How do i pattern match and keep writing to new file until another pattern match - perl

Question

My goal is to find and print all the lines in a "big.v" file starting from pattern match "module" until "endmodule" into individual files.
big.v: module test;
<bunch of code>
endmodule
module foo;
<bunch of code>
endmodule
And the individual files would look like:
test.v : module test;
..
endmodule
foo.v: module test1;
..
endmodule
I got most of it working using:
use strict;
use warnings;
#open(my $fh, ">", $f1) || die "Couldn't open '".$f."' for writing because: ".$!;
while (<>) {
my $line = $_;
if ($line =~ /(module)(\s+)(\w+)(.*)/) {
my $modname = $3;
open(my $fh1, ">", $modname.".v") ;
print $fh1 $line."\n";
## how do i keep writing next lines to this file until following pattern
if ($line =~ /(endmodule)(\s+)(.*)/) { close $fh1;}
}
}
Thanks,

Answer 1

There's a useful perl construct called the 'range operator':
http://perldoc.perl.org/perlop.html#Range-Operators
It works like this:
while ( <$file> ) {
if ( m/startpattern/ .. m/endpattern/ ) {
print;
}
}
So given your example - I think this should do the trick:
my $output;
while ( my $line = <STDIN> ) {
if ( $line =~ m/module/ .. m/endmodule/ ) {
my ( $modname ) = ( $line =~ m/module\s+(\w+)/ );
if ( defined $modname) {
open ( $output, ">", "$modname.v" ) or warn $!;
}
print {$output} $line;
}
}
Edit: But given your source data - you don't actually need to use a range operator I don't think. You could just close/reopen new 'output' files as you go. This assumes that you could 'cut up' your file based on 'module' lines, which isn't necessarily a valid assumption.
But sort of more like this:
use strict;
use warnings;
open ( my $input, "<", "big.v" ) or die $!;
my $output;
while ( my $line = <$input> ) {
if ( $line =~ m/^\s*module/ ) {
#start of module line found
#close filehandle if it's open
close($output) if defined $output;
#extract the module name from the line.
my ($modulename) = ( $line =~ m/module\s+(\w+)/ );
#open new output file (overwriting)
open( $output, ">", "$modulename.v" ) or warn $!;
}
#this test might not be necessary.
if ( defined $output ) {
print {$output} $line;
}
}