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Parser.cpp
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Parser.cpp
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/*
* Copyright (c) 2020, Stephan Unverwerth <s.unverwerth@serenityos.org>
* Copyright (c) 2020-2022, Linus Groh <linusg@serenityos.org>
* Copyright (c) 2021-2022, David Tuin <davidot@serenityos.org>
* Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
* Copyright (c) 2023, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "Parser.h"
#include <AK/Array.h>
#include <AK/CharacterTypes.h>
#include <AK/HashTable.h>
#include <AK/ScopeGuard.h>
#include <AK/StdLibExtras.h>
#include <AK/TemporaryChange.h>
#include <LibJS/Runtime/RegExpObject.h>
#include <LibRegex/Regex.h>
namespace JS {
class ScopePusher {
// NOTE: We really only need ModuleTopLevel and NotModuleTopLevel as the only
// difference seems to be in https://tc39.es/ecma262/#sec-static-semantics-varscopeddeclarations
// where ModuleItemList only does the VarScopedDeclaration and not the
// TopLevelVarScopedDeclarations.
enum class ScopeLevel {
NotTopLevel,
ScriptTopLevel,
ModuleTopLevel,
FunctionTopLevel,
StaticInitTopLevel
};
public:
enum class ScopeType {
Function,
Program,
Block,
ForLoop,
With,
Catch,
ClassStaticInit,
ClassField,
ClassDeclaration,
};
private:
ScopePusher(Parser& parser, ScopeNode* node, ScopeLevel scope_level, ScopeType type)
: m_parser(parser)
, m_scope_level(scope_level)
, m_type(type)
{
m_parent_scope = exchange(m_parser.m_state.current_scope_pusher, this);
if (type != ScopeType::Function) {
VERIFY(node || (m_parent_scope && scope_level == ScopeLevel::NotTopLevel));
if (!node)
m_node = m_parent_scope->m_node;
else
m_node = node;
}
if (!is_top_level())
m_top_level_scope = m_parent_scope->m_top_level_scope;
else
m_top_level_scope = this;
}
bool is_top_level()
{
return m_scope_level != ScopeLevel::NotTopLevel;
}
public:
static ScopePusher function_scope(Parser& parser, RefPtr<Identifier const> function_name = nullptr)
{
ScopePusher scope_pusher(parser, nullptr, ScopeLevel::FunctionTopLevel, ScopeType::Function);
if (function_name) {
scope_pusher.m_bound_names.set(function_name->string());
}
return scope_pusher;
}
static ScopePusher program_scope(Parser& parser, Program& program)
{
return ScopePusher(parser, &program, program.type() == Program::Type::Script ? ScopeLevel::ScriptTopLevel : ScopeLevel::ModuleTopLevel, ScopeType::Program);
}
static ScopePusher block_scope(Parser& parser, ScopeNode& node)
{
return ScopePusher(parser, &node, ScopeLevel::NotTopLevel, ScopeType::Block);
}
static ScopePusher for_loop_scope(Parser& parser, ScopeNode& node)
{
return ScopePusher(parser, &node, ScopeLevel::NotTopLevel, ScopeType::ForLoop);
}
static ScopePusher with_scope(Parser& parser, ScopeNode& node)
{
ScopePusher scope_pusher(parser, &node, ScopeLevel::NotTopLevel, ScopeType::With);
return scope_pusher;
}
static ScopePusher catch_scope(Parser& parser, RefPtr<BindingPattern const> const& pattern, DeprecatedFlyString const& parameter)
{
ScopePusher scope_pusher(parser, nullptr, ScopeLevel::NotTopLevel, ScopeType::Catch);
if (pattern) {
// NOTE: Nothing in the callback throws an exception.
