1Text::Diff(3)         User Contributed Perl Documentation        Text::Diff(3)
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3
4

NAME

6       Text::Diff - Perform diffs on files and record sets
7

SYNOPSIS

9           use Text::Diff;
10
11           ## Mix and match filenames, strings, file handles, producer subs,
12           ## or arrays of records; returns diff in a string.
13           ## WARNING: can return B<large> diffs for large files.
14           my $diff = diff "file1.txt", "file2.txt", { STYLE => "Context" };
15           my $diff = diff \$string1,   \$string2,   \%options;
16           my $diff = diff \*FH1,       \*FH2;
17           my $diff = diff \&reader1,   \&reader2;
18           my $diff = diff \@records1,  \@records2;
19
20           ## May also mix input types:
21           my $diff = diff \@records1,  "file_B.txt";
22

DESCRIPTION

24       "diff()" provides a basic set of services akin to the GNU "diff"
25       utility.  It is not anywhere near as feature complete as GNU "diff",
26       but it is better integrated with Perl and available on all platforms.
27       It is often faster than shelling out to a system's "diff" executable
28       for small files, and generally slower on larger files.
29
30       Relies on Algorithm::Diff for, well, the algorithm.  This may not
31       produce the same exact diff as a system's local "diff" executable, but
32       it will be a valid diff and comprehensible by "patch".  We haven't seen
33       any differences between Algorithm::Diff's logic and GNU diff's, but we
34       have not examined them to make sure they are indeed identical.
35
36       Note: If you don't want to import the "diff" function, do one of the
37       following:
38
39          use Text::Diff ();
40
41          require Text::Diff;
42
43       That's a pretty rare occurence, so "diff()" is exported by default.
44       =head1 OPTIONS
45
46       diff() takes two parameters from which to draw input and a set of
47       options to control it's output.  The options are:
48
49       FILENAME_A, MTIME_A, FILENAME_B, MTIME_B
50           The name of the file and the modification time "files"
51
52           These are filled in automatically for each file when diff() is
53           passed a filename, unless a defined value is passed in.
54
55           If a filename is not passed in and FILENAME_A and FILENAME_B are
56           not provided or "undef", the header will not be printed.
57
58           Unused on "OldStyle" diffs.
59
60       OFFSET_A, OFFSET_B
61           The index of the first line / element.  These default to 1 for all
62           parameter types except ARRAY references, for which the default is
63           0.  This is because ARRAY references are presumed to be data
64           structures, while the others are line oriented text.
65
66       STYLE
67           "Unified", "Context", "OldStyle", or an object or class reference
68           for a class providing "file_header()", "hunk_header()", "hunk()",
69           "hunk_footer()" and "file_footer()" methods.  The two footer()
70           methods are provided for overloading only; none of the formats
71           provide them.
72
73           Defaults to "Unified" (unlike standard "diff", but Unified is
74           what's most often used in submitting patches and is the most human
75           readable of the three.
76
77           If the package indicated by the STYLE has no hunk() method,
78           c<diff()> will load it automatically (lazy loading).  Since all
79           such packages should inherit from Text::Diff::Base, this should be
80           marvy.
81
82           Styles may be specified as class names ("STYLE =" "Foo"), in which
83           case they will be "new()"ed with no parameters, or as objects
84           ("STYLE =" Foo->new>).
85
86       CONTEXT
87           How many lines before and after each diff to display.  Ignored on
88           old-style diffs.  Defaults to 3.
89
90       OUTPUT
91           Examples and their equivalent subroutines:
92
93               OUTPUT   => \*FOOHANDLE,   # like: sub { print FOOHANDLE shift() }
94               OUTPUT   => \$output,      # like: sub { $output .= shift }
95               OUTPUT   => \@output,      # like: sub { push @output, shift }
96               OUTPUT   => sub { $output .= shift },
97
98           If no "OUTPUT" is supplied, returns the diffs in a string.  If
99           "OUTPUT" is a "CODE" ref, it will be called once with the
100           (optional) file header, and once for each hunk body with the text
101           to emit.  If "OUTPUT" is an IO::Handle, output will be emitted to
102           that handle.
103
104       FILENAME_PREFIX_A, FILENAME_PREFIX_B
105           The string to print before the filename in the header. Unused on
106           "OldStyle" diffs.  Defaults are "---", "+++" for Unified and "***",
107           "+++" for Context.
108
109       KEYGEN, KEYGEN_ARGS
110           These are passed to "traverse_sequences" in Algorithm::Diff.
111
112       Note: if neither "FILENAME_" option is defined, the header will not be
113       printed.  If at one is present, the other and both MTIME_ options must
114       be present or "Use of undefined variable" warnings will be generated
115       (except on "OldStyle" diffs, which ignores these options).
116

