| 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 |
| 11 | version control features (@pxref{Version Control}) are also |
| 12 | particularly useful for this purpose. |
| 13 | |
| 14 | @menu |
| 15 | * Change Log:: Maintaining a change history for your program. |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 143 | @ignore |
| 144 | @c This is commented out because the command is specific |
| 145 | @c to maintenance of Emacs itself. |
| 146 | |
| 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 |
| 158 | Emacs source directory. It then scans @file{ChangeLog} files and Lisp |
| 159 | source files under that directory for information about authors of |
| 160 | individual packages, and people who made changes in source files, and |
| 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 |
| 163 | existing @file{AUTHORS} file. |
| 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. |
| 169 | @end ignore |
| 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 |
| 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 |
| 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. |
| 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}. You can tag struct members with the @samp{--members} |
| 234 | option. |
| 235 | |
| 236 | @item |
| 237 | In C++ code, in addition to all the tag constructs of C code, member |
| 238 | functions are also recognized, and optionally member variables if you |
| 239 | use the @samp{--members} option. Tags for variables and functions in |
| 240 | classes are named @samp{@var{class}::@var{variable}} and |
| 241 | @samp{@var{class}::@var{function}}. @code{operator} definitions have |
| 242 | tag names like @samp{operator+}. |
| 243 | |
| 244 | @item |
| 245 | In Java code, tags include all the constructs recognized in C++, plus |
| 246 | the @code{interface}, @code{extends} and @code{implements} constructs. |
| 247 | Tags for variables and functions in classes are named |
| 248 | @samp{@var{class}.@var{variable}} and @samp{@var{class}.@var{function}}. |
| 249 | |
| 250 | @item |
| 251 | In La@TeX{} text, the argument of any of the commands @code{\chapter}, |
| 252 | @code{\section}, @code{\subsection}, @code{\subsubsection}, |
| 253 | @code{\eqno}, @code{\label}, @code{\ref}, @code{\cite}, |
| 254 | @code{\bibitem}, @code{\part}, @code{\appendix}, @code{\entry}, |
| 255 | @code{\index}, @code{\def}, @code{\newcommand}, @code{\renewcommand}, |
| 256 | @code{\newenvironment} or @code{\renewenvironment} is a tag.@refill |
| 257 | |
| 258 | Other commands can make tags as well, if you specify them in the |
| 259 | environment variable @env{TEXTAGS} before invoking @code{etags}. The |
| 260 | value of this environment variable should be a colon-separated list of |
| 261 | command names. For example, |
| 262 | |
| 263 | @example |
| 264 | TEXTAGS="mycommand:myothercommand" |
| 265 | export TEXTAGS |
| 266 | @end example |
| 267 | |
| 268 | @noindent |
| 269 | specifies (using Bourne shell syntax) that the commands |
| 270 | @samp{\mycommand} and @samp{\myothercommand} also define tags. |
| 271 | |
| 272 | @item |
| 273 | In Lisp code, any function defined with @code{defun}, any variable |
| 274 | defined with @code{defvar} or @code{defconst}, and in general the first |
| 275 | argument of any expression that starts with @samp{(def} in column zero is |
| 276 | a tag. |
| 277 | |
| 278 | @item |
| 279 | In Scheme code, tags include anything defined with @code{def} or with a |
| 280 | construct whose name starts with @samp{def}. They also include variables |
| 281 | set with @code{set!} at top level in the file. |
| 282 | @end itemize |
| 283 | |
| 284 | Several other languages are also supported: |
| 285 | |
| 286 | @itemize @bullet |
| 287 | |
| 288 | @item |
| 289 | In Ada code, functions, procedures, packages, tasks and types are |
| 290 | tags. Use the @samp{--packages-only} option to create tags for |
| 291 | packages only. |
| 292 | |