MUST(pattern->for_each_bound_identifier([&](auto const& identifier) {
scope_pusher.m_forbidden_var_names.set(identifier.string());
scope_pusher.m_bound_names.set(identifier.string());
}));
} else if (!parameter.is_empty()) {
scope_pusher.m_var_names.set(parameter);
scope_pusher.m_bound_names.set(parameter);
}
return scope_pusher;
}
static ScopePusher static_init_block_scope(Parser& parser, ScopeNode& node)
{
ScopePusher scope_pusher(parser, &node, ScopeLevel::StaticInitTopLevel, ScopeType::ClassStaticInit);
return scope_pusher;
}
static ScopePusher class_field_scope(Parser& parser, ScopeNode& node)
{
ScopePusher scope_pusher(parser, &node, ScopeLevel::NotTopLevel, ScopeType::ClassField);
return scope_pusher;
}
static ScopePusher class_declaration_scope(Parser& parser, RefPtr<Identifier const> class_name)
{
ScopePusher scope_pusher(parser, nullptr, ScopeLevel::NotTopLevel, ScopeType::ClassDeclaration);
if (class_name) {
scope_pusher.m_bound_names.set(class_name->string());
}
return scope_pusher;
}
ScopeType type() const { return m_type; }
void add_declaration(NonnullRefPtr<Declaration const> declaration)
{
if (declaration->is_lexical_declaration()) {
// NOTE: Nothing in the callback throws an exception.
MUST(declaration->for_each_bound_identifier([&](auto const& identifier) {
auto const& name = identifier.string();
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()) {
// NOTE: Nothing in the callback throws an exception.
MUST(declaration->for_each_bound_identifier([&](auto const& identifier) {
auto const& name = identifier.string();
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->is_top_level())
break;
VERIFY(pusher->m_parent_scope != nullptr);
pusher = pusher->m_parent_scope;
}
VERIFY(pusher->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_scope_level != ScopeLevel::NotTopLevel && m_scope_level != ScopeLevel::ModuleTopLevel) {
// Only non-top levels and Module don't var declare the top functions
// NOTE: Nothing in the callback throws an exception.
MUST(declaration->for_each_bound_identifier([&](auto const& identifier) {
m_var_names.set(identifier.string());
}));
m_node->add_var_scoped_declaration(move(declaration));
} else {
VERIFY(is<FunctionDeclaration>(*declaration));
auto& function_declaration = static_cast<FunctionDeclaration const&>(*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<FunctionDeclaration const>(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<FunctionParameter> 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(DeprecatedFlyString const& 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;
m_screwed_by_eval_in_scope_chain = true;
}
void set_contains_access_to_arguments_object() { m_contains_access_to_arguments_object = true; }
void set_scope_node(ScopeNode* node) { m_node = node; }
void set_function_parameters(Vector<FunctionParameter> const& parameters)
{
m_function_parameters = parameters;
for (auto& parameter : parameters) {
parameter.binding.visit(
[&](Identifier const& identifier) {
register_identifier(identifier);
m_function_parameters_candidates_for_local_variables.set(identifier.string());
m_forbidden_lexical_names.set(identifier.string());
},
[&](NonnullRefPtr<BindingPattern const> const& binding_pattern) {
// NOTE: Nothing in the callback throws an exception.
MUST(binding_pattern->for_each_bound_identifier([&](auto const& identifier) {
m_forbidden_lexical_names.set(identifier.string());
}));
});
}
}
~ScopePusher()
{
VERIFY(is_top_level() || m_parent_scope);
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;
m_parent_scope->m_contains_await_expression |= m_contains_await_expression;
}
if (!m_node) {
m_parser.m_state.current_scope_pusher = m_parent_scope;
return;
}
if (m_parent_scope && m_contains_direct_call_to_eval) {
m_parent_scope->m_screwed_by_eval_in_scope_chain = true;
}
for (auto& it : m_identifier_groups) {
auto const& identifier_group_name = it.key;
auto& identifier_group = it.value;
if (m_parser.m_state.in_catch_parameter_context) {
// NOTE: The parser currently cannot determine if an identifier captured by a function belongs to the environment created by a catch parameter.
// As a result, any identifiers used inside the catch parameter are not considered as candidates for optimization in local or global variable access.
continue;
}
bool scope_has_declaration = false;
if (is_top_level() && m_var_names.contains(identifier_group_name))
scope_has_declaration = true;
else if (m_lexical_names.contains(identifier_group_name) || m_function_names.contains(identifier_group_name))
scope_has_declaration = true;
if (m_type == ScopeType::Function && !m_is_arrow_function && identifier_group_name == "arguments"sv)
scope_has_declaration = true;
bool hoistable_function_declaration = false;
for (auto const& function_declaration : m_functions_to_hoist) {
if (function_declaration->name() == identifier_group_name)
hoistable_function_declaration = true;
}
if ((m_type == ScopeType::ClassDeclaration || m_type == ScopeType::Catch) && m_bound_names.contains(identifier_group_name)) {
// NOTE: Currently, the parser cannot recognize that assigning a named function expression creates a scope with a binding for the function name.
