A struct with three raw pointers to other GC'd types is a pretty big
liability, let's just turn this into a Cell itself.
This comes with the additional benefit of being able to capture it in
a lambda effortlessly, without having to create handles for individual
members.
This will allow us to move the underlying console from GlobalObject to
ConsoleObject without still having to do a 'console' property lookup on
the GlobalObject.
Intrinsics, i.e. mostly constructor and prototype objects, but also
things like empty and new object shape now live on a new heap-allocated
JS::Intrinsics object, thus completing the long journey of taking all
the magic away from the global object.
This represents the Realm's [[Intrinsics]] slot in the spec and matches
its existing [[GlobalObject]] / [[GlobalEnv]] slots in terms of
architecture.
In the majority of cases it should now be possibly to fully allocate a
regular object without the global object existing, and in fact that's
what we do now - the realm is allocated before the global object, and
the intrinsics between both :^)
The Intl mathematical value is much like ECMA-262's mathematical value
in that it is meant to represent an arbitrarily precise number. The Intl
MV further allows positive/negative infinity, negative zero, and NaN.
This implementation is *not* arbitrarily precise. Rather, it is a
replacement for the use of Value within Intl.NumberFormat. The exact
syntax of the Intl MV is still being worked on, but abstracting this
away into its own class will allow hooking in the finalized Intl MV
more easily, and makes implementing Intl.NumberFormat.formatRange
easier.
Note the methods added here are essentially the same as the static
helpers in Intl/NumberFormat.cpp.
This was defined twice, despite being the very same thing:
- ClassElement::ClassFieldDefinition
- ECMAScriptFunctionObject::InstanceField
Move the former to a new header and use it everywhere. Also update the
define_field() AO to take a single field instead of separate name and
initializer arguments.
This is an editorial change in the Temporal spec.
See: https://github.com/tc39/proposal-temporal/commit/983902e
We already had these defined as structs, but now they're properly
defined in the spec (opposed to the previous anonymous records), and we
don't have to make up our own names anymore :^)
Note that while we're usually not including 'record' in the name, in
this case the 'Duration Record' has a name clash with the Duration
object. Additionally, later editorial changes introduce CreateFooRecord
AOs, so let's just go with FooRecord structs here.
Note: MarkedVector is still relatively new and has zero users right now,
so these changes don't affect any code other than the class itself.
Reasons for this are the rather limited API:
- Despite the name and unlike MarkedValueList, MarkedVector isn't
actually a Vector, it *wraps* a Vector. This means that plenty of
convenient APIs are unavailable and have to be exported on the class
separately and forwarded to the internal Vector, or need to go through
the exposed Span - both not great options.
- Exposing append(Cell*) and prepend(Cell*) on the base class means that
it was possible to append any Cell type, not just T! All the strong
typing guarantees are basically gone, and MarkedVector doesn't do much
more than casting Cells to the appropriate type through the exposed
Span.
All of this combined means that MarkedVector - in its current form -
doesn't provide much value over MarkedValueList, and that we have to
maintain two separate, yet almost identical classes.
Let's fix this!
The updated MarkedVector steals various concepts from the existing
MarkedValueList, especially the ability to copy. On the other hand, it
remains generic enough to handle both Cell* and Value for T, making
MarkedValueList effectively redundant :^)
Additionally, by inheriting from Vector we get all the current and
future APIs without having to select and expose them separately.
MarkedVectorBase remains and takes care of communicating creation and
destruction of the class to the heap. Visiting the contained values is
handled via a pure virtual method gather_roots(), which is being called
by the Heap's function of the same name; much like the VM has one.
From there, values are added to the roots HashTable if they are cells
for T = Value, and unconditionally for any other T.
As a small additional improvement the template now also takes an
inline_capacity parameter, defaulting to 32, and forwards it to the
Vector template; allowing for possible future optimizations of current
uses of MarkedValueList, which hard-codes it to 32.
The environment settings object is effectively the context a piece of
script is running under, for example, it contains the origin,
responsible document, realm, global object and event loop for the
current context. This effectively replaces ScriptExecutionContext, but
it cannot be removed in this commit as EventTarget still depends on it.
https://html.spec.whatwg.org/multipage/webappapis.html#environment-settings-object
This commit removes all exception related code:
Remove VM::exception(), VM::throw_exception() etc. Any leftover
throw_exception calls are moved to throw_completion.
The one method left is clear_exception() which is now a no-op. Most of
these calls are just to clear whatever exception might have been thrown
when handling a Completion. So to have a cleaner commit this will be
removed in a next commit.
It also removes the actual Exception and TemporaryClearException classes
since these are no longer used.
In any spot where the exception was actually used an attempt was made to
preserve that behavior. However since it is no longer tracked by the VM
we cannot access exceptions which were thrown in previous calls.
