package PickDiff ;

use strict ;
use warnings ;

# $like must be sub-ref ; predicate : sub (file-name) -> bool
my $like = sub { die "PickDuff: don't know what to like" ; } ;
sub set_like { my $self = shift ; $like = shift ; $like ; }

sub TIEHANDLE
  { my ( $class, $fh ) = @_ ;
    bless { fh => $fh, like => 1 }, $class ;
  }

sub READLINE
  { my $self = shift ;
    my $fh = $self -> {fh} ;
    my $line ;
    while ( 1 )
      { $line = <$fh> ;
        return undef unless defined $line ;
        if ( $line =~ /^(Modified|Added|Deleted):/ )
          { my $file = ( split ' ', $line ) [ 1 ] ;
            $self -> { like } = &$like ( $file ) ;
          }
        last if $self -> { like } ; 
      }
    $line ;
  }

sub CLOSE
  { close shift->{fh}
    or die $!
     ? "Error closing diff pipe: $!"
     : "Exit status $? from diff pipe" ;
  }

1 ;