This also renames ErrorType::StringMatchAllNonGlobalRegExp to
ErrorType::StringNonGlobalRegExp (removes "MatchAll") because this error
is now used in the same way from multiple operations.
To make this happen, this patch implements the SetImmutablePrototype
abstract operation (as a method on Object) and then overrides
[[SetPrototypeOf]] on ObjectPrototype.
This is a huge patch, I know. In hindsight this perhaps could've been
done slightly more incremental, but I started and then fixed everything
until it worked, and here we are. I tried splitting of some completely
unrelated changes into separate commits, however. Anyway.
This is a rewrite of most of Object, and by extension large parts of
Array, Proxy, Reflect, String, TypedArray, and some other things.
What we already had worked fine for about 90% of things, but getting the
last 10% right proved to be increasingly difficult with the current code
that sort of grew organically and is only very loosely based on the
spec - this became especially obvious when we started fixing a large
number of test262 failures.
Key changes include:
- 1:1 matching function names and parameters of all object-related
functions, to avoid ambiguity. Previously we had things like put(),
which the spec doesn't have - as a result it wasn't always clear which
need to be used.
- Better separation between object abstract operations and internal
methods - the former are always the same, the latter can be overridden
(and are therefore virtual). The internal methods (i.e. [[Foo]] in the
spec) are now prefixed with 'internal_' for clarity - again, it was
previously not always clear which AO a certain method represents,
get() could've been both Get and [[Get]] (I don't know which one it
was closer to right now).
Note that some of the old names have been kept until all code relying
on them is updated, but they are now simple wrappers around the
closest matching standard abstract operation.
- Simplifications of the storage layer: functions that write values to
storage are now prefixed with 'storage_' to make their purpose clear,
and as they are not part of the spec they should not contain any steps
specified by it. Much functionality is now covered by the layers above
it and was removed (e.g. handling of accessors, attribute checks).
- PropertyAttributes has been greatly simplified, and is being replaced
by PropertyDescriptor - a concept similar to the current
implementation, but more aligned with the actual spec. See the commit
message of the previous commit where it was introduced for details.
- As a bonus, and since I had to look at the spec a whole lot anyway, I
introduced more inline comments with the exact steps from the spec -
this makes it super easy to verify correctness.
- East-const all the things.
As a result of all of this, things are much more correct but a bit
slower now. Retaining speed wasn't a consideration at all, I have done
no profiling of the new code - there might be low hanging fruits, which
we can then harvest separately.
Special thanks to Idan for helping me with this by tracking down bugs,
updating everything outside of LibJS to work with these changes (LibWeb,
Spreadsheet, HackStudio), as well as providing countless patches to fix
regressions I introduced - there still are very few (we got it down to
5), but we also get many new passing test262 tests in return. :^)
Co-authored-by: Idan Horowitz <idan.horowitz@gmail.com>
These will be removed in favour of just taking the argument and
'risking' a ToObject on null or undefined - this is how the spec does
it.
While that will make the message slightly less specific, it'll bring
the code closer to the spec and reduce complexity, which are both
preferable at the moment.
Doing this is a previous, separate commit is simply an attempt to make
the object rewrite commit smaller.
This includes checking that the target is a constructor, not just a
function, as well as switching the order of the list creation and
argument validation to match the specification, to ensure correct
exception throwing order.
This regressed recently and would only output a bunch of '[object Foo]',
the reason being that String(value) failed in some cases - which is
easily fixed by trying that first and using Object.prototype.toString()
as a fallback in the case of an exception :^)
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 was missing step 3 from the spec:
3. If Type(O) is not Object, return O.
Also use RequireObjectCoercible() for a better error message and make
the rest of the code a bit easier to read and more similar to the spec
text.
String objects are a bit special since the indexed properties are
overridden by the contents of the underlying PrimitiveString.
getOwnPropertyDescriptor() was not taking this into account, and would
instead return undefined when asked about an indexed property in a
String object.
Stage 3 since August 2019 - we already have shebang stripping
implemented in js(1), so this removes it from there in favor of adding
support to the lexer directly.
Most straightforward proposal and implementation I've ever seen :^)
https://github.com/tc39/proposal-hashbang
Since we have had eval() for a while now, we can finally use it here -
this allows us to get rid of the confusing return statements in tested
source code.
Using String() like we did before depends on objects having either
toString, valueOf, or @@toPrimitive, which is not the case for objects
with no prototype.
