if (!is_private_identifier_valid()) syntax_error(String::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value())); return { create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, consume().value()) }; default: if (match_identifier_name()) goto read_as_identifier; break; } expected("primary expression"); consume(); return { create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }) }; } NonnullRefPtr Parser::parse_regexp_literal() { auto rule_start = push_start(); auto pattern = consume().value(); // Remove leading and trailing slash. pattern = pattern.substring_view(1, pattern.length() - 2); auto flags = String::empty(); auto parsed_flags = RegExpObject::default_flags; if (match(TokenType::RegexFlags)) { auto flags_start = position(); flags = consume().value(); auto parsed_flags_or_error = regex_flags_from_string(flags); if (parsed_flags_or_error.is_error()) syntax_error(parsed_flags_or_error.release_error(), flags_start); else parsed_flags = parsed_flags_or_error.release_value(); } auto parsed_pattern = parse_regex_pattern(pattern, parsed_flags.has_flag_set(ECMAScriptFlags::Unicode)); auto parsed_regex = Regex::parse_pattern(parsed_pattern, parsed_flags); if (parsed_regex.error != regex::Error::NoError) syntax_error(String::formatted("RegExp compile error: {}", Regex(parsed_regex, parsed_pattern, parsed_flags).error_string()), rule_start.position()); SourceRange range { m_state.current_token.filename(), rule_start.position(), position() }; return create_ast_node(move(range), move(parsed_regex), move(parsed_pattern), move(parsed_flags), pattern.to_string(), move(flags)); } NonnullRefPtr Parser::parse_unary_prefixed_expression() { auto rule_start = push_start(); auto precedence = g_operator_precedence.get(m_state.current_token.type()); auto associativity = operator_associativity(m_state.current_token.type()); switch (m_state.current_token.type()) { case TokenType::PlusPlus: { consume(); auto rhs_start = position(); auto rhs = parse_expression(precedence, associativity); // FIXME: Apparently for functions this should also not be enforced on a parser level, // other engines throw ReferenceError for ++foo() if (!is(*rhs) && !is(*rhs)) syntax_error(String::formatted("Right-hand side of prefix increment operator must be identifier or member expression, got {}", rhs->class_name()), rhs_start); if (m_state.strict_mode && is(*rhs)) { auto& identifier = static_cast(*rhs); auto& name = identifier.string(); check_identifier_name_for_assignment_validity(name); } return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UpdateOp::Increment, move(rhs), true); } case TokenType::MinusMinus: { consume(); auto rhs_start = position(); auto rhs = parse_expression(precedence, associativity); // FIXME: Apparently for functions this should also not be enforced on a parser level, // other engines throw ReferenceError for --foo() if (!is(*rhs) && !is(*rhs)) syntax_error(String::formatted("Right-hand side of prefix decrement operator must be identifier or member expression, got {}", rhs->class_name()), rhs_start); if (m_state.strict_mode && is(*rhs)) { auto& identifier = static_cast(*rhs); auto& name = identifier.string(); check_identifier_name_for_assignment_validity(name); } return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UpdateOp::Decrement, move(rhs), true); } case TokenType::ExclamationMark: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UnaryOp::Not, parse_expression(precedence, associativity)); case TokenType::Tilde: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UnaryOp::BitwiseNot, parse_expression(precedence, associativity)); case TokenType::Plus: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UnaryOp::Plus, parse_expression(precedence, associativity)); case TokenType::Minus: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UnaryOp::Minus, parse_expression(precedence, associativity)); case TokenType::Typeof: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UnaryOp::Typeof, parse_expression(precedence, associativity)); case TokenType::Void: consume(); // FIXME: This check is really hiding the fact that we don't deal with different expressions correctly. if (match(TokenType::Yield) && m_state.in_generator_function_context) syntax_error("'yield' is not an identifier in generator function context"); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UnaryOp::Void, parse_expression(precedence, associativity)); case TokenType::Delete: { consume(); auto rhs_start = position(); auto rhs = parse_expression(precedence, associativity); if (is(*rhs) && m_state.strict_mode) { syntax_error("Delete of an unqualified identifier in strict mode.", rhs_start); } if (is(*rhs)) { auto& member_expression = static_cast(*rhs); if (member_expression.ends_in_private_name()) syntax_error("Private fields cannot be deleted"); } return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UnaryOp::Delete, move(rhs)); } default: expected("primary expression"); consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); } } NonnullRefPtr Parser::parse_property_key() { auto rule_start = push_start(); if (match(TokenType::StringLiteral)) { return parse_string_literal(consume()); } else if (match(TokenType::NumericLiteral)) { return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, consume().double_value()); } else if (match(TokenType::BigIntLiteral)) { return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, consume().value()); } else if (match(TokenType::BracketOpen)) { consume(TokenType::BracketOpen); auto result = parse_expression(2); consume(TokenType::BracketClose); return result; } else { if (!match_identifier_name()) expected("IdentifierName"); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, consume().value()); } } NonnullRefPtr Parser::parse_object_expression() { auto rule_start = push_start(); consume(TokenType::CurlyOpen); NonnullRefPtrVector properties; ObjectProperty::Type property_type; Optional invalid_object_literal_property_range; auto skip_to_next_property = [&] { while (!done() && !match(TokenType::Comma) && !match(TokenType::CurlyOpen)) consume(); }; // It is a Syntax Error if PropertyNameList of PropertyDefinitionList contains any duplicate // entries for "__proto__" and at least two of those entries were obtained from productions of // the form PropertyDefinition : PropertyKey : AssignmentExpression . bool has_direct_proto_property = false; while (!done() && !match(TokenType::CurlyClose)) { property_type = ObjectProperty::Type::KeyValue; RefPtr property_name; RefPtr property_value; FunctionKind function_kind { FunctionKind::Normal }; if (match(TokenType::TripleDot)) { consume(); property_name = parse_expression(4); properties.append(create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, *property_name, nullptr, ObjectProperty::Type::Spread, false)); if (!match(TokenType::Comma)) break; consume(TokenType::Comma); continue; } auto type = m_state.current_token.type(); auto function_start = position(); if (match(TokenType::Async)) { auto lookahead_token = next_token(); if (lookahead_token.type() != TokenType::ParenOpen && lookahead_token.type() != TokenType::Colon && lookahead_token.type() != TokenType::Comma && lookahead_token.type() != TokenType::CurlyClose && lookahead_token.type() != TokenType::Async && !lookahead_token.trivia_contains_line_terminator()) { consume(TokenType::Async); function_kind = FunctionKind::Async; } } if (match(TokenType::Asterisk)) { consume(); property_type = ObjectProperty::Type::KeyValue; property_name = parse_property_key(); VERIFY(function_kind == FunctionKind::Normal || function_kind == FunctionKind::Async); function_kind = function_kind == FunctionKind::Normal ? FunctionKind::Generator : FunctionKind::AsyncGenerator; } else if (match_identifier()) { auto identifier = consume(); if (identifier.original_value() == "get"sv && match_property_key()) { property_type = ObjectProperty::Type::Getter; property_name = parse_property_key(); } else if (identifier.original_value() == "set"sv && match_property_key()) { property_type = ObjectProperty::Type::Setter; property_name = parse_property_key(); } else { property_name = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, identifier.value()); property_value = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, identifier.value()); } } else { property_name = parse_property_key(); } bool is_proto = (type == TokenType::StringLiteral || type == TokenType::Identifier) && is(*property_name) && static_cast(*property_name).value() == "__proto__"; if (property_type == ObjectProperty::Type::Getter || property_type == ObjectProperty::Type::Setter) { if (!match(TokenType::ParenOpen)) { expected("'(' for object getter or setter property"); skip_to_next_property(); continue; } } if (match(TokenType::Equals)) { // Not a valid object literal, but a valid assignment target consume(); // Parse the expression and throw it away auto expression = parse_expression(2); if (!invalid_object_literal_property_range.has_value()) invalid_object_literal_property_range = expression->source_range(); } else if (match(TokenType::ParenOpen)) { VERIFY(property_name); u8 parse_options = FunctionNodeParseOptions::AllowSuperPropertyLookup; if (property_type == ObjectProperty::Type::Getter) parse_options |= FunctionNodeParseOptions::IsGetterFunction; if (property_type == ObjectProperty::Type::Setter) parse_options |= FunctionNodeParseOptions::IsSetterFunction; if (function_kind == FunctionKind::Generator || function_kind == FunctionKind::AsyncGenerator) parse_options |= FunctionNodeParseOptions::IsGeneratorFunction; if (function_kind == FunctionKind::Async || function_kind == FunctionKind::AsyncGenerator) parse_options |= FunctionNodeParseOptions::IsAsyncFunction; auto function = parse_function_node(parse_options, function_start); properties.append(create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, *property_name, function, property_type, true)); } else if (match(TokenType::Colon)) { if (!property_name) { expected("a property name"); skip_to_next_property(); continue; } consume(); if (is_proto) { if (has_direct_proto_property) syntax_error("Property name '__proto__' must not appear more than once in object literal"); has_direct_proto_property = true; } properties.append(create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, *property_name, parse_expression(2), property_type, false)); } else if (property_name && property_value) { if (m_state.strict_mode && is(*property_name)) { auto& string_literal = static_cast(*property_name); if (is_strict_reserved_word(string_literal.value())) syntax_error(String::formatted("'{}' is a reserved keyword", string_literal.value())); } properties.append(create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, *property_name, *property_value, property_type, false)); } else { expected("a property"); skip_to_next_property(); continue; } if (!match(TokenType::Comma)) break; consume(TokenType::Comma); } consume(TokenType::CurlyClose); return create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, move(properties), move(invalid_object_literal_property_range)); } NonnullRefPtr Parser::parse_array_expression() { auto rule_start = push_start(); consume(TokenType::BracketOpen); Vector> elements; while (match_expression() || match(TokenType::TripleDot) || match(TokenType::Comma)) { RefPtr expression; if (match(TokenType::TripleDot)) { consume(TokenType::TripleDot); expression = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, parse_expression(2)); } else if (match_expression()) { expression = parse_expression(2); } elements.append(expression); if (!match(TokenType::Comma)) break; consume(TokenType::Comma); } consume(TokenType::BracketClose); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(elements)); } NonnullRefPtr Parser::parse_string_literal(const Token& token, bool in_template_literal) { auto rule_start = push_start(); auto status = Token::StringValueStatus::Ok; auto string = token.string_value(status); if (status != Token::StringValueStatus::Ok) { String message; if (status == Token::StringValueStatus::LegacyOctalEscapeSequence) { m_state.string_legacy_octal_escape_sequence_in_scope = true; if (in_template_literal) message = "Octal escape sequence not allowed in template literal"; else if (m_state.strict_mode) message = "Octal escape sequence in string literal not allowed in strict mode"; } else if (status == Token::StringValueStatus::MalformedHexEscape || status == Token::StringValueStatus::MalformedUnicodeEscape) { auto type = status == Token::StringValueStatus::MalformedUnicodeEscape ? "unicode" : "hexadecimal"; message = String::formatted("Malformed {} escape sequence", type); } else if (status == Token::StringValueStatus::UnicodeEscapeOverflow) { message = "Unicode code_point must not be greater than 0x10ffff in escape sequence"; } else { VERIFY_NOT_REACHED(); } if (!message.is_empty()) syntax_error(message, Position { token.line_number(), token.line_column() }); } auto is_use_strict_directive = !in_template_literal && (token.value() == "'use strict'" || token.value() == "\"use strict\""); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, string, is_use_strict_directive); } NonnullRefPtr Parser::parse_template_literal(bool is_tagged) { auto rule_start = push_start(); consume(TokenType::TemplateLiteralStart); NonnullRefPtrVector expressions; NonnullRefPtrVector raw_strings; auto append_empty_string = [this, &rule_start, &expressions, &raw_strings, is_tagged]() { auto string_literal = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, ""); expressions.append(string_literal); if (is_tagged) raw_strings.append(string_literal); }; if (!match(TokenType::TemplateLiteralString)) append_empty_string(); while (!done() && !match(TokenType::TemplateLiteralEnd) && !match(TokenType::UnterminatedTemplateLiteral)) { if (match(TokenType::TemplateLiteralString)) { auto token = consume(); expressions.append(parse_string_literal(token, true)); if (is_tagged) raw_strings.append(create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, token.raw_template_value())); } else if (match(TokenType::TemplateLiteralExprStart)) { consume(TokenType::TemplateLiteralExprStart); if (match(TokenType::TemplateLiteralExprEnd)) { syntax_error("Empty template literal expression block"); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, expressions); } expressions.append(parse_expression(0)); if (match(TokenType::UnterminatedTemplateLiteral)) { syntax_error("Unterminated template literal"); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, expressions); } consume(TokenType::TemplateLiteralExprEnd); if (!match(TokenType::TemplateLiteralString)) append_empty_string(); } else { expected("Template literal string or expression"); break; } } if (match(TokenType::UnterminatedTemplateLiteral)) { syntax_error("Unterminated template literal"); } else { consume(TokenType::TemplateLiteralEnd); } if (is_tagged) return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, expressions, raw_strings); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, expressions); } NonnullRefPtr Parser::parse_expression(int min_precedence, Associativity associativity, const Vector& forbidden) { auto rule_start = push_start(); auto [expression, should_continue_parsing] = parse_primary_expression(); auto check_for_invalid_object_property = [&](auto& expression) { if (is(*expression)) { if (auto range = static_cast(*expression).invalid_property_range(); range.has_value()) syntax_error("Invalid property in object literal", range->start); } }; if (is(*expression) && m_state.current_scope_pusher) { auto identifier_instance = static_ptr_cast(expression); auto function_scope = m_state.current_scope_pusher->last_function_scope(); auto function_parent_scope = function_scope ? function_scope->parent_scope() : nullptr; bool has_not_been_declared_as_variable = true; for (auto scope = m_state.current_scope_pusher; scope != function_parent_scope; scope = scope->parent_scope()) { if (scope->has_declaration(identifier_instance->string())) { has_not_been_declared_as_variable = false; break; } } if (has_not_been_declared_as_variable) { if (identifier_instance->string() == "arguments"sv) m_state.current_scope_pusher->set_contains_access_to_arguments_object(); } } while (match(TokenType::TemplateLiteralStart)) { auto template_literal = parse_template_literal(true); expression = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(expression), move(template_literal)); } if (should_continue_parsing) { while (match_secondary_expression(forbidden)) { int new_precedence = g_operator_precedence.get(m_state.current_token.type()); if (new_precedence < min_precedence) break; if (new_precedence == min_precedence && associativity == Associativity::Left) break; check_for_invalid_object_property(expression); Associativity new_associativity = operator_associativity(m_state.current_token.type()); expression = parse_secondary_expression(move(expression), new_precedence, new_associativity); while (match(TokenType::TemplateLiteralStart) && !is(*expression)) { auto template_literal = parse_template_literal(true); expression = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(expression), move(template_literal)); } } } if (is(*expression)) syntax_error("'super' keyword unexpected here"); check_for_invalid_object_property(expression); if (is(*expression) && m_state.current_scope_pusher) { auto& callee = static_ptr_cast(expression)->callee(); if (is(callee)) { auto& identifier_instance = static_cast(callee); if (identifier_instance.string() == "eval"sv) { bool has_not_been_declared_as_variable = true; for (auto scope = m_state.current_scope_pusher; scope; scope = scope->parent_scope()) { if (scope->has_declaration(identifier_instance.string())) { has_not_been_declared_as_variable = false; break; } } if (has_not_been_declared_as_variable) m_state.current_scope_pusher->set_contains_direct_call_to_eval(); } } } if (match(TokenType::Comma) && min_precedence <= 1) { NonnullRefPtrVector expressions; expressions.append(expression); while (match(TokenType::Comma)) { consume(); expressions.append(parse_expression(2)); } expression = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(expressions)); } return expression; } NonnullRefPtr Parser::parse_secondary_expression(NonnullRefPtr lhs, int min_precedence, Associativity associativity) { auto rule_start = push_start(); switch (m_state.current_token.type()) { case TokenType::Plus: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::Addition, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::PlusEquals: return parse_assignment_expression(AssignmentOp::AdditionAssignment, move(lhs), min_precedence, associativity); case TokenType::Minus: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::Subtraction, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::MinusEquals: return parse_assignment_expression(AssignmentOp::SubtractionAssignment, move(lhs), min_precedence, associativity); case TokenType::Asterisk: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::Multiplication, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::AsteriskEquals: return parse_assignment_expression(AssignmentOp::MultiplicationAssignment, move(lhs), min_precedence, associativity); case TokenType::Slash: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::Division, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::SlashEquals: return parse_assignment_expression(AssignmentOp::DivisionAssignment, move(lhs), min_precedence, associativity); case TokenType::Percent: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::Modulo, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::PercentEquals: return parse_assignment_expression(AssignmentOp::ModuloAssignment, move(lhs), min_precedence, associativity); case TokenType::DoubleAsterisk: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::Exponentiation, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::DoubleAsteriskEquals: return parse_assignment_expression(AssignmentOp::ExponentiationAssignment, move(lhs), min_precedence, associativity); case TokenType::GreaterThan: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::GreaterThan, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::GreaterThanEquals: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::GreaterThanEquals, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::LessThan: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::LessThan, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::LessThanEquals: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::LessThanEquals, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::EqualsEqualsEquals: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::StrictlyEquals, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::ExclamationMarkEqualsEquals: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::StrictlyInequals, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::EqualsEquals: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::LooselyEquals, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::ExclamationMarkEquals: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::LooselyInequals, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::In: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::In, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::Instanceof: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::InstanceOf, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::Ampersand: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::BitwiseAnd, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::AmpersandEquals: return parse_assignment_expression(AssignmentOp::BitwiseAndAssignment, move(lhs), min_precedence, associativity); case TokenType::Pipe: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::BitwiseOr, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::PipeEquals: return parse_assignment_expression(AssignmentOp::BitwiseOrAssignment, move(lhs), min_precedence, associativity); case TokenType::Caret: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::BitwiseXor, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::CaretEquals: return parse_assignment_expression(AssignmentOp::BitwiseXorAssignment, move(lhs), min_precedence, associativity); case TokenType::ShiftLeft: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::LeftShift, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::ShiftLeftEquals: return parse_assignment_expression(AssignmentOp::LeftShiftAssignment, move(lhs), min_precedence, associativity); case TokenType::ShiftRight: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::RightShift, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::ShiftRightEquals: return parse_assignment_expression(AssignmentOp::RightShiftAssignment, move(lhs), min_precedence, associativity); case TokenType::UnsignedShiftRight: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, BinaryOp::UnsignedRightShift, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::UnsignedShiftRightEquals: return parse_assignment_expression(AssignmentOp::UnsignedRightShiftAssignment, move(lhs), min_precedence, associativity); case TokenType::ParenOpen: return parse_call_expression(move(lhs)); case TokenType::Equals: return parse_assignment_expression(AssignmentOp::Assignment, move(lhs), min_precedence, associativity); case TokenType::Period: consume(); if (match(TokenType::PrivateIdentifier)) { if (!is_private_identifier_valid()) syntax_error(String::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value())); else if (is(*lhs)) syntax_error(String::formatted("Cannot access private field or method '{}' on super", m_state.current_token.value())); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(lhs), create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, consume().value())); } else if (!match_identifier_name()) { expected("IdentifierName"); } return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(lhs), create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, consume().value())); case TokenType::BracketOpen: { consume(TokenType::BracketOpen); auto expression = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(lhs), parse_expression(0), true); consume(TokenType::BracketClose); return expression; } case TokenType::PlusPlus: // FIXME: Apparently for functions this should also not be enforced on a parser level, // other engines throw ReferenceError for foo()++ if (!is(*lhs) && !is(*lhs)) syntax_error(String::formatted("Left-hand side of postfix increment operator must be identifier or member expression, got {}", lhs->class_name())); if (m_state.strict_mode && is(*lhs)) { auto& identifier = static_cast(*lhs); auto& name = identifier.string(); check_identifier_name_for_assignment_validity(name); } consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UpdateOp::Increment, move(lhs)); case TokenType::MinusMinus: // FIXME: Apparently for functions this should also not be enforced on a parser level, // other engines throw ReferenceError for foo()-- if (!is(*lhs) && !is(*lhs)) syntax_error(String::formatted("Left-hand side of postfix increment operator must be identifier or member expression, got {}", lhs->class_name())); if (m_state.strict_mode && is(*lhs)) { auto& identifier = static_cast(*lhs); auto& name = identifier.string(); check_identifier_name_for_assignment_validity(name); } consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, UpdateOp::Decrement, move(lhs)); case