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1 | @c This is part of the Emacs manual. |
2 | @c Copyright (C) 1985,86,87,93,94,95,97,99,00,2001 Free Software Foundation, Inc. | |
3 | @c See file emacs.texi for copying conditions. | |
4 | @node Maintaining, Abbrevs, Building, Top | |
5 | @chapter Maintaining Programs | |
6 | @cindex Lisp editing | |
7 | @cindex C editing | |
8 | @cindex program editing | |
9 | ||
10 | This chapter describes Emacs features for maintaining programs. The | |
d7ed11cd RS |
11 | version control features (@pxref{Version Control}) are also |
12 | particularly useful for this purpose. | |
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13 | |
14 | @menu | |
15 | * Change Log:: Maintaining a change history for your program. | |
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16 | * Tags:: Go direct to any function in your program in one |
17 | command. Tags remembers which file it is in. | |
18 | * Emerge:: A convenient way of merging two versions of a program. | |
19 | @end menu | |
20 | ||
21 | @node Change Log | |
22 | @section Change Logs | |
23 | ||
24 | @cindex change log | |
25 | @kindex C-x 4 a | |
26 | @findex add-change-log-entry-other-window | |
27 | The Emacs command @kbd{C-x 4 a} adds a new entry to the change log | |
28 | file for the file you are editing | |
29 | (@code{add-change-log-entry-other-window}). If that file is actually | |
30 | a backup file, it makes an entry appropriate for the file's | |
31 | parent---that is useful for making log entries for functions that | |
32 | have been deleted in the current version. | |
33 | ||
34 | A change log file contains a chronological record of when and why you | |
35 | have changed a program, consisting of a sequence of entries describing | |
36 | individual changes. Normally it is kept in a file called | |
37 | @file{ChangeLog} in the same directory as the file you are editing, or | |
38 | one of its parent directories. A single @file{ChangeLog} file can | |
39 | record changes for all the files in its directory and all its | |
40 | subdirectories. | |
41 | ||
1e4cb307 RS |
42 | You should put a copyright notice and permission notice at the |
43 | end of the change log file. Here is an example: | |
44 | ||
45 | @example | |
46 | Copyright 1997, 1998 Free Software Foundation, Inc. | |
47 | Copying and distribution of this file, with or without modification, are | |
48 | permitted provided the copyright notice and this notice are preserved. | |
49 | @end example | |
50 | ||
51 | @noindent | |
52 | Of course, you should substitute the proper years and copyright holder. | |
53 | ||
f00366c2 RS |
54 | A change log entry starts with a header line that contains the |
55 | current date, your name, and your email address (taken from the | |
56 | variable @code{user-mail-address}). Aside from these header lines, | |
57 | every line in the change log starts with a space or a tab. The bulk | |
58 | of the entry consists of @dfn{items}, each of which starts with a line | |
59 | starting with whitespace and a star. Here are two entries, both dated | |
60 | in May 1993, each with two items: | |
61 | ||
62 | @iftex | |
63 | @medbreak | |
64 | @end iftex | |
65 | @smallexample | |
66 | 1993-05-25 Richard Stallman <rms@@gnu.org> | |
67 | ||
68 | * man.el: Rename symbols `man-*' to `Man-*'. | |
69 | (manual-entry): Make prompt string clearer. | |
70 | ||
71 | * simple.el (blink-matching-paren-distance): | |
72 | Change default to 12,000. | |
73 | ||
74 | 1993-05-24 Richard Stallman <rms@@gnu.org> | |
75 | ||
76 | * vc.el (minor-mode-map-alist): Don't use it if it's void. | |
77 | (vc-cancel-version): Doc fix. | |
78 | @end smallexample | |
79 | ||
80 | One entry can describe several changes; each change should have its | |
81 | own item. Normally there should be a blank line between items. When | |
82 | items are related (parts of the same change, in different places), group | |
83 | them by leaving no blank line between them. The second entry above | |
84 | contains two items grouped in this way. | |
85 | ||
86 | @kbd{C-x 4 a} visits the change log file and creates a new entry | |
87 | unless the most recent entry is for today's date and your name. It | |
88 | also creates a new item for the current file. For many languages, it | |
89 | can even guess the name of the function or other object that was | |
90 | changed. | |
91 | ||
92 | @vindex add-log-keep-changes-together | |
93 | When the option @code{add-log-keep-changes-together} is | |
94 | non-@code{nil}, @kbd{C-x 4 a} adds to any existing entry for the file | |
95 | rather than starting a new entry. | |
96 | ||
97 | @vindex change-log-version-info-enabled | |
98 | @vindex change-log-version-number-regexp-list | |
99 | @cindex file version in change log entries | |
100 | If the value of the variable @code{change-log-version-info-enabled} | |
101 | is non-@code{nil}, @kbd{C-x 4 a} adds the file's version number to the | |
102 | change log entry. It finds the version number by searching the first | |
103 | ten percent of the file, using regular expressions from the variable | |
104 | @code{change-log-version-number-regexp-list}. | |
105 | ||
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106 | @vindex add-log-always-start-new-record |
107 | If @code{add-log-always-start-new-record} is non-@code{nil}, | |
108 | @kbd{C-x 4 a} always makes a new entry, even if the last entry | |
109 | was made by you and on the same date. | |
110 | ||
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111 | @cindex Change Log mode |
112 | @findex change-log-mode | |
113 | The change log file is visited in Change Log mode. In this major | |
114 | mode, each bunch of grouped items counts as one paragraph, and each | |
115 | entry is considered a page. This facilitates editing the entries. | |
116 | @kbd{C-j} and auto-fill indent each new line like the previous line; | |
117 | this is convenient for entering the contents of an entry. | |
118 | ||
119 | @findex change-log-merge | |
120 | You can use the command @kbd{M-x change-log-merge} to merge other | |
121 | log files into a buffer in Change Log Mode, preserving the date | |
122 | ordering of entries. | |
123 | ||
124 | @findex change-log-redate | |
125 | @cindex converting change log date style | |
126 | Versions of Emacs before 20.1 used a different format for the time of | |
127 | the change log entry: | |
128 | ||
129 | @smallexample | |
130 | Fri May 25 11:23:23 1993 Richard Stallman <rms@@gnu.org> | |
131 | @end smallexample | |
132 | ||
133 | @noindent | |
134 | The @kbd{M-x change-log-redate} command converts all the old-style | |
135 | date entries in the change log file visited in the current buffer to | |
136 | the new format, to make the file uniform in style. This is handy when | |
137 | entries are contributed by many different people, some of whom use old | |
138 | versions of Emacs. | |
139 | ||
140 | Version control systems are another way to keep track of changes in your | |
141 | program and keep a change log. @xref{Log Buffer}. | |
142 | ||
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143 | @ignore |
144 | @c This is commented out because the command is specific | |
145 | @c to maintenance of Emacs itself. | |
146 | ||
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147 | @node Authors |
148 | @section @file{AUTHORS} files | |
149 | @cindex @file{AUTHORS} file | |
150 | ||
151 | Programs which have many contributors usually include a file named | |
152 | @file{AUTHORS} in their distribution, which lists the individual | |
153 | contributions. Emacs has a special command for maintaining the | |
154 | @file{AUTHORS} file that is part of the Emacs distribution. | |
155 | ||
156 | @findex authors | |
