Intersection regex?

mpeters

Hi:

How does one represent the intersection (i.e. "A ∩ B") of two substrings in a regular expression?

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Comments

Tbag

You mean, like:

my $string = "abba";

And you're looking for "bb" given a regex "[.bb|bb.]" ?

Adam Stoller

You mean, like:

my $string = "abba";

And you're looking for "bb" given a regex "[.bb|bb.]" ?

Square-brackets '[...]' in regex's generally denote a character class and not a pattern - parentheses are used to denote alternate patterns - e.g.: /(.bb|bb.)/ - which can be simplified to just /bb/ in this case.

However, I'm still not sure I understand the original question - perhaps a more verbose example might help elicit responses...

mpeters

Square-brackets '[...]' in regex's generally denote a character class and not a pattern - parentheses are used to denote alternate patterns - e.g.: /(.bb|bb.)/ - which can be simplified to just /bb/ in this case.

However, I'm still not sure I understand the original question - perhaps a more verbose example might help elicit responses...

Given a set of files...


foo.htm
bar.doc
baz.pdf
index.htm
.bashrc
output_text
...et cetera...

...we want to make certain that index.htm and only index.htm has been submitted in a workflow. The proposed solution to this is to determine the intersection of the set containing all files within the domain of discourse (potentially an open set, if I'm not mistaken) and the set containing only index.htm via an if() block, such as...


if(  $my_deployed_files =~ m{index\.html?}g && $my_deployed_files !~ m{every other file NOT including index.html?}g  ) {

    # do something...

} # end if

Adam Stoller

Given a set of files...

foo.htm bar.doc baz.pdf index.htm .bashrc output_text ...et cetera...

...we want to make certain that index.htm and only index.htm has been submitted in a workflow. The proposed solution to this is to determine the intersection of the set containing all files within the domain of discourse (potentially an open set, if I'm not mistaken) and the set containing only index.htm via an if() block, such as...

if( $my_deployed_files =~ m{index\.html?}g && $my_deployed_files !~ m{every other file NOT including index.html?}g ) { # do something... } # end if

Where are you getting the list of deployed files from?
Presumably if it's actually a list - the above could be accomplished with something like:

...
if (@list == 1 && $list[0] =~ /index\.html$/){
   # do something ...
}
...