| 293 | In Ada, the same name can be used for different kinds of entity |
| 294 | (e.g.@:, for a procedure and for a function). Also, for things like |
| 295 | packages, procedures and functions, there is the spec (i.e.@: the |
| 296 | interface) and the body (i.e.@: the implementation). To make it |
| 297 | easier to pick the definition you want, Ada tag name have suffixes |
| 298 | indicating the type of entity: |
| 299 | |
| 300 | @table @samp |
| 301 | @item /b |
| 302 | package body. |
| 303 | @item /f |
| 304 | function. |
| 305 | @item /k |
| 306 | task. |
| 307 | @item /p |
| 308 | procedure. |
| 309 | @item /s |
| 310 | package spec. |
| 311 | @item /t |
| 312 | type. |
| 313 | @end table |
| 314 | |
| 315 | Thus, @kbd{M-x find-tag @key{RET} bidule/b @key{RET}} will go |
| 316 | directly to the body of the package @code{bidule}, while @kbd{M-x |
| 317 | find-tag @key{RET} bidule @key{RET}} will just search for any tag |
| 318 | @code{bidule}. |
| 319 | |
| 320 | @item |
| 321 | In assembler code, labels appearing at the beginning of a line, |
| 322 | followed by a colon, are tags. |
| 323 | |
| 324 | @item |
| 325 | In Bison or Yacc input files, each rule defines as a tag the nonterminal |
| 326 | it constructs. The portions of the file that contain C code are parsed |
| 327 | as C code. |
| 328 | |
| 329 | @item |
| 330 | In Cobol code, tags are paragraph names; that is, any word starting in |
| 331 | column 8 and followed by a period. |
| 332 | |
| 333 | @item |
| 334 | In Erlang code, the tags are the functions, records and macros defined |
| 335 | in the file. |
| 336 | |
| 337 | @item |
| 338 | In Fortran code, functions, subroutines and block data are tags. |
| 339 | |
| 340 | @item |
| 341 | In HTML input files, the tags are the @code{title} and the @code{h1}, |
| 342 | @code{h2}, @code{h3} headers. Also, tags are @code{name=} in anchors |
| 343 | and all occurrences of @code{id=}. |
| 344 | |
| 345 | @item |
| 346 | In makefiles, targets are tags; additionally, variables are tags |
| 347 | unless you specify @samp{--no-globals}. |
| 348 | |
| 349 | @item |
| 350 | In Objective C code, tags include Objective C definitions for classes, |
| 351 | class categories, methods and protocols. Tags for variables and |
| 352 | functions in classes are named @samp{@var{class}::@var{variable}} and |
| 353 | @samp{@var{class}::@var{function}}. |
| 354 | |
| 355 | @item |
| 356 | In Pascal code, the tags are the functions and procedures defined in |
| 357 | the file. |
| 358 | |
| 359 | @item |
| 360 | In Perl code, the tags are the packages, subroutines and variables |
| 361 | defined by the @code{package}, @code{sub}, @code{my} and @code{local} |
| 362 | keywords. Use @samp{--globals} if you want to tag global variables. |
| 363 | Tags for subroutines are named @samp{@var{package}::@var{sub}}. The |
| 364 | name for subroutines defined in the default package is |
| 365 | @samp{main::@var{sub}}. |
| 366 | |
| 367 | @item |
| 368 | In PHP code, tags are functions, classes and defines. When using the |
| 369 | @samp{--members} option, vars are tags too. |
| 370 | |
| 371 | @item |
| 372 | In PostScript code, the tags are the functions. |
| 373 | |
| 374 | @item |
| 375 | In Prolog code, tags are predicates and rules at the beginning of |
| 376 | line. |
| 377 | |
| 378 | @item |
| 379 | In Python code, @code{def} or @code{class} at the beginning of a line |
| 380 | generate a tag. |
| 381 | @end itemize |
| 382 | |
| 383 | You can also generate tags based on regexp matching (@pxref{Etags |
| 384 | Regexps}) to handle other formats and languages. |
| 385 | |
| 386 | @node Create Tags Table |
| 387 | @subsection Creating Tags Tables |
| 388 | @cindex @code{etags} program |
| 389 | |
| 390 | The @code{etags} program is used to create a tags table file. It knows |
| 391 | the syntax of several languages, as described in |
| 392 | @iftex |
| 393 | the previous section. |
| 394 | @end iftex |
| 395 | @ifinfo |
