Re^2: Question on RE based matching

Hi ww,
Here is the complete code:

#!/usr/bin/perl

use strict;
use warnings;
our ($fileIn, $fileOut);

use Getopt::Long;

GetOptions(
     'FileIn=s' => \$fileIn,
     'FileOut=s' => \$fileOut,
  );

if($fileIn && $fileOut) {
   open(INPUT,"<","$fileIn");
   #undef $/;
   while(<INPUT>) {
   next if /^\n/;
   s/\t+//g;
   s/^\s+//g;
   if(/^HEADER(.*?)^GENRE_BY(.*)/sm) {
    print ;
   }
  }
 }
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I saved this code into a file called x.pl. Made x.pl into an excutable code.
I executed, ./x.pl -fileIn lla -fileOut out_file
where the input file lla contains:

HEADER(
   LIBDAT("GTASK")
   VENDOR("DeltaQ")
   Environment("zeronom")
   TASK_VERSION("5.2")
   GENRE_BY("dumpTc")
)
...
...
HEADER(
   LIBDAT("GTASK")
   VENDOR("DeltaQ")
   Environment("zeronom")
   TASK_VERSION("5.2")
   GENERATED_BY("dumpTc")
)
...
...
HEADER(
   LIBDAT("GTASK")
   VENDOR("DeltaQ")
   Environment("zeronom")
   TASK_VERSION("5.2.1")
   GENRE_BY("dumpTc")
)
...
...
[download]

I am possibly doing something wrong. Any help will be great!
Christina J.

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Re^3: Question on RE based matching by almut (Canon) on Nov 19, 2007 at 10:12 UTC
Your (main) problem is that you're matching against individual lines, i.e. `'HEADER('`, next `' LIBDAT("GTASK")'`, and so on. In other words, the regex can never find 'HEADER...' and 'GENRE_BY...' at the same time. One way around this would be to split the input appropriately (as shown in the snippet by GrandFather). Another way would be to use the flip-flop operator `..` to accumulate the necessary lines as shown below. The expression `if (/^HEADER/ .. /^\)/)` is true starting with a line matching `/^HEADER/` up until a line matching `/^\)/`, in which case you append the current line to the accumulator (`$entry`). Upon the next line (not being `HEADER` or `)`) the flip-flop is reset to false. (I've put in an additional end-of-entry test (`if (/^\)`), so the code will correctly deal with the case where a new HEADER line is immediately following a previous entry (without any other lines in between) — if your input always has other stuff in between the entries, you could also just put the regex test directly in an `else` branch of the flip-flop test...) `#!/usr/bin/perl use strict; use warnings; use Getopt::Long; GetOptions( 'FileIn=s' => \my $fileIn, 'FileOut=s' => \my $fileOut, ); if ($fileIn && $fileOut) { open(INPUT,"<","$fileIn"); my $entry = ""; while (<INPUT>) { next if /^\n/; if (/^HEADER/ .. /^\)/) { # flip-flop $entry .= $_; # accumulate input } if (/^\)/) { # end of entry # check for desired type of entry if ($entry =~ /^HEADER(.?)^\sGENRE_BY(.*)/sm) { print $entry; } $entry = ""; # reset accumulator } } }` [download]	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^3: Question on RE based matching
by almut (Canon) on Nov 19, 2007 at 10:12 UTC

Your (main) problem is that you're matching against individual lines, i.e. 'HEADER(', next ' LIBDAT("GTASK")', and so on. In other words, the regex can never find 'HEADER...' and 'GENRE_BY...' at the same time.

One way around this would be to split the input appropriately (as shown in the snippet by GrandFather). Another way would be to use the flip-flop operator .. to accumulate the necessary lines as shown below. The expression if (/^HEADER/ .. /^\)/) is true starting with a line matching /^HEADER/ up until a line matching /^\)/, in which case you append the current line to the accumulator ($entry). Upon the next line (not being HEADER or )) the flip-flop is reset to false.

if (/^\)

immediately

else

#!/usr/bin/perl

use strict;
use warnings;

use Getopt::Long;

GetOptions(
     'FileIn=s'  => \my $fileIn,
     'FileOut=s' => \my $fileOut,
  );

if ($fileIn && $fileOut) {
    open(INPUT,"<","$fileIn");

    my $entry = "";
    while (<INPUT>) {
        next if /^\n/;
        
        if (/^HEADER/ .. /^\)/) {  # flip-flop
            $entry .= $_;          # accumulate input
        }
        if (/^\)/) {               # end of entry
            # check for desired type of entry
            if ($entry =~ /^HEADER(.*?)^\s*GENRE_BY(.*)/sm) {
                print $entry;
            }
            $entry = "";           # reset accumulator
        }
    }
}
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