NAME

       PPI::Normal - Normalize Perl Documents

   DESCRIPTION
       Perl Documents, as created by PPI, are typically filled with all sorts of mess such as
       whitespace and comments and other things that don't effect the actual meaning of the code.

       In addition, because there is more than one way to do most things, and the syntax of Perl
       itself is quite flexible, there are many ways in which the "same" code can look quite
       different.

       PPI::Normal attempts to resolve this by providing a variety of mechanisms and algorithms
       to "normalize" Perl Documents, and determine a sort of base form for them (although this
       base form will be a memory structure, and not something that can be turned back into Perl
       source code).

       The process itself is quite complex, and so for convenience and extensibility it has been
       separated into a number of layers. At a later point, it will be possible to write Plugin
       classes to insert additional normalization steps into the various different layers.

       In addition, you can choose to do the normalization only as deep as a particular layer,
       depending on aggressively you want the normalization process to be.

METHODS

   register $function => $layer, ...
       The "register" method is used by normalization method providers to tell the normalization
       engines which functions need to be run, and in which layer they apply.

       Provide a set of key/value pairs, where the key is the full name of the function (in
       string form), and the value is the layer (see description of the layers above) in which it
       should be run.

       Returns true if all functions are registered, or "undef" on error.

   new
         my $level_1 = PPI::Normal->new;
         my $level_2 = PPI::Normal->new(2);

       Creates a new normalization object, to which Document objects can be passed to be
       normalized.

       Of course, what you probably REALLY want is just to call PPI::Document's "normalize"
       method.

       Takes an optional single parameter of the normalisation layer to use, which at this time
       can be either "1" or "2".

       Returns a new "PPI::Normal" object, or "undef" on error.

layer

       The "layer" accessor returns the normalisation layer of the object.

   process
       The "process" method takes anything that can be converted to a PPI::Document (object,
       SCALAR ref, filename), loads it and applies the normalisation process to the document.

       Returns a PPI::Document::Normalized object, or "undef" on error.

NOTES

       The following normalisation layers are implemented. When writing plugins, you should
       register each transformation function with the appropriate layer.

   Layer 1 - Insignificant Data Removal
       The basic step common to all normalization, layer 1 scans through the Document and removes
       all whitespace, comments, POD, and anything else that returns false for its "significant"
       method.

       It also checks each Element and removes known-useless sub-element metadata such as the
       Element's physical position in the file.

   Layer 2 - Significant Element Removal
       After the removal of the insignificant data, Layer 2 removed larger, more complex, and
       superficially "significant" elements, that can be removed for the purposes of
       normalisation.

       Examples from this layer include pragmas, now-useless statement separators (since the PDOM
       tree is holding statement elements), and several other minor bits and pieces.

   Layer 3 - TO BE COMPLETED
       This version of the forward-port of the Perl::Compare functionality to the 0.900+ API of
       PPI only implements Layer 1 and 2 at this time.

TO DO

       - Write the other 4-5 layers :)

SUPPORT

       See the support section in the main module.

AUTHOR

       Adam Kennedy <adamk@cpan.org>

COPYRIGHT

       Copyright 2005 - 2011 Adam Kennedy.

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

       The full text of the license can be found in the LICENSE file included with this module.