SVN::Web::DiffParser - Parse patch files containing unified and standard diffs

SVN-Web documentation Contained in the SVN-Web distribution.

Index

Code Index:

NAME

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SVN::Web::DiffParser - Parse patch files containing unified and standard diffs

NOTE

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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.

SYNOPSIS

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    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
    $parser->simplify;

    # 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;

DESCRIPTION

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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 @@
     ONE
     TWO
    -THREE
    +honk
     FOUR
    +honk
    +honk

Standard diffs look like the following.

    diff something something.4
    3c3
    < THREE
    ---
    > honk
    4a5,6
    > 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.

METHODS

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new

    $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.

Diff

String that contains a diff. This diff will be parse before new returns.

File

File name or file handle that is parsed before new returns.

Simplify

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

Strip N leading directories from all filenames. Less then useful for standard diffs produced by cvs diff, because they don't contain directory information.

Verbose

If true, print copious details of what is going on.

parse_file

    $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.

parse

    $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

    %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

    @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.

CHANGE METHODS

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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.

type

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

filename1

Filename of the from-file.

filename2

Filename of the to-file.

line1

Line in the from-file the operation starts at.

line2

Line in the to-file the operation starts at.

size

Number of lines affected by this operation.

text

    @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'.

BUGS

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

Missing support for context diffs.

SEE ALSO

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Text::Diff, Arch, diff.

AUTHOR

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Philip Gwyn, <gwyn-at-cpan.org>

COPYRIGHT AND LICENSE

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Copyright (C) 2006 by Philip Gwyn

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.

SVN-Web documentation Contained in the SVN-Web distribution. 
package SVN::Web::DiffParser;
# $Id: Parser.pm,v 1.3 2006/04/13 01:47:37 fil Exp $

use 5.00404;
use strict;
use vars qw( $VERSION );

use Carp;
use IO::File;

$VERSION = '0.53';
$VERSION = eval $VERSION;  # see L<perlmodstyle>

####################################################
sub new
{
    my( $package, @args ) = @_;

    my $self = bless { changes=>[], 
                       source=>'' }, $package;

    my $parms;
    if( 1==@args ) {
        if( 'HASH' eq ref $args[0] ) {
            $parms = $args[0];
        }
        else {
            my $diff = $args[0];
            if( ref $diff or $diff !~ /\n/ ) {
                $parms = { File => $diff };
            }
            else {
                $parms = { Diff => $diff };
            }
        }
    }
    else {
        $parms = { @args };
    }

    $self->__init( $parms );
    return $self;
}

sub __init 
{
    my( $self, $parms ) = @_;

    $self->{verbose}  = 1 if $parms->{Verbose};
    $self->{simplify} = $parms->{Simplify};
    $self->{strip}    = $parms->{Strip};

    if( $parms->{ File } ) {
        $self->parse_file( $parms->{File} );
    }
    elsif( $parms->{ Diff } ) {
        $self->parse( $parms->{Diff} );
    }
    return $self;
}

####################################################
sub source
{
    my( $self ) = @_;
    return $self->{source};
}

####################################################
sub changes
{
    my( $self, $file ) = @_;
    my $ret = $self->{changes};
    if( $file ) {
        $ret = [];
        foreach my $ch ( @{ $self->{changes} } ) {
            next unless $ch->filename1 eq $file or
                        $ch->filename2 eq $file;
            push @$ret, $ch;
        }
    }

    return @$ret if wantarray;
    return 0+@$ret;
}


####################################################
sub files
{
    my( $self ) = @_;
    my %ret;
    foreach my $ch ( $self->changes ) {
        $ret{$ch->filename1} = $ch->filename2;
    }
    return %ret;
}


####################################################
sub simplify
{
    my( $self ) = @_;

    my @keep;
    my $prev;
    foreach my $ch ( $self->changes ) {
        if( $ch->type eq '' ) {                 # skip no-change
            undef( $prev );
            next;
        }
    
        if( $prev ) {
            my $size = $prev->size;
            ## Combine ADD/REMOVE lines
            if( $prev->type ne $ch->type and # ADD->REMOVE or REMOVE->ADD
                $prev->filename1 eq $ch->filename1 and
                $prev->filename2 eq $ch->filename2 and
                           $size == $ch->size ) {  #close

                if( $prev->type eq 'REMOVE' and
                        $prev->line2 == $ch->line2 and
                        ($prev->line1+$size) == $ch->line1 ) {
                    $prev->{type} = 'MODIFY';
                    $prev->{lines} = $ch->{lines};
                    undef( $prev );
                    next;
                }
                elsif( $prev->type eq 'ADD' and
                        ($prev->line2+$size) == $ch->line2 and
                        $prev->line1 == $ch->line1 ) {
                    $prev->{type} = 'MODIFY';
                    undef( $prev );
                    next;
                }
                # same size, same file, but not at the same spot
            }
        }
        push @keep, $ch;
        $prev = $ch;
    }
    $self->{changes} = \@keep;
}


