File Coverage

blib/lib/Tie/FileSection.pm

Criterion	Covered	Total	%
statement	89	95	93.6
branch	44	50	88.0
condition	36	42	85.7
subroutine	8	10	80.0
pod	1	1	100.0
total	178	198	89.9

use strict;
package Tie::FileSection;
$Tie::FileSection::VERSION = '0.171861';
# ABSTRACT: restrict files sequential access using array like boundaries
require Tie::Handle;
our @ISA  = qw( Tie::StdHandle );

sub new{
   my $pkg = $_[0] eq __PACKAGE__ ? shift : __PACKAGE__ ;
   my %opts = @_;
   $opts{filename} || $opts{file} or die "filename|file parameter is mandatory!";
   my $first_line       = $opts{first_line} // 0;
   my $last_line        = $opts{last_line} // 0;
   my $use_real_line_nr = $opts{use_real_line_nr};
   my $FH = $opts{file};
   if(!$FH && defined $opts{filename}){
      open $FH, '<', $opts{filename} or die "** could not open file $opts{filename} : $!\n";
   }
   tie *F, $pkg, $FH, $first_line, $last_line, $use_real_line_nr;
   return \*F;
}

sub TIEHANDLE{
   my ($pkg, $FH, $first_line, $last_line, $use_real_line_nr) = @_;
   my $self = bless {
         handle           => $FH,
         first_line       => $first_line,
         last_line        => $last_line,
         init             => 0, #lazy read
         curr_line        => 0,
         use_real_line_nr => $use_real_line_nr,
         line_buffer      => [],
         tell_buffer      => [],
      }, $pkg;
   return $self;
}

sub UNTIE{
   my $fh = $_[0]->{handle};
   undef $_[0];
   close( $fh );
}

sub EOF{
   my $self = shift;
   my $f = $self->{first_line};
   my $l = $self->{last_line};
   if($f>=0 && $l>0 && $f > $l){ #static EOF
      return 1;
   }
   if($f<0 && $l<0 && $l < $f ){ #static EOF
      return 1;
   }

   if($f<0 && $l>0){
      return abs($f) + $self->{curr_line} >= $l;
   }

   if($self->{init} && 0 <= $l && $l >= $self->{curr_line}){
      return 1;
   }

   if(eof( $self->{handle} )){
      #take in account buffer here
      if($l < 0 && scalar(@{$self->{line_buffer}})
         return 1;
      }
      else{
         #buffer not empty
         return if @{$self->{line_buffer}};
      }

      return 1;
   }
   return;
}

sub TELL {
   my $self = shift;
   $. = $self->{curr_line};
   return tell($self->{handle}) unless $self->{use_buffer};
   return $self->{tell_buffer}[0];
}

sub _readline{
   my $self = shift;
   my $fh   = $self->{handle};
   my $l    = $self->{last_line};
   my $tellbuff = $self->{tell_buffer};
   my $linebuff = $self->{line_buffer};
   unless($self->{init}++){
      my $f    = $self->{first_line};
      if($f > 0){
         my $i = $f;
         while(--$i && defined scalar <$fh>){
         }
      }
      elsif($f < 0){
         #need to read until eof for abs($f) records
         for(1..abs $f){
            push @$tellbuff, tell($fh);
            push @$linebuff, scalar <$fh>;
         }
         $self->{use_buffer}++;
         while(!eof $fh){
            shift @$tellbuff;
            shift @$linebuff;
            push @$tellbuff, tell($fh);
            push @$linebuff, scalar <$fh>;
         }
      }
      if($f > 0 && $l < 0){
         for(1..abs $l){
            push @$tellbuff, tell($fh);
            push @$linebuff, scalar <$fh>;
         }
         $self->{use_buffer}++;
      }
      if(eof($fh)){
         #add the final pos if requested aftere EOF.
         push @$tellbuff, tell($fh);
      }
      if($self->{use_real_line_nr}){
         $. -= @$linebuff if $self->{use_buffer};
         $self->{curr_line} = $.;
      }
      else {
         $. = undef;
      }
   }
   #read one line and return it, take in accound first_line/last_line and buffer
   my $eof = eof($fh);
   my $pos  = tell($fh);
   my $line = $eof ? undef : <$fh>;
   if($self->{use_buffer}){
      unless($eof){
         push @$linebuff, $line;
         push @$tellbuff, $pos;
      }
      elsif($l < 0 && scalar(@$linebuff)
         return;
      }
      $line = shift @$linebuff;
      shift @$tellbuff unless @$tellbuff == 1;  #always keep last pos
   }
   $self->{curr_line}++;
   $. = $self->{curr_line};
   return $line;
}

sub READLINE {
   my $self = shift;
   return if $self->EOF;   #test basics boundaries
   unless(wantarray){
      return $self->_readline;
   }
   #ARRAY
   my @rows;
   while(defined($_=$self->READLINE)){
      push @rows, $_;
   }
   @rows;
}

sub CLOSE   { close($_[0]->{handle}) }
sub FILENO  { fileno($_[0]->{handle}) }
1;

__END__