157 | The @kbd{M-x authors} command prompts for the name of the root of the | |
9cd6acef | 158 | Emacs source directory. It then scans @file{ChangeLog} files and Lisp |
f00366c2 | 159 | source files under that directory for information about authors of |
d7ed11cd | 160 | individual packages, and people who made changes in source files, and |
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161 | puts the information it gleans into a buffer named @samp{*Authors*}. |
162 | You can then edit the contents of that buffer and merge it with the | |
24cc235a | 163 | existing @file{AUTHORS} file. |
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164 | |
165 | Do not assume that this command finds all the contributors; don't | |
166 | assume that a person not listed in the output was not a contributor. | |
167 | If you merged in someone's contribution and did not put his name | |
168 | in the change log, he won't show up in @kbd{M-x authors} either. | |
e4059eed | 169 | @end ignore |
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170 | |
171 | @node Tags | |
172 | @section Tags Tables | |
173 | @cindex tags table | |
174 | ||
175 | A @dfn{tags table} is a description of how a multi-file program is | |
176 | broken up into files. It lists the names of the component files and the | |
177 | names and positions of the functions (or other named subunits) in each | |
178 | file. Grouping the related files makes it possible to search or replace | |
179 | through all the files with one command. Recording the function names | |
180 | and positions makes possible the @kbd{M-.} command which finds the | |
181 | definition of a function by looking up which of the files it is in. | |
182 | ||
183 | Tags tables are stored in files called @dfn{tags table files}. The | |
184 | conventional name for a tags table file is @file{TAGS}. | |
185 | ||
186 | Each entry in the tags table records the name of one tag, the name of the | |
bf8dd4e3 FP |
187 | file that the tag is defined in (implicitly), and the position in that |
188 | file of the tag's definition. When a file parsed by @code{etags} is | |
0f5401a8 FP |
189 | generated from a different source file, like a C file generated from a |
190 | Cweb source file, the tags of the parsed file reference the source | |
191 | file. | |
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192 | |
193 | Just what names from the described files are recorded in the tags table | |
194 | depends on the programming language of the described file. They | |
195 | normally include all file names, functions and subroutines, and may | |
196 | also include global variables, data types, and anything else | |
197 | convenient. Each name recorded is called a @dfn{tag}. | |
198 | ||
199 | @cindex C++ class browser, tags | |
200 | @cindex tags, C++ | |
201 | @cindex class browser, C++ | |
202 | @cindex Ebrowse | |
203 | See also the Ebrowse facility, which is tailored for C++. | |
204 | @xref{Top,, Ebrowse, ebrowse, Ebrowse User's Manual}. | |
205 | ||
206 | @menu | |
207 | * Tag Syntax:: Tag syntax for various types of code and text files. | |
208 | * Create Tags Table:: Creating a tags table with @code{etags}. | |
209 | * Etags Regexps:: Create arbitrary tags using regular expressions. | |
210 | * Select Tags Table:: How to visit a tags table. | |
211 | * Find Tag:: Commands to find the definition of a specific tag. | |
212 | * Tags Search:: Using a tags table for searching and replacing. | |
213 | * List Tags:: Listing and finding tags defined in a file. | |
214 | @end menu | |
215 | ||
216 | @node Tag Syntax | |
217 | @subsection Source File Tag Syntax | |
218 | ||
219 | Here is how tag syntax is defined for the most popular languages: | |
220 | ||
221 | @itemize @bullet | |
222 | @item | |
223 | In C code, any C function or typedef is a tag, and so are definitions of | |
224 | @code{struct}, @code{union} and @code{enum}. | |
225 | @code{#define} macro definitions and @code{enum} constants are also | |
226 | tags, unless you specify @samp{--no-defines} when making the tags table. | |
227 | Similarly, global variables are tags, unless you specify | |
228 | @samp{--no-globals}. Use of @samp{--no-globals} and @samp{--no-defines} | |
229 | can make the tags table file much smaller. | |
230 | ||
231 | You can tag function declarations and external variables in addition | |
232 | to function definitions by giving the @samp{--declarations} option to | |
233 | @code{etags}. | |
234 | ||
235 | @item | |
236 | In C++ code, in addition to all the tag constructs of C code, member | |
237 | functions are also recognized, and optionally member variables if you | |
238 | use the @samp{--members} option. Tags for variables and functions in | |
239 | classes are named @samp{@var{class}::@var{variable}} and | |
240 | @samp{@var{class}::@var{function}}. @code{operator} definitions have | |
241 | tag names like @samp{operator+}. | |
242 | ||
243 | @item | |
244 | In Java code, tags include all the constructs recognized in C++, plus | |
245 | the @code{interface}, @code{extends} and @code{implements} constructs. | |
246 | Tags for variables and functions in classes are named | |
247 | @samp{@var{class}.@var{variable}} and @samp{@var{class}.@var{function}}. | |
248 | ||
249 | @item | |
250 | In La@TeX{} text, the argument of any of the commands @code{\chapter}, | |
251 | @code{\section}, @code{\subsection}, @code{\subsubsection}, | |
e4a1e8d9 FP |
252 | @code{\eqno}, @code{\label}, @code{\ref}, @code{\cite}, |
253 | @code{\bibitem}, @code{\part}, @code{\appendix}, @code{\entry}, | |
254 | @code{\index}, @code{\def}, @code{\newcomand}, @code{\renewcommand}, | |
255 | @code{\newenvironment} or @code{\renewenvironment} is a tag.@refill | |
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256 | |
257 | Other commands can make tags as well, if you specify them in the | |
258 | environment variable @env{TEXTAGS} before invoking @code{etags}. The | |
259 | value of this environment variable should be a colon-separated list of | |
260 | command names. For example, | |
261 | ||
262 | @example | |
e4a1e8d9 | 263 | TEXTAGS="mycommand:myothercommand" |
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264 | export TEXTAGS |
265 | @end example | |
266 | ||
267 | @noindent | |
e4a1e8d9 FP |
268 | specifies (using Bourne shell syntax) that the commands |
269 | @samp{\mycommand} and @samp{\myothercommand} also define tags. | |
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270 | |
271 | @item | |
272 | In Lisp code, any function defined with @code{defun}, any variable | |
273 | defined with @code{defvar} or @code{defconst}, and in general the first | |
274 | argument of any expression that starts with @samp{(def} in column zero, is | |
275 | a tag. | |
276 | ||
277 | @item | |
278 | In Scheme code, tags include anything defined with @code{def} or with a | |
279 | construct whose name starts with @samp{def}. They also include variables | |
280 | set with @code{set!} at top level in the file. | |
281 | @end itemize | |
282 | ||
283 | Several other languages are also supported: | |
284 | ||
285 | @itemize @bullet | |
286 | ||
287 | @item | |
288 | In Ada code, functions, procedures, packages, tasks, and types are | |
289 | tags. Use the @samp{--packages-only} option to create tags for | |
290 | packages only. | |
291 | ||
292 | In Ada, the same name can be used for different kinds of entity | |
293 | (e.g.@:, for a procedure and for a function). Also, for things like | |
294 | packages, procedures and functions, there is the spec (i.e.@: the | |
295 | interface) and the body (i.e.@: the implementation). To make it | |
296 | easier to pick the definition you want, Ada tag name have suffixes | |
297 | indicating the type of entity: | |
298 | ||
299 | @table @samp | |
