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LibJS: Bring Reference records a bit closer to the ECMAScript spec

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Our Reference class now has the same fields as the spec:

- Base (a non-nullish value, an environment record, or `unresolvable`)
- Referenced Name (the name of the binding)
- Strict (whether the reference originated in strict mode code)
- ThisValue (if non-empty, the reference represents a `super` keyword)

The main difference from before is that we now resolve the environment
record that a reference interacts with. Previously we simply resolved
to either "local variable" or "global variable".

The associated abstract operations are still largely non-conforming,
since we don't yet implement proper variable bindings. But this patch
should at least fix a handful of test262 cases. :^)

There's one minor regression: some TypeError message strings get
a little worse due to doing a RequireObjectCoercible earlier in the
evaluation of MemberExpression.
This commit is contained in:
Andreas Kling 2021-06-25 16:27:59 +02:00
parent 6e1932e8b2
commit bce7fdba81
6 changed files with 193 additions and 123 deletions
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33
Userland/Libraries/LibJS/AST.cpp
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@ -130,7 +130,7 @@ CallExpression::ThisAndCallee CallExpression::compute_this_and_callee(Interprete
if (is<MemberExpression>(*m_callee)) {
auto& member_expression = static_cast<MemberExpression const&>(*m_callee);
Value callee;
Object* this_value = nullptr;
Value this_value;
if (is<SuperExpression>(member_expression.object())) {
auto super_base = interpreter.current_function_environment_record()->get_super_base();
@ -141,7 +141,7 @@ CallExpression::ThisAndCallee CallExpression::compute_this_and_callee(Interprete
auto property_name = member_expression.computed_property_name(interpreter, global_object);
if (!property_name.is_valid())
return {};
auto reference = Reference(super_base, property_name);
auto reference = Reference { super_base, property_name, super_base };
callee = reference.get(global_object);
if (vm.exception())
return {};
@ -153,9 +153,7 @@ CallExpression::ThisAndCallee CallExpression::compute_this_and_callee(Interprete
callee = reference.get(global_object);
if (vm.exception())
return {};
this_value = reference.base().to_object(global_object);
if (vm.exception())
return {};
this_value = reference.get_this_value();
}
return { this_value, callee };
@ -667,9 +665,9 @@ Reference Expression::to_reference(Interpreter&, GlobalObject&) const
return {};
}
Reference Identifier::to_reference(Interpreter& interpreter, GlobalObject&) const
Reference Identifier::to_reference(Interpreter& interpreter, GlobalObject& global_object) const
{
return interpreter.vm().resolve_binding(string());
return interpreter.vm().resolve_binding(global_object, string());
}
Reference MemberExpression::to_reference(Interpreter& interpreter, GlobalObject& global_object) const
@ -677,10 +675,16 @@ Reference MemberExpression::to_reference(Interpreter& interpreter, GlobalObject&
auto object_value = m_object->execute(interpreter, global_object);
if (interpreter.exception())
return {};
object_value = require_object_coercible(global_object, object_value);
if (interpreter.exception())
return {};
auto property_name = computed_property_name(interpreter, global_object);
if (!property_name.is_valid())
return {};
return { object_value, property_name };
return Reference {};
return Reference { object_value, property_name, object_value };
}
Value UnaryExpression::execute(Interpreter& interpreter, GlobalObject& global_object) const
@ -701,12 +705,10 @@ Value UnaryExpression::execute(Interpreter& interpreter, GlobalObject& global_ob
if (interpreter.exception()) {
return {};
}
// FIXME: standard recommends checking with is_unresolvable but it ALWAYS return false here
if (reference.is_local_variable() || reference.is_global_variable()) {
const auto& name = reference.name();
lhs_result = interpreter.vm().get_variable(name.to_string(), global_object).value_or(js_undefined());
if (interpreter.exception())
return {};
if (reference.is_unresolvable()) {
lhs_result = js_undefined();
} else {
lhs_result = reference.get(global_object, false);
}
} else {
lhs_result = m_lhs->execute(interpreter, global_object);
@ -1477,6 +1479,7 @@ Value UpdateExpression::execute(Interpreter& interpreter, GlobalObject& global_o
InterpreterNodeScope node_scope { interpreter, *this };
auto reference = m_argument->to_reference(interpreter, global_object);
if (interpreter.exception())
return {};
auto old_value = reference.get(global_object);