Formatting Classes

118       These functions implement the output formats.  They are grouped in to
119       classes so diff() can use class names to call the correct set of output
120       routines and so that you may inherit from them easily.  There are no
121       constructors or instance methods for these classes, though subclasses
122       may provide them if need be.
123
124       Each class has file_header(), hunk_header(), hunk(), and footer()
125       methods identical to those documented in the Text::Diff::Unified
126       section.  header() is called before the hunk() is first called,
127       footer() afterwards.  The default footer function is an empty method
128       provided for overloading:
129
130           sub footer { return "End of patch\n" }
131
132       Some output formats are provided by external modules (which are loaded
133       automatically), such as Text::Diff::Table.  These are are documented
134       here to keep the documentation simple.
135
136   Text::Diff::Base
137       Returns "" for all methods (other than "new()").
138
139   Text::Diff::Unified
140         --- A   Mon Nov 12 23:49:30 2001
141         +++ B   Mon Nov 12 23:49:30 2001
142         @@ -2,13 +2,13 @@
143          2
144          3
145          4
146         -5d
147         +5a
148          6
149          7
150          8
151          9
152         +9a
153          10
154          11
155         -11d
156          12
157          13
158
159       file_header
160             $s = Text::Diff::Unified->file_header( $options );
161
162           Returns a string containing a unified header.  The sole parameter
163           is the options hash passed in to diff(), containing at least:
164
165             FILENAME_A  => $fn1,
166             MTIME_A     => $mtime1,
167             FILENAME_B  => $fn2,
168             MTIME_B     => $mtime2
169
170           May also contain
171
172             FILENAME_PREFIX_A    => "---",
173             FILENAME_PREFIX_B    => "+++",
174
175           to override the default prefixes (default values shown).
176
177       hunk_header
178             Text::Diff::Unified->hunk_header( \@ops, $options );
179
180           Returns a string containing the output of one hunk of unified diff.
181
182       Text::Diff::Unified::hunk
183             Text::Diff::Unified->hunk( \@seq_a, \@seq_b, \@ops, $options );
184
185           Returns a string containing the output of one hunk of unified diff.
186
187   Text::Diff::Table
188         +--+----------------------------------+--+------------------------------+
189         |  |../Test-Differences-0.2/MANIFEST  |  |../Test-Differences/MANIFEST  |
190         |  |Thu Dec 13 15:38:49 2001          |  |Sat Dec 15 02:09:44 2001      |
191         +--+----------------------------------+--+------------------------------+
192         |  |                                  * 1|Changes                       *
193         | 1|Differences.pm                    | 2|Differences.pm                |
194         | 2|MANIFEST                          | 3|MANIFEST                      |
195         |  |                                  * 4|MANIFEST.SKIP                 *
196         | 3|Makefile.PL                       | 5|Makefile.PL                   |
197         |  |                                  * 6|t/00escape.t                  *
198         | 4|t/00flatten.t                     | 7|t/00flatten.t                 |
199         | 5|t/01text_vs_data.t                | 8|t/01text_vs_data.t            |
200         | 6|t/10test.t                        | 9|t/10test.t                    |
201         +--+----------------------------------+--+------------------------------+
202
203       This format also goes to some pains to highlight "invisible" characters
204       on differing elements by selectively escaping whitespace:
205
206         +--+--------------------------+--------------------------+
207         |  |demo_ws_A.txt             |demo_ws_B.txt             |
208         |  |Fri Dec 21 08:36:32 2001  |Fri Dec 21 08:36:50 2001  |
209         +--+--------------------------+--------------------------+
210         | 1|identical                 |identical                 |
211         * 2|        spaced in         |        also spaced in    *
212         * 3|embedded space            |embedded        tab       *
213         | 4|identical                 |identical                 |
214         * 5|        spaced in         |\ttabbed in               *
215         * 6|trailing spaces\s\s\n     |trailing tabs\t\t\n       *
216         | 7|identical                 |identical                 |
217         * 8|lf line\n                 |crlf line\r\n             *
218         * 9|embedded ws               |embedded\tws              *
219         +--+--------------------------+--------------------------+
220
221       See "Text::Diff::Table" for more details, including how the whitespace
222       escaping works.
223
224   Text::Diff::Context
225           *** A   Mon Nov 12 23:49:30 2001
226           --- B   Mon Nov 12 23:49:30 2001
227           ***************
228           *** 2,14 ****
229             2
230             3
231             4
232           ! 5d
233             6
234             7
235             8
236             9
237             10
238             11
239           - 11d
240             12
241             13
242           --- 2,14 ----
243             2
244             3
245             4
246           ! 5a
247             6
248             7
249             8
250             9
251           + 9a
252             10
253             11
254             12
255             13
256
257       Note: hunk_header() returns only "***************\n".
258
259   Text::Diff::OldStyle
260           5c5
261           < 5d
262           ---
263           > 5a
264           9a10
265           > 9a
266           12d12
267           < 11d
268
269       Note: no file_header().
270

LIMITATIONS

272       Must suck both input files entirely in to memory and store them with a
273       normal amount of Perlish overhead (one array location) per record.
274       This is implied by the implementation of Algorithm::Diff, which takes
275       two arrays.  If Algorithm::Diff ever offers an incremental mode, this
276       can be changed (contact the maintainers of Algorithm::Diff and
277       Text::Diff if you need this; it shouldn't be too terribly hard to tie
278       arrays in this fashion).
279
280       Does not provide most of the more refined GNU diff options: recursive
281       directory tree scanning, ignoring blank lines / whitespace, etc., etc.
282       These can all be added as time permits and need arises, many are rather
283       easy; patches quite welcome.
284
285       Uses closures internally, this may lead to leaks on "perl" versions
286       5.6.1 and prior if used many times over a process' life time.
287

AUTHOR

289       Adam Kennedy <adamk@cpan.org>
290
291       Barrie Slaymaker <barries@slaysys.com>
292
294       Some parts copyright 2009 Adam Kennedy.
295
296       Copyright 2001 Barrie Slaymaker.  All Rights Reserved.
297
298       You may use this under the terms of either the Artistic License or GNU
299       Public License v 2.0 or greater.
300
301
302
303perl v5.12.0                      2009-07-16                     Text::Diff(3)
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