Regular expression question

TASdvlper has asked for the wisdom of the Perl Monks concerning the following question:

Hello all,

Thanks to a lot of help here, I'm getting better at regexp, but I have a problem where I'm not even sure where to start.

I want to check a string that contains one or more of the following comma seperated values (in any order): -config,-files,-params,-driverPath,-appPath,-batchPath. I do not want to allow duplicates or the string could match: NONE. So, following are some examples:

$s = "-config,-files"  VALID
$s = "-files,-batchPath"  VALID
$s = "-files,-batch-driverPath"  NOT VALID, not comma seperated.
$s = "NONE"     VALID
$s = "NONE,-params"    NOT VALID, can not mix [NONE] with other values
+.
$s = " -config, -files "   NOT VALID, spaces not allowed (beginning, m
+iddle or end)
$s = "-test"               NOT VALID, not a valid parameter
$s = "-files,-test,-batchPath"   NOT VALID, valid parameters mixed wit
+h invalid parameters.
$s = "-files,files"    NOT VALID, same valid listed 2x
$s = "-config,-files,-params,-driverPath,-appPath,-batchPath"     VALI
+D
[download]

Any help would be greatly appreciated.

Comment on Regular expression question Download Code

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Re: Regular expression question by kvale (Monsignor) on Apr 26, 2004 at 16:41 UTC
Frankly, I would not use a regexp for this (untested) : `my %opts; undef @opts{ qw\|-config -files -params -driverPath -appPath -batchPath NONE\| }; my %seen; for my $e (split /,/ $str) { print "BAD op: $e\n" unless exists $opts{$e}; print "Duplicate: $e\n" if $seen{$e}; print "Incompatible with NONE\n" if $seen{NONE} && scalar keys %see +n > 1; $seen{$e}; }` [download] -Mark	[reply] [d/l]
Re: Regular expression question by japhy (Canon) on Apr 26, 2004 at 17:14 UTC
Assuming you have the string in `$s`: `my %on = (); $s .= ","; unless ($s =~ s/NONE,//) { $on{$_} = $s =~ s/-$_,// for qw( config files params driverPath appPath batchPath ); } die if length $s;` [download] _____________________________________________________ Jeff`[japhy]`Pinyan: Perl, regex, and perl hacker, who'd like a job (NYC-area) `s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;`	[reply] [d/l]
Re: Regular expression question by ccn (Vicar) on Apr 26, 2004 at 16:42 UTC
`sub is_allowed { my $s = shift; return 1 if $s eq 'NONE'; my %allowed, %seen; @allowed{split /,/,'-config,-files,-params,-driverPath,-appPath,-b +atchPath'} = (); ### (incorrect line)return if !exists $allowed{$_} or $seen{$_}++ +foreach split /,/, $s; (!exists $allowed{$_} or $seen{$_}++) and return foreach split /, +/, $s; return 1; }` [download] Upd: incorect "EXPR if COND for LIST" construction fixed	[reply] [d/l]
Re: Re: Regular expression question by dave_the_m (Monsignor) on Apr 26, 2004 at 16:59 UTC
`return if !exists $allowed{$_} or $seen{$_}++ foreach split /,/, $ +s;` [download] That won't work as you can't have stacked statement modifiers.	[reply] [d/l]
Re: Regular expression question by CountZero (Bishop) on Apr 26, 2004 at 19:25 UTC
Instead of splitting on comma, I'd split on ,- Then run the results of the split against the array or list of acceptable keywords (less the starting - of course). Doing so would automatically invalidate the following cases: `-files,-batch-driverPath` : "batch-driverPath" will not be recognized as a valid keyword `-config, -files` : "-config, -files " will not be split on ,- so it will never form a valid keyword As this `split` keeps leading and trailing whitespace, the leading and trailing whitespace cases are invalidated as well. The only things you still have to do "by hand" is checking for incompatible combinations or multiple occurrences of the same keywords. This is left as an exercise for the readers. CountZero "If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law	[reply] [d/l] [select]


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