300 | @item /b | |
301 | package body. | |
302 | @item /f | |
303 | function. | |
304 | @item /k | |
305 | task. | |
306 | @item /p | |
307 | procedure. | |
308 | @item /s | |
309 | package spec. | |
310 | @item /t | |
311 | type. | |
312 | @end table | |
313 | ||
314 | Thus, @kbd{M-x find-tag @key{RET} bidule/b @key{RET}} will go | |
315 | directly to the body of the package @code{bidule}, while @kbd{M-x | |
316 | find-tag @key{RET} bidule @key{RET}} will just search for any tag | |
317 | @code{bidule}. | |
318 | ||
319 | @item | |
320 | In assembler code, labels appearing at the beginning of a line, | |
321 | followed by a colon, are tags. | |
322 | ||
323 | @item | |
324 | In Bison or Yacc input files, each rule defines as a tag the nonterminal | |
325 | it constructs. The portions of the file that contain C code are parsed | |
326 | as C code. | |
327 | ||
328 | @item | |
329 | In Cobol code, tags are paragraph names; that is, any word starting in | |
330 | column 8 and followed by a period. | |
331 | ||
332 | @item | |
333 | In Erlang code, the tags are the functions, records, and macros defined | |
334 | in the file. | |
335 | ||
336 | @item | |
47d7776c | 337 | In Fortran code, functions, subroutines and block data are tags. |
f00366c2 RS |
338 | |
339 | @item | |
f175bfff FP |
340 | In makefiles, targets are tags; additionally, variables are tags |
341 | unless you specify @samp{--no-globals}. | |
f00366c2 RS |
342 | |
343 | @item | |
344 | In Objective C code, tags include Objective C definitions for classes, | |
3e7eaab2 FP |
345 | class categories, methods, and protocols. Tags for variables and |
346 | functions in classes are named @samp{@var{class}::@var{variable}} and | |
347 | @samp{@var{class}::@var{function}}. | |
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348 | |
349 | @item | |
350 | In Pascal code, the tags are the functions and procedures defined in | |
351 | the file. | |
352 | ||
353 | @item | |
3e7eaab2 FP |
354 | In Perl code, the tags are the packages, subroutines and variables |
355 | defined by the @code{package}, @code{sub}, @code{my} and @code{local} | |
356 | keywords. Use @samp{--globals} if you want to tag global variables. | |
357 | Tags for subroutines are named @samp{@var{package}::@var{sub}}. The | |
358 | name for subroutines defined in the default package is | |
359 | @samp{main::@var{sub}}. | |
f00366c2 | 360 | |
e94a3679 FP |
361 | @item |
362 | In PHP code, tags are functions, classes and defines. When using the | |
363 | @samp{--members} option, vars are tags too. | |
364 | ||
f00366c2 RS |
365 | @item |
366 | In PostScript code, the tags are the functions. | |
367 | ||
368 | @item | |
e94a3679 FP |
369 | In Prolog code, tags are predicates and rules at the beginning of |
370 | line. | |
f00366c2 RS |
371 | |
372 | @item | |
373 | In Python code, @code{def} or @code{class} at the beginning of a line | |
374 | generate a tag. | |
375 | @end itemize | |
376 | ||
377 | You can also generate tags based on regexp matching (@pxref{Etags | |
378 | Regexps}) to handle other formats and languages. | |
379 | ||
380 | @node Create Tags Table | |
381 | @subsection Creating Tags Tables | |
382 | @cindex @code{etags} program | |
383 | ||
384 | The @code{etags} program is used to create a tags table file. It knows | |
385 | the syntax of several languages, as described in | |
386 | @iftex | |
387 | the previous section. | |
388 | @end iftex | |
389 | @ifinfo | |
390 | @ref{Tag Syntax}. | |
391 | @end ifinfo | |
392 | Here is how to run @code{etags}: | |
393 | ||
394 | @example | |
395 | etags @var{inputfiles}@dots{} | |
396 | @end example | |
397 | ||
398 | @noindent | |
399 | The @code{etags} program reads the specified files, and writes a tags | |
400 | table named @file{TAGS} in the current working directory. | |
401 | ||
402 | If the specified files don't exist, @code{etags} looks for | |
403 | compressed versions of them and uncompresses them to read them. Under | |
404 | MS-DOS, @code{etags} also looks for file names like @file{mycode.cgz} | |
405 | if it is given @samp{mycode.c} on the command line and @file{mycode.c} | |
406 | does not exist. | |
407 | ||
408 | @code{etags} recognizes the language used in an input file based on | |
409 | its file name and contents. You can specify the language with the | |
410 | @samp{--language=@var{name}} option, described below. | |
411 | ||
412 | If the tags table data become outdated due to changes in the files | |
413 | described in the table, the way to update the tags table is the same | |
55d3737d RS |
414 | way it was made in the first place. If the tags table fails to record |
415 | a tag, or records it for the wrong file, then Emacs cannot possibly | |
416 | find its definition until you update the tags table. However, if the | |
f00366c2 | 417 | position recorded in the tags table becomes a little bit wrong (due to |
55d3737d RS |
418 | other editing), the only consequence is a slight delay in finding the |
419 | tag. Even if the stored position is very far wrong, Emacs will still | |
420 | find the tag, after searching most of the file for it. Even that | |
421 | delay is hardly noticeable with today's computers. | |
f00366c2 RS |
422 | |
423 | So you should update a tags table when you define new tags that you want | |
424 | to have listed, or when you move tag definitions from one file to another, | |
425 | or when changes become substantial. Normally there is no need to update | |
426 | the tags table after each edit, or even every day. | |
427 | ||
428 | One tags table can virtually include another. Specify the included | |
429 | tags file name with the @samp{--include=@var{file}} option when | |
430 | creating the file that is to include it. The latter file then acts as | |
431 | if it covered all the source files specified in the included file, as | |
432 | well as the files it directly contains. | |
433 | ||
434 | If you specify the source files with relative file names when you run | |
435 | @code{etags}, the tags file will contain file names relative to the | |
436 | directory where the tags file was initially written. This way, you can | |
437 | move an entire directory tree containing both the tags file and the | |
438 | source files, and the tags file will still refer correctly to the source | |
439 | files. | |
440 | ||
441 | If you specify absolute file names as arguments to @code{etags}, then | |
442 | the tags file will contain absolute file names. This way, the tags file | |
443 | will still refer to the same files even if you move it, as long as the | |
444 | source files remain in the same place. Absolute file names start with | |
445 | @samp{/}, or with @samp{@var{device}:/} on MS-DOS and MS-Windows. | |
446 | ||
447 | When you want to make a tags table from a great number of files, you | |
448 | may have problems listing them on the command line, because some systems | |
449 | have a limit on its length. The simplest way to circumvent this limit | |
450 | is to tell @code{etags} to read the file names from its standard input, | |
451 | by typing a dash in place of the file names, like this: | |
452 | ||
453 | @smallexample | |
454 | find . -name "*.[chCH]" -print | etags - | |
455 | @end smallexample | |
456 | ||
457 | Use the option @samp{--language=@var{name}} to specify the language | |
458 | explicitly. You can intermix these options with file names; each one | |
459 | applies to the file names that follow it. Specify | |
460 | @samp{--language=auto} to tell @code{etags} to resume guessing the | |
461 | language from the file names and file contents. Specify | |
462 | @samp{--language=none} to turn off language-specific processing | |
463 | entirely; then @code{etags} recognizes tags by regexp matching alone | |
