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Re: Parsing... possible w/o too much stress ?

by BrowserUk (Patriarch)
on Mar 19, 2003 at 16:39 UTC ( [id://244374]=note: print w/replies, xml ) Need Help??


in reply to Parsing... possible w/o too much stress ?

If the snippet you show indicates that the bit you wish to remove is the outermost level, and it is not embedded within, or alongside other structures, this is one occasion when the greediness of dot-star comes into its own.

#!perl -slw use strict; my $body = $1 if join('',<DATA>) =~ m[env\s*{(.*)}$]s; print $body; __DATA__ env { "{"; F { "'{\"\{" } g { '}'; } }

Output

C:\test>244329 "{"; F { "'{\"\{" } g { '}'; } C:\test>

Of course, I can imagine any number of scenarios in which this would not work, but in the absence of further info, attempting to compensate for them would simply be guesswork. If you have a better description of the application, I would relish the opportunity to practice my regex skills on real data.

As effective as Parser::RecDescent is for complex grammers, it seems overkill for this application as described. What's the point in having the much vaunted Perl 5 regex engine, if noone is going to learn to use it?

The regex notation is a mini-language of its own. Like any language, it takes time to learn. Like any language it takes practice to master.


Examine what is said, not who speaks.
1) When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
2) The only way of discovering the limits of the possible is to venture a little way past them into the impossible
3) Any sufficiently advanced technology is indistinguishable from magic.
Arthur C. Clarke.

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Re: Re: Parsing... possible w/o too much stress ?
by antifun (Sexton) on Mar 19, 2003 at 21:16 UTC

    This will work as long as the brace that closes the env block is the last one. To wit:

    env { anything you want here } not-env { other stuff }

    is not going to work.

    Now, it's possible that his input might look as simple as your example...but then he (hopefully) would have figured out a solution for that case already; something brain-dead like cat input | awk '{if (first == 1) {print l; l = $0;} else {first=1} }' for instance.

    A poster above said it already -- if it nests, don't use regexes. Even if you do get it to work, you'll wish you hadn't.

    ---
    "I hate it when I think myself into a corner."
    Matt Mitchell

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