There are two such cases which might have different behavior:
- In Web::DOM::Document::interpreter() the on_call_stack_emptied hook
used to print any uncaught exception but this is now no longer
possible as the VM does not store uncaught exceptions.
- In js the code used to be interruptable by throwing an exception on
the VM. This is no longer possible but was already somewhat fragile
before as you could happen to throw an exception just before a VERIFY.
Given we usually call objects Foo{Object,Constructor,Prototype} or
Foo{,Constructor,Prototype}, this name was an odd choice.
The new one matches the spec better, which calls it the "Generator
Prototype Object", so we simply omit the Object suffix as usual as it's
implied.
This abstracts a vector of Cell* with a strongly typed span() accessor
that gives you Span<T*> instead of Span<Cell*>.
It is intended to replace MarkedValueList in situations where you only
need to store pointers to Cell (or an even more specific type of Cell).
The API can definitely be improved, it's just the bare basics for now.
This adds plumbing for the Intl.DateTimeFormat object, constructor, and
prototype.
Note that unlike other Intl objects, the Intl.DateTimeFormat object has
a LibUnicode structure as a base. This is to prevent wild amounts of
code duplication between LibUnicode, Intl.DateTimeFormat, and other
not-yet-defined Intl structures, because there's 12 fields shared
between them.
This commit adds support for the most bare bones version of async
functions, support for async generator functions, async arrow functions
and await expressions are TODO.
The old versions were renamed to JS_DECLARE_OLD_NATIVE_FUNCTION and
JS_DEFINE_OLD_NATIVE_FUNCTION, and will be eventually removed once all
native functions were converted to the new format.
We decided that we want to move away from throwing exceptions in AOs
and regular functions implicitly and then returning some
default-constructed value (usually an empty JS::Value) - this requires
remembering to check for an exception at the call site, which is
error-prone. It's also awkward for return values that cannot be
default-constructed, e.g. MarkedValueList.
Instead, the thrown value should be part of the function return value.
The solution to this is moving closer to the spec and using something
they call "completion records":
https://tc39.es/ecma262/#sec-completion-record-specification-type
This has various advantages:
- It becomes crystal clear whether some AO can fail or not, and errors
need to be handled and values unwrapped explicitly (for that reason
compatibility with the TRY() macro is already built-in, and a similar
TRY_OR_DISCARD() macro has been added specifically for use in LibJS,
while the majority of functions doesn't return ThrowCompletionOr yet)
- We no longer need to mix "valid" and "invalid" values of various types
for the success and exception outcomes (e.g. null/non-null AK::String,
empty/non-empty JS::Value)
- Subsequently it's no longer possible to accidentally use an exception
outcome return value as a success outcome return value (e.g. any AO
that returns a numeric type would return 0 even after throwing an
exception, at least before we started making use of Optional for that)
- Eventually the VM will no longer need to store an exception, and
temporarily clearing an exception (e.g. to call a function) becomes
obsolete - instead, completions will simply propagate up to the caller
outside of LibJS, which then can deal with it in any way
- Similar to throw we'll be able to implement the functionality of
break, continue, and return using completions, which will lead to
easier to understand code and fewer workarounds - the current
unwinding mechanism is not even remotely similar to the spec's
approach
The spec's NormalCompletion and ThrowCompletion AOs have been
implemented as simple wrappers around the JS::Completion constructor.
UpdateEmpty has been implemented as a JS::Completion method.
There's also a new VM::throw_completion<T>() helper, which basically
works like VM::throw_exception<T>() - it creates a T object (usually a
JS::Error), and returns it wrapped in a JS::Completion of Type::Throw.
Two temporary usage patterns have emerged:
1. Callee already returns ThrowCompletionOr, but caller doesn't:
auto foo = TRY_OR_DISCARD(bar());
2. Caller already returns ThrowCompletionOr, but callee doesn't:
auto foo = bar();
if (auto* exception = vm.exception())
return throw_completion(exception->value());
Eventually all error handling and unwrapping can be done with just TRY()
or possibly even operator? in the future :^)
Co-authored-by: Andreas Kling <kling@serenityos.org>
To help alleviate memory usage when creating and copying large strings,
create a simple wrapper around a Vector<u16> to reference count UTF-16
strings.
Add a JS_ENUMERATE_INTL_OBJECTS macro and use it to generate:
- Forward declarations
- CommonPropertyNames class name members
- Constructor and prototype GlobalObject members, getters, visitors,
and initialize_constructor() calls
This commit adds the PlainYearMonth object itself, its constructor and
prototype (currently empty), and the CreateTemporalYearMonth and
ISOYearMonthWithinLimits abstract operations.
This commit adds the ZonedDateTime object itself, its constructor and
prototype (currently empty), and the CreateTemporalZonedDateTime
abstract operation.