TokenType::DoubleAmpersand: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, LogicalOp::And, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::DoubleAmpersandEquals: return parse_assignment_expression(AssignmentOp::AndAssignment, move(lhs), min_precedence, associativity); case TokenType::DoublePipe: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, LogicalOp::Or, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::DoublePipeEquals: return parse_assignment_expression(AssignmentOp::OrAssignment, move(lhs), min_precedence, associativity); case TokenType::DoubleQuestionMark: consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, LogicalOp::NullishCoalescing, move(lhs), parse_expression(min_precedence, associativity)); case TokenType::DoubleQuestionMarkEquals: return parse_assignment_expression(AssignmentOp::NullishAssignment, move(lhs), min_precedence, associativity); case TokenType::QuestionMark: return parse_conditional_expression(move(lhs)); case TokenType::QuestionMarkPeriod: // FIXME: This should allow `(new Foo)?.bar', but as our parser strips parenthesis, // we can't really tell if `lhs' was parenthesized at this point. if (is(lhs.ptr())) { syntax_error("'new' cannot be used with optional chaining", position()); consume(); return lhs; } return parse_optional_chain(move(lhs)); default: expected("secondary expression"); consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); } } bool Parser::is_private_identifier_valid() const { VERIFY(match(TokenType::PrivateIdentifier)); if (!m_state.referenced_private_names) return false; // We might not have hit the declaration yet so class will check this in the end m_state.referenced_private_names->set(m_state.current_token.value()); return true; } RefPtr Parser::synthesize_binding_pattern(Expression const& expression) { VERIFY(is(expression) || is(expression)); // Clear any syntax error that has occurred in the range that 'expression' spans. m_state.errors.remove_all_matching([range = expression.source_range()](auto const& error) { return error.position.has_value() && range.contains(*error.position); }); // Make a parser and parse the source for this expression as a binding pattern. // NOTE: There's currently a fundamental problem that we pass the *next* (a.k.a. `current_token`) // token's position to most nodes' SourceRange when using `rule_start.position(), position()`. // This means that `source` will contain the subsequent token's trivia, if any (which is fine). auto source_start_offset = expression.source_range().start.offset; auto source_end_offset = expression.source_range().end.offset; auto source = m_state.lexer.source().substring_view(source_start_offset, source_end_offset - source_start_offset); Lexer lexer { source, m_state.lexer.filename(), expression.source_range().start.line, expression.source_range().start.column }; Parser parser { lexer }; parser.m_state.strict_mode = m_state.strict_mode; parser.m_state.allow_super_property_lookup = m_state.allow_super_property_lookup; parser.m_state.allow_super_constructor_call = m_state.allow_super_constructor_call; parser.m_state.in_function_context = m_state.in_function_context; parser.m_state.in_formal_parameter_context = m_state.in_formal_parameter_context; parser.m_state.in_generator_function_context = m_state.in_generator_function_context; parser.m_state.await_expression_is_valid = m_state.await_expression_is_valid; parser.m_state.in_arrow_function_context = m_state.in_arrow_function_context; parser.m_state.in_break_context = m_state.in_break_context; parser.m_state.in_continue_context = m_state.in_continue_context; parser.m_state.string_legacy_octal_escape_sequence_in_scope = m_state.string_legacy_octal_escape_sequence_in_scope; parser.m_state.in_class_field_initializer = m_state.in_class_field_initializer; parser.m_state.in_class_static_init_block = m_state.in_class_static_init_block; parser.m_state.referenced_private_names = m_state.referenced_private_names; auto result = parser.parse_binding_pattern(AllowDuplicates::Yes, AllowMemberExpressions::Yes); if (parser.has_errors()) m_state.errors.extend(parser.errors()); return result; } NonnullRefPtr Parser::parse_assignment_expression(AssignmentOp assignment_op, NonnullRefPtr lhs, int min_precedence, Associativity associativity) { auto rule_start = push_start(); VERIFY(match(TokenType::Equals) || match(TokenType::PlusEquals) || match(TokenType::MinusEquals) || match(TokenType::AsteriskEquals) || match(TokenType::SlashEquals) || match(TokenType::PercentEquals) || match(TokenType::DoubleAsteriskEquals) || match(TokenType::AmpersandEquals) || match(TokenType::PipeEquals) || match(TokenType::CaretEquals) || match(TokenType::ShiftLeftEquals) || match(TokenType::ShiftRightEquals) || match(TokenType::UnsignedShiftRightEquals) || match(TokenType::DoubleAmpersandEquals) || match(TokenType::DoublePipeEquals) || match(TokenType::DoubleQuestionMarkEquals)); consume(); if (assignment_op == AssignmentOp::Assignment) { if (is(*lhs) || is(*lhs)) { auto binding_pattern = synthesize_binding_pattern(*lhs); if (binding_pattern) { auto rhs = parse_expression(min_precedence, associativity); return create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, assignment_op, binding_pattern.release_nonnull(), move(rhs)); } } } if (!is(*lhs) && !is(*lhs) && !is(*lhs)) { syntax_error("Invalid left-hand side in assignment"); } else if (m_state.strict_mode && is(*lhs)) { auto name = static_cast(*lhs).string(); check_identifier_name_for_assignment_validity(name); } else if (m_state.strict_mode && is(*lhs)) { syntax_error("Cannot assign to function call"); } auto rhs = parse_expression(min_precedence, associativity); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, assignment_op, move(lhs), move(rhs)); } NonnullRefPtr Parser::parse_identifier() { auto identifier_start = position(); auto token = consume_identifier(); if (m_state.in_class_field_initializer && token.value() == "arguments"sv) syntax_error("'arguments' is not allowed in class field initializer"); return create_ast_node( { m_state.current_token.filename(), identifier_start, position() }, token.value()); } Vector Parser::parse_arguments() { Vector arguments; consume(TokenType::ParenOpen); while (match_expression() || match(TokenType::TripleDot)) { if (match(TokenType::TripleDot)) { consume(); arguments.append({ parse_expression(2), true }); } else { arguments.append({ parse_expression(2), false }); } if (!match(TokenType::Comma)) break; consume(); } consume(TokenType::ParenClose); return arguments; } NonnullRefPtr Parser::parse_call_expression(NonnullRefPtr lhs) { auto rule_start = push_start(); if (!m_state.allow_super_constructor_call && is(*lhs)) syntax_error("'super' keyword unexpected here"); auto arguments = parse_arguments(); if (is(*lhs)) return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(arguments)); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(lhs), move(arguments)); } NonnullRefPtr Parser::parse_new_expression() { auto rule_start = push_start(); consume(TokenType::New); auto callee = parse_expression(g_operator_precedence.get(TokenType::New), Associativity::Right, { TokenType::ParenOpen, TokenType::QuestionMarkPeriod }); if (is(*callee)) syntax_error("Cannot call new on dynamic import", callee->source_range().start); Vector arguments; if (match(TokenType::ParenOpen)) { consume(TokenType::ParenOpen); while (match_expression() || match(TokenType::TripleDot)) { if (match(TokenType::TripleDot)) { consume(); arguments.append({ parse_expression(2), true }); } else { arguments.append({ parse_expression(2), false }); } if (!match(TokenType::Comma)) break; consume(); } consume(TokenType::ParenClose); } return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(callee), move(arguments)); } NonnullRefPtr Parser::parse_yield_expression() { auto rule_start = push_start(); if (m_state.in_formal_parameter_context) syntax_error("'Yield' expression is not allowed in formal parameters of generator function"); consume(TokenType::Yield); RefPtr argument; bool yield_from = false; if (!m_state.current_token.trivia_contains_line_terminator()) { if (match(TokenType::Asterisk)) { consume(); yield_from = true; } if (yield_from || match_expression() || match(TokenType::Class)) argument = parse_expression(2); } return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(argument), yield_from); } NonnullRefPtr Parser::parse_await_expression() { auto rule_start = push_start(); if (m_state.in_formal_parameter_context) syntax_error("'Await' expression is not allowed in formal parameters of an async function"); consume(TokenType::Await); auto precedence = g_operator_precedence.get(TokenType::Await); auto associativity = operator_associativity(TokenType::Await); auto argument = parse_expression(precedence, associativity); m_state.current_scope_pusher->set_contains_await_expression(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(argument)); } NonnullRefPtr Parser::parse_return_statement() { auto rule_start = push_start(); if (!m_state.in_function_context && !m_state.in_arrow_function_context) syntax_error("'return' not allowed outside of a function"); consume(TokenType::Return); // Automatic semicolon insertion: terminate statement when return is followed by newline if (m_state.current_token.trivia_contains_line_terminator()) return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, nullptr); if (match_expression()) { auto expression = parse_expression(0); consume_or_insert_semicolon(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(expression)); } consume_or_insert_semicolon(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, nullptr); } void Parser::parse_statement_list(ScopeNode& output_node, AllowLabelledFunction allow_labelled_functions) { while (!done()) { if (match_declaration()) { auto declaration = parse_declaration(); VERIFY(m_state.current_scope_pusher); m_state.current_scope_pusher->add_declaration(declaration); output_node.append(move(declaration)); } else if (match_statement()) { output_node.append(parse_statement(allow_labelled_functions)); } else { break; } } } // FunctionBody, https://tc39.es/ecma262/#prod-FunctionBody NonnullRefPtr Parser::parse_function_body(Vector const& parameters, FunctionKind function_kind, bool& contains_direct_call_to_eval) { auto rule_start = push_start(); auto function_body = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); ScopePusher function_scope = ScopePusher::function_scope(*this, function_body, parameters); // FIXME <- auto has_use_strict = parse_directive(function_body); bool previous_strict_mode = m_state.strict_mode; if (has_use_strict) { m_state.strict_mode = true; function_body->set_strict_mode(); if (!is_simple_parameter_list(parameters)) syntax_error("Illegal 'use strict' directive in function with non-simple parameter list"); } else if (previous_strict_mode) { function_body->set_strict_mode(); } parse_statement_list(function_body); // If we're parsing the function body standalone, e.g. via CreateDynamicFunction, we must have reached EOF here. // Otherwise, we need a closing curly bracket (which is consumed elsewhere). If we get neither, it's an error. if (!match(TokenType::Eof) && !match(TokenType::CurlyClose)) expected(Token::name(TokenType::CurlyClose)); // If the function contains 'use strict' we need to check the parameters (again). if (function_body->in_strict_mode() || function_kind != FunctionKind::Normal) { Vector parameter_names; for (auto& parameter : parameters) { parameter.binding.visit( [&](FlyString const& parameter_name) { check_identifier_name_for_assignment_validity(parameter_name, function_body->in_strict_mode()); if (function_kind == FunctionKind::Generator && parameter_name == "yield"sv) syntax_error("Parameter name 'yield' not allowed in this context"); if (function_kind == FunctionKind::Async && parameter_name == "await"sv) syntax_error("Parameter name 'await' not allowed in this context"); for (auto& previous_name : parameter_names) { if (previous_name == parameter_name) { syntax_error(String::formatted("Duplicate parameter '{}' not allowed in strict mode", parameter_name)); } } parameter_names.append(parameter_name); }, [&](NonnullRefPtr const& binding) { binding->for_each_bound_name([&](auto& bound_name) { if (function_kind == FunctionKind::Generator && bound_name == "yield"sv) syntax_error("Parameter name 'yield' not allowed in this context"); if (function_kind == FunctionKind::Async && bound_name == "await"sv) syntax_error("Parameter name 'await' not allowed in this context"); for (auto& previous_name : parameter_names) { if (previous_name == bound_name) { syntax_error(String::formatted("Duplicate parameter '{}' not allowed in strict mode", bound_name)); break; } } parameter_names.append(bound_name); }); }); } } m_state.strict_mode = previous_strict_mode; contains_direct_call_to_eval = function_scope.contains_direct_call_to_eval(); return function_body; } NonnullRefPtr Parser::parse_block_statement() { auto rule_start = push_start(); auto block = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); ScopePusher block_scope = ScopePusher::block_scope(*this, block); consume(TokenType::CurlyOpen); parse_statement_list(block); consume(TokenType::CurlyClose); return block; } template NonnullRefPtr Parser::parse_function_node(u8 parse_options, Optional const& function_start) { auto rule_start = function_start.has_value() ? RulePosition { *this, *function_start } : push_start(); VERIFY(!