// As a result, function names are not considered as candidates for optimization in global variable access.
continue;
}
if (m_type == ScopeType::Function && m_bound_names.contains(identifier_group_name)) {
// NOTE: Currently parser can't determine that named function expression assigment creates scope with binding for funciton name so function names are not considered as candidates to be optmized in global variables access
identifier_group.might_be_variable_in_lexical_scope_in_named_function_assignment = true;
}
if (m_type == ScopeType::ClassDeclaration || m_type == ScopeType::Catch) {
// NOTE: Class declaration and catch scopes do not have own ScopeNode hence can't contain declaration of any variable
scope_has_declaration = false;
}
if (m_type == ScopeType::Function) {
if (!m_contains_access_to_arguments_object && m_function_parameters_candidates_for_local_variables.contains(identifier_group_name)) {
scope_has_declaration = true;
} else if (m_forbidden_lexical_names.contains(identifier_group_name)) {
// NOTE: If an identifier is used as a function parameter that cannot be optimized locally or globally, it is simply ignored.
continue;
}
}
if (m_type == ScopeType::Function && hoistable_function_declaration) {
// NOTE: Hoistable function declarations are currently not optimized into global or local variables, but future improvements may change that.
continue;
}
if (m_type == ScopeType::Program) {
auto can_use_global_for_identifier = !(identifier_group.used_inside_with_statement || identifier_group.might_be_variable_in_lexical_scope_in_named_function_assignment || identifier_group.used_inside_scope_with_eval || m_parser.m_state.initiated_by_eval);
if (can_use_global_for_identifier) {
for (auto& identifier : identifier_group.identifiers)
identifier->set_is_global();
}
} else if (scope_has_declaration) {
if (hoistable_function_declaration)
continue;
if (!identifier_group.captured_by_nested_function && !identifier_group.used_inside_with_statement) {
if (m_screwed_by_eval_in_scope_chain)
continue;
auto local_scope = last_function_scope();
if (!local_scope) {
// NOTE: If there is no function scope, we are in a *descendant* of the global program scope.
// While we cannot make `let` and `const` into locals in the topmost program scope,
// as that would break expected web behavior where subsequent <script> elements should see
// lexical bindings created by earlier <script> elements, we *can* promote them in descendant scopes.
// Of course, global `var` bindings can never be made into locals, as they get hoisted to the topmost program scope.
if (identifier_group.declaration_kind == DeclarationKind::Var)
continue;
// Add these locals to the top-level scope. (We only produce one executable for the entire program
// scope, so that's where the locals have to be stored.)
local_scope = m_top_level_scope;
}
auto local_variable_index = local_scope->m_node->add_local_variable(identifier_group_name);
for (auto& identifier : identifier_group.identifiers)
identifier->set_local_variable_index(local_variable_index);
}
} else {
if (m_function_parameters.has_value() || m_type == ScopeType::ClassField || m_type == ScopeType::ClassStaticInit) {
// NOTE: Class fields and class static initialization sections implicitly create functions
identifier_group.captured_by_nested_function = true;
}
if (m_type == ScopeType::With)
identifier_group.used_inside_with_statement = true;
if (m_contains_direct_call_to_eval)
identifier_group.used_inside_scope_with_eval = true;
if (m_parent_scope) {
if (auto maybe_parent_scope_identifier_group = m_parent_scope->m_identifier_groups.get(identifier_group_name); maybe_parent_scope_identifier_group.has_value()) {
maybe_parent_scope_identifier_group.value().identifiers.extend(identifier_group.identifiers);
if (identifier_group.captured_by_nested_function)
maybe_parent_scope_identifier_group.value().captured_by_nested_function = true;
if (identifier_group.used_inside_with_statement)
maybe_parent_scope_identifier_group.value().used_inside_with_statement = true;
if (identifier_group.might_be_variable_in_lexical_scope_in_named_function_assignment)
maybe_parent_scope_identifier_group.value().might_be_variable_in_lexical_scope_in_named_function_assignment = true;
if (identifier_group.used_inside_scope_with_eval)
maybe_parent_scope_identifier_group.value().used_inside_scope_with_eval = true;
} else {
m_parent_scope->m_identifier_groups.set(identifier_group_name, identifier_group);
}
}
}
}
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 (is_top_level()) {
m_node->add_hoisted_function(move(m_functions_to_hoist[i]));
} else {
if (!m_parent_scope->m_lexical_names.contains(function_declaration->name()) && !m_parent_scope->m_function_names.contains(function_declaration->name()))
m_parent_scope->m_functions_to_hoist.append(move(m_functions_to_hoist[i]));
}
}
VERIFY(m_parser.m_state.current_scope_pusher == this);
m_parser.m_state.current_scope_pusher = m_parent_scope;
}
