ladybird/Libraries/LibJS/Runtime/Reference.h

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/*
* Copyright (c) 2020-2021, Andreas Kling <andreas@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <LibJS/Runtime/Environment.h>
#include <LibJS/Runtime/EnvironmentCoordinate.h>
#include <LibJS/Runtime/PropertyKey.h>
#include <LibJS/Runtime/Value.h>
namespace JS {
Reference make_private_reference(VM&, Value base_value, DeprecatedFlyString const& private_identifier);
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class Reference {
public:
enum class BaseType : u8 {
Unresolvable,
Value,
Environment,
};
Reference(BaseType type, PropertyKey name, bool strict)
: m_base_type(type)
, m_name(move(name))
, m_strict(strict)
{
}
Reference(Value base, PropertyKey name, Value this_value, bool strict = false)
: m_base_type(BaseType::Value)
, m_base_value(base)
, m_name(move(name))
, m_this_value(this_value)
, m_strict(strict)
{
}
Reference(Environment& base, DeprecatedFlyString referenced_name, bool strict = false, Optional<EnvironmentCoordinate> environment_coordinate = {})
: m_base_type(BaseType::Environment)
, m_base_environment(&base)
, m_name(move(referenced_name))
, m_strict(strict)
, m_environment_coordinate(move(environment_coordinate))
{
}
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Reference(Value base, PrivateName name)
: m_base_type(BaseType::Value)
, m_base_value(base)
, m_name(move(name))
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, m_strict(true)
{
}
Value base() const
{
VERIFY(m_base_type == BaseType::Value);
return m_base_value;
}
Environment& base_environment() const
{
VERIFY(m_base_type == BaseType::Environment);
return *m_base_environment;
}
PropertyKey const& name() const { return m_name.get<PropertyKey>(); }
PrivateName const& private_name() const { return m_name.get<PrivateName>(); }
bool is_strict() const { return m_strict; }
// 6.2.4.2 IsUnresolvableReference ( V ), https://tc39.es/ecma262/#sec-isunresolvablereference
bool is_unresolvable() const { return m_base_type == BaseType::Unresolvable; }
// 6.2.4.1 IsPropertyReference ( V ), https://tc39.es/ecma262/#sec-ispropertyreference
bool is_property_reference() const
{
if (is_unresolvable())
return false;
if (m_base_type == BaseType::Environment)
return false;
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return true;
}
// 6.2.4.7 GetThisValue ( V ), https://tc39.es/ecma262/#sec-getthisvalue
Value get_this_value() const
{
VERIFY(is_property_reference());
if (is_super_reference())
return m_this_value;
return m_base_value;
}
// 6.2.4.3 IsSuperReference ( V ), https://tc39.es/ecma262/#sec-issuperreference
bool is_super_reference() const
{
return !m_this_value.is_empty();
}
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// 6.2.4.4 IsPrivateReference ( V ), https://tc39.es/ecma262/#sec-isprivatereference
bool is_private_reference() const
{
return m_name.has<PrivateName>();
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}
// Note: Non-standard helper.
bool is_environment_reference() const
{
return m_base_type == BaseType::Environment;
}
ThrowCompletionOr<void> initialize_referenced_binding(VM&, Value value, Environment::InitializeBindingHint hint = Environment::InitializeBindingHint::Normal) const;
LibJS: Make scoping follow the spec Before this we used an ad-hoc combination of references and 'variables' stored in a hashmap. This worked in most cases but is not spec like. Additionally hoisting, dynamically naming functions and scope analysis was not done properly. This patch fixes all of that by: - Implement BindingInitialization for destructuring assignment. - Implementing a new ScopePusher which tracks the lexical and var scoped declarations. This hoists functions to the top level if no lexical declaration name overlaps. Furthermore we do checking of redeclarations in the ScopePusher now requiring less checks all over the place. - Add methods for parsing the directives and statement lists instead of having that code duplicated in multiple places. This allows declarations to pushed to the appropriate scope more easily. - Remove the non spec way of storing 'variables' in DeclarativeEnvironment and make Reference follow the spec instead of checking both the bindings and 'variables'. - Remove all scoping related things from the Interpreter. And instead use environments as specified by the spec. This also includes fixing that NativeFunctions did not produce a valid FunctionEnvironment which could cause issues with callbacks and eval. All FunctionObjects now have a valid NewFunctionEnvironment implementation. - Remove execute_statements from Interpreter and instead use ASTNode::execute everywhere this simplifies AST.cpp as you no longer need to worry about which method to call. - Make ScopeNodes setup their own environment. This uses four different methods specified by the spec {Block, Function, Eval, Global}DeclarationInstantiation with the annexB extensions. - Implement and use NamedEvaluation where specified. Additionally there are fixes to things exposed by these changes to eval, {for, for-in, for-of} loops and assignment. Finally it also fixes some tests in test-js which where passing before but not now that we have correct behavior :^).
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ThrowCompletionOr<void> put_value(VM&, Value);
ThrowCompletionOr<Value> get_value(VM&) const;
ThrowCompletionOr<bool> delete_(VM&);
bool is_valid_reference() const { return true; }
Optional<EnvironmentCoordinate> environment_coordinate() const { return m_environment_coordinate; }
private:
Completion throw_reference_error(VM&) const;
BaseType m_base_type { BaseType::Unresolvable };
union {
Value m_base_value {};
mutable Environment* m_base_environment;
};
Variant<PropertyKey, PrivateName> m_name;
Value m_this_value;
bool m_strict { false };
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Optional<EnvironmentCoordinate> m_environment_coordinate;
};
}