04-Nov-2013 12:28, Robert Schadek пишет:
On 11/04/2013 06:48 AM, Philippe Sigaud wrote:
On Sun, Nov 3, 2013 at 7:08 PM, Timothee Cour
<thelastmamm...@gmail.com <mailto:thelastmamm...@gmail.com>> wrote:
On Sun, Nov 3, 2013 at 1:13 AM, Philippe Sigaud
<philippe.sig...@gmail.com <mailto:philippe.sig...@gmail.com>>wrote:
My current plan is to write different engines, and letting
either the user select them at compile-time, or to have the
parser decide which one to use, depending on the grammar. I'm
pretty sure the 'Type 3' parts of a grammar (regular
expressions) could be bone by using std.regex, for example.
even lexing can't be done with regex, eg nesting comments : /+ ... +/
Also, although it may seem cleaner at first to combine lexing and
parsing in 1 big grammar (as done in pegged), it usually is faster
do feed a (separate) lexer output into parser.
Lexing, yes. I was imprecise: even in a context-free grammar, some
rules are regular and could use std.regex (the ct part) as the
underlying engine, just for that rule.
Lexing can not be done with regex. Think myArray[1. ] ! What is next a
dot or a number.
You could use lookahead extension ;)
In general I would not recommend ATM to use std.regex for
performance-critical lexer if only because it wasn't tuned for such a
use case yet.
I have plans for extending std.regex capabilities in many directions,
lexing being one important use case.
--
Dmitry Olshansky