Michael Shipper
and 1 contributors

NAME

Data::Range::Compare::Stream::Iterator::File - Simple File Iterator

SYNOPSIS

  use Data::Range::Compare::Stream;
  use Data::Range::Compare::Stream::Iterator::File;

  my $iterator=Data::Range::Compare::Stream::Iterator::File->new(
    filename=>'some_file.csv',
  );

  while($iterator->has_next) {
    my $next_range=$iterator->get_next;
    print $next_range,"\n";
  }

DESCRIPTION

This module implements a very simple file iterator interface. This iterator interface assumes that the data is pre-sorted. The result objects returned are ranges: The class the objects are constructed from is determined by $iterator->NEW_FROM. Parsing is handled by $iterator->parse_line.

OO Methods

  • my $iterator=new Data::Range::Compare::Stream::Iterator::File;

    Instance Constructor, all arguments are optional

    One of the following arguments is mandatory:

      filename=>'source_file.csv'  
        # the file is assumed to be an absolute or relative path to the file location.
    
      fh=>\*GLOB|IO::File->new('somefile')
        # The object itself is assumed to be an open file handle
        # filename will be set to the object ref of the fh=>xxx object

    Optional arguments:

       factory_instance =>$obj
         # defines the object that implements the $obj->factory($start,$end,$data).
         # new ranges are constructed from the factory interfcae.  If a factory interface
         # is not created an instance of Data::Range::Compare::Stream is assumed.
    
       NEW_FROM=>'Data::Range::Compare::Stream',
         # Depricated!
         # sets the object class new ranges will be created from
    
       parse_line=>undef|code_ref
         # Default: undef, Sets the code ref to be used when parsing a line
         # if not set the default internals will be used
    
       result_to_line=>undef|code_ref
         # Default: undef, Sets the code ref used to convert a result to a line that can be parsed
         # if not set the default internals will be used
  • if($iterator->in_error) { ... }

    Returns true if there was a problem opening the file.

  • my $class=$iterator->NEW_FROM;

    $class will contain the name of the class new ranges are to be constructed from. The resulting class is required to extend or implement Data::Range::Compare::Stream.

  • my $ref=$self->parse_line($line);

    Given a $line returns the arguments required to construct an object that extends or implements Data::Range::Compare::Stream. When overloading or passing in constructor arguments that provide a call back make sure result_to_line produces the expected line parse_line expects.

      sub parse_line {
        my ($self,$line)=@_;
        return $self->{parse_line}->($line) if defined($self->{parse_line});
        chomp $line;
        [split /\s+/,$line];
      }
  • while($iterator->has_next) { do something }

    Returns true when there are more rows to fetch.

  • my $range=$iterator->get_next;

    Returns the next $range from the given source file.

  • my $line=$iterator->result_to_line($range);

    Given a $range from $iterator->get_next, this interface converts the $range object into a line that can be parsed by $iterator->parse_line($line). Think of this function as a data serializer for range objects generated by an $iterator object. The code can be described as follows:

      sub result_to_line {
        my ($self,$range)=@_;
        my $line=$range->range_start_to_string.' '.$range->range_end_to_string."\n";
        return $line;
      }
  • my $size=$iterator->get_size

    Returns the number of lines in the source file.

  • my $pos=$iterator->get_pos;

    Returns the current line the iterator is on.

SEE ALSO

Data::Range::Compare::Stream::Cookbook

AUTHOR

Michael Shipper

Source-Forge Project

As of version 0.001 the Project has been moved to Source-Forge.net

Data Range Compare https://sourceforge.net/projects/data-range-comp/

COPYRIGHT

Copyright 2011 Michael Shipper. All rights reserved.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.