(parse_options & FunctionNodeParseOptions::IsGetterFunction && parse_options & FunctionNodeParseOptions::IsSetterFunction)); TemporaryChange super_property_access_rollback(m_state.allow_super_property_lookup, !!(parse_options & FunctionNodeParseOptions::AllowSuperPropertyLookup)); TemporaryChange super_constructor_call_rollback(m_state.allow_super_constructor_call, !!(parse_options & FunctionNodeParseOptions::AllowSuperConstructorCall)); TemporaryChange break_context_rollback(m_state.in_break_context, false); TemporaryChange continue_context_rollback(m_state.in_continue_context, false); TemporaryChange class_field_initializer_rollback(m_state.in_class_field_initializer, false); TemporaryChange might_need_arguments_object_rollback(m_state.function_might_need_arguments_object, false); constexpr auto is_function_expression = IsSame; FunctionKind function_kind; if ((parse_options & FunctionNodeParseOptions::IsGeneratorFunction) != 0 && (parse_options & FunctionNodeParseOptions::IsAsyncFunction) != 0) function_kind = FunctionKind::AsyncGenerator; else if ((parse_options & FunctionNodeParseOptions::IsGeneratorFunction) != 0) function_kind = FunctionKind::Generator; else if ((parse_options & FunctionNodeParseOptions::IsAsyncFunction) != 0) function_kind = FunctionKind::Async; else function_kind = FunctionKind::Normal; String name; if (parse_options & FunctionNodeParseOptions::CheckForFunctionAndName) { if (function_kind == FunctionKind::Normal && match(TokenType::Async) && !next_token().trivia_contains_line_terminator()) { function_kind = FunctionKind::Async; consume(TokenType::Async); parse_options |= FunctionNodeParseOptions::IsAsyncFunction; } consume(TokenType::Function); if (match(TokenType::Asterisk)) { function_kind = function_kind == FunctionKind::Normal ? FunctionKind::Generator : FunctionKind::AsyncGenerator; consume(TokenType::Asterisk); parse_options |= FunctionNodeParseOptions::IsGeneratorFunction; } if (FunctionNodeType::must_have_name() || match_identifier()) name = consume_identifier().value(); else if (is_function_expression && (match(TokenType::Yield) || match(TokenType::Await))) name = consume().value(); check_identifier_name_for_assignment_validity(name); if (function_kind == FunctionKind::AsyncGenerator && (name == "await"sv || name == "yield"sv)) syntax_error(String::formatted("async generator function is not allowed to be called '{}'", name)); if (m_state.in_class_static_init_block && name == "await"sv) syntax_error("'await' is a reserved word"); } TemporaryChange class_static_initializer_rollback(m_state.in_class_static_init_block, false); TemporaryChange generator_change(m_state.in_generator_function_context, function_kind == FunctionKind::Generator || function_kind == FunctionKind::AsyncGenerator); TemporaryChange async_change(m_state.await_expression_is_valid, function_kind == FunctionKind::Async || function_kind == FunctionKind::AsyncGenerator); consume(TokenType::ParenOpen); i32 function_length = -1; auto parameters = parse_formal_parameters(function_length, parse_options); consume(TokenType::ParenClose); if (function_length == -1) function_length = parameters.size(); TemporaryChange function_context_rollback(m_state.in_function_context, true); auto old_labels_in_scope = move(m_state.labels_in_scope); ScopeGuard guard([&]() { m_state.labels_in_scope = move(old_labels_in_scope); }); consume(TokenType::CurlyOpen); bool contains_direct_call_to_eval = false; auto body = parse_function_body(parameters, function_kind, contains_direct_call_to_eval); consume(TokenType::CurlyClose); auto has_strict_directive = body->in_strict_mode(); if (has_strict_directive) check_identifier_name_for_assignment_validity(name, true); auto function_start_offset = rule_start.position().offset; auto function_end_offset = position().offset - m_state.current_token.trivia().length(); auto source_text = String { m_state.lexer.source().substring_view(function_start_offset, function_end_offset - function_start_offset) }; return create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, name, move(source_text), move(body), move(parameters), function_length, function_kind, has_strict_directive, m_state.function_might_need_arguments_object, contains_direct_call_to_eval); } Vector Parser::parse_formal_parameters(int& function_length, u8 parse_options) { auto rule_start = push_start(); bool has_default_parameter = false; bool has_rest_parameter = false; TemporaryChange formal_parameter_context_change { m_state.in_formal_parameter_context, true }; Vector parameters; auto consume_identifier_or_binding_pattern = [&]() -> Variant> { if (auto pattern = parse_binding_pattern(AllowDuplicates::No, AllowMemberExpressions::No)) return pattern.release_nonnull(); auto token = consume_identifier(); auto parameter_name = token.value(); check_identifier_name_for_assignment_validity(parameter_name); for (auto& parameter : parameters) { bool has_same_name = parameter.binding.visit( [&](FlyString const& name) { return name == parameter_name; }, [&](NonnullRefPtr const& bindings) { bool found_duplicate = false; bindings->for_each_bound_name([&](auto& bound_name) { if (bound_name == parameter_name) found_duplicate = true; }); return found_duplicate; }); if (!has_same_name) continue; String message; if (parse_options & FunctionNodeParseOptions::IsArrowFunction) message = String::formatted("Duplicate parameter '{}' not allowed in arrow function", parameter_name); else if (m_state.strict_mode) message = String::formatted("Duplicate parameter '{}' not allowed in strict mode", parameter_name); else if (has_default_parameter || match(TokenType::Equals)) message = String::formatted("Duplicate parameter '{}' not allowed in function with default parameter", parameter_name); else if (has_rest_parameter) message = String::formatted("Duplicate parameter '{}' not allowed in function with rest parameter", parameter_name); if (!message.is_empty()) syntax_error(message, Position { token.line_number(), token.line_column() }); break; } return FlyString { token.value() }; }; while (match(TokenType::CurlyOpen) || match(TokenType::BracketOpen) || match_identifier() || match(TokenType::TripleDot)) { if (parse_options & FunctionNodeParseOptions::IsGetterFunction) syntax_error("Getter function must have no arguments"); if (parse_options & FunctionNodeParseOptions::IsSetterFunction && (parameters.size() >= 1 || match(TokenType::TripleDot))) syntax_error("Setter function must have one argument"); auto is_rest = false; if (match(TokenType::TripleDot)) { consume(); has_rest_parameter = true; function_length = parameters.size(); is_rest = true; } auto parameter = consume_identifier_or_binding_pattern(); RefPtr default_value; if (match(TokenType::Equals)) { consume(); if (is_rest) syntax_error("Rest parameter may not have a default initializer"); TemporaryChange change(m_state.in_function_context, true); has_default_parameter = true; function_length = parameters.size(); default_value = parse_expression(2); bool is_generator = parse_options & FunctionNodeParseOptions::IsGeneratorFunction; if ((is_generator || m_state.strict_mode) && default_value && default_value->fast_is() && static_cast(*default_value).string() == "yield"sv) syntax_error("Generator function parameter initializer cannot contain a reference to an identifier named \"yield\""); } parameters.append({ move(parameter), default_value, is_rest }); if (!match(TokenType::Comma) || is_rest) break; consume(TokenType::Comma); } if (parse_options & FunctionNodeParseOptions::IsSetterFunction && parameters.is_empty()) syntax_error("Setter function must have one argument"); // If we're parsing the parameters standalone, e.g. via CreateDynamicFunction, we must have reached EOF here. // Otherwise, we need a closing parenthesis (which is consumed elsewhere). If we get neither, it's an error. if (!match(TokenType::Eof) && !match(TokenType::ParenClose)) expected(Token::name(TokenType::ParenClose)); return parameters; } static constexpr AK::Array s_reserved_words = { "break", "case", "catch", "class", "const", "continue", "debugger", "default", "delete", "do", "else", "enum", "export", "extends", "false", "finally", "for", "function", "if", "import", "in", "instanceof", "new", "null", "return", "super", "switch", "this", "throw", "true", "try", "typeof", "var", "void", "while", "with" }; RefPtr Parser::parse_binding_pattern(Parser::AllowDuplicates allow_duplicates, Parser::AllowMemberExpressions allow_member_expressions) { auto rule_start = push_start(); TokenType closing_token; bool is_object = true; if (match(TokenType::BracketOpen)) { consume(); closing_token = TokenType::BracketClose; is_object = false; } else if (match(TokenType::CurlyOpen)) { consume(); closing_token = TokenType::CurlyClose; } else { return {}; } Vector entries; while (!match(closing_token)) { if (!is_object && match(TokenType::Comma)) { consume(); entries.append(BindingPattern::BindingEntry {}); continue; } auto is_rest = false; if (match(TokenType::TripleDot)) { consume(); is_rest = true; } decltype(BindingPattern::BindingEntry::name) name = Empty {}; decltype(BindingPattern::BindingEntry::alias) alias = Empty {}; RefPtr initializer = {}; if (is_object) { bool needs_alias = false; if (allow_member_expressions == AllowMemberExpressions::Yes && is_rest) { auto expression_position = position(); auto expression = parse_expression(2, Associativity::Right, { TokenType::Equals }); if (is(*expression)) alias = static_ptr_cast(expression); else if (is(*expression)) name = static_ptr_cast(expression); else syntax_error("Invalid destructuring assignment target", expression_position); } else if (match_identifier_name() || match(TokenType::StringLiteral) || match(TokenType::NumericLiteral)) { if (match(TokenType::StringLiteral) || match(TokenType::NumericLiteral)) needs_alias = true; if (match(TokenType::StringLiteral)) { auto token = consume(TokenType::StringLiteral); auto string_literal = parse_string_literal(token); name = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, string_literal->value()); } else { name = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, consume().value()); } } else if (match(TokenType::BracketOpen)) { consume(); auto expression = parse_expression(0); name = move(expression); consume(TokenType::BracketClose); } else { expected("identifier or computed property name"); return {}; } if (!is_rest && match(TokenType::Colon)) { consume(); if (allow_member_expressions == AllowMemberExpressions::Yes) { auto expression_position = position(); auto expression = parse_expression(2, Associativity::Right, { TokenType::Equals }); if (is(*expression) || is(*expression)) { if (auto synthesized_binding_pattern = synthesize_binding_pattern(*expression)) alias = synthesized_binding_pattern.release_nonnull(); else syntax_error("Invalid destructuring assignment target", expression_position); } else if (is(*expression)) { alias = static_ptr_cast(expression); } else if (is(*expression)) { alias = static_ptr_cast(expression); } else { syntax_error("Invalid destructuring assignment target", expression_position); } } else if (match(TokenType::CurlyOpen) || match(TokenType::BracketOpen)) { auto binding_pattern = parse_binding_pattern(allow_duplicates, allow_member_expressions); if (!binding_pattern) return {}; alias = binding_pattern.release_nonnull(); } else if (match_identifier_name()) { alias = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, consume().value()); } else { expected("identifier or binding pattern"); return {}; } } else if (needs_alias) { expected("alias for string or numeric literal name"); return {}; } } else { if (allow_member_expressions == AllowMemberExpressions::Yes) { auto expression_position = position(); auto expression = parse_expression(2, Associativity::Right, { TokenType::Equals }); if (is(*expression) || is(*expression)) { if (auto synthesized_binding_pattern = synthesize_binding_pattern(*expression)) alias = synthesized_binding_pattern.release_nonnull(); else syntax_error("Invalid destructuring