464 | (@pxref{Etags Regexps}). | |
465 | ||
e4a1e8d9 FP |
466 | The option @samp{--parse-stdin=@var{file}} is mostly useful when |
467 | calling @code{etags} from programs. It can be used (only once) in | |
468 | place of a file name on the command line. @code{Etags} will read from | |
469 | standard input and mark the produced tags as belonging to the file | |
470 | @var{file}. | |
471 | ||
f00366c2 RS |
472 | @samp{etags --help} prints the list of the languages @code{etags} |
473 | knows, and the file name rules for guessing the language. It also prints | |
474 | a list of all the available @code{etags} options, together with a short | |
475 | explanation. | |
476 | ||
477 | @node Etags Regexps | |
478 | @subsection Etags Regexps | |
479 | ||
480 | The @samp{--regex} option provides a general way of recognizing tags | |
481 | based on regexp matching. You can freely intermix it with file names. | |
ed1b7d5e RS |
482 | If you specify multiple @samp{--regex} options, all of them are used |
483 | in parallel, but each one applies only to the source files that follow | |
484 | it. The syntax is: | |
f00366c2 RS |
485 | |
486 | @smallexample | |
cc76b311 FP |
487 | --regex=[@var{@{language@}}]/@var{tagregexp}/[@var{nameregexp}/]@var{modifiers} |
488 | @end smallexample | |
489 | ||
ed1b7d5e RS |
490 | The essential part of the option value is @var{tagregexp}, the |
491 | regexp for matching tags. It is always used anchored, that is, it | |
492 | only matches at the beginning of a line. If you want to allow | |
493 | indented tags, use a regexp that matches initial whitespace; start it | |
494 | with @samp{[ \t]*}. | |
495 | ||
496 | In these regular expressions, @samp{\} quotes the next character, and | |
497 | all the GCC character escape sequences are supported (@samp{\a} for | |
498 | bell, @samp{\b} for back space, @samp{\d} for delete, @samp{\e} for | |
499 | escape, @samp{\f} for formfeed, @samp{\n} for newline, @samp{\r} for | |
500 | carriage return, @samp{\t} for tab, and @samp{\v} for vertical tab). | |
501 | ||
502 | Ideally, @var{tagregexp} should not match more characters than are | |
503 | needed to recognize what you want to tag. If the syntax requires you | |
504 | to write @var{tagregexp} so it matches more characters beyond the tag | |
505 | itself, you should add a @var{nameregexp}, to pick out just the tag. | |
506 | This will enable Emacs to find tags more accurately and to do | |
507 | completion on tag names more reliably. You can find some examples | |
508 | below. | |
509 | ||
510 | The @var{modifiers} are a sequence of zero or more characters that | |
511 | modify the way @code{etags} does the matching. A regexp with no | |
512 | modifiers is applied sequentially to each line of the input file, in a | |
513 | case-sensitive way. The modifiers and their meanings are: | |
cc76b311 FP |
514 | |
515 | @table @samp | |
516 | @item i | |
ed1b7d5e | 517 | Ignore case when matching this regexp. |
cc76b311 | 518 | @item m |
ed1b7d5e RS |
519 | Match this regular expression against the whole file, so that |
520 | multi-line matches are possible. | |
cc76b311 | 521 | @item s |
ed1b7d5e RS |
522 | Match this regular expression against the whole file, and allow |
523 | @samp{.} in @var{tagregexp} to match newlines. | |
cc76b311 FP |
524 | @end table |
525 | ||
ed1b7d5e | 526 | The @samp{-R} option cancels all the regexps defined by preceding |
f00366c2 RS |
527 | @samp{--regex} options. It applies to the file names following it, as |
528 | you can see from the following example: | |
529 | ||
530 | @smallexample | |
648ed8f4 | 531 | etags --regex=/@var{reg1}/i voo.doo --regex=/@var{reg2}/m \ |
f00366c2 RS |
532 | bar.ber -R --lang=lisp los.er |
533 | @end smallexample | |
534 | ||
535 | @noindent | |
536 | Here @code{etags} chooses the parsing language for @file{voo.doo} and | |
537 | @file{bar.ber} according to their contents. @code{etags} also uses | |
538 | @var{reg1} to recognize additional tags in @file{voo.doo}, and both | |
539 | @var{reg1} and @var{reg2} to recognize additional tags in | |
648ed8f4 FP |
540 | @file{bar.ber}. @var{reg1} is checked against each line of |
541 | @file{voo.doo} and @file{bar.ber}, in a case-insensitive way, while | |
542 | @var{reg2} is checked against the whole @file{bar.ber} file, | |
543 | permitting multi-line matches, in a case-sensitive way. @code{etags} | |
ed1b7d5e RS |
544 | uses only the Lisp tags rules, with no user-specified regexp matching, |
545 | to recognize tags in @file{los.er}. | |
f00366c2 | 546 | |
b8fc5a9c FP |
547 | You can restrict a @samp{--regex} option to match only files of a |
548 | given language by using the optional prefix @var{@{language@}}. | |
648ed8f4 FP |
549 | (@samp{etags --help} prints the list of languages recognized by |
550 | @code{etags}.) This is particularly useful when storing many | |
551 | predefined regular expressions for @code{etags} in a file. The | |
f00366c2 RS |
552 | following example tags the @code{DEFVAR} macros in the Emacs source |
553 | files, for the C language only: | |
554 | ||
555 | @smallexample | |
556 | --regex='@{c@}/[ \t]*DEFVAR_[A-Z_ \t(]+"\([^"]+\)"/' | |
557 | @end smallexample | |
558 | ||
559 | @noindent | |
ed1b7d5e RS |
560 | When you have complex regular expressions, you can store the list of |
561 | them in a file. The following option syntax instructs @code{etags} to | |
562 | read two files of regular expressions. The regular expressions | |
563 | contained in the second file are matched without regard to case. | |
f00366c2 RS |
564 | |
565 | @smallexample | |
ed1b7d5e | 566 | --regex=@@@var{case-sensitive-file} --ignore-case-regex=@@@var{ignore-case-file} |
f00366c2 RS |
567 | @end smallexample |
568 | ||
569 | @noindent | |
ed1b7d5e RS |
570 | A regex file for @code{etags} contains one regular expression per |
571 | line. Empty lines, and lines beginning with space or tab are ignored. | |
572 | When the first character in a line is @samp{@@}, @code{etags} assumes | |
573 | that the rest of the line is the name of another file of regular | |
574 | expressions; thus, one such file can include another file. All the | |
575 | other lines are taken to be regular expressions. If the first | |
576 | non-whitespace text on the line is @samp{--}, that line is a comment. | |
577 | ||
578 | For example, we can create a file called @samp{emacs.tags} with the | |
f00366c2 RS |
579 | following contents: |
580 | ||
581 | @smallexample | |
582 | -- This is for GNU Emacs C source files | |
583 | @{c@}/[ \t]*DEFVAR_[A-Z_ \t(]+"\([^"]+\)"/\1/ | |
584 | @end smallexample | |
585 | ||
586 | @noindent | |
587 | and then use it like this: | |
588 | ||
589 | @smallexample | |
590 | etags --regex=@@emacs.tags *.[ch] */*.[ch] | |
591 | @end smallexample | |
592 | ||
593 | Here are some more examples. The regexps are quoted to protect them | |
594 | from shell interpretation. | |
595 | ||
596 | @itemize @bullet | |
597 | ||
598 | @item | |
599 | Tag Octave files: | |
600 | ||
601 | @smallexample | |
602 | etags --language=none \ | |
603 | --regex='/[ \t]*function.*=[ \t]*\([^ \t]*\)[ \t]*(/\1/' \ | |
604 | --regex='/###key \(.*\)/\1/' \ | |
605 | --regex='/[ \t]*global[ \t].*/' \ | |
606 | *.m | |
607 | @end smallexample | |
608 | ||
609 | @noindent | |
610 | Note that tags are not generated for scripts, so that you have to add | |
611 | a line by yourself of the form @samp{###key @var{scriptname}} if you | |
612 | want to jump to it. | |
613 | ||
614 | @item | |
615 | Tag Tcl files: | |
616 | ||
617 | @smallexample | |
618 | etags --language=none --regex='/proc[ \t]+\([^ \t]+\)/\1/' *.tcl | |
619 | @end smallexample | |
620 | ||
621 | @item | |
622 | Tag VHDL files: | |
623 | ||
624 | @smallexample | |
625 | etags --language=none \ | |