void set_contains_await_expression()
{
m_contains_await_expression = true;
}
bool contains_await_expression() const
{
return m_contains_await_expression;
}
bool can_have_using_declaration() const
{
return m_scope_level != ScopeLevel::ScriptTopLevel;
}
void register_identifier(NonnullRefPtr<Identifier> id, Optional<DeclarationKind> declaration_kind = {})
{
if (auto maybe_identifier_group = m_identifier_groups.get(id->string()); maybe_identifier_group.has_value()) {
maybe_identifier_group.value().identifiers.append(id);
} else {
m_identifier_groups.set(id->string(), IdentifierGroup {
.captured_by_nested_function = false,
.identifiers = { id },
.declaration_kind = declaration_kind,
});
}
}
bool uses_this() const { return m_uses_this; }
bool uses_this_from_environment() const { return m_uses_this_from_environment; }
void set_uses_this()
{
auto const* closest_function_scope = last_function_scope();
auto uses_this_from_environment = closest_function_scope && closest_function_scope->m_is_arrow_function;
for (auto* scope_ptr = this; scope_ptr; scope_ptr = scope_ptr->m_parent_scope) {
if (scope_ptr->m_type == ScopeType::Function) {
scope_ptr->m_uses_this = true;
if (uses_this_from_environment)
scope_ptr->m_uses_this_from_environment = true;
}
}
}
void set_uses_new_target()
{
for (auto* scope_ptr = this; scope_ptr; scope_ptr = scope_ptr->m_parent_scope) {
if (scope_ptr->m_type == ScopeType::Function) {
scope_ptr->m_uses_this = true;
scope_ptr->m_uses_this_from_environment = true;
}
}
}
void set_is_arrow_function()
{
m_is_arrow_function = true;
}
private:
void throw_identifier_declared(DeprecatedFlyString const& name, NonnullRefPtr<Declaration const> const& declaration)
{
m_parser.syntax_error(ByteString::formatted("Identifier '{}' already declared", name), declaration->source_range().start);
}
Parser& m_parser;
ScopeNode* m_node { nullptr };
ScopeLevel m_scope_level { ScopeLevel::NotTopLevel };
ScopeType m_type;
ScopePusher* m_parent_scope { nullptr };
ScopePusher* m_top_level_scope { nullptr };
HashTable<DeprecatedFlyString> m_lexical_names;
HashTable<DeprecatedFlyString> m_var_names;
HashTable<DeprecatedFlyString> m_function_names;
HashTable<DeprecatedFlyString> m_forbidden_lexical_names;
HashTable<DeprecatedFlyString> m_forbidden_var_names;
Vector<NonnullRefPtr<FunctionDeclaration const>> m_functions_to_hoist;
HashTable<DeprecatedFlyString> m_bound_names;
HashTable<DeprecatedFlyString> m_function_parameters_candidates_for_local_variables;
struct IdentifierGroup {
bool captured_by_nested_function { false };
bool used_inside_with_statement { false };
bool used_inside_scope_with_eval { false };
bool might_be_variable_in_lexical_scope_in_named_function_assignment { false };
Vector<NonnullRefPtr<Identifier>> identifiers;
Optional<DeclarationKind> declaration_kind;
};
HashMap<DeprecatedFlyString, IdentifierGroup> m_identifier_groups;
Optional<Vector<FunctionParameter>> m_function_parameters;
bool m_contains_access_to_arguments_object { false };
bool m_contains_direct_call_to_eval { false };
bool m_contains_await_expression { false };
bool m_screwed_by_eval_in_scope_chain { false };
// Function uses this binding from function environment if:
// 1. It's an arrow function or establish parent scope for an arrow function
// 2. Uses new.target
bool m_uses_this_from_environment { false };
bool m_uses_this { false };
bool m_is_arrow_function { 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<size_t>(op.token)] = op.precedence;
}
}
constexpr int get(TokenType token) const
{
int p = m_token_precedence[static_cast<size_t>(token)];
if (p == 0) {
warnln("Internal Error: No precedence for operator {}", Token::name(token));
VERIFY_NOT_REACHED();
return -1;
}
return p;
}
constexpr int get_unary(TokenType token) const
{
constexpr int operator_precedence_unary_plus_minus = 17;
switch (token) {
case TokenType::Minus:
case TokenType::Plus:
return operator_precedence_unary_plus_minus;
default:
return get(token);
}
}
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 OperatorPrecedence const 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, Optional<EvalInitialState> initial_state_for_eval)
: m_source_code(SourceCode::create(lexer.filename(), String::from_byte_string(lexer.source()).release_value_but_fixme_should_propagate_errors()))
, m_state(move(lexer), program_type)
, m_program_type(program_type)
{
if (initial_state_for_eval.has_value()) {
m_state.initiated_by_eval = true;
m_state.in_eval_function_context = initial_state_for_eval->in_eval_function_context;
m_state.allow_super_property_lookup = initial_state_for_eval->allow_super_property_lookup;
m_state.allow_super_constructor_call = initial_state_for_eval->allow_super_constructor_call;
m_state.in_class_field_initializer = initial_state_for_eval->in_class_field_initializer;
}
}
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)) {
auto raw_value = m_state.current_token.original_value();
// It cannot be a labelled function since we hit a string literal.
