This is an experimental interpreter for a subset of Self. It has nearly no runtime system. Super calls and direct resends are missing. I wrote it some years ago (in Java) to get a grasp on the non-trivial message execution semantic of this interesting programming language. I haven't checked with the Self system so I might have got some methods or some semantics wrong.
Most code is from 2013 and was written for Dart 1.x but in 2022 I ported it to
the then current Dart 2.19. Run dart pub get to initialize the project, then
run dart test to run all unit tests and run dart run to start a simple REPL.
Use ^C or ^D to end it.
The Makefile helps in creating a code coverage report.
Currently, the interpreter is lacking support for both undirected and for
directed resends. Neither does the parser understands them nor can the runtime
system execute them. A resend is a NAME (or resend keyword) followed by a DOT
followed by either a NAME, OPERATOR or KEYWORD, without whitespace inbetween. I
might be able to use (\w+)\.(?=\S)|(\w+) to distinguish resends from normal
names. Then a _T.res could denote resend identifiers, swallowing the dot.
The bigger problem is that to search for a resend message, I cannot start with
the receiver for the method lookup but need to start at the parents of the
object the current method belongs to. This is an information I don't keep track
of. When normally searching for a method, I find and return the Slot. I'd have
to store a reference to the object in each slot. Or at least return that object
together with the slot and then store a reference in the method object. Or at
least for methods that have a resend instruction. But I don't want to modify the
instructions so I probably need to add a hidden slot.
The findSlot call should return a (Slot, SelfObject) tuple. We could then
store the holder inside the current activation (that is method) as a slot called
(holder). A resend would then read that (holder) slot and starts findSlot
with its parents.