626 | --regex='/[ \t]*\(ARCHITECTURE\|CONFIGURATION\) +[^ ]* +OF/' \ | |
627 | --regex='/[ \t]*\(ATTRIBUTE\|ENTITY\|FUNCTION\|PACKAGE\ | |
628 | \( BODY\)?\|PROCEDURE\|PROCESS\|TYPE\)[ \t]+\([^ \t(]+\)/\3/' | |
629 | @end smallexample | |
630 | @end itemize | |
631 | ||
632 | @node Select Tags Table | |
633 | @subsection Selecting a Tags Table | |
634 | ||
635 | @vindex tags-file-name | |
636 | @findex visit-tags-table | |
637 | Emacs has at any time one @dfn{selected} tags table, and all the commands | |
638 | for working with tags tables use the selected one. To select a tags table, | |
639 | type @kbd{M-x visit-tags-table}, which reads the tags table file name as an | |
640 | argument. The name @file{TAGS} in the default directory is used as the | |
641 | default file name. | |
642 | ||
643 | All this command does is store the file name in the variable | |
644 | @code{tags-file-name}. Emacs does not actually read in the tags table | |
645 | contents until you try to use them. Setting this variable yourself is just | |
646 | as good as using @code{visit-tags-table}. The variable's initial value is | |
647 | @code{nil}; that value tells all the commands for working with tags tables | |
648 | that they must ask for a tags table file name to use. | |
649 | ||
650 | Using @code{visit-tags-table} when a tags table is already loaded | |
651 | gives you a choice: you can add the new tags table to the current list | |
652 | of tags tables, or start a new list. The tags commands use all the tags | |
653 | tables in the current list. If you start a new list, the new tags table | |
654 | is used @emph{instead} of others. If you add the new table to the | |
655 | current list, it is used @emph{as well as} the others. When the tags | |
656 | commands scan the list of tags tables, they don't always start at the | |
657 | beginning of the list; they start with the first tags table (if any) | |
658 | that describes the current file, proceed from there to the end of the | |
659 | list, and then scan from the beginning of the list until they have | |
660 | covered all the tables in the list. | |
661 | ||
662 | @vindex tags-table-list | |
663 | You can specify a precise list of tags tables by setting the variable | |
664 | @code{tags-table-list} to a list of strings, like this: | |
665 | ||
666 | @c keep this on two lines for formatting in smallbook | |
667 | @example | |
668 | @group | |
669 | (setq tags-table-list | |
670 | '("~/emacs" "/usr/local/lib/emacs/src")) | |
671 | @end group | |
672 | @end example | |
673 | ||
674 | @noindent | |
675 | This tells the tags commands to look at the @file{TAGS} files in your | |
676 | @file{~/emacs} directory and in the @file{/usr/local/lib/emacs/src} | |
677 | directory. The order depends on which file you are in and which tags | |
678 | table mentions that file, as explained above. | |
679 | ||
680 | Do not set both @code{tags-file-name} and @code{tags-table-list}. | |
681 | ||
682 | @node Find Tag | |
683 | @subsection Finding a Tag | |
684 | ||
685 | The most important thing that a tags table enables you to do is to find | |
686 | the definition of a specific tag. | |
687 | ||
688 | @table @kbd | |
689 | @item M-.@: @var{tag} @key{RET} | |
690 | Find first definition of @var{tag} (@code{find-tag}). | |
691 | @item C-u M-. | |
692 | Find next alternate definition of last tag specified. | |
693 | @item C-u - M-. | |
694 | Go back to previous tag found. | |
695 | @item C-M-. @var{pattern} @key{RET} | |
696 | Find a tag whose name matches @var{pattern} (@code{find-tag-regexp}). | |
697 | @item C-u C-M-. | |
698 | Find the next tag whose name matches the last pattern used. | |
699 | @item C-x 4 .@: @var{tag} @key{RET} | |
700 | Find first definition of @var{tag}, but display it in another window | |
701 | (@code{find-tag-other-window}). | |
702 | @item C-x 5 .@: @var{tag} @key{RET} | |
703 | Find first definition of @var{tag}, and create a new frame to select the | |
704 | buffer (@code{find-tag-other-frame}). | |
705 | @item M-* | |
706 | Pop back to where you previously invoked @kbd{M-.} and friends. | |
707 | @end table | |
708 | ||
709 | @kindex M-. | |
710 | @findex find-tag | |
711 | @kbd{M-.}@: (@code{find-tag}) is the command to find the definition of | |
712 | a specified tag. It searches through the tags table for that tag, as a | |
713 | string, and then uses the tags table info to determine the file that the | |
714 | definition is in and the approximate character position in the file of | |
715 | the definition. Then @code{find-tag} visits that file, moves point to | |
716 | the approximate character position, and searches ever-increasing | |
717 | distances away to find the tag definition. | |
718 | ||
719 | If an empty argument is given (just type @key{RET}), the balanced | |
720 | expression in the buffer before or around point is used as the | |
721 | @var{tag} argument. @xref{Expressions}. | |
722 | ||
723 | You don't need to give @kbd{M-.} the full name of the tag; a part | |
724 | will do. This is because @kbd{M-.} finds tags in the table which | |
725 | contain @var{tag} as a substring. However, it prefers an exact match | |
726 | to a substring match. To find other tags that match the same | |
727 | substring, give @code{find-tag} a numeric argument, as in @kbd{C-u | |
728 | M-.}; this does not read a tag name, but continues searching the tags | |
729 | table's text for another tag containing the same substring last used. | |
730 | If you have a real @key{META} key, @kbd{M-0 M-.}@: is an easier | |
731 | alternative to @kbd{C-u M-.}. | |
732 | ||
733 | @kindex C-x 4 . | |
734 | @findex find-tag-other-window | |
735 | @kindex C-x 5 . | |
736 | @findex find-tag-other-frame | |
737 | Like most commands that can switch buffers, @code{find-tag} has a | |
738 | variant that displays the new buffer in another window, and one that | |
739 | makes a new frame for it. The former is @kbd{C-x 4 .}, which invokes | |
740 | the command @code{find-tag-other-window}. The latter is @kbd{C-x 5 .}, | |
741 | which invokes @code{find-tag-other-frame}. | |
742 | ||
743 | To move back to places you've found tags recently, use @kbd{C-u - | |
744 | M-.}; more generally, @kbd{M-.} with a negative numeric argument. This | |
745 | command can take you to another buffer. @kbd{C-x 4 .} with a negative | |
746 | argument finds the previous tag location in another window. | |
747 | ||
748 | @kindex M-* | |
749 | @findex pop-tag-mark | |
750 | @vindex find-tag-marker-ring-length | |
751 | As well as going back to places you've found tags recently, you can go | |
752 | back to places @emph{from where} you found them. Use @kbd{M-*}, which | |
753 | invokes the command @code{pop-tag-mark}, for this. Typically you would | |
754 | find and study the definition of something with @kbd{M-.} and then | |
755 | return to where you were with @kbd{M-*}. | |
756 | ||
757 | Both @kbd{C-u - M-.} and @kbd{M-*} allow you to retrace your steps to | |
758 | a depth determined by the variable @code{find-tag-marker-ring-length}. | |
759 | ||
760 | @findex find-tag-regexp | |
761 | @kindex C-M-. | |
762 | The command @kbd{C-M-.} (@code{find-tag-regexp}) visits the tags that | |
763 | match a specified regular expression. It is just like @kbd{M-.} except | |
764 | that it does regexp matching instead of substring matching. | |
765 | ||
766 | @node Tags Search | |
767 | @subsection Searching and Replacing with Tags Tables | |
768 | @cindex search and replace in multiple files | |
769 | @cindex multiple-file search and replace | |
770 | ||
771 | The commands in this section visit and search all the files listed in the | |
772 | selected tags table, one by one. For these commands, the tags table serves | |
773 | only to specify a sequence of files to search. | |
