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LibJS: Convert get_identifier_reference() to ThrowCompletionOr

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And while we're here add spec comments.
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davidot 2021-12-30 13:19:05 +01:00 • committed by Linus Groh
parent 676554d3f8
commit d72022ba04
2 changed files with 14 additions and 5 deletions
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17
Userland/Libraries/LibJS/Runtime/VM.cpp
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@ -426,7 +426,7 @@ ThrowCompletionOr<void> VM::iterator_binding_initialization(BindingPattern const
} }
// 9.1.2.1 GetIdentifierReference ( env, name, strict ), https://tc39.es/ecma262/#sec-getidentifierreference // 9.1.2.1 GetIdentifierReference ( env, name, strict ), https://tc39.es/ecma262/#sec-getidentifierreference
Reference VM::get_identifier_reference(Environment* environment, FlyString name, bool strict, size_t hops) ThrowCompletionOr<Reference> VM::get_identifier_reference(Environment* environment, FlyString name, bool strict, size_t hops)
{ {
// 1. If env is the value null, then // 1. If env is the value null, then
if (!environment) { if (!environment) {
@ -434,17 +434,26 @@ Reference VM::get_identifier_reference(Environment* environment, FlyString name,
return Reference { Reference::BaseType::Unresolvable, move(name), strict }; return Reference { Reference::BaseType::Unresolvable, move(name), strict };
} }
// 2. Let exists be ? env.HasBinding(name).
Optional<size_t> index; Optional<size_t> index;
auto exists = TRY_OR_DISCARD(environment->has_binding(name, &index)); auto exists = TRY(environment->has_binding(name, &index));
// Note: This is an optimization for looking up the same reference.
Optional<EnvironmentCoordinate> environment_coordinate; Optional<EnvironmentCoordinate> environment_coordinate;
if (index.has_value()) if (index.has_value())
environment_coordinate = EnvironmentCoordinate { .hops = hops, .index = index.value() }; environment_coordinate = EnvironmentCoordinate { .hops = hops, .index = index.value() };
if (exists) // 3. If exists is true, then
if (exists) {
// a. Return the Reference Record { [[Base]]: env, [[ReferencedName]]: name, [[Strict]]: strict, [[ThisValue]]: empty }.
return Reference { *environment, move(name), strict, environment_coordinate }; return Reference { *environment, move(name), strict, environment_coordinate };
else }
// 4. Else,
else {
// a. Let outer be env.[[OuterEnv]].
// b. Return ? GetIdentifierReference(outer, name, strict).
return get_identifier_reference(environment->outer_environment(), move(name), strict, hops + 1); return get_identifier_reference(environment->outer_environment(), move(name), strict, hops + 1);
}
} }
// 9.4.2 ResolveBinding ( name [ , env ] ), https://tc39.es/ecma262/#sec-resolvebinding // 9.4.2 ResolveBinding ( name [ , env ] ), https://tc39.es/ecma262/#sec-resolvebinding

2
Userland/Libraries/LibJS/Runtime/VM.h
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@ -193,7 +193,7 @@ public:
FlyString unwind_until_label() const { return m_unwind_until_label; } FlyString unwind_until_label() const { return m_unwind_until_label; }
ThrowCompletionOr<Reference> resolve_binding(FlyString const&, Environment* = nullptr); ThrowCompletionOr<Reference> resolve_binding(FlyString const&, Environment* = nullptr);
Reference get_identifier_reference(Environment*, FlyString, bool strict, size_t hops = 0); ThrowCompletionOr<Reference> get_identifier_reference(Environment*, FlyString, bool strict, size_t hops = 0);
template<typename T, typename... Args> template<typename T, typename... Args>
void throw_exception(GlobalObject& global_object, Args&&... args) void throw_exception(GlobalObject& global_object, Args&&... args)