On 24/03/2016 17:13, Ned Batchelder wrote:
On Thursday, March 24, 2016 at 12:12:55 PM UTC-4, BartC wrote:
On 24/03/2016 15:30, Ned Batchelder wrote:
On Thursday, March 24, 2016 at 9:51:11 AM UTC-4, Steven D'Aprano wrote:
You know what is missing from this conversation?
For one of Bart's critics to actually show faster code.
There's plenty of people telling him off for writing unpythonic and slow
code, but I haven't seen anyone actually demonstrating that Python is
faster than his results show.
As I mentioned before, I'm happy to explain the fuller Python way to
write code, but I don't think Bart wants to learn it, because he is
focused on a different goal than, "write real Python code the best
possible way."
Here, for example, is a real lexer for JavaScript that I wrote:
https://bitbucket.org/ned/jslex/src
Thanks for that.
I don't have any JS to throw at it, but it seems happy with any bits of
source code or even just text.
Using your short driver program (with the prints commented out), and
tested with 'bible.txt' as input (ie. mostly English words), then your
JS lexer was roughly half the speed of the Python version I linked to
last week (with the if-elif chains and working with strings).
I have tried to find your code, but cannot find in the forest of this thread.
Can you provide a link to it online? I would be very interested to understand
the difference in performance.
This the version I used today:
http://pastebin.com/dtM8WnFZ
(others I've experimented with aren't much faster or slower.)
Testing it with lots of C source, the difference is narrower.
(Note that the two will be doing different jobs; one or two things are
not complete on mine, such as the final calculation for floating point
literals. And the number of tokens read is a bit different. But then
they are expecting a different language.
Also, I only tested with large monolithic files (to make measuring easier).
In terms of getting through the same amount of input however, I think
the comparisons aren't too far off.)
This is the test code I used for your JS lexer:
"""A main program for jslex."""
import sys
from jslex import JsLexer
def show_js_tokens(jstext, ws=False):
line = 1
lexer = JsLexer()
n=0
for name, tok in lexer.lex(jstext):
n+=1
# print_it = True
# if name == 'ws' and not ws:
# print_it = False
# if print_it:
# print "%4d %s: %r" % (line, name, tok)
line += tok.count("\n")
print line,n
if __name__ == '__main__':
file="bigpy"
# file="sqlite"
# file="bible.txt"
show_js_tokens(open(file).read())
--
Bartc
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