use Text::Diff;
## Mix and match filenames, strings, file handles, producer subs,
## or arrays of records; returns diff in a string.
## WARNING: can return B<large> diffs for large files.
my $diff = diff "file1.txt", "file2.txt", { STYLE => "Context" };
my $diff = diff \$string1, \$string2, \%options;
my $diff = diff \*FH1, \*FH2;
my $diff = diff \&reader1, \&reader2;
my $diff = diff \@records1, \@records2;
## May also mix input types:
my $diff = diff \@records1, "file_B.txt";
Relies on Algorithm::Diff for, well, the algorithm. This may not produce the same exact diff as a system's local "diff" executable, but it will be a valid diff and comprehensible by "patch". We haven't seen any differences between Algorithm::Diff's logic and GNU "diff"'s, but we have not examined them to make sure they are indeed identical.
Note: If you don't want to import the "diff" function, do one of the following:
use Text::Diff (); require Text::Diff;
That's a pretty rare occurrence, so "diff()" is exported by default.
If you pass a filename, but the file can't be read, then "diff()" will "croak".
These are filled in automatically for each file when "diff()" is passed a filename, unless a defined value is passed in.
If a filename is not passed in and FILENAME_A and FILENAME_B are not provided or are "undef", the header will not be printed.
Unused on "OldStyle" diffs.
Defaults to ``Unified'' (unlike standard "diff", but Unified is what's most often used in submitting patches and is the most human readable of the three.
If the package indicated by the STYLE has no "hunk()" method, "diff()" will load it automatically (lazy loading). Since all such packages should inherit from "Text::Diff::Base", this should be marvy.
Styles may be specified as class names ("STYLE => 'Foo'"), in which case they will be "new()"ed with no parameters, or as objects ("STYLE => Foo->new").
OUTPUT => \*FOOHANDLE, # like: sub { print FOOHANDLE shift() }
OUTPUT => \$output, # like: sub { $output .= shift }
OUTPUT => \@output, # like: sub { push @output, shift }
OUTPUT => sub { $output .= shift },
If no "OUTPUT" is supplied, returns the diffs in a string. If "OUTPUT" is a "CODE" ref, it will be called once with the (optional) file header, and once for each hunk body with the text to emit. If "OUTPUT" is an IO::Handle, output will be emitted to that handle.
Note: if neither "FILENAME_" option is defined, the header will not be printed. If at least one is present, the other and both "MTIME_" options must be present or ``Use of undefined variable'' warnings will be generated (except on "OldStyle" diffs, which ignores these options).
Each class has "file_header()", "hunk_header()", "hunk()", and "footer()" methods identical to those documented in the "Text::Diff::Unified" section. "header()" is called before the "hunk()" is first called, "footer()" afterwards. The default footer function is an empty method provided for overloading:
sub footer { return "End of patch\n" }
Some output formats are provided by external modules (which are loaded automatically), such as Text::Diff::Table. These are are documented here to keep the documentation simple.
--- A Mon Nov 12 23:49:30 2001 +++ B Mon Nov 12 23:49:30 2001 @@ -2,13 +2,13 @@ 2 3 4 -5d +5a 6 7 8 9 +9a 10 11 -11d 12 13
$s = Text::Diff::Unified->file_header( $options );
Returns a string containing a unified header. The sole parameter is the "options" hash passed in to "diff()", containing at least:
FILENAME_A => $fn1, MTIME_A => $mtime1, FILENAME_B => $fn2, MTIME_B => $mtime2
May also contain
FILENAME_PREFIX_A => "---", FILENAME_PREFIX_B => "+++",
to override the default prefixes (default values shown).
Text::Diff::Unified->hunk_header( \@ops, $options );
Returns a string containing the heading of one hunk of unified diff.
Text::Diff::Unified->hunk( \@seq_a, \@seq_b, \@ops, $options );
Returns a string containing the output of one hunk of unified diff.
+--+----------------------------------+--+------------------------------+ | |../Test-Differences-0.2/MANIFEST | |../Test-Differences/MANIFEST | | |Thu Dec 13 15:38:49 2001 | |Sat Dec 15 02:09:44 2001 | +--+----------------------------------+--+------------------------------+ | | * 1|Changes * | 1|Differences.pm | 2|Differences.pm | | 2|MANIFEST | 3|MANIFEST | | | * 4|MANIFEST.SKIP * | 3|Makefile.PL | 5|Makefile.PL | | | * 6|t/00escape.t * | 4|t/00flatten.t | 7|t/00flatten.t | | 5|t/01text_vs_data.t | 8|t/01text_vs_data.t | | 6|t/10test.t | 9|t/10test.t | +--+----------------------------------+--+------------------------------+
This format also goes to some pains to highlight ``invisible'' characters on differing elements by selectively escaping whitespace:
+--+--------------------------+--------------------------+ | |demo_ws_A.txt |demo_ws_B.txt | | |Fri Dec 21 08:36:32 2001 |Fri Dec 21 08:36:50 2001 | +--+--------------------------+--------------------------+ | 1|identical |identical | * 2| spaced in | also spaced in * * 3|embedded space |embedded tab * | 4|identical |identical | * 5| spaced in |\ttabbed in * * 6|trailing spaces\s\s\n |trailing tabs\t\t\n * | 7|identical |identical | * 8|lf line\n |crlf line\r\n * * 9|embedded ws |embedded\tws * +--+--------------------------+--------------------------+
See Text::Diff::Table for more details, including how the whitespace escaping works.
*** A Mon Nov 12 23:49:30 2001
--- B Mon Nov 12 23:49:30 2001
***************
*** 2,14 ****
2
3
4
! 5d
6
7
8
9
10
11
- 11d
12
13
--- 2,14 ----
2
3
4
! 5a
6
7
8
9
+ 9a
10
11
12
13
Note: "hunk_header()" returns only ``***************\n''.
5c5
< 5d
---
> 5a
9a10
> 9a
12d12
< 11d
Does not provide most of the more refined GNU "diff" options: recursive directory tree scanning, ignoring blank lines / whitespace, etc., etc. These can all be added as time permits and need arises, many are rather easy; patches quite welcome.
Uses closures internally, this may lead to leaks on Perl versions 5.6.1 and prior if used many times over a process' life time.
YAML::Diff - find difference between two YAML documents.
HTML::Differences - find difference between two HTML documents. This uses a more sane approach than HTML::Diff.
XML::Diff - find difference between two XML documents.
Array::Diff - find the differences between two Perl arrays.
Hash::Diff - find the differences between two Perl hashes.
Data::Diff - find difference between two arbitrary data structures.
Barrie Slaymaker <barries@slaysys.com>
Copyright 2001 Barrie Slaymaker. All Rights Reserved.
You may use this under the terms of either the Artistic License or GNU Public License v 2.0 or greater.