Unix/Linux Go Back    


CentOS 7.0 - man page for text::diff (centos section 3)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)


Text::Diff(3)		       User Contributed Perl Documentation		    Text::Diff(3)

NAME
       Text::Diff - Perform diffs on files and record sets

SYNOPSIS
	   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";

DESCRIPTION
       "diff()" provides a basic set of services akin to the GNU "diff" utility.  It is not
       anywhere near as feature complete as GNU "diff", but it is better integrated with Perl and
       available on all platforms.  It is often faster than shelling out to a system's "diff"
       executable for small files, and generally slower on larger files.

       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 occurence, so "diff()" is exported by default.  =head1 OPTIONS

       diff() takes two parameters from which to draw input and a set of options to control it's
       output.	The options are:

       FILENAME_A, MTIME_A, FILENAME_B, MTIME_B
	   The name of the file and the modification time "files"

	   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
	   "undef", the header will not be printed.

	   Unused on "OldStyle" diffs.

       OFFSET_A, OFFSET_B
	   The index of the first line / element.  These default to 1 for all parameter types
	   except ARRAY references, for which the default is 0.  This is because ARRAY references
	   are presumed to be data structures, while the others are line oriented text.

       STYLE
	   "Unified", "Context", "OldStyle", or an object or class reference for a class
	   providing "file_header()", "hunk_header()", "hunk()", "hunk_footer()" and
	   "file_footer()" methods.  The two footer() methods are provided for overloading only;
	   none of the formats provide them.

	   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, c<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>).

       CONTEXT
	   How many lines before and after each diff to display.  Ignored on old-style diffs.
	   Defaults to 3.

       OUTPUT
	   Examples and their equivalent subroutines:

	       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.

       FILENAME_PREFIX_A, FILENAME_PREFIX_B
	   The string to print before the filename in the header. Unused on "OldStyle" diffs.
	   Defaults are "---", "+++" for Unified and "***", "+++" for Context.

       KEYGEN, KEYGEN_ARGS
	   These are passed to "traverse_sequences" in Algorithm::Diff.

       Note: if neither "FILENAME_" option is defined, the header will not be printed.	If at 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).

Formatting Classes
       These functions implement the output formats.  They are grouped in to classes so diff()
       can use class names to call the correct set of output routines and so that you may inherit
       from them easily.  There are no constructors or instance methods for these classes, though
       subclasses may provide them if need be.

       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.

   Text::Diff::Base
       Returns "" for all methods (other than "new()").

   Text::Diff::Unified
	 --- 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

       file_header
	     $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).

       hunk_header
	     Text::Diff::Unified->hunk_header( \@ops, $options );

	   Returns a string containing the output of one hunk of unified diff.

       Text::Diff::Unified::hunk
	     Text::Diff::Unified->hunk( \@seq_a, \@seq_b, \@ops, $options );

	   Returns a string containing the output of one hunk of unified diff.

   Text::Diff::Table
	 +--+----------------------------------+--+------------------------------+
	 |  |../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.

   Text::Diff::Context
	   *** 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".

   Text::Diff::OldStyle
	   5c5
	   < 5d
	   ---
	   > 5a
	   9a10
	   > 9a
	   12d12
	   < 11d

       Note: no file_header().

LIMITATIONS
       Must suck both input files entirely in to memory and store them with a normal amount of
       Perlish overhead (one array location) per record.  This is implied by the implementation
       of Algorithm::Diff, which takes two arrays.  If Algorithm::Diff ever offers an incremental
       mode, this can be changed (contact the maintainers of Algorithm::Diff and Text::Diff if
       you need this; it shouldn't be too terribly hard to tie arrays in this fashion).

       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.

AUTHOR
       Adam Kennedy <adamk@cpan.org>

       Barrie Slaymaker <barries@slaysys.com>

COPYRIGHT
       Some parts copyright 2009 Adam Kennedy.

       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.

perl v5.16.3				    2011-04-17				    Text::Diff(3)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums


All times are GMT -4. The time now is 02:28 PM.