SVN::Web::DiffParser(3) Parse patch files containing unified and standard diffs


This is Text::Diff::Parser, plus some local bug fixes that were exposed by use with SVN::Web. For more details about Text::Diff::Parser please see CPAN.


use SVN::Web::DiffParser;
# create the object
my $parser = SVN::Web::DiffParser->new();
# With options
$parser = SVN::Web::DiffParser->new( Simplify=>1, # simplify the diff
Strip=>2 ); # strip 2 directories
# Create object. Parse $file
$parser = SVN::Web::DiffParser->new( $file );
$parser = SVN::Web::DiffParser->new( File=>$file );
# Create object. Parse text
my $parser = SVN::Web::DiffParser->new( $text );
$parser = SVN::Web::DiffParser->new( Diff=>$text );
# parse a file
$parser->parse_file( $filename );
# parse a string
$parser->parse( $text );

# Remove no-change lines. Combine line substitutions
# Find results
foreach my $change ( $parser->changes ) {
print "File1: ", $change->filename1;
print "Line1: ", $change->line1;
print "File2: ", $change->filename2;
print "Line2: ", $change->line2;
print "Type: ", $change->type;
my $size = $change->size;
foreach my $line ( 0..($size-1) ) {
print "Line: ", $change->line( $size );
# In scalar context, returns the number of changes
my $n = $parser->changes;
print "There are $n changes",
# Get the changes to a given file
my @changes = $parser->changes( 'Makefile.PL' );
# Get list of files changed by the diff
my @files = $parser->files;


"SVN::Web::DiffParser" parses diff files and patches. It allows you to access the changes to a file in a standardized way, even if multiple patch formats are used.

A diff may be viewed a series of operations on a file, either adding, removing or modifying lines of one file (the "from-file") to produce another file (the "to-file"). Diffs are generally produced either by hand with diff, or by your version control system ("cvs diff", "svn diff", ...). Some diff formats, notably unified diffs, also contain null operations, that is lines that

"SVN::Web::DiffParser" currently parses unified diff format and standard diff format.

Unified diffs look like the following.

    --- Filename1 2006-04-12 18:47:22.000000000 -0400
    +++ Filename2 2006-04-12 19:21:16.000000000 -0400
    @@ -1,4 +1,6 @@

Standard diffs look like the following.

    diff something something.4
    < THREE
    > honk
    > honk
    > honk

The diff line isn't in fact part of the format but is necessary to find which files the chunks deal with. It is output by "cvs diff" and "svn diff" so that isn't a problem.



    $parser = SVN::Web::DiffParser->new;
    $parser = SVN::Web::DiffParser->new( $file );
    $parser = SVN::Web::DiffParser->new( $handle );
    $parser = SVN::Web::DiffParser->new( %params );
    $parser = SVN::Web::DiffParser->new( \%params );

Object constructor.

String that contains a diff. This diff will be parse before "new" returns.
File name or file handle that is parsed before "new" returns.
Simplifying a patch involves dropping all null-operations and converting and remove operation followed by an add operation (or an add followed by a remove) of the same size on the same lines into a modify operation.
Strip N leading directories from all filenames. Less then useful for standard diffs produced by "cvs diff", because they don't contain directory information.
If true, print copious details of what is going on.


    $parser->parse_file( $file );
    $parser->parse_file( $handle );

Read and parse the file or file handle specified. Will "die" if it fails, returns true on success. Contents of the file may then be accessed with "changes" and "files".


    $parser->parse( $string );

Parses the diff present in $string. Will "die" if it fails, returns true on success. Contents of the file may then be accessed with "changes" and "files".


    %files = $parser->files;

Fetch a list of all the files that were referenced in the patch. The keys are original files ("from-file") and the values are the modified files ("to-file").


    @changes = $parser->changes;
    $n = $parser->changes;
    @changes = $parser->changes( $file );
    $n = $parser->changes( $file );

Return all the operations (array context) or the number of operations in the patch file. If $file is specified, only returns changes to that file ("from-file" or "to-file").

Elements of the returned array are change objects, as described in "CHANGE METHODS" below.


The "changes" method returns an array of objects that describe each operation. You may use the following methods to find out details of the operation.


Returns the type of operation, either 'ADD', 'REMOVE', 'MODIFY' or '' (null operation).


Filename of the "from-file".


Filename of the "to-file".


Line in the "from-file" the operation starts at.


Line in the "to-file" the operation starts at.


Number of lines affected by this operation.


    @lines = $ch->text;
    $line  = $ch->text( $N );

Fetch the text of the line $N if present or all lines of affected by this operation. For '' (null) and 'REMOVE' operations, these are the lines present before the operation was done ('from-file'. For 'ADD' and 'MODIFY' operations, these are the lines present after the operation was done ('to-file'.


I'm not 100% sure of standard diff handling.

Missing support for context diffs.


Philip Gwyn, <>


Copyright (C) 2006 by Philip Gwyn

Copyright (C) 2012 by Dean Hamstead

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of Perl 5 you may have available.