assignment target", expression_position); } else if (is(*expression)) { alias = static_ptr_cast(expression); } else if (is(*expression)) { alias = static_ptr_cast(expression); } else { syntax_error("Invalid destructuring assignment target", expression_position); } } else if (match(TokenType::BracketOpen) || match(TokenType::CurlyOpen)) { auto pattern = parse_binding_pattern(allow_duplicates, allow_member_expressions); if (!pattern) { expected("binding pattern"); return {}; } alias = pattern.release_nonnull(); } else if (match_identifier_name()) { // BindingElement must always have an Empty name field auto identifier_name = consume_identifier().value(); alias = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, identifier_name); } else { expected("identifier or binding pattern"); return {}; } } if (match(TokenType::Equals)) { if (is_rest) { syntax_error("Unexpected initializer after rest element"); return {}; } consume(); initializer = parse_expression(2); if (!initializer) { expected("initialization expression"); return {}; } } entries.append(BindingPattern::BindingEntry { move(name), move(alias), move(initializer), is_rest }); if (match(TokenType::Comma)) { if (is_rest) { syntax_error("Rest element may not be followed by a comma"); return {}; } consume(); } else if (is_object && !match(TokenType::CurlyClose)) { consume(TokenType::Comma); } } while (!is_object && match(TokenType::Comma)) consume(); consume(closing_token); auto kind = is_object ? BindingPattern::Kind::Object : BindingPattern::Kind::Array; auto pattern = adopt_ref(*new BindingPattern); pattern->entries = move(entries); pattern->kind = kind; Vector bound_names; pattern->for_each_bound_name([&](auto& name) { if (allow_duplicates == AllowDuplicates::No) { if (bound_names.contains_slow(name)) syntax_error("Duplicate parameter names in bindings"); bound_names.append(name); } check_identifier_name_for_assignment_validity(name); }); return pattern; } NonnullRefPtr Parser::parse_variable_declaration(bool for_loop_variable_declaration) { auto rule_start = push_start(); DeclarationKind declaration_kind; switch (m_state.current_token.type()) { case TokenType::Var: declaration_kind = DeclarationKind::Var; break; case TokenType::Let: declaration_kind = DeclarationKind::Let; break; case TokenType::Const: declaration_kind = DeclarationKind::Const; break; default: VERIFY_NOT_REACHED(); } consume(); NonnullRefPtrVector declarations; for (;;) { Variant, NonnullRefPtr, Empty> target {}; if (match_identifier()) { auto identifier_start = push_start(); auto name = consume_identifier().value(); target = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, name); check_identifier_name_for_assignment_validity(name); if ((declaration_kind == DeclarationKind::Let || declaration_kind == DeclarationKind::Const) && name == "let"sv) syntax_error("Lexical binding may not be called 'let'"); } else if (auto pattern = parse_binding_pattern(declaration_kind != DeclarationKind::Var ? AllowDuplicates::No : AllowDuplicates::Yes, AllowMemberExpressions::No)) { target = pattern.release_nonnull(); if ((declaration_kind == DeclarationKind::Let || declaration_kind == DeclarationKind::Const)) { target.get>()->for_each_bound_name([this](auto& name) { if (name == "let"sv) syntax_error("Lexical binding may not be called 'let'"); }); } } else if (!m_state.in_generator_function_context && match(TokenType::Yield)) { if (m_state.strict_mode) syntax_error("Identifier must not be a reserved word in strict mode ('yield')"); target = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, consume().value()); } else if (!m_state.await_expression_is_valid && match(TokenType::Async)) { if (m_program_type == Program::Type::Module) syntax_error("Identifier must not be a reserved word in modules ('async')"); target = create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, consume().value()); } if (target.has()) { expected("identifier or a binding pattern"); if (match(TokenType::Comma)) { consume(); continue; } break; } RefPtr init; if (match(TokenType::Equals)) { consume(); // In a for loop 'in' can be ambiguous so we do not allow it // 14.7.4 The for Statement, https://tc39.es/ecma262/#prod-ForStatement and 14.7.5 The for-in, for-of, and for-await-of Statements, https://tc39.es/ecma262/#prod-ForInOfStatement if (for_loop_variable_declaration) init = parse_expression(2, Associativity::Right, { TokenType::In }); else init = parse_expression(2); } else if (!for_loop_variable_declaration && declaration_kind == DeclarationKind::Const) { syntax_error("Missing initializer in 'const' variable declaration"); } else if (!for_loop_variable_declaration && target.has>()) { syntax_error("Missing initializer in destructuring assignment"); } declarations.append(create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, move(target).downcast, NonnullRefPtr>(), move(init))); if (match(TokenType::Comma)) { consume(); continue; } break; } if (!for_loop_variable_declaration) consume_or_insert_semicolon(); auto declaration = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, declaration_kind, move(declarations)); return declaration; } NonnullRefPtr Parser::parse_throw_statement() { auto rule_start = push_start(); consume(TokenType::Throw); // Automatic semicolon insertion: terminate statement when throw is followed by newline if (m_state.current_token.trivia_contains_line_terminator()) { syntax_error("No line break is allowed between 'throw' and its expression"); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() })); } auto expression = parse_expression(0); consume_or_insert_semicolon(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(expression)); } NonnullRefPtr Parser::parse_break_statement() { auto rule_start = push_start(); consume(TokenType::Break); FlyString target_label; if (match(TokenType::Semicolon)) { consume(); } else { if (!m_state.current_token.trivia_contains_line_terminator() && match_identifier()) { target_label = consume().value(); auto label = m_state.labels_in_scope.find(target_label); if (label == m_state.labels_in_scope.end()) syntax_error(String::formatted("Label '{}' not found", target_label)); } consume_or_insert_semicolon(); } if (target_label.is_null() && !m_state.in_break_context) syntax_error("Unlabeled 'break' not allowed outside of a loop or switch statement"); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, target_label); } NonnullRefPtr Parser::parse_continue_statement() { auto rule_start = push_start(); if (!m_state.in_continue_context) syntax_error("'continue' not allow outside of a loop"); consume(TokenType::Continue); FlyString target_label; if (match(TokenType::Semicolon)) { consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, target_label); } if (!m_state.current_token.trivia_contains_line_terminator() && match_identifier()) { auto label_position = position(); target_label = consume().value(); auto label = m_state.labels_in_scope.find(target_label); if (label == m_state.labels_in_scope.end()) syntax_error(String::formatted("Label '{}' not found or invalid", target_label)); else label->value = label_position; } consume_or_insert_semicolon(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, target_label); } NonnullRefPtr Parser::parse_conditional_expression(NonnullRefPtr test) { auto rule_start = push_start(); consume(TokenType::QuestionMark); auto consequent = parse_expression(2); consume(TokenType::Colon); auto alternate = parse_expression(2); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(test), move(consequent), move(alternate)); } NonnullRefPtr Parser::parse_optional_chain(NonnullRefPtr base) { auto rule_start = push_start(); Vector chain; do { if (match(TokenType::QuestionMarkPeriod)) { consume(TokenType::QuestionMarkPeriod); switch (m_state.current_token.type()) { case TokenType::ParenOpen: chain.append(OptionalChain::Call { parse_arguments(), OptionalChain::Mode::Optional }); break; case TokenType::BracketOpen: consume(); chain.append(OptionalChain::ComputedReference { parse_expression(0), OptionalChain::Mode::Optional }); consume(TokenType::BracketClose); break; case TokenType::PrivateIdentifier: { if (!is_private_identifier_valid()) syntax_error(String::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value())); auto start = position(); auto private_identifier = consume(); chain.append(OptionalChain::PrivateMemberReference { create_ast_node({ m_state.current_token.filename(), start, position() }, private_identifier.value()), OptionalChain::Mode::Optional }); break; } case TokenType::TemplateLiteralStart: // 13.3.1.1 - Static Semantics: Early Errors // OptionalChain : // ?. TemplateLiteral // OptionalChain TemplateLiteral // This is a hard error. syntax_error("Invalid tagged template literal after ?.", position()); break; default: if (match_identifier_name()) { auto start = position(); auto identifier = consume(); chain.append(OptionalChain::MemberReference { create_ast_node({ m_state.current_token.filename(), start, position() }, identifier.value()), OptionalChain::Mode::Optional, }); } else { syntax_error("Invalid optional chain reference after ?.", position()); } break; } } else if (match(TokenType::ParenOpen)) { chain.append(OptionalChain::Call { parse_arguments(), OptionalChain::Mode::NotOptional }); } else if (match(TokenType::Period)) { consume(); if (match(TokenType::PrivateIdentifier)) { auto start = position(); auto private_identifier = consume(); chain.append(OptionalChain::PrivateMemberReference { create_ast_node({ m_state.current_token.filename(), start, position() }, private_identifier.value()), OptionalChain::Mode::NotOptional, }); } else if (match_identifier_name()) { auto start = position(); auto identifier = consume(); chain.append(OptionalChain::MemberReference { create_ast_node({ m_state.current_token.filename(), start, position() }, identifier.value()), OptionalChain::Mode::NotOptional, }); } else { expected("an identifier"); break; } } else if (match(TokenType::TemplateLiteralStart)) { // 13.3.1.1 - Static Semantics: Early Errors // OptionalChain : // ?. TemplateLiteral // OptionalChain TemplateLiteral syntax_error("Invalid tagged template literal after optional chain", position()); break; } else if (match(TokenType::BracketOpen)) { consume(); chain.append(OptionalChain::ComputedReference { parse_expression(2), OptionalChain::Mode::NotOptional }); consume(TokenType::BracketClose); } else { break; } } while (!done()); return create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, move(base), move(chain)); } NonnullRefPtr Parser::parse_try_statement() { auto rule_start = push_start(); consume(TokenType::Try); auto block = parse_block_statement(); RefPtr handler; if (match(TokenType::Catch)) handler = parse_catch_clause(); RefPtr finalizer; if (match(TokenType::Finally)) { consume(); finalizer = parse_block_statement(); } if (!handler && !finalizer) syntax_error("try statement must have a 'catch' or 'finally' clause"); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(block), move(handler), move(finalizer)); } NonnullRefPtr Parser::parse_do_while_statement() { auto rule_start = push_start(); consume(TokenType::Do); auto body = [&]() -> NonnullRefPtr { TemporaryChange break_change(m_state.in_break_context, true); TemporaryChange continue_change(m_state.in_continue_context, true); return parse_statement(); }(); consume(TokenType::While); consume(TokenType::ParenOpen); auto test = parse_expression(0); consume(TokenType::ParenClose); // Since ES 2015 a missing semicolon is inserted here, despite the regular ASI rules not applying if (match(TokenType::Semicolon)) consume(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(test), move(body)); } NonnullRefPtr Parser::parse_while_statement() { auto rule_start = push_start(); consume(TokenType::While); consume(TokenType::ParenOpen); auto test = parse_expression(0); consume(TokenType::ParenClose); TemporaryChange break_change(m_state.in_break_context, true); TemporaryChange continue_change(m_state.in_continue_context, true); auto body = parse_statement(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(test), move(body)); } NonnullRefPtr Parser::parse_switch_statement() { auto rule_start = push_start(); consume(TokenType::Switch); consume(TokenType::ParenOpen); auto determinant = parse_expression(0); consume(TokenType::ParenClose); consume(TokenType::CurlyOpen); NonnullRefPtrVector cases; auto switch_statement = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(determinant)); ScopePusher switch_scope = ScopePusher::block_scope(*this, switch_statement); auto has_default = false; while (match(TokenType::Case) || match(TokenType::Default)) { if (match(TokenType::Default)) { if (has_default) syntax_error("Multiple 'default' clauses