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LibJS: Make scoping follow the spec

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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 :^).
This commit is contained in:
davidot 2021-09-22 12:44:56 +02:00 • committed by Linus Groh
parent 4428e494b0
commit 830ea0414c
Notes: sideshowbarker 2024-07-18 03:18:05 +09:00
44 changed files with 2622 additions and 1548 deletions
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57
Userland/Libraries/LibJS/Runtime/Reference.cpp
View file

@ -31,15 +31,6 @@ void Reference::put_value(GlobalObject& global_object, Value value)
}
if (is_property_reference()) {
// FIXME: This is an ad-hoc hack until we support proper variable bindings.
if (!m_base_value.is_object() && vm.in_strict_mode()) {
if (m_base_value.is_nullish())
vm.throw_exception<TypeError>(global_object, ErrorType::ReferenceNullishSetProperty, m_name, m_base_value.to_string_without_side_effects());
else
vm.throw_exception<TypeError>(global_object, ErrorType::ReferencePrimitiveSetProperty, m_name, m_base_value.typeof(), m_base_value.to_string_without_side_effects());
return;
}
auto* base_obj = m_base_value.to_object(global_object);
if (!base_obj)
return;
@ -56,29 +47,8 @@ void Reference::put_value(GlobalObject& global_object, Value value)
}
VERIFY(m_base_type == BaseType::Environment);
// FIXME: This entire following section is 100% not spec-compliant.
auto existing_variable = m_base_environment->get_from_environment(m_name.as_string());
Variable variable {
.value = value,
.declaration_kind = existing_variable.has_value() ? existing_variable->declaration_kind : DeclarationKind::Var
};
// FIXME: This is a hack until we support proper variable bindings.
if (variable.declaration_kind == DeclarationKind::Const) {
vm.throw_exception<TypeError>(global_object, ErrorType::InvalidAssignToConst);
return;
}
bool succeeded = m_base_environment->put_into_environment(m_name.as_string(), variable);
if (vm.exception())
return;
if (!succeeded) {
if (m_base_environment->has_binding(m_name.as_string())) {
m_base_environment->set_mutable_binding(global_object, m_name.as_string(), value, is_strict());
return;
}
}
VERIFY(m_base_environment);
m_base_environment->set_mutable_binding(global_object, m_name.as_string(), value, m_strict);
}
void Reference::throw_reference_error(GlobalObject& global_object) const
@ -91,7 +61,7 @@ void Reference::throw_reference_error(GlobalObject& global_object) const
}
// 6.2.4.5 GetValue ( V ), https://tc39.es/ecma262/#sec-getvalue
Value Reference::get_value(GlobalObject& global_object, bool throw_if_undefined) const
Value Reference::get_value(GlobalObject& global_object) const
{
if (!is_valid_reference() || is_unresolvable()) {
throw_reference_error(global_object);
@ -106,19 +76,8 @@ Value Reference::get_value(GlobalObject& global_object, bool throw_if_undefined)
}
VERIFY(m_base_type == BaseType::Environment);
// FIXME: This entire section is 100% not spec-compliant.
auto value = m_base_environment->get_from_environment(m_name.as_string());
if (!value.has_value()) {
if (m_base_environment->has_binding(m_name.as_string()))
return m_base_environment->get_binding_value(global_object, m_name.as_string(), is_strict());
if (!throw_if_undefined) {
// FIXME: This is an ad-hoc hack for the `typeof` operator until we support proper variable bindings.
return js_undefined();
}
throw_reference_error(global_object);
return {};
}
return value->value;
VERIFY(m_base_environment);
return m_base_environment->get_binding_value(global_object, m_name.as_string(), m_strict);
}
// 13.5.1.2 Runtime Semantics: Evaluation, https://tc39.es/ecma262/#sec-delete-operator-runtime-semantics-evaluation
@ -177,11 +136,7 @@ bool Reference::delete_(GlobalObject& global_object)
VERIFY(m_base_type == BaseType::Environment);
// c. Return ? base.DeleteBinding(ref.[[ReferencedName]]).
if (m_base_environment->has_binding(m_name.as_string()))
return m_base_environment->delete_binding(global_object, m_name.as_string());
// FIXME: This is ad-hoc, we should be calling DeleteBinding.
return m_base_environment->delete_from_environment(m_name.as_string());
return m_base_environment->delete_binding(global_object, m_name.as_string());
}
String Reference::to_string() const