[Smee-development] Smee Status and next steps

[Pennell, D. <DPe...@qu...>]

Current status:
Parsing
=======
- All syntax should be accepted except RegExp literals and Unicode source.
- Error reporting is dismal - most errors end up as "Unexpected token", some
as infinite loops in parser

Core Engine
==========================
- All expressions (except those involving RegExp literals) are implemented
and have test cases.
- Number to string conversion is imcomplete - I need to tackle the "Gay
algorithm".
  The biggest issue is that doubles are going to print with "d" at the end.
- Runtime error reporting could certainly be improved.  The spec generally
just says "throw XXXError", I've begun using
  Mozilla as a reference for adding a reasonable message to XXXError.
- Runtime environment is now "thread-safe".  All execution state is in the
execution context.

Objects
=======
- Global
  All except parseInt(), parseFloat(), decodeURI(), decodeURIComponent(),
encodeURI(), encodeURIComponent()
- Function
  Enough exists to support builtin functions and user defined function, none
of the Function.prototype functions
  except toString() are implemented yet.
  Additional property:  setting trace to true (or anything that will convert
to true) will generate SmeeFunctionEnter
  and SmeeFunctionExit exceptions. The exceptions carry the name of the
function, the arguments and on exit, the
  return value.
- Array
  Functionally complete, but it deserves some performance improvement.
- String
  All functions complete except those that take RegExp objects as arguments:
match(), replace(), search(), split().
  Several functions need additional Unicode support: localeCompare(),
toLowerCase(), toLocaleLowerCase(), 
  toUpperCase(), toLocaleUpperCase()
- Boolean
  Complete
- Number
  All functions except those that convert to strings (that pesky Gay
algorithm again):  toFixed(),toExponential(),
  toPrecision()
  Additonal functions:  toInt32(), toUint16() and toUint32().
- Math
  All functions except atan2() and pow()
- Date
  Locale specific functions are identical to the non-locale versions.
  Specification allows implementation choice on string representation, both
for Date->string and string->Date.
  Smee uses a simple yyyy.mm.dd-hh:mm:ss.mmm format.
- RegExp
  The object exists and could be constructed, but none of the functions are
implemented.
  Vassili Bykov provided a summary of the differences between his Regex11
and the ECMAScript spec.  There are quite
  a few issues, many of which are resolved in his next version.  I'm trying
to decide if I should wait for his next
  version or just build my own from the ECMAScript spec.  I may just provide
a first cut that uses Vassili's code and
  then decide.
- Error (and its children)
  Complete.

Next Steps
==========
- Finish string->number, Global and Math
- SmeeHostObject will wrap any non-Smee object.  You will have a choice of
instantiating this in promiscuous mode
  or of explicitly specifying which bits of the protocol are exposed.  In
promiscuous mode accessor methods will 
  appear as value properties and all other methods will appear as function
properties.  The host objects class will
  appear as the prototype.  New properties will be added to the wrapper.  I
haven't enough time thinking about
  the controlled access instantiation protocol yet.  It seems clear that you
will want to provide a collection of
  methods that are accessible, but I'm not sure what else is needed.
- Move prototype functions from class side to instance side
  It seemed like the right choice at the time, but now that I have a better
understanding of prototype functions,
  "this" and function tranferrance, I realize that I can move these to the
instance side and simplify things.
- Implement RegExp.  I'll probably do this in two phases - use Regex11 in
the first phase, and either use its
  successor in the second phase or roll my own.  The first phase would also
involve completing the String prototype
  functions.
- Improve error handling in parser
- Improve error reporting in parser and runtime
- Add Unicode support
- Performance.  Improve performance when and if necessary.  I've run one
test so far:
  Parse 'a+b*2'.  Instantiate global context.  In loop, set values for a and
b in context, execute program and retrieve
  result.  On my 1GHz notebook, it executes at 30 KHz.  I need to run tests
with function calls, I expect that they
  need some work.