On Thu, 19 Apr 2012, Frank Shearar wrote:
I found a serious bug in parsing numbers with negative exponents. It
was completey broken, in fact, parsing 1e-1 as 10, not 1 / 10. Anyway.
This version fixes that, and adds a bunch of tests demonstrating that
number parsing will return rationals if it can.
It's significantly slower than Squeak's SqNumberParser:
Time millisecondsToRun: [100000 timesRepeat: [SqNumberParser parse:
'1234567890']] => 466
Time millisecondsToRun: [100000 timesRepeat: [PPSmalltalkNumberParser
parse: '1234567890']] => 32082
I've attached a MessageTally spying on the latter: I've not much skill
in reading these, but nothing leaps out at me as being obviously
awful.
Didn't check the code, just the tally, and I think that
PPSmalltalkNumberParser(PPSmalltalkNumberGrammar)>>digitsBase: is begging
for optimization. It's probably also the cause of the high amount of
garbage which causes significant amount of time spent with garbage
collection.
It's also interesting is that the finalization process does so much work,
there may be something wrong with your image.
Levente
frank
On 14 September 2011 20:26, Frank Shearar <frank.shea...@gmail.com> wrote:
On 3 September 2011 19:35, Nicolas Cellier
<nicolas.cellier.aka.n...@gmail.com> wrote:
2011/9/3 Frank Shearar <frank.shea...@gmail.com>:
On 3 September 2011 18:50, Lukas Renggli <reng...@gmail.com> wrote:
I think it is a good idea to have the number parser separate, after
all it might also make sense to use it separately.
It seems that the new Smalltalk grammar is significantly slower. The
benchmark PPSmalltalkClassesTests class>>#benchmark: that uses the
source code of the collection hierarchy and does not especially target
number literals runs 30% slower.
Also I see that "Number readFrom: ..." is still used within the
grammar. This seems to be a bit strange, no?
Yes: it's a double-parse, which is a bit lame. First, we parse the
literal with PPSmalltalkNumberParser, which ensures that the thing
given to Number class >> #readFrom: is a well-formed token (so, in
particular, Squeak's Number doesn't get to see anything other than a
well-formed token).
It sounds like you're happy with the basic concept, so maybe I should
remove the Number class >> #readFrom: stuff, see if I can't remove the
performance issues, and resubmit the patch.
frank
Yes, a NumberParser is essentially parsing, and this duplication sounds useless.
The main feature of interest in NumberParser that I consider a
requirement and should find its equivalence in a PetitNumberParser is:
- round a decimal representation to nearest Float
It's simple, just convert a Fraction asFloat in a single final step to
avoid cumulating round off errors - see
#makeFloatFromMantissa:exponent:base:
The second feature of interest in NumberParser is the ability to
parser LargeInteger efficiently by avoiding (10 * largeValue +
digitValue) loops, and replacing them with a log(n) cost.
This would be a simple thing to implement in a functional language.
Hopefully this won't offend your sensibilities too much :). It does,
in fact, use 10* loops - I wrote an experimental "front half * rear
half" recursion, which was slower in my benchmarks.
This version has the grammar and parser doing no string->number
conversion at all. PPSmalltalkNumberMaker supplies a number of utility
methods designed to stop one from making malformed numbers. It also
supplies a builder interface that the parser uses to construct
numbers.
frank
Nicolas
Lukas
On 3 September 2011 17:18, Frank Shearar <frank.shea...@gmail.com> wrote:
On 3 September 2011 15:56, Lukas Renggli <reng...@gmail.com> wrote:
On 3 September 2011 16:51, Frank Shearar <frank.shea...@gmail.com> wrote:
Hi Lukas,
I haven't :) mainly because I'm unsure where to put it - is there
perhaps a PP Inbox, or shall I just post the merged version, or what's
your preference? (How about an mcd between my merge and PP's head?)
Just put the .mcz at some public URL (dropbox, squeak source, ...) or
attach it to a mail.
Ah, great - here it is. You'll see I've written the grammar as a
separate class. That was really more to make what I'd done more
obvious and to minimise the change to PPSmalltalkGrammar, but perhaps
it's not a bad idea anyway: it's easy to see the number literal
subgrammar.
frank
Lukas
--
Lukas Renggli
www.lukas-renggli.ch
--
Lukas Renggli
www.lukas-renggli.ch
