Re: lpeg pattern repetition
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- Subject: Re: lpeg pattern repetition
- From: Roberto Ierusalimschy <roberto@...>
- Date: Mon, 2 Jun 2008 01:57:21 -0300
> One question, would your solution of:
>
> line = lpeg.P" says hello"
> p = (1 - line)^0 * line
>
> be more efficient if written as:
>
> line = lpeg.P" says hello"
> p = (1 - #line)^0 * line
>
> I have added a "#" to "line" so as to consume no input, on the basis that
> "consuming input" might take more work than not doing so. Or is that
> irrelevant?
Actually, consuming no input is slightly less efficient, because the
machine must consume the input (otherwise how to match it?) and then
backtrack. But in this particular case we have '-line', so it does
not consume input anyway.
-- Roberto