####################################################
sub parse_file
{
    my( $self, $file ) = @_;

    my $fh;
    if( ref $file ) {               # assume it's a file handle
        $self->{source} = 'user filehandle';
        $fh = $file;
    }
    else {
        $self->{source} = $file;
        $fh = IO::File->new;
        $fh->open( $file ) or croak "Unable to open $file: $!";
    }

    $self->{changes}=[];
    $self->{state}={ OK=>1 };

    while( <$fh> ) {
        $self->{state}{context} = "line $. of $self->{source}";
        $self->_parse_line( $_ );
    }
    my $ok = $self->{state}{OK};
    delete $self->{state};
    $self->simplify if $self->{simplify};
    return $ok;
}


####################################################
sub parse
{
    my( $self, $text ) = @_;
    $self->{source} = "user string";
    $self->{changes}=[];
    $self->{state}={ OK=>1 };

    my $l=1;
    while( $text =~ /(.+?\n)/g ) {
        $self->{state}{context} = "line $l of string";
        $self->_parse_line( $1 );
        $l++;
    }
    my $ok = $self->{state}{OK};
    delete $self->{state};
    $self->simplify if $self->{simplify};
    return $ok;

}

####################################################
sub _parse_line
{
    my( $self, $line ) = @_;
    $self->{verbose} and warn "Parsing $line";

    my $state = $self->{state};

    if( $state->{unified} ) {
        $self->_unified_line( $line );        
        return if $state->{unified};
    }
    elsif( $state->{standard} ) {
        $self->_standard_line( $line );        
        return if $state->{standard};
    }

    my $file = '(?:-r\d(?:\.\d+)+)|(?:[^-].+)';

    if( $line =~ /^diff\s+($file)\s+($file)\s*$/ ) {
        my @match = ( $1, $2 );
        $self->{verbose} and warn "Diff $1 $2";
        $state->{filename1} = $self->_filename( $match[0] );
        $state->{filename2} = $self->_filename( $match[1] );
    } 
    elsif( $line =~ /^(\d+)(?:,\d+)?[acd](\d+)(?:,\d+)?$/  ) {
        $state->{standard} = 1;
        push @{ $self->{changes} }, bless {
                            at1 => $1, line1 => $1,
                            at2 => $2, line2 => $2,
                            filename1 => $state->{filename1},
                            filename2 => $state->{filename2},
                            timestamp1 => '',
                            timestamp2 => ''
                        }, 'SVN::Web::DiffParser::Change';        
        $self->{verbose} and warn "Standard diff line1=$1 line2=$2";
    }
    elsif( $line =~ /^--- (.+?)\t(.+)$/ or 
            $line =~ /^--- ([^\s]+)\s+(.+)$/) {
        $state->{unified} = 1;
        my $stamp = $2;
        my $name = $self->_filename( $1 );
        $self->{verbose} and warn "Unified diff";
        push @{ $self->{changes} }, bless {
                            type=>'',
                            filename1=>$name,
                            timestamp1=>$stamp,
                        }, 'SVN::Web::DiffParser::Change';
    }
    elsif( $line =~ /^\*\*\* (.+?)\t(.+)$/ or 
            $line =~ /^\*\*\* ([^\s]+)\s+(.+)$/) {
        die "Context diff not yet supported at $state->{context}";
    }
}

####################################################
sub _filename
{
    my( $self, $file ) = @_;
    return $file unless $self->{strip};
    my $n = $self->{strip};
    $file =~ s(^[^/]+/)() while $n--;
    return $file;
}

####################################################
sub _standard_line
{
    my( $self, $line ) = @_;

    my %types = ( ' '=>'', '>'=>'ADD', '<'=>'REMOVE' );

    my $change = $self->{changes}[-1];
 
    if( $line =~ /^([<>])(.+)$/ ) {
        my( $mod, $text ) = ( $1, $2 );
        $mod = $types{$mod};
        $self->_new_line( $mod, $text );
        return;
    }
    if( $line =~ /^---$/ ) {            # pivot
        $self->{verbose} and warn "Pivot";
        return;
    }
    delete $self->{state}{standard};    # let _parse_file deal with it
}