in switch statement"); has_default = true; } switch_statement->add_case(parse_switch_case()); } consume(TokenType::CurlyClose); return switch_statement; } NonnullRefPtr Parser::parse_with_statement() { auto rule_start = push_start(); consume(TokenType::With); consume(TokenType::ParenOpen); auto object = parse_expression(0); consume(TokenType::ParenClose); auto body = parse_statement(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(object), move(body)); } NonnullRefPtr Parser::parse_switch_case() { auto rule_start = push_start(); RefPtr test; if (consume().type() == TokenType::Case) { test = parse_expression(0); } consume(TokenType::Colon); NonnullRefPtrVector consequent; TemporaryChange break_change(m_state.in_break_context, true); auto switch_case = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(test)); parse_statement_list(switch_case); return switch_case; } NonnullRefPtr Parser::parse_catch_clause() { auto rule_start = push_start(); consume(TokenType::Catch); FlyString parameter; RefPtr pattern_parameter; auto should_expect_parameter = false; if (match(TokenType::ParenOpen)) { should_expect_parameter = true; consume(); if (match_identifier_name() && (!match(TokenType::Yield) || !m_state.in_generator_function_context) && (!match(TokenType::Async) || !m_state.await_expression_is_valid) && (!match(TokenType::Await) || !m_state.in_class_static_init_block)) parameter = consume().value(); else pattern_parameter = parse_binding_pattern(AllowDuplicates::No, AllowMemberExpressions::No); consume(TokenType::ParenClose); } if (should_expect_parameter && parameter.is_empty() && !pattern_parameter) expected("an identifier or a binding pattern"); HashTable bound_names; if (pattern_parameter) { pattern_parameter->for_each_bound_name( [&](auto& name) { check_identifier_name_for_assignment_validity(name); bound_names.set(name); }); } if (!parameter.is_empty()) { check_identifier_name_for_assignment_validity(parameter); bound_names.set(parameter); } ScopePusher catch_scope = ScopePusher::catch_scope(*this, pattern_parameter, parameter); auto body = parse_block_statement(); body->for_each_lexically_declared_name([&](auto const& name) { if (bound_names.contains(name)) syntax_error(String::formatted("Identifier '{}' already declared as catch parameter", name)); }); if (pattern_parameter) { return create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, pattern_parameter.release_nonnull(), move(body)); } return create_ast_node( { m_state.current_token.filename(), rule_start.position(), position() }, move(parameter), move(body)); } NonnullRefPtr Parser::parse_if_statement() { auto rule_start = push_start(); auto parse_function_declaration_as_block_statement = [&] { // https://tc39.es/ecma262/#sec-functiondeclarations-in-ifstatement-statement-clauses // Code matching this production is processed as if each matching occurrence of // FunctionDeclaration[?Yield, ?Await, ~Default] was the sole StatementListItem // of a BlockStatement occupying that position in the source code. VERIFY(match(TokenType::Function)); auto block = create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); ScopePusher block_scope = ScopePusher::block_scope(*this, *block); auto declaration = parse_declaration(); VERIFY(m_state.current_scope_pusher); block_scope.add_declaration(declaration); VERIFY(is(*declaration)); auto& function_declaration = static_cast(*declaration); if (function_declaration.kind() == FunctionKind::Generator) syntax_error("Generator functions can only be declared in top-level or within a block"); if (function_declaration.kind() == FunctionKind::Async) syntax_error("Async functions can only be declared in top-level or within a block"); block->append(move(declaration)); return block; }; consume(TokenType::If); consume(TokenType::ParenOpen); auto predicate = parse_expression(0); consume(TokenType::ParenClose); RefPtr consequent; if (!m_state.strict_mode && match(TokenType::Function)) consequent = parse_function_declaration_as_block_statement(); else consequent = parse_statement(); RefPtr alternate; if (match(TokenType::Else)) { consume(); if (!m_state.strict_mode && match(TokenType::Function)) alternate = parse_function_declaration_as_block_statement(); else alternate = parse_statement(); } return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(predicate), move(*consequent), move(alternate)); } NonnullRefPtr 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 = [&]() { 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.await_expression_is_valid) 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.await_expression_is_valid) syntax_error("for-await-of is only allowed in async function context"); is_await_loop = IsForAwaitLoop::Yes; } consume(TokenType::ParenOpen); Optional scope_pusher; RefPtr init; if (!match(TokenType::Semicolon)) { if (match_variable_declaration()) { auto declaration = parse_variable_declaration(true); if (declaration->declaration_kind() == DeclarationKind::Var) { m_state.current_scope_pusher->add_declaration(declaration); } else { // This does not follow the normal declaration structure so we need additional checks. HashTable bound_names; declaration->for_each_bound_name([&](auto const& name) { if (bound_names.set(name) != AK::HashSetResult::InsertedNewEntry) syntax_error(String::formatted("Identifier '{}' already declared in for loop initializer", name), declaration->source_range().start); }); } init = move(declaration); if (match_for_in_of()) return parse_for_in_of_statement(*init, is_await_loop); if (static_cast(*init).declaration_kind() == DeclarationKind::Const) { for (auto& variable : static_cast(*init).declarations()) { if (!variable.init()) syntax_error("Missing initializer in 'const' variable declaration"); } } } else if (match_expression()) { auto lookahead_token = next_token(); bool starts_with_async_of = match(TokenType::Async) && match_of(lookahead_token); init = parse_expression(0, Associativity::Right, { TokenType::In }); if (match_for_in_of()) { 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, is_await_loop); } } else { syntax_error("Unexpected token in for loop"); } } consume(TokenType::Semicolon); RefPtr test; if (!match(TokenType::Semicolon)) test = parse_expression(0); consume(TokenType::Semicolon); RefPtr update; if (!match(TokenType::ParenClose)) update = parse_expression(0); consume(TokenType::ParenClose); TemporaryChange break_change(m_state.in_break_context, true); TemporaryChange continue_change(m_state.in_continue_context, true); ScopePusher for_loop_scope = ScopePusher::for_loop_scope(*this, init); auto body = parse_statement(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(init), move(test), move(update), move(body)); } NonnullRefPtr Parser::parse_for_in_of_statement(NonnullRefPtr lhs, IsForAwaitLoop is_for_await_loop) { Variant, NonnullRefPtr> for_declaration = lhs; auto rule_start = push_start(); auto has_annexB_for_in_init_extension = false; if (is(*lhs)) { auto& declaration = static_cast(*lhs); if (declaration.declarations().size() > 1) { syntax_error("Multiple declarations not allowed in for..in/of"); } else if (declaration.declarations().size() < 1) { syntax_error("Need exactly one variable declaration in for..in/of"); } else { // AnnexB extension B.3.5 Initializers in ForIn Statement Heads, https://tc39.es/ecma262/#sec-initializers-in-forin-statement-heads auto& variable = declaration.declarations().first(); if (variable.init()) { if (m_state.strict_mode || declaration.declaration_kind() != DeclarationKind::Var || !variable.target().has>()) syntax_error("Variable initializer not allowed in for..in/of"); else has_annexB_for_in_init_extension = true; } } } else if (!lhs->is_identifier() && !is(*lhs)) { bool valid = false; if (is(*lhs) || is(*lhs)) { auto synthesized_binding_pattern = synthesize_binding_pattern(static_cast(*lhs)); if (synthesized_binding_pattern) { for_declaration = synthesized_binding_pattern.release_nonnull(); valid = true; } } if (!valid) syntax_error(String::formatted("Invalid left-hand side in for-loop ('{}')", lhs->class_name())); } auto in_or_of = consume(); auto is_in = in_or_of.type() == TokenType::In; if (!is_in) { if (is(*lhs)) { auto& member = static_cast(*lhs); if (member.object().is_identifier() && static_cast(member.object()).string() == "let"sv) syntax_error("For of statement may not start with let."); } if (has_annexB_for_in_init_extension) syntax_error("Variable initializer not allowed in for..of", rule_start.position()); } auto rhs = parse_expression(is_in ? 0 : 2); consume(TokenType::ParenClose); TemporaryChange break_change(m_state.in_break_context, true); TemporaryChange continue_change(m_state.in_continue_context, true); ScopePusher for_loop_scope = ScopePusher::for_loop_scope(*this, lhs); auto body = parse_statement(); if (is_in) return create_ast_node({ 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({ m_state.current_token.filename(), rule_start.position(), position() }, move(for_declaration), move(rhs), move(body)); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(for_declaration), move(rhs), move(body)); } NonnullRefPtr Parser::parse_debugger_statement() { auto rule_start = push_start(); consume(TokenType::Debugger); consume_or_insert_semicolon(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }); } bool Parser::match(TokenType type) const { return m_state.current_token.type() == type; } bool Parser::match_expression() const { auto type = m_state.current_token.type(); if (type == TokenType::Import) { auto lookahead_token = next_token(); return lookahead_token.type() == TokenType::Period || lookahead_token.type() == TokenType::ParenOpen; } return type == TokenType::BoolLiteral || type == TokenType::NumericLiteral || type == TokenType::BigIntLiteral || type == TokenType::StringLiteral || type == TokenType::TemplateLiteralStart || type == TokenType::NullLiteral || match_identifier() || type == TokenType::PrivateIdentifier || type == TokenType::Await || type == TokenType::New || type == TokenType::Class || type == TokenType::CurlyOpen || type == TokenType::BracketOpen || type == TokenType::ParenOpen || type == TokenType::Function || type == TokenType::Async || type == TokenType::This || type == TokenType::Super || type == TokenType::RegexLiteral || type == TokenType::Slash // Wrongly recognized regex by lexer || type == TokenType::SlashEquals // Wrongly recognized regex by lexer (/=a/ is a valid regex) || type == TokenType::Yield || match_unary_prefixed_expression(); } bool Parser::match_unary_prefixed_expression() const { auto type = m_state.current_token.type(); return type == TokenType::PlusPlus || type == TokenType::MinusMinus || type == TokenType::ExclamationMark || type == TokenType::Tilde || type == TokenType::Plus || type == TokenType::Minus || type == TokenType::Typeof || type == TokenType::Void || type == TokenType::Delete; } bool Parser::match_secondary_expression(const Vector& forbidden) const { auto type = m_state.current_token.type(); if (forbidden.contains_slow(type)) return false; return type == TokenType::Plus || type == TokenType::PlusEquals || type == TokenType::Minus || type == TokenType::MinusEquals || type == TokenType::Asterisk || type == TokenType::AsteriskEquals || type == TokenType::Slash || type == TokenType::SlashEquals || type == TokenType::Percent || type == TokenType::PercentEquals || type == TokenType::DoubleAsterisk || type == TokenType::DoubleAsteriskEquals || type == TokenType::Equals || type == TokenType::EqualsEqualsEquals || type == TokenType::ExclamationMarkEqualsEquals || type == TokenType::EqualsEquals || type == TokenType::ExclamationMarkEquals || type == TokenType::GreaterThan || type == TokenType::GreaterThanEquals || type == TokenType::LessThan || type == TokenType::LessThanEquals || type == TokenType::ParenOpen || type == TokenType::Period || type == TokenType::BracketOpen || (type == TokenType::PlusPlus && !m_state.current_token.trivia_contains_line_terminator()) || (type == TokenType::MinusMinus && !m_state.current_token.trivia_contains_line_terminator()) || type == TokenType::In || type == TokenType::Instanceof || type == TokenType::QuestionMark || type == TokenType::Ampersand || type == TokenType::AmpersandEquals || type == TokenType::Pipe || type == TokenType::PipeEquals || type == TokenType::Caret || type == TokenType::CaretEquals || type == TokenType::ShiftLeft || type == TokenType::ShiftLeftEquals || type == TokenType::ShiftRight || type == TokenType::ShiftRightEquals || type == TokenType::UnsignedShiftRight || type == TokenType::UnsignedShiftRightEquals || type == TokenType::DoubleAmpersand || type == TokenType::DoubleAmpersandEquals || type == TokenType::DoublePipe || type == TokenType::DoublePipeEquals || type == TokenType::DoubleQuestionMark || type == TokenType::DoubleQuestionMarkEquals || type == TokenType::QuestionMarkPeriod; } bool Parser::match_statement() const { auto type = m_state.current_token.type(); return match_expression() || type == TokenType::Return || type == TokenType::Yield || type == TokenType::Do || type == TokenType::If || type == TokenType::Throw || type == TokenType::Try || type == TokenType::While || type == TokenType::With || type == TokenType::For || type == TokenType::CurlyOpen || type == TokenType::Switch || type == TokenType::Break || type == TokenType::Continue || type == TokenType::Var || type == TokenType::Debugger || type == TokenType::Semicolon; } bool Parser::match_export_or_import() const { auto type = m_state.current_token.type(); return type == TokenType::Export || type == TokenType::Import; } bool Parser::match_declaration() const { auto type = m_state.current_token.type(); if (type == TokenType::Let && !m_state.strict_mode) { return try_match_let_declaration(); } if (type == TokenType::Async) { auto lookahead_token = next_token(); return lookahead_token.type() == TokenType::Function && !lookahead_token.trivia_contains_line_terminator(); } return type == TokenType::Function || type == TokenType::Class || type == TokenType::Const || type == TokenType::Let; } Token Parser::next_token(size_t steps) const { Lexer lookahead_lexer = m_state.lexer; Token lookahead_token; while (steps > 0) { lookahead_token = lookahead_lexer.next(); steps--; } return lookahead_token; } bool Parser::try_match_let_declaration() const { VERIFY(m_state.current_token.type() == TokenType::Let); auto token_after = next_token(); if (token_after.is_identifier_name() && token_after.value() != "in"sv) return true; if (token_after.type() == TokenType::CurlyOpen || token_after.type() == TokenType::BracketOpen) return true; return false; } bool Parser::match_variable_declaration() const { auto type = m_state.current_token.type(); if (type == TokenType::Let && !m_state.strict_mode) { return try_match_let_declaration(); } return type == TokenType::Var || type == TokenType::Let || type == TokenType::Const; } bool Parser::match_identifier() const { if (m_state.current_token.type() == TokenType::EscapedKeyword) { if (m_state.current_token.value() == "let"sv) return !m_state.strict_mode; if (m_state.current_token.value() == "yield"sv) return !m_state.strict_mode && !m_state.in_generator_function_context; if (m_state.current_token.value() == "await"sv) return m_program_type != Program::Type::Module && !m_state.await_expression_is_valid && !m_state.in_class_static_init_block; return true; } return m_state.current_token.type() == TokenType::Identifier || m_state.current_token.type() == TokenType::Async || (m_state.current_token.type() == TokenType::Let && !m_state.strict_mode) || (m_state.current_token.type() == TokenType::Await && m_program_type != Program::Type::Module && !m_state.await_expression_is_valid && !m_state.in_class_static_init_block) || (m_state.current_token.type() == TokenType::Yield && !m_state.in_generator_function_context && !m_state.strict_mode); // See note in Parser::parse_identifier(). } bool Parser::match_identifier_name() const { return m_state.current_token.is_identifier_name(); } bool Parser::match_property_key() const { auto type = m_state.current_token.type(); return match_identifier_name() || type == TokenType::BracketOpen || type == TokenType::StringLiteral || type == TokenType::NumericLiteral || type == TokenType::BigIntLiteral; } bool Parser::done() const { return match(TokenType::Eof); } Token Parser::consume() { auto old_token = m_state.current_token; m_state.current_token = m_state.lexer.next(); // NOTE: This is the bare minimum needed to decide whether we might need an arguments object // in a function expression or declaration. ("might" because the AST implements some further // conditions from the spec that rule out the need for allocating one) if (old_token.type() == TokenType::Identifier && old_token.value().is_one_of("arguments"sv, "eval"sv)) m_state.function_might_need_arguments_object = true; return old_token; } void Parser::consume_or_insert_semicolon() { // Semicolon was found and will be consumed if (match(TokenType::Semicolon)) { consume(); return; } // Insert semicolon if... // ...token is preceded by one or more newlines if (m_state.current_token.trivia_contains_line_terminator()) return; // ...token is a closing curly brace if (match(TokenType::CurlyClose)) return; // ...token is eof if (match(TokenType::Eof)) return; // No rule for semicolon insertion applies -> syntax error expected("Semicolon"); } Token Parser::consume_identifier() { if (match(TokenType::Identifier)) return consume(TokenType::Identifier); if (match(TokenType::EscapedKeyword)) return consume(TokenType::EscapedKeyword); // Note that 'let' is not a reserved keyword, but our lexer considers it such // As it's pretty nice to have that (for syntax highlighting and such), we'll // special-case it here instead. if (match(TokenType::Let)) { if (m_state.strict_mode) syntax_error("'let' is not allowed as an identifier in strict mode"); return consume(); } 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(); } 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(); } if (match(TokenType::Async)) return consume(); expected("Identifier"); return consume(); } // https://tc39.es/ecma262/#prod-IdentifierReference Token Parser::consume_identifier_reference() { if (match(TokenType::Identifier)) return consume(TokenType::Identifier); if (match(TokenType::EscapedKeyword)) { auto name = m_state.current_token.value(); if (m_state.strict_mode && (name == "let"sv || name == "yield"sv)) syntax_error(String::formatted("'{}' is not allowed as an identifier in strict mode", name)); if (m_program_type == Program::Type::Module && name == "await"sv) syntax_error("'await' is not allowed as an identifier in module"); return consume(); } // 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(); } if (match(TokenType::Yield)) { if (m_state.strict_mode) syntax_error("Identifier reference may not be 'yield' in strict mode"); return consume(); } if (match(TokenType::Await)) { if (m_program_type == Program::Type::Module) syntax_error("'await' is not allowed as an identifier in module"); return consume(); } if (match(TokenType::Async)) return consume(); expected(Token::name(TokenType::Identifier)); return consume(); } Token Parser::consume(TokenType expected_type) { if (!match(expected_type)) { expected(Token::name(expected_type)); } auto token = consume(); if (expected_type == TokenType::Identifier) { if (m_state.strict_mode && is_strict_reserved_word(token.value())) syntax_error(String::formatted("Identifier must not be a reserved word in strict mode ('{}')", token.value())); } return token; } Token Parser::consume_and_validate_numeric_literal() { auto is_unprefixed_octal_number = [](StringView value) { return value.length() > 1 && value[0] == '0' && is_ascii_digit(value[1]); }; auto literal_start = position(); auto token = consume(TokenType::NumericLiteral); if (m_state.strict_mode && is_unprefixed_octal_number(token.value())) syntax_error("Unprefixed octal number not allowed in strict mode", literal_start); if (match_identifier_name() && m_state.current_token.trivia().is_empty()) syntax_error("Numeric literal must not be immediately followed by identifier"); return token; } void Parser::expected(const char* what) { auto message = m_state.current_token.message(); if (message.is_empty()) message = String::formatted("Unexpected token {}. Expected {}", m_state.current_token.name(), what); syntax_error(message); } Position Parser::position() const { return { m_state.current_token.line_number(), m_state.current_token.line_column(), m_state.current_token.offset(), }; } bool Parser::try_parse_arrow_function_expression_failed_at_position(const Position& position) const { auto it = m_token_memoizations.find(position); if (it == m_token_memoizations.end()) return false; return (*it).value.try_parse_arrow_function_expression_failed; } void Parser::set_try_parse_arrow_function_expression_failed_at_position(const Position& position, bool failed) { m_token_memoizations.set(position, { failed }); } void Parser::syntax_error(const String& message, Optional position) { if (!position.has_value()) position = this->position(); m_state.errors.append({ message, position }); } void Parser::save_state() { m_saved_state.append(m_state); } void Parser::load_state() { VERIFY(!m_saved_state.is_empty()); m_state = m_saved_state.take_last(); } void Parser::discard_saved_state() { m_saved_state.take_last(); } void Parser::check_identifier_name_for_assignment_validity(StringView name, bool force_strict) { // FIXME: this is now called from multiple places maybe the error message should be dynamic? if (any_of(s_reserved_words, [&](auto& value) { return name == value; })) { syntax_error("Binding pattern target may not be a reserved word"); } else if (m_state.strict_mode || force_strict) { if (name.is_one_of("arguments"sv, "eval"sv)) syntax_error("Binding pattern target may not be called 'arguments' or 'eval' in strict mode"); else if (is_strict_reserved_word(name)) syntax_error(String::formatted("Binding pattern target may not be called '{}' in strict mode", name)); } } bool Parser::match_assert_clause() const { return !m_state.current_token.trivia_contains_line_terminator() && m_state.current_token.original_value() == "assert"sv; } FlyString Parser::consume_string_value() { VERIFY(match(TokenType::StringLiteral)); auto string_token = consume(); FlyString value = parse_string_literal(string_token, false)->value(); // This also checks IsStringWellFormedUnicode which makes sure there is no unpaired surrogate // Surrogates are at least 3 bytes if (value.length() < 3) return value; Utf8View view { value.view().substring_view(value.length() - 3) }; VERIFY(view.length() <= 3); auto codepoint = *view.begin(); if (Utf16View::is_high_surrogate(codepoint)) { syntax_error("StringValue ending with unpaired high surrogate"); VERIFY(view.length() == 1); } return value; } // AssertClause, https://tc39.es/proposal-import-assertions/#prod-AssertClause ModuleRequest Parser::parse_module_request() { // Does not include the 'from' since that is not always required. if (!match(TokenType::StringLiteral)) { expected("ModuleSpecifier (string)"); return ModuleRequest { "!!invalid!!" }; } ModuleRequest request { consume_string_value() }; if (!match_assert_clause()) return request; VERIFY(m_state.current_token.original_value() == "assert"sv); consume(TokenType::Identifier); consume(TokenType::CurlyOpen); while (!done() && !match(TokenType::CurlyClose)) { String key; if (match(TokenType::StringLiteral)) { key = parse_string_literal(m_state.current_token)->value().to_string(); consume(); } else if (match_identifier_name()) { key = consume().value(); } else { expected("IdentifierName or StringValue as AssertionKey"); consume(); } consume(TokenType::Colon); if (match(TokenType::StringLiteral)) { for (auto& entries : request.assertions) { if (entries.key == key) syntax_error(String::formatted("Duplicate assertion clauses with name: {}", key)); } request.add_assertion(move(key), parse_string_literal(m_state.current_token)->value().to_string()); } consume(TokenType::StringLiteral); if (match(TokenType::Comma)) consume(TokenType::Comma); else break; } consume(TokenType::CurlyClose); return request; } static FlyString namespace_string_value = "*"; static FlyString default_string_value = "default"; NonnullRefPtr Parser::parse_import_statement(Program& program) { // We use the extended syntax which adds: // ImportDeclaration: // import ImportClause FromClause [no LineTerminator here] AssertClause; // import ModuleSpecifier [no LineTerminator here] AssertClause; // From: https://tc39.es/proposal-import-assertions/#prod-ImportDeclaration auto rule_start = push_start(); if (program.type() != Program::Type::Module) syntax_error("Cannot use import statement outside a module"); consume(TokenType::Import); if (match(TokenType::StringLiteral)) { // import ModuleSpecifier ; auto module_request = parse_module_request(); return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(module_request)); } auto match_imported_binding = [&] { return match_identifier() || match(TokenType::Yield) || match(TokenType::Await); }; auto match_as = [&] { return match(TokenType::Identifier) && m_state.current_token.original_value() == "as"sv; }; bool continue_parsing = true; struct ImportWithLocation { ImportStatement::ImportEntry entry; Position position; }; Vector entries_with_location; // import ImportClause FromClause ; // ImportClause : // ImportedDefaultBinding // NameSpaceImport // NamedImports // ImportedDefaultBinding , NameSpaceImport // ImportedDefaultBinding , NamedImports if (match_imported_binding()) { // ImportedDefaultBinding : ImportedBinding auto id_position = position(); auto bound_name = consume().value(); entries_with_location.append({ { default_string_value, bound_name }, id_position }); if (match(TokenType::Comma)) { consume(TokenType::Comma); } else { continue_parsing = false; } } if (!continue_parsing) { // skip the rest } else if (match(TokenType::Asterisk)) { // NameSpaceImport : * as ImportedBinding consume(TokenType::Asterisk); if (!match_as()) syntax_error(String::formatted("Unexpected token: {}", m_state.current_token.name())); consume(TokenType::Identifier); if (match_imported_binding()) { auto namespace_position = position(); auto namespace_name = consume().value(); entries_with_location.append({ { namespace_string_value, namespace_name }, namespace_position }); } else { syntax_error(String::formatted("Unexpected token: {}", m_state.current_token.name())); } } else if (match(TokenType::CurlyOpen)) { // NamedImports : // { ImportSpecifier ,_opt } (repeated any amount of times) consume(TokenType::CurlyOpen); while (!done() && !match(TokenType::CurlyClose)) { if (match_identifier_name()) { // ImportSpecifier : ImportedBinding auto require_as = !match_imported_binding(); auto name_position = position(); auto name = consume().value(); if (match_as()) { consume(TokenType::Identifier); auto alias_position = position(); auto alias = consume_identifier().value(); check_identifier_name_for_assignment_validity(alias); entries_with_location.append({ { name, alias }, alias_position }); } else if (require_as) { syntax_error(String::formatted("Unexpected reserved word '{}'", name)); } else { check_identifier_name_for_assignment_validity(name); entries_with_location.append({ { name, name }, name_position }); } } else if (match(TokenType::StringLiteral)) { // ImportSpecifier : ModuleExportName as ImportedBinding auto name = consume_string_value(); if (!match_as()) expected("as"); consume(TokenType::Identifier); auto alias_position = position(); auto alias = consume_identifier().value(); check_identifier_name_for_assignment_validity(alias); entries_with_location.append({ { move(name), alias }, alias_position }); } else { expected("identifier"); break; } if (!match(TokenType::Comma)) break; consume(TokenType::Comma); } consume(TokenType::CurlyClose); } else { expected("import clauses"); } auto from_statement = consume(TokenType::Identifier).original_value(); if (from_statement != "from"sv) syntax_error(String::formatted("Expected 'from' got {}", from_statement)); auto module_request = parse_module_request(); Vector entries; entries.ensure_capacity(entries_with_location.size()); for (auto& entry : entries_with_location) { for (auto& import_statement : program.imports()) { if (import_statement.has_bound_name(entry.entry.local_name)) syntax_error(String::formatted("Identifier '{}' already declared", entry.entry.local_name), entry.position); } for (auto& new_entry : entries) { if (new_entry.local_name == entry.entry.local_name) syntax_error(String::formatted("Identifier '{}' already declared", entry.entry.local_name), entry.position); } entries.append(move(entry.entry)); } return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(module_request), move(entries)); } NonnullRefPtr Parser::parse_export_statement(Program& program) { // We use the extended syntax which adds: // ExportDeclaration: // export ExportFromClause FromClause [no LineTerminator here] AssertClause ; // From: https://tc39.es/proposal-import-assertions/#prod-ExportDeclaration auto rule_start = push_start(); if (program.type() != Program::Type::Module) syntax_error("Cannot use export statement outside a module"); auto match_as = [&] { return match(TokenType::Identifier) && m_state.current_token.original_value() == "as"sv; }; auto match_from = [&] { return match(TokenType::Identifier) && m_state.current_token.original_value() == "from"sv; }; auto match_default = [&] { return match(TokenType::Default) && m_state.current_token.original_value() == "default"sv; }; consume(TokenType::Export); struct EntryAndLocation { ExportStatement::ExportEntry entry; Position position; void to_module_request(ModuleRequest from_module) { entry.kind = ExportStatement::ExportEntry::Kind::ModuleRequest; entry.module_request = move(from_module); } }; Vector entries_with_location; RefPtr expression = {}; bool is_default = false; if (match_default()) { is_default = true; auto default_position = position(); consume(TokenType::Default); FlyString local_name; auto lookahead_token = next_token(); // Note: For some reason the spec here has declaration which can have no name // and the rest of the parser is just not setup for that. With these // hacks below we get through most things but we should probably figure // out a better solution. I have attempted to explain why/what these "hacks" do below. // The summary is treat named declarations just as declarations and hack around unnamed // declarations with expression see also SourceTextModule::initialize_environment. // As far as I'm aware the only problem (which is a tricky one) is: // `export default function() {}()` // Since we parse this as an expression you are immediately allowed to call it // which is incorrect and this should give a SyntaxError. auto match_function_declaration = [&] { // Hack part 1. // Match a function declaration with a name, since we have async and generator // and asyncgenerator variants this is quite complicated. auto current_type = m_state.current_token.type(); Lexer lookahead_lexer = m_state.lexer; lookahead_lexer.next(); if (current_type == TokenType::Function) { if (lookahead_token.type() == TokenType::Asterisk) return lookahead_lexer.next().type() != TokenType::ParenOpen; // function * else return lookahead_token.type() != TokenType::ParenOpen; // function } if (current_type == TokenType::Async) { if (lookahead_token.type() != TokenType::Function) return false; if (lookahead_token.trivia_contains_line_terminator()) return false; auto lookahead_two_token = lookahead_lexer.next(); if (lookahead_two_token.type() == TokenType::Asterisk) return lookahead_lexer.next().type() != TokenType::ParenOpen; // async function * else return lookahead_two_token.type() != TokenType::ParenOpen; // async function } return false; }; if (match_function_declaration()) { auto function_declaration = parse_function_node(); m_state.current_scope_pusher->add_declaration(function_declaration); local_name = function_declaration->name(); expression = move(function_declaration); } else if (match(TokenType::Class) && lookahead_token.type() != TokenType::CurlyOpen && lookahead_token.type() != TokenType::Extends) { // Hack part 2. // Attempt to detect classes with names only as those are declarations, // this actually seems to cover all cases already. auto class_expression = parse_class_declaration(); m_state.current_scope_pusher->add_declaration(class_expression); local_name = class_expression->name(); expression = move(class_expression); } else if (match_expression()) { // Hack part 3. // Even though the unnamed declarations look like expression we should // not treat them as such and thus not consume a semicolon after them. bool special_case_declaration_without_name = match(TokenType::Class) || match(TokenType::Function) || (match(TokenType::Async) && lookahead_token.type() == TokenType::Function && !lookahead_token.trivia_contains_line_terminator()); expression = parse_expression(2); if (!special_case_declaration_without_name) consume_or_insert_semicolon(); if (is(*expression)) { auto const& class_expression = static_cast(*expression); if (class_expression.has_name()) local_name = class_expression.name(); } } else { expected("Declaration or assignment expression"); local_name = "!!invalid!!"; } if (local_name.is_null()) { local_name = ExportStatement::local_name_for_default; } entries_with_location.append({ { default_string_value, move(local_name) }, default_position }); } else { enum FromSpecifier { NotAllowed, Optional, Required } check_for_from { NotAllowed }; if (match(TokenType::Asterisk)) { auto asterisk_position = position(); consume(TokenType::Asterisk); if (match_as()) { consume(TokenType::Identifier); if (match_identifier_name()) { auto namespace_position = position(); auto exported_name = consume().value(); entries_with_location.append({ { exported_name, namespace_string_value }, namespace_position }); } else { expected("identifier"); } } else { entries_with_location.append({ { {}, namespace_string_value }, asterisk_position }); } check_for_from = Required; } else if (match_declaration()) { auto decl_position = position(); auto declaration = parse_declaration(); m_state.current_scope_pusher->add_declaration(declaration); if (is(*declaration)) { auto& func = static_cast(*declaration); entries_with_location.append({ { func.name(), func.name() }, func.source_range().start }); } else if (is(*declaration)) { auto& class_declaration = static_cast(*declaration); entries_with_location.append({ { class_declaration.name(), class_declaration.name() }, class_declaration.source_range().start }); } else { VERIFY(is(*declaration)); auto& variables = static_cast(*declaration); VERIFY(variables.is_lexical_declaration()); for (auto& decl : variables.declarations()) { decl.target().visit( [&](NonnullRefPtr const& identifier) { entries_with_location.append({ { identifier->string(), identifier->string() }, identifier->source_range().start }); }, [&](NonnullRefPtr const& binding) { binding->for_each_bound_name([&](auto& name) { entries_with_location.append({ { name, name }, decl_position }); }); }); } } expression = declaration; } else if (match(TokenType::Var)) { auto variable_position = position(); auto variable_declaration = parse_variable_declaration(); m_state.current_scope_pusher->add_declaration(variable_declaration); for (auto& decl : variable_declaration->declarations()) { decl.target().visit( [&](NonnullRefPtr const& identifier) { entries_with_location.append({ { identifier->string(), identifier->string() }, identifier->source_range().start }); }, [&](NonnullRefPtr const& binding) { binding->for_each_bound_name([&](auto& name) { entries_with_location.append({ { name, name }, variable_position }); }); }); } expression = variable_declaration; } else if (match(TokenType::CurlyOpen)) { consume(TokenType::CurlyOpen); check_for_from = Optional; auto parse_export_specifier = [&](bool lhs) -> FlyString { if (match_identifier_name()) { return consume().value(); } if (match(TokenType::StringLiteral)) { // It is a Syntax Error if ReferencedBindings of NamedExports contains any StringLiterals. // Only for export { "a" as "b" }; // <-- no from if (lhs) check_for_from = Required; return consume_string_value(); } expected("ExportSpecifier (string or identifier)"); return {}; }; while (!done() && !match(TokenType::CurlyClose)) { auto identifier_position = position(); auto identifier = parse_export_specifier(true); if (identifier.is_empty()) break; if (match_as()) { consume(TokenType::Identifier); auto export_name = parse_export_specifier(false); if (export_name.is_empty()) break; entries_with_location.append({ { move(export_name), move(identifier) }, identifier_position }); } else { entries_with_location.append({ { identifier, identifier }, identifier_position }); } if (!match(TokenType::Comma)) break; consume(TokenType::Comma); } consume(TokenType::CurlyClose); } else { syntax_error("Unexpected token 'export'", rule_start.position()); } if (check_for_from != NotAllowed && match_from()) { consume(TokenType::Identifier); auto from_specifier = parse_module_request(); // FIXME: We can probably store only one module request // per ExportStatement like we do with ImportStatement. for (auto& entry : entries_with_location) entry.to_module_request(from_specifier); } else if (check_for_from == Required) { expected("from"); } if (check_for_from != NotAllowed) consume_or_insert_semicolon(); } Vector entries; entries.ensure_capacity(entries_with_location.size()); for (auto& entry : entries_with_location) { for (auto& export_statement : program.exports()) { if (export_statement.has_export(entry.entry.export_name)) syntax_error(String::formatted("Duplicate export with name: '{}'", entry.entry.export_name), entry.position); } for (auto& new_entry : entries) { if (new_entry.export_name == entry.entry.export_name) syntax_error(String::formatted("Duplicate export with name: '{}'", entry.entry.export_name), entry.position); } entries.append(move(entry.entry)); } return create_ast_node({ m_state.current_token.filename(), rule_start.position(), position() }, move(expression), move(entries), is_default); } }