774 | ||
775 | @table @kbd | |
776 | @item M-x tags-search @key{RET} @var{regexp} @key{RET} | |
777 | Search for @var{regexp} through the files in the selected tags | |
778 | table. | |
779 | @item M-x tags-query-replace @key{RET} @var{regexp} @key{RET} @var{replacement} @key{RET} | |
780 | Perform a @code{query-replace-regexp} on each file in the selected tags table. | |
781 | @item M-, | |
782 | Restart one of the commands above, from the current location of point | |
783 | (@code{tags-loop-continue}). | |
784 | @end table | |
785 | ||
786 | @findex tags-search | |
787 | @kbd{M-x tags-search} reads a regexp using the minibuffer, then | |
788 | searches for matches in all the files in the selected tags table, one | |
789 | file at a time. It displays the name of the file being searched so you | |
790 | can follow its progress. As soon as it finds an occurrence, | |
791 | @code{tags-search} returns. | |
792 | ||
793 | @kindex M-, | |
794 | @findex tags-loop-continue | |
795 | Having found one match, you probably want to find all the rest. To find | |
796 | one more match, type @kbd{M-,} (@code{tags-loop-continue}) to resume the | |
797 | @code{tags-search}. This searches the rest of the current buffer, followed | |
798 | by the remaining files of the tags table.@refill | |
799 | ||
800 | @findex tags-query-replace | |
801 | @kbd{M-x tags-query-replace} performs a single | |
802 | @code{query-replace-regexp} through all the files in the tags table. It | |
803 | reads a regexp to search for and a string to replace with, just like | |
804 | ordinary @kbd{M-x query-replace-regexp}. It searches much like @kbd{M-x | |
805 | tags-search}, but repeatedly, processing matches according to your | |
806 | input. @xref{Replace}, for more information on query replace. | |
807 | ||
808 | @vindex tags-case-fold-search | |
809 | @cindex case-sensitivity and tags search | |
810 | You can control the case-sensitivity of tags search commands by | |
811 | customizing the value of the variable @code{tags-case-fold-search}. The | |
812 | default is to use the same setting as the value of | |
813 | @code{case-fold-search} (@pxref{Search Case}). | |
814 | ||
815 | It is possible to get through all the files in the tags table with a | |
816 | single invocation of @kbd{M-x tags-query-replace}. But often it is | |
817 | useful to exit temporarily, which you can do with any input event that | |
818 | has no special query replace meaning. You can resume the query replace | |
819 | subsequently by typing @kbd{M-,}; this command resumes the last tags | |
820 | search or replace command that you did. | |
821 | ||
822 | The commands in this section carry out much broader searches than the | |
823 | @code{find-tag} family. The @code{find-tag} commands search only for | |
824 | definitions of tags that match your substring or regexp. The commands | |
825 | @code{tags-search} and @code{tags-query-replace} find every occurrence | |
826 | of the regexp, as ordinary search commands and replace commands do in | |
827 | the current buffer. | |
828 | ||
829 | These commands create buffers only temporarily for the files that they | |
830 | have to search (those which are not already visited in Emacs buffers). | |
831 | Buffers in which no match is found are quickly killed; the others | |
832 | continue to exist. | |
833 | ||
834 | It may have struck you that @code{tags-search} is a lot like | |
835 | @code{grep}. You can also run @code{grep} itself as an inferior of | |
836 | Emacs and have Emacs show you the matching lines one by one. This works | |
837 | much like running a compilation; finding the source locations of the | |
838 | @code{grep} matches works like finding the compilation errors. | |
839 | @xref{Compilation}. | |
840 | ||
841 | @node List Tags | |
842 | @subsection Tags Table Inquiries | |
843 | ||
844 | @table @kbd | |
845 | @item M-x list-tags @key{RET} @var{file} @key{RET} | |
846 | Display a list of the tags defined in the program file @var{file}. | |
847 | @item M-x tags-apropos @key{RET} @var{regexp} @key{RET} | |
848 | Display a list of all tags matching @var{regexp}. | |
849 | @end table | |
850 | ||
851 | @findex list-tags | |
852 | @kbd{M-x list-tags} reads the name of one of the files described by | |
853 | the selected tags table, and displays a list of all the tags defined in | |
854 | that file. The ``file name'' argument is really just a string to | |
855 | compare against the file names recorded in the tags table; it is read as | |
856 | a string rather than as a file name. Therefore, completion and | |
857 | defaulting are not available, and you must enter the file name the same | |
858 | way it appears in the tags table. Do not include a directory as part of | |
859 | the file name unless the file name recorded in the tags table includes a | |
860 | directory. | |
861 | ||
862 | @findex tags-apropos | |
863 | @vindex tags-apropos-verbose | |
864 | @kbd{M-x tags-apropos} is like @code{apropos} for tags | |
865 | (@pxref{Apropos}). It finds all the tags in the selected tags table | |
866 | whose entries match @var{regexp}, and displays them. If the variable | |
867 | @code{tags-apropos-verbose} is non-@code{nil}, it displays the names | |
868 | of the tags files together with the tag names. | |
869 | ||
870 | @vindex tags-tag-face | |
871 | @vindex tags-apropos-additional-actions | |
872 | You can customize the appearance of the output with the face | |
873 | @code{tags-tag-face}. You can display additional output with @kbd{M-x | |
874 | tags-apropos} by customizing the variable | |
875 | @code{tags-apropos-additional-actions}---see its documentation for | |
876 | details. | |
877 | ||
878 | You can also use the collection of tag names to complete a symbol | |
879 | name in the buffer. @xref{Symbol Completion}. | |
880 | ||
ebe19e1b | 881 | @node Emerge |
f00366c2 RS |
882 | @section Merging Files with Emerge |
883 | @cindex Emerge | |
884 | @cindex merging files | |
885 | ||
886 | It's not unusual for programmers to get their signals crossed and modify | |
887 | the same program in two different directions. To recover from this | |
888 | confusion, you need to merge the two versions. Emerge makes this | |
889 | easier. See also @ref{Comparing Files}, for commands to compare | |
b5f1c9fa | 890 | in a more manual fashion, and @ref{Top, Ediff,, ediff, The Ediff Manual}. |
f00366c2 RS |
891 | |
892 | @menu | |
893 | * Overview of Emerge:: How to start Emerge. Basic concepts. | |
894 | * Submodes of Emerge:: Fast mode vs. Edit mode. | |
895 | Skip Prefers mode and Auto Advance mode. | |
896 | * State of Difference:: You do the merge by specifying state A or B | |
897 | for each difference. | |
898 | * Merge Commands:: Commands for selecting a difference, | |
899 | changing states of differences, etc. | |
900 | * Exiting Emerge:: What to do when you've finished the merge. | |
901 | * Combining in Emerge:: How to keep both alternatives for a difference. | |
902 | * Fine Points of Emerge:: Misc. | |
903 | @end menu | |
904 | ||
905 | @node Overview of Emerge | |
906 | @subsection Overview of Emerge | |
907 | ||
908 | To start Emerge, run one of these four commands: | |
909 | ||
910 | @table @kbd | |
911 | @item M-x emerge-files | |
912 | @findex emerge-files | |
913 | Merge two specified files. | |
914 | ||
915 | @item M-x emerge-files-with-ancestor | |
916 | @findex emerge-files-with-ancestor | |
917 | Merge two specified files, with reference to a common ancestor. | |
918 | ||
919 | @item M-x emerge-buffers | |
920 | @findex emerge-buffers | |
921 | Merge two buffers. | |
922 | ||
923 | @item M-x emerge-buffers-with-ancestor | |
924 | @findex emerge-buffers-with-ancestor | |
925 | Merge two buffers with reference to a common ancestor in a third | |