auto statement = parse_statement(AllowLabelledFunction::No);
body.append(statement);
VERIFY(is<ExpressionStatement>(*statement));
auto& expression = static_cast<ExpressionStatement const&>(*statement).expression();
if (!is<StringLiteral>(expression))
break;
if (raw_value.is_one_of("'use strict'"sv, "\"use strict\"")) {
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<Program> Parser::parse_program(bool starts_in_strict_mode)
{
auto rule_start = push_start();
auto program = adopt_ref(*new Program({ m_source_code, 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->set_end_offset({}, position().offset);
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.is_module_request() || entry.kind == ExportEntry::Kind::EmptyNamedExport)
return;
auto const& exported_name = entry.local_or_import_name;
bool found = false;
// NOTE: Nothing in the callback throws an exception.
MUST(program.for_each_lexically_declared_identifier([&](auto const& identifier) {
if (identifier.string() == exported_name)
found = true;
}));
if (found)
continue;
// NOTE: Nothing in the callback throws an exception.
MUST(program.for_each_var_declared_identifier([&](auto const& identifier) {
if (identifier.string() == exported_name)
found = true;
}));
for (auto& import : program.imports()) {
if (import->has_bound_name(exported_name.value())) {
found = true;
break;
}
}
if (!found)
syntax_error(ByteString::formatted("'{}' in export is not declared", exported_name), export_statement->source_range().start);
}
}
}
NonnullRefPtr<Declaration const> 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<FunctionDeclaration>();
switch (m_state.current_token.type()) {
case TokenType::Class:
return parse_class_declaration();
case TokenType::Function:
return parse_function_node<FunctionDeclaration>();
case TokenType::Let:
case TokenType::Const:
return parse_variable_declaration();
case TokenType::Identifier:
if (m_state.current_token.original_value() == "using"sv) {
if (!m_state.current_scope_pusher->can_have_using_declaration())
syntax_error("'using' not allowed outside of block, for loop or function");
return parse_using_declaration();
}
[[fallthrough]];
default:
expected("declaration");
consume();
return create_ast_node<ErrorDeclaration>({ m_source_code, rule_start.position(), position() });
}
}
NonnullRefPtr<Statement const> 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<EmptyStatement>({ m_source_code, 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(ByteString::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(ByteString::formatted("let followed by [ is not allowed in single-statement context"));
}
auto expr = parse_expression(0);
consume_or_insert_semicolon();
return create_ast_node<ExpressionStatement>({ m_source_code, rule_start.position(), position() }, move(expr));
}
expected("statement");
consume();
return create_ast_node<ErrorStatement>({ m_source_code, 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<StringView, 9> strict_reserved_words = { "implements"sv, "interface"sv, "let"sv, "package"sv, "private"sv, "protected"sv, "public"sv, "static"sv, "yield"sv };
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<FunctionParameter> const& parameters)
{
return all_of(parameters, [](FunctionParameter const& parameter) {
return !parameter.is_rest && parameter.default_value.is_null() && parameter.binding.has<NonnullRefPtr<Identifier const>>();
});
}
RefPtr<FunctionExpression const> 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;
}