4 commits

Author	SHA1	Message	Date
Andreas Kling	8286f8b996	LibJS: Add property configuration transitions ... Object.defineProperty() can now change the attributes of a property already on the object. Internally this becomes a shape transition with the TransitionType::Configure. Such transitions don't expand the property storage capacity, but rather simply keep attributes up to date when generating a property table.	2020-04-10 00:36:06 +02:00
Andreas Kling	e6d920d87d	LibJS: Add Object.defineProperty() and start caring about attributes ... We now care (a little bit) about the "configurable" and "writable" property attributes. Property attributes are stored together with the property name in the Shape object. Forward transitions are not attribute-savvy and will cause poor Shape reuse in the case of multiple same-name properties with different attributes. Oh, and this patch also adds Object.getOwnPropertyDescriptor() :^)	2020-04-10 00:36:06 +02:00
Andreas Kling	e323246517	Meta: Add missing copyright headers	2020-04-06 11:09:01 +02:00
Andreas Kling	5e6e1fd482	LibJS: Start implementing object shapes ... This patch adds JS::Shape, which implements a transition tree for our Object class. Object property keys, prototypes and attributes are now stored in a Shape, and each Object has a Shape. When adding a property to an Object, we make a transition from the old Shape to a new Shape. If we've made the same exact transition in the past (with another Object), we reuse the same transition and both objects may now share a Shape. This will become the foundation of inline caching and other engine optimizations in the future. :^)	2020-04-02 19:32:21 +02:00