926 | buffer. | |
927 | @end table | |
928 | ||
929 | @cindex merge buffer (Emerge) | |
930 | @cindex A and B buffers (Emerge) | |
931 | The Emerge commands compare two files or buffers, and display the | |
932 | comparison in three buffers: one for each input text (the @dfn{A buffer} | |
933 | and the @dfn{B buffer}), and one (the @dfn{merge buffer}) where merging | |
934 | takes place. The merge buffer shows the full merged text, not just the | |
935 | differences. Wherever the two input texts differ, you can choose which | |
936 | one of them to include in the merge buffer. | |
937 | ||
938 | The Emerge commands that take input from existing buffers use only the | |
939 | accessible portions of those buffers, if they are narrowed | |
940 | (@pxref{Narrowing}). | |
941 | ||
942 | If a common ancestor version is available, from which the two texts to | |
943 | be merged were both derived, Emerge can use it to guess which | |
944 | alternative is right. Wherever one current version agrees with the | |
945 | ancestor, Emerge presumes that the other current version is a deliberate | |
946 | change which should be kept in the merged version. Use the | |
947 | @samp{with-ancestor} commands if you want to specify a common ancestor | |
948 | text. These commands read three file or buffer names---variant A, | |
949 | variant B, and the common ancestor. | |
950 | ||
951 | After the comparison is done and the buffers are prepared, the | |
952 | interactive merging starts. You control the merging by typing special | |
953 | @dfn{merge commands} in the merge buffer. The merge buffer shows you a | |
954 | full merged text, not just differences. For each run of differences | |
955 | between the input texts, you can choose which one of them to keep, or | |
956 | edit them both together. | |
957 | ||
958 | The merge buffer uses a special major mode, Emerge mode, with commands | |
959 | for making these choices. But you can also edit the buffer with | |
960 | ordinary Emacs commands. | |
961 | ||
962 | At any given time, the attention of Emerge is focused on one | |
963 | particular difference, called the @dfn{selected} difference. This | |
964 | difference is marked off in the three buffers like this: | |
965 | ||
966 | @example | |
967 | vvvvvvvvvvvvvvvvvvvv | |
968 | @var{text that differs} | |
969 | ^^^^^^^^^^^^^^^^^^^^ | |
970 | @end example | |
971 | ||
972 | @noindent | |
973 | Emerge numbers all the differences sequentially and the mode | |
974 | line always shows the number of the selected difference. | |
975 | ||
976 | Normally, the merge buffer starts out with the A version of the text. | |
977 | But when the A version of a difference agrees with the common ancestor, | |
978 | then the B version is initially preferred for that difference. | |
979 | ||
980 | Emerge leaves the merged text in the merge buffer when you exit. At | |
981 | that point, you can save it in a file with @kbd{C-x C-w}. If you give a | |
982 | numeric argument to @code{emerge-files} or | |
983 | @code{emerge-files-with-ancestor}, it reads the name of the output file | |
984 | using the minibuffer. (This is the last file name those commands read.) | |
985 | Then exiting from Emerge saves the merged text in the output file. | |
986 | ||
987 | Normally, Emerge commands save the output buffer in its file when you | |
988 | exit. If you abort Emerge with @kbd{C-]}, the Emerge command does not | |
989 | save the output buffer, but you can save it yourself if you wish. | |
990 | ||
991 | @node Submodes of Emerge | |
992 | @subsection Submodes of Emerge | |
993 | ||
994 | You can choose between two modes for giving merge commands: Fast mode | |
995 | and Edit mode. In Fast mode, basic merge commands are single | |
996 | characters, but ordinary Emacs commands are disabled. This is | |
997 | convenient if you use only merge commands. In Edit mode, all merge | |
998 | commands start with the prefix key @kbd{C-c C-c}, and the normal Emacs | |
999 | commands are also available. This allows editing the merge buffer, but | |
1000 | slows down Emerge operations. | |
1001 | ||
1002 | Use @kbd{e} to switch to Edit mode, and @kbd{C-c C-c f} to switch to | |
1003 | Fast mode. The mode line indicates Edit and Fast modes with @samp{E} | |
1004 | and @samp{F}. | |
1005 | ||
1006 | Emerge has two additional submodes that affect how particular merge | |
1007 | commands work: Auto Advance mode and Skip Prefers mode. | |
1008 | ||
1009 | If Auto Advance mode is in effect, the @kbd{a} and @kbd{b} commands | |
1010 | advance to the next difference. This lets you go through the merge | |
1011 | faster as long as you simply choose one of the alternatives from the | |
1012 | input. The mode line indicates Auto Advance mode with @samp{A}. | |
1013 | ||
1014 | If Skip Prefers mode is in effect, the @kbd{n} and @kbd{p} commands | |
1015 | skip over differences in states prefer-A and prefer-B (@pxref{State of | |
1016 | Difference}). Thus you see only differences for which neither version | |
1017 | is presumed ``correct.'' The mode line indicates Skip Prefers mode with | |
1018 | @samp{S}. | |
1019 | ||
1020 | @findex emerge-auto-advance-mode | |
1021 | @findex emerge-skip-prefers-mode | |
1022 | Use the command @kbd{s a} (@code{emerge-auto-advance-mode}) to set or | |
1023 | clear Auto Advance mode. Use @kbd{s s} | |
1024 | (@code{emerge-skip-prefers-mode}) to set or clear Skip Prefers mode. | |
1025 | These commands turn on the mode with a positive argument, turns it off | |
1026 | with a negative or zero argument, and toggle the mode with no argument. | |
1027 | ||
1028 | @node State of Difference | |
1029 | @subsection State of a Difference | |
1030 | ||
1031 | In the merge buffer, a difference is marked with lines of @samp{v} and | |
1032 | @samp{^} characters. Each difference has one of these seven states: | |
1033 | ||
1034 | @table @asis | |
1035 | @item A | |
1036 | The difference is showing the A version. The @kbd{a} command always | |
1037 | produces this state; the mode line indicates it with @samp{A}. | |
1038 | ||
1039 | @item B | |
1040 | The difference is showing the B version. The @kbd{b} command always | |
1041 | produces this state; the mode line indicates it with @samp{B}. | |
1042 | ||
1043 | @item default-A | |
1044 | @itemx default-B | |
1045 | The difference is showing the A or the B state by default, because you | |
1046 | haven't made a choice. All differences start in the default-A state | |
1047 | (and thus the merge buffer is a copy of the A buffer), except those for | |
1048 | which one alternative is ``preferred'' (see below). | |
1049 | ||
1050 | When you select a difference, its state changes from default-A or | |
1051 | default-B to plain A or B. Thus, the selected difference never has | |
1052 | state default-A or default-B, and these states are never displayed in | |
1053 | the mode line. | |
1054 | ||
1055 | The command @kbd{d a} chooses default-A as the default state, and @kbd{d | |
1056 | b} chooses default-B. This chosen default applies to all differences | |
1057 | which you haven't ever selected and for which no alternative is preferred. | |
1058 | If you are moving through the merge sequentially, the differences you | |
1059 | haven't selected are those following the selected one. Thus, while | |
1060 | moving sequentially, you can effectively make the A version the default | |
1061 | for some sections of the merge buffer and the B version the default for | |
1062 | others by using @kbd{d a} and @kbd{d b} between sections. | |
1063 | ||
1064 | @item prefer-A | |
1065 | @itemx prefer-B | |
1066 | The difference is showing the A or B state because it is | |
1067 | @dfn{preferred}. This means that you haven't made an explicit choice, | |
