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Re: Allow digits in identifiers (issue 6493072)
From: |
k-ohara5a5a |
Subject: |
Re: Allow digits in identifiers (issue 6493072) |
Date: |
Wed, 05 Sep 2012 06:59:16 +0000 |
While we are thinking about this, I suggest we remove (later) the rule
forbidding backing-up states in the scanner. It made only a 0.2% in the
worst-case scenario I could think of.
The rule had been violated, giving us the slightly slower scanner, for
about ten years (I estimate) prior to the warning-cleanup patch da949cdc
one year ago.
It costs a lot of programmer time to make the extra rules to save that
0.2%, and I know of no efficient cure for patterns that can require
arbitrary amounts of backing up. \violin1_2_3_4_5
http://codereview.appspot.com/6493072/diff/5015/lily/lexer.ll
File lily/lexer.ll (left):
http://codereview.appspot.com/6493072/diff/5015/lily/lexer.ll#oldcode34
lily/lexer.ll:34: flex -b <this lexer file>
`-b, --backup, `%option backup''
Generate backing-up information to `lex.backup'. This is a list
of
scanner states which require backing up and the input characters
on
which they do so. By adding rules one can remove backing-up
states. If _all_ backing-up states are eliminated and `-Cf' or
`-CF' is used, the generated scanner will run faster (see the
`--perf-report' flag). Only users who wish to squeeze every last
cycle out of their scanners need worry about this option. (*note
Performance::).
http://codereview.appspot.com/6493072/
- Re: Allow digits in identifiers (issue 6493072), (continued)
Re: Allow digits in identifiers (issue 6493072), k-ohara5a5a, 2012/09/03
Re: Allow digits in identifiers (issue 6493072),
k-ohara5a5a <=
Re: Allow digits in identifiers (issue 6493072), dak, 2012/09/05
Re: Allow digits in identifiers (issue 6493072), dak, 2012/09/05