####################################################
sub _unified_line
{
    my( $self, $line ) = @_;
 
    my %types = ( ' '=>'', '+'=>'ADD', '-'=>'REMOVE' );

    my $change = $self->{changes}[-1];
    if( $line =~ /^\+\+\+ (.+?)\t(.+)$/ or 
            $line =~ /^\+\+\+ ([^\s]+)\s+(.+)$/) {
        $change->{timestamp2} = $2;
        $change->{filename2} = $self->_filename( $1 );
        $change->{lines} = [];
        return;
    }
    die "Missing +++ line before $line" 
	unless exists $change->{filename2} and defined $change->{filename2};
    if( $line =~ /^\@\@ -(\d+),(\d+) [+](\d+),(\d+) \@\@$/ ) {
        my @match = ($1, $2, $3, $4);
        if( @{ $change->{lines} } ) {
            $change = $self->_new_chunk;
        }
        @{ $change }{ qw( line1 size1 line2 size2 ) } = @match;
        $change->{at1} = $change->{line1};
        $change->{at2} = $change->{line2};
        return;
    }

    # Files that have been newly added and only contain one line have
    # a hunk marker that looks like "@@ -0,0 +1 @@". Handle that.
    # This code should be refactored with the code above, since only
    # the regexp and the assignment to @match are different.
    if( $line =~ /^\@\@ -(\d+),(\d+) [+](\d+) \@\@$/ ) {
        my @match = ($1, $2, $3, 1);
        if( @{ $change->{lines} } ) {
            $change = $self->_new_chunk;
        }
        @{ $change }{ qw( line1 size1 line2 size2 ) } = @match;
        $change->{at1} = $change->{line1};
        $change->{at2} = $change->{line2};
        return;
    }

    die "Missing \@\@ line before $line at $self->{state}{context}\n"
	unless exists $change->{line1} and defined $change->{line1};

    if( $line =~ /^([-+ ])(.*)$/) {
        my( $mod, $text ) = ( $1, $2 );
        $mod = $types{$mod};
        $self->_new_line( $mod, $text );
        return;
    }
    # Anything else is the end of the diff, so fall through to the
    # diff detection bit
    $self->{state}{unified} = 0;
}

sub _new_type
{
    my( $self, $mod ) = @_;
    my $change = $self->{changes}[-1];

    push @{ $self->{changes} }, bless { 
                                    filename1 => $change->{filename1},
                                    filename2 => $change->{filename2},
                                    line1 => $change->{at1},
                                    line2 => $change->{at2},
                                    at1 => $change->{at1},
                                    at2 => $change->{at2},
                                    type => $mod,
                                    lines => []
                                }, 'SVN::Web::DiffParser::Change';
    return $self->{changes}[-1];
}

sub _new_chunk
{
    my( $self ) = @_;
    my $change = $self->{changes}[-1];
    push @{ $self->{changes} }, bless {
                                    type => '',
                                    filename1 => $change->{filename1},
                                    filename2 => $change->{filename2},
                                    lines => []
                                }, 'SVN::Web::DiffParser::Change';
    return $self->{changes}[-1];
}

sub _new_line
{
    my( $self, $mod, $text ) = @_;

    $self->{verbose} and warn "_new_line";
    my $change = $self->{changes}[-1];
    if( defined $change->{type} ) {
        if( $change->{type} ne $mod ) {
            $self->{verbose} and warn "_new_type";
            $change = $self->_new_type( $mod );
        }
    }
    else {
        $change->{type} = $mod;
    }

    $change->{at1}++ unless $mod eq 'ADD';    # - or ' ', advance in file1
    $change->{at2}++ unless $mod eq 'REMOVE'; # + or ' ', advance in file2
    push @{ $change->{lines} }, $text;
}

######################################################################
package SVN::Web::DiffParser::Change;

use strict;

sub filename1 { $_[0]->{filename1} }
sub filename2 { $_[0]->{filename2} }
sub line1 { $_[0]->{line1} }
sub line2 { $_[0]->{line2} }
sub size  { 0+@{$_[0]->{lines}} }

sub type  
{ 
    my( $self ) = @_;

    return $self->{type} if $self->{type} eq 'ADD' or
                            $self->{type} eq 'REMOVE' or
                            $self->{type} eq 'MODIFY';
    return '';
}
    
sub text
{
    my( $self, $n ) = @_;
    return @{ $self->{lines} } if 1==@_;

    return $self->{lines}[$n];
}
    


1;
__END__



$Log: Parser.pm,v $
Revision 1.3  2006/04/13 01:47:37  fil
Tweak

Revision 1.2  2006/04/13 01:43:27  fil
Tweak for move coverage
Add coverage stanza to Makefile.PL
Added BUGS and SEE ALSO section