1068 | but one alternative seems likely to be right because the other | |
1069 | alternative agrees with the common ancestor. Thus, where the A buffer | |
1070 | agrees with the common ancestor, the B version is preferred, because | |
1071 | chances are it is the one that was actually changed. | |
1072 | ||
1073 | These two states are displayed in the mode line as @samp{A*} and @samp{B*}. | |
1074 | ||
1075 | @item combined | |
1076 | The difference is showing a combination of the A and B states, as a | |
1077 | result of the @kbd{x c} or @kbd{x C} commands. | |
1078 | ||
1079 | Once a difference is in this state, the @kbd{a} and @kbd{b} commands | |
1080 | don't do anything to it unless you give them a numeric argument. | |
1081 | ||
1082 | The mode line displays this state as @samp{comb}. | |
1083 | @end table | |
1084 | ||
1085 | @node Merge Commands | |
1086 | @subsection Merge Commands | |
1087 | ||
1088 | Here are the Merge commands for Fast mode; in Edit mode, precede them | |
1089 | with @kbd{C-c C-c}: | |
1090 | ||
1091 | @table @kbd | |
1092 | @item p | |
1093 | Select the previous difference. | |
1094 | ||
1095 | @item n | |
1096 | Select the next difference. | |
1097 | ||
1098 | @item a | |
1099 | Choose the A version of this difference. | |
1100 | ||
1101 | @item b | |
1102 | Choose the B version of this difference. | |
1103 | ||
1104 | @item C-u @var{n} j | |
1105 | Select difference number @var{n}. | |
1106 | ||
1107 | @item . | |
1108 | Select the difference containing point. You can use this command in the | |
1109 | merge buffer or in the A or B buffer. | |
1110 | ||
1111 | @item q | |
1112 | Quit---finish the merge. | |
1113 | ||
1114 | @item C-] | |
1115 | Abort---exit merging and do not save the output. | |
1116 | ||
1117 | @item f | |
1118 | Go into Fast mode. (In Edit mode, this is actually @kbd{C-c C-c f}.) | |
1119 | ||
1120 | @item e | |
1121 | Go into Edit mode. | |
1122 | ||
1123 | @item l | |
1124 | Recenter (like @kbd{C-l}) all three windows. | |
1125 | ||
1126 | @item - | |
1127 | Specify part of a prefix numeric argument. | |
1128 | ||
1129 | @item @var{digit} | |
1130 | Also specify part of a prefix numeric argument. | |
1131 | ||
1132 | @item d a | |
1133 | Choose the A version as the default from here down in | |
1134 | the merge buffer. | |
1135 | ||
1136 | @item d b | |
1137 | Choose the B version as the default from here down in | |
1138 | the merge buffer. | |
1139 | ||
1140 | @item c a | |
1141 | Copy the A version of this difference into the kill ring. | |
1142 | ||
1143 | @item c b | |
1144 | Copy the B version of this difference into the kill ring. | |
1145 | ||
1146 | @item i a | |
1147 | Insert the A version of this difference at point. | |
1148 | ||
1149 | @item i b | |
1150 | Insert the B version of this difference at point. | |
1151 | ||
1152 | @item m | |
1153 | Put point and mark around the difference. | |
1154 | ||
1155 | @item ^ | |
1156 | Scroll all three windows down (like @kbd{M-v}). | |
1157 | ||
1158 | @item v | |
1159 | Scroll all three windows up (like @kbd{C-v}). | |
1160 | ||
1161 | @item < | |
1162 | Scroll all three windows left (like @kbd{C-x <}). | |
1163 | ||
1164 | @item > | |
1165 | Scroll all three windows right (like @kbd{C-x >}). | |
1166 | ||
1167 | @item | | |
1168 | Reset horizontal scroll on all three windows. | |
1169 | ||
1170 | @item x 1 | |
1171 | Shrink the merge window to one line. (Use @kbd{C-u l} to restore it | |
1172 | to full size.) | |
1173 | ||
1174 | @item x c | |
1175 | Combine the two versions of this difference (@pxref{Combining in | |
1176 | Emerge}). | |
1177 | ||
1178 | @item x f | |
1179 | Show the names of the files/buffers Emerge is operating on, in a Help | |
1180 | window. (Use @kbd{C-u l} to restore windows.) | |
1181 | ||
1182 | @item x j | |
1183 | Join this difference with the following one. | |
1184 | (@kbd{C-u x j} joins this difference with the previous one.) | |
1185 | ||
1186 | @item x s | |
1187 | Split this difference into two differences. Before you use this | |
1188 | command, position point in each of the three buffers at the place where | |
1189 | you want to split the difference. | |
1190 | ||
1191 | @item x t | |
1192 | Trim identical lines off the top and bottom of the difference. | |
1193 | Such lines occur when the A and B versions are | |
1194 | identical but differ from the ancestor version. | |
1195 | @end table | |
1196 | ||
1197 | @node Exiting Emerge | |
1198 | @subsection Exiting Emerge | |
1199 | ||
1200 | The @kbd{q} command (@code{emerge-quit}) finishes the merge, storing | |
1201 | the results into the output file if you specified one. It restores the | |
1202 | A and B buffers to their proper contents, or kills them if they were | |
1203 | created by Emerge and you haven't changed them. It also disables the | |
1204 | Emerge commands in the merge buffer, since executing them later could | |
1205 | damage the contents of the various buffers. | |
1206 | ||
1207 | @kbd{C-]} aborts the merge. This means exiting without writing the | |
1208 | output file. If you didn't specify an output file, then there is no | |
1209 | real difference between aborting and finishing the merge. | |
1210 | ||
1211 | If the Emerge command was called from another Lisp program, then its | |
1212 | return value is @code{t} for successful completion, or @code{nil} if you | |
1213 | abort. | |
1214 | ||
1215 | @node Combining in Emerge | |
1216 | @subsection Combining the Two Versions | |
1217 | ||
1218 | Sometimes you want to keep @emph{both} alternatives for a particular | |
1219 | difference. To do this, use @kbd{x c}, which edits the merge buffer | |
1220 | like this: | |
1221 | ||
1222 | @example | |
1223 | @group | |
1224 | #ifdef NEW | |
1225 | @var{version from A buffer} | |
1226 | #else /* not NEW */ | |
1227 | @var{version from B buffer} | |
1228 | #endif /* not NEW */ | |
1229 | @end group | |
1230 | @end example | |
1231 | ||
1232 | @noindent | |
1233 | @vindex emerge-combine-versions-template | |
1234 | While this example shows C preprocessor conditionals delimiting the two | |
1235 | alternative versions, you can specify the strings to use by setting | |
1236 | the variable @code{emerge-combine-versions-template} to a string of your | |
1237 | choice. In the string, @samp{%a} says where to put version A, and | |
1238 | @samp{%b} says where to put version B. The default setting, which | |
1239 | produces the results shown above, looks like this: | |
1240 | ||
1241 | @example | |
1242 | @group | |
1243 | "#ifdef NEW\n%a#else /* not NEW */\n%b#endif /* not NEW */\n" | |
1244 | @end group | |
1245 | @end example | |
1246 | ||
1247 | @node Fine Points of Emerge | |
1248 | @subsection Fine Points of Emerge | |
1249 | ||
1250 | During the merge, you mustn't try to edit the A and B buffers yourself. | |
1251 | Emerge modifies them temporarily, but ultimately puts them back the way | |
1252 | they were. | |
1253 | ||
1254 | You can have any number of merges going at once---just don't use any one | |
1255 | buffer as input to more than one merge at once, since the temporary | |
1256 | changes made in these buffers would get in each other's way. | |
1257 | ||
1258 | Starting Emerge can take a long time because it needs to compare the | |
1259 | files fully. Emacs can't do anything else until @code{diff} finishes. | |
1260 | Perhaps in the future someone will change Emerge to do the comparison in | |
1261 | the background when the input files are large---then you could keep on | |
1262 | doing other things with Emacs until Emerge is ready to accept | |
1263 | commands. | |
1264 | ||
1265 | @vindex emerge-startup-hook | |
1266 | After setting up the merge, Emerge runs the hook | |
1267 | @code{emerge-startup-hook} (@pxref{Hooks}). |