Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
The main motivation behind this is to remove JS specifics of the Realm
from the implementation of the Heap.
As a side effect of this change, this is a bit nicer to read than the
previous approach, and in my opinion, also makes it a little more clear
that this method is specific to a JavaScript Realm.
We have multiple array types now, so ArrayInvalidLength has been
replaced with a generic InvalidLength.
Also fixes a small issue in the Array constructor, it should throw
RangeError for invalid lengths, not TypeError.
Roughly 7% of test-js runtime was spent creating FlyStrings from string
literals. This patch frontloads that work and caches all the commonly
used names in LibJS on a CommonPropertyNames struct that hangs off VM.
More work on decoupling the general runtime from Interpreter. The goal
is becoming clearer. Interpreter should be one possible way to execute
code inside a VM. In the future we might have other ways :^)
This patch moves the exception state, call stack and scope stack from
Interpreter to VM. I'm doing this to help myself discover what the
split between Interpreter and VM should be, by shuffling things around
and seeing what falls where.
With these changes, we no longer have a persistent lexical environment
for the current global object on the Interpreter's call stack. Instead,
we push/pop that environment on Interpreter::run() enter/exit.
Since it should only be used to find the global "this", and not for
variable storage (that goes directly into the global object instead!),
I had to insert some short-circuiting when walking the environment
parent chain during variable lookup.
Note that this is a "stepping stone" commit, not a final design.
Divide the Object constructor into three variants:
- The regular one (takes an Object& prototype)
- One for use by GlobalObject
- One for use by objects without a prototype (e.g ObjectPrototype)
Also let's settle on calling the operation of fetching the "this" value
from the Interpreter and converting it to a specific Object pointer
typed_this() since consistency is nice.
To make sure that everything is set up correctly in objects before we
start adding properties to them, we split cell allocation into 3 steps:
1. Allocate a cell of appropriate size from the Heap
2. Call the C++ constructor on the cell
3. Call initialize() on the constructed object
The job of initialize() is to define all the initial properties.
Doing it in a second pass guarantees that the Object has a valid Shape
and can find its own GlobalObject.
More work towards supporting multiple global objects. Native C++ code
now get a GlobalObject& and don't have to ask the Interpreter for it.
I've added macros for declaring and defining native callbacks since
this was pretty tedious and this makes it easier next time we want to
change any of these signatures.
This patch adds an IndexedProperties object for storing indexed
properties within an Object. This accomplishes two goals: indexed
properties now have an associated descriptor, and objects now gracefully
handle sparse properties.
The IndexedProperties class is a wrapper around two other classes, one
for simple indexed properties storage, and one for general indexed
property storage. Simple indexed property storage is the common-case,
and is simply a vector of properties which all have attributes of
default_attributes (writable, enumerable, and configurable).
General indexed property storage is for a collection of indexed
properties where EITHER one or more properties have attributes other
than default_attributes OR there is a property with a large index (in
particular, large is '200' or higher).
Indexed properties are now treated relatively the same as storage within
the various Object methods. Additionally, there is a custom iterator
class for IndexedProperties which makes iteration easy. The iterator
skips empty values by default, but can be configured otherwise.
Likewise, it evaluates getters by default, but can be set not to.
Previously, the Object class had many different types of functions for
each action. For example: get_by_index, get(PropertyName),
get(FlyString). This is a bit verbose, so these methods have been
shortened to simply use the PropertyName structure. The methods then
internally call _by_index if necessary. Note that the _by_index
have been made private to enforce this change.
Secondly, a clear distinction has been made between "putting" and
"defining" an object property. "Putting" should mean modifying a
(potentially) already existing property. This is akin to doing "a.b =
'foo'".
This implies two things about put operations:
- They will search the prototype chain for setters and call them, if
necessary.
- If no property exists with a particular key, the put operation
should create a new property with the default attributes
(configurable, writable, and enumerable).
In contrast, "defining" a property should completely overwrite any
existing value without calling setters (if that property is
configurable, of course).
Thus, all of the many JS objects have had any "put" calls changed to
"define_property" calls. Additionally, "put_native_function" and
"put_native_property" have had their "put" replaced with "define".
Finally, "put_own_property" has been made private, as all necessary
functionality should be exposed with the put and define_property
methods.
This patch is unfortunately rather large and might make some things feel
bloated, but it is necessary to fix a few flaws in LibJS, primarily
blindly coercing values to numbers without exception checks - i.e.
interpreter.argument(0).to_i32(); // can fail!!!
Some examples where the interpreter would actually crash:
var o = { toString: () => { throw Error() } };
+o;
o - 1;
"foo".charAt(o);
"bar".repeat(o);
To fix this, we now have the following...
to_double(Interpreter&)
to_i32()
to_i32(Interpreter&)
to_size_t()
to_size_t(Interpreter&)
...and a whole lot of exception checking.
There's intentionally no to_double(), use as_double() directly instead.
This way we still can use these convenient utility functions but don't
need to check for exceptions if we are sure the value already is a
number.
Fixes#2267.
Passing a Heap& to it only to then call interpreter() on that is weird.
Let's just give it the Interpreter& directly, like some of the other
to_something() functions.
Everyone who constructs an Object must now pass a prototype object when
applicable. There's still a fair amount of code that passes something
fetched from the Interpreter, but this brings us closer to being able
to detach prototypes from Interpreter eventually.
Let's start moving towards native JS objects taking their prototype as
a constructor argument.
This will eventually allow us to move prototypes off of Interpreter and
into GlobalObject.
Objects can have both named and indexed properties. Previously we kept
all property names as strings. This patch separates named and indexed
properties and splits them between Object::m_storage and m_elements.
This allows us to do much faster array-style access using numeric
indices. It also makes the Array class much less special, since all
Objects now have number-indexed storage. :^)
Object now has virtual get_own_property() and put_own_property() member
functions that can be overridden to provide custom behavior.
We use these virtuals to move Array-specific access behavior to Array.
This function is ultimately supposed to be generic and allow any |this|
that has a length property, but for now it only works on our own Array
object type.
