Thanks Gordon!
The really answered a question I had and also explains why you didn't
just use the ANTLR rewriter to create the tree or nodes during
parsing. I really understand now.
And as you said, a top down walk should work for what we have to do
and it is quite maintainable. Which will mean more development from
more devs.
Our current plans involve running generated js through googles closure
compiler which drastically optimizes the code before it even gets to
the browser's parser and compiler.
Thanks for the info.
Mike
Quoting Gordon Smith <gosm...@adobe.com>:
I would be surprised if the BURM is faster than a simple top-down walk.
The main advantage of using a BURM is that it allows for
optimizations to be easily coded as alternate reductions with lower
cost. Typically there are many difference sequences of bottom-up
reductions that could be applied to reduce the tree, and the BURM
actually computes the *lowest-cost* sequence out of all possible
sequences. (It is solving a complicated optimization problem,
although in an efficient way.)
As a trivial example, in addition to writing a reduction for
expression + expression
that reduces
a + b
to instructions like
push a
push b
add
and
1 + 2
to (inefficient) instructions like
push 1
push 2
add
you can write a reduction for
constant + constant
and assign it a lower "cost" so that
1 + 2
reduces to
push 3
In the case of JavaScript, I'll bet that today's JavaScript engines
are good at doing various optimizations, so I don't see why an
AS->JS cross-compiler needs to do them in advance using a BURM.
- Gordon
-----Original Message-----
From: Alex Harui [mailto:aha...@adobe.com]
Sent: Friday, December 14, 2012 10:34 AM
To: flex-dev@incubator.apache.org
Subject: Re: [FalconJx] Prototype ActionScript -> JavaScript
compiler code up in svn
On 12/14/12 10:04 AM, "Michael Schmalle" <apa...@teotigraphix.com> wrote:
Quoting Alex Harui <aha...@adobe.com>:
On 12/14/12 4:24 AM, "Erik de Bruin" <e...@ixsoftware.nl> wrote:
Dude,
"goog" it is.
I just needed a little pep-talk, I guess ;-)
Right now, I'm trying to get FalconJS to compile an MXML file and
output the goog stuff. That work got delayed because there were more
distractions from the 4.9 release than I expected. Then I will try
to get the BURM/Reducer/Emitter to do the same. Mike sent me what he
tried to do in this area so I can reference it if needed.
We are definitely in prototype/research mode and different angles
should be investigated. The key to the "Apache Way" is that if we
have to make choices in deciding what to ship, it should be done
on technical merit.
What context are you speaking from? compiler, js framework?
In theory, everything in Apache is decided on technical merit. If
your version of AS to JS turns out to be faster and easier to
maintain, it will win.
It will be interesting to figure out what to do if the BURM version
is significantly faster, but my gut says that won't be the case.
--
Alex Harui
Flex SDK Team
Adobe Systems, Inc.
http://blogs.adobe.com/aharui
--
Michael Schmalle - Teoti Graphix, LLC
http://www.teotigraphix.com
http://blog.teotigraphix.com
