NAME

Algorithm::Diff3::DiffHeckel - P. Heckel's diff plugin

SYNOPSIS

  use Algorithm::Diff3;
  my $f = Algorithm::Diff3::Factory->new;
  my $p = $f->create_diff;
  my $mytext   = $f->create_text([ map{chomp;$_} <F0> ]);
  my $original = $f->create_text([ map{chomp;$_} <F1> ]);
  my $diff2 = $p->diff( $origial, $mytext );
  $diff2->each(sub{
      my( $r ) = @_;
      print $r->as_string, "\n";
      if ( $r->type ne 'd' ) {
          print '-', $original->as_string_at( $_ ) for $r->rangeB;
      }
      if ( $r->type ne 'a' ) {
          print '+', $mytext->as_string_at( $_ ) for $r->rangeA;
      }
  });

ABSTRACT

This is a package for Algorithm::Diff3 to compute difference sets between two text buffers based on the P. Heckel's algorithm. Anyone may change this to an another diff or a its wrapper module by injecting of a your custom Factory instanse.

DESCRIPTION

Algorithm::Diff3 needs a support of computing difference sets between two text buffers (diff). As the diff(1) command, the required diff module creates a list of tapples recorded an information set of a change type (such as a,c,d) and a range of line numbers between two text buffers.

Since there are several algorithms and their implementations for the diff computation, Algorithm::Diff3 makes a plan independ on any specific diff routine. It calls a pluggable diff processor instanse specifed in a factory commonly used in Algorithm::Diff3. Anyone may change diff plugin according to their text properties.

For users convenience, Algorithm::Diff3 includes small diff based on the P. Heckel's algorithm. On the other hands, many other systems use the popular Least Common Seaquense (LCS) algorithm. The merits for each algorithms are case by case. In author's experience, two algorithms generates almost same results for small local changes in the text. In some cases, such as moving blocks of lines, it happened quite differences in results.

create

Author recommends you to create an instanse of diff prosessor by using with a factory as follows.

  use SomeFactory;
  my $f = SomeFactory->new;
  my $p = $f->create_diff;

Algorithm::Diff3::Factory is a class to packaging several classes for the buildin diff processor.

diff

Performing the diff process, we send a `diff' message with two text instanses to the receiver

  my $diff2 = $p->diff( $origial, $mytext );

Where the parameters of text might be a kind of as follows.

Scalar string separated by ``\n''.
Unblessed or blessed one dimentional array refs.
An already blessed instanse by Algorithm::Diff3::Text or an another the equivalent type as one (not required descendant class of one).

After the process, the receiver returns the list as difference sets.

AUTHOR

MIZUTANI Tociyuki <tociyuki@gmail.com>

COPYRIGHT AND LICENSE

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version.

Algorithm::Diff3::DiffHeckel - P. Heckel's diff plugin