Re: Right Associative Matching Example (for Docs)

On Thu, 18 Dec 2008 15:02:47 +0100
Paolo <[email protected]> wrote:

> On Thu, Dec 18, 2008 at 04:15:55AM -0700, Chris Babcock wrote:
> > Use right associative matching when working with tabular data and
> > you want to match columns near the end of the line. For example,
> > parsing a CSV file with /(?i:":*:email:".+?"([[:print:]]+?)".+?\n)/
> > matches the column after :email:
> > while /(?ir:":*:email:".+?"([[:print:]]+?)".+?\n)/ matches the last
> > column on the line. 
> 
> what's the wanted result here? I get:
> 
> $ cat /tmp/csv.csv
> "1","a","[email protected]","uno","due","tre"
> "2","b","[email protected]","uno","due","tre"
> "3","c","[email protected]","uno","due","tre"
> 
> $ crm '-{isolate (:e:) /[email protected]/
>     match (:: :a:) /(?ir:":*:e:".+?"([[:print:]]+?)".+?\n)/
>     output /a=:*:a:\n/
>   }' < /tmp/csv.csv
> a=,
> 
> $ crm '-{isolate (:e:) /[email protected]/
>     match (:: :a:) /(?i:":*:e:".+?"([[:print:]]+?)".+?\n)/
>     output /a=:*:a:\n/
>   }' < /tmp/csv.csv 
> a=,
> 
> not very meaningful to me.

Try:

crm '-{isolate (:e:) /[email protected]/
    match (:: :a:) /(?ir:":*:e:".+?"([[:print:]]+?)".*?\n)/
    output /a=:*:a:\n/
  }' < /tmp/csv.csv

The problem is that I was overcompensating for a bad habit. I've been
trying to break the habit of using * when I mean +. If you don't have a
comma or some other character at the end of the line then the closing
quotes go to satisfy the ".+?" and the comma becomes the last 'field'.

Chris


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