NAME

       VCS::Lite - Minimal version control system

SYNOPSIS

         use VCS::Lite;

         # diff

         my $lit = VCS::Lite->new('/home/me/foo1.txt');
         my $lit2 = VCS::Lite->new('/home/me/foo2.txt');
         my $difftxt = $lit->delta($lit2)->diff;
         print OUTFILE $difftxt;

         # patch

         my $delt = VCS::Lite::Delta->new('/home/me/patch.diff');
         my $lit3 = $lit->patch($delt);
         print OUTFILE $lit3->text;

         # merge

         my $lit4 = $lit->merge($lit->delta($lit2),$lit->delta($lit3));
         print OUTFILE $lit4->text;

DESCRIPTION

       This module provides the functions normally associated with a version control system, but
       without needing or implementing a version control system. Applications include wikis,
       document management systems and configuration management.

       It makes use of the module Algorithm::Diff. It provides the facility for basic diffing,
       patching and merging.

API

   new
       The underlying storage concept of VCS::Lite is an array. The members of the array can be
       anything that a scalar can represent (including references to structures and objects). The
       default is for the object to hold an array of scalars as strings corresponding to lines of
       text.

       The basic form of the constructor is as follows:

         my $lite = VCS::Lite->new( '/my/file');

       which slurps the file to make an object. The full form is as follows:

         my $lite = VCS::Lite->new( $object_id, $separation, $source, ...);

       $object_id
           This is a string to identify what is being diffed, patched or merged, in the
           application's environment. If there is no $source, this is used as a filename from
           which to read the content.

       $separation
           This is an optional parameter, which can be used via $/ to split the input file into
           tokens. The default is for lines of text. If you pass in a string to be tokenized,
           this will use $sep as a regular expression

           $separation can be a scalar or scalar ref, where this is used to break up the input
           stream. All values permitted for $/ are allowed (see perlvar).

           $separation can also be a hashref, to give a finer level of control. For example:

             {  in => '\n',
                out => '\n',
                chomp => 1 }

           'in' is the input record separator to use (the same as you would pass as $sep).  Note
           that all values allowed for $/, and indeed the value of $/ passed in is what is used
           as a default. 'in' can be a string or a regexp.

           'out' is the character used on joining the members to output the results (text method
           in scalar context). This is the output record separator $\. Note that 'out' defaults
           differently depening on the setting of 'chomp': if 'chomp' is off, 'out' will default
           to the empty string, or rather the passed in value of $\. If 'chomp' is on, 'out' will
           default to 'in' - note that you should specify 'out' explicitly if you are using a
           regexp for 'in'.

           If the 'chomp' flag is set, the text matching 'in' is removed from the input lines as
           they are read. 'chomp' is not on by default, as this is new functionality in release
           0.08.

       $source
           if unspecified causes $object_id to be opened as a file and its entire contents read
           in. The alternative is to supply $source, which can be one of the following:

           "scalar"
               This is a string which is tokenized using $separation

           "arrayref"
               Array of tokens

           "filehandle" or "globref"
               Contents of file are slurped

           "callback"
               This is called successively to obtain tokens until received undef.

       In the Perl spirit of DWIM, new assumes that given an arrayref, you have already done all
       the work of making your list of whatevers. Given a string (filename) or a file handle, the
       file is slurped, reading each line of text into a member of the array. Given a callback,
       the routine is called successively with arguments $p1, $p2, etc. and is expected to return
       a scalar which is added (pushed on) to the array.

   apply
         $lite->apply($lite2);
         $lite->apply($lite3, base => 'original');

       This method call corresponds approximately to a version control system's check-in
       function. This causes $lite to be modified, so that its contents now reflect those of
       $lite2.

       $lite does retain the original contents, available via original. However, unlike in a
       version control system, the object holds only the first original and latest contents.

       The VCS::Lite object passed in can also have its own original version. If this is the
       case, merging will be performed to incorporate the change as if it had come from a
       different branch. To facilitiate the merging process, optionally specify a base version,
       which can be the string 'original', 'contents' (the default) or a VCS::Lite object whose
       contents will be used.  This corresponds to the "common ancestor" in version control
       systems.

   original
       This returns a VCS::Lite object for the original version, before changes were applied with
       apply.

   text
         my $foo = $lite->text;
         my $bar = $lit2->text('|');
         my @baz = $lit3->text;

       In scalar context, returns the equivalent of the file contents slurped (the optional
       separation parameter, defaulting to $_, is used to join the strings together). In list
       context, returns the list of lines or records.

   id
         my $fil = $lite->id

       Returns the name associated with the VCS::Lite element when it was created by new. This is
       usually the file name.

   delta
         my $delt = $lit->delta($lit2);

       Perform the difference between two VCS::Lite objects. This object returns a
       VCS::Lite::Delta object.

   diff
       This is for backward compatibility with early versions. $lite->diff($lite2) is equivalent
       to $lite->delta($lite2)->diff.

   patch
         my $lit3 = $lit->patch($delt);

       Applies a patch to a VCS::Lite object. Accepts a file handle or file name string. Reads
       the file in diff format, and applies it. Returns a VCS::Lite object for the patched
       source.

   merge
         my $lit4 = $lit->merge($lit1,$lit2,\&confl);

       Performs the "parallelogram of merging". This applies two different change streams
       represented by VCS::Lite objects. Returns a VCS::Lite object with both sets of changes
       merged.

       The third parameter to the method is a sub which is called whenever a merge conflict
       occurs. This needs to either resolve the conflict or insert the necessary text to
       highlight the conflict.

SEE ALSO

       Algorithm::Diff.

BUGS, PATCHES & FIXES

       At the time of release there is one known bug within VCS-Lite:

       http://rt.cpan.org/Public/Bug/Display.html?id=20738

       Unfortunately Ivor's original svn repository is no longer available, and any work which
       had done on fixing this bug has now been lost. As time allows I will review the examples
       and try to implement an appropriate solution.

       If you spot a bug or are experiencing difficulties that are not explained within the POD
       documentation, please send an email to barbie@cpan.org or submit a bug to the RT system
       (see link below). However, it would help greatly if you are able to pinpoint problems or
       even supply a patch.

       http://rt.cpan.org/Public/Dist/Display.html?Name=VCS-Lite

       Fixes are dependent upon their severity and my availability. Should a fix not be
       forthcoming, please feel free to (politely) remind me.

AUTHOR

         Original Author: Ivor Williams (RIP)          2002-2009
         Current Maintainer: Barbie <barbie@cpan.org>  2009-2015

COPYRIGHT

         Copyright (c) Ivor Williams, 2002-2006
         Copyright (c) Barbie,        2009-2015

LICENCE

       This distribution is free software; you can redistribute it and/or modify it under the
       Artistic Licence v2.

ACKNOWLEDGEMENTS

       Colin Robertson for suggesting and providing patches for support of files with
       unterminated last lines.