| 396 | @ref{Tag Syntax}. |
| 397 | @end ifinfo |
| 398 | Here is how to run @code{etags}: |
| 399 | |
| 400 | @example |
| 401 | etags @var{inputfiles}@dots{} |
| 402 | @end example |
| 403 | |
| 404 | @noindent |
| 405 | The @code{etags} program reads the specified files, and writes a tags |
| 406 | table named @file{TAGS} in the current working directory. |
| 407 | |
| 408 | If the specified files don't exist, @code{etags} looks for |
| 409 | compressed versions of them and uncompresses them to read them. Under |
| 410 | MS-DOS, @code{etags} also looks for file names like @file{mycode.cgz} |
| 411 | if it is given @samp{mycode.c} on the command line and @file{mycode.c} |
| 412 | does not exist. |
| 413 | |
| 414 | @code{etags} recognizes the language used in an input file based on |
| 415 | its file name and contents. You can specify the language with the |
| 416 | @samp{--language=@var{name}} option, described below. |
| 417 | |
| 418 | If the tags table data become outdated due to changes in the files |
| 419 | described in the table, the way to update the tags table is the same |
| 420 | way it was made in the first place. If the tags table fails to record |
| 421 | a tag, or records it for the wrong file, then Emacs cannot possibly |
| 422 | find its definition until you update the tags table. However, if the |
| 423 | position recorded in the tags table becomes a little bit wrong (due to |
| 424 | other editing), the only consequence is a slight delay in finding the |
| 425 | tag. Even if the stored position is very far wrong, Emacs will still |
| 426 | find the tag, after searching most of the file for it. Even that |
| 427 | delay is hardly noticeable with today's computers. |
| 428 | |
| 429 | So you should update a tags table when you define new tags that you want |
| 430 | to have listed, or when you move tag definitions from one file to another, |
| 431 | or when changes become substantial. Normally there is no need to update |
| 432 | the tags table after each edit, or even every day. |
| 433 | |
| 434 | One tags table can virtually include another. Specify the included |
| 435 | tags file name with the @samp{--include=@var{file}} option when |
| 436 | creating the file that is to include it. The latter file then acts as |
| 437 | if it covered all the source files specified in the included file, as |
| 438 | well as the files it directly contains. |
| 439 | |
| 440 | If you specify the source files with relative file names when you run |
| 441 | @code{etags}, the tags file will contain file names relative to the |
| 442 | directory where the tags file was initially written. This way, you can |
| 443 | move an entire directory tree containing both the tags file and the |
| 444 | source files, and the tags file will still refer correctly to the source |
| 445 | files. |
| 446 | |
| 447 | If you specify absolute file names as arguments to @code{etags}, then |
| 448 | the tags file will contain absolute file names. This way, the tags file |
| 449 | will still refer to the same files even if you move it, as long as the |
| 450 | source files remain in the same place. Absolute file names start with |
| 451 | @samp{/}, or with @samp{@var{device}:/} on MS-DOS and MS-Windows. |
| 452 | |
| 453 | When you want to make a tags table from a great number of files, you |
| 454 | may have problems listing them on the command line, because some systems |
| 455 | have a limit on its length. The simplest way to circumvent this limit |
| 456 | is to tell @code{etags} to read the file names from its standard input, |
| 457 | by typing a dash in place of the file names, like this: |
| 458 | |
| 459 | @smallexample |
| 460 | find . -name "*.[chCH]" -print | etags - |
| 461 | @end smallexample |
| 462 | |
| 463 | Use the option @samp{--language=@var{name}} to specify the language |
| 464 | explicitly. You can intermix these options with file names; each one |
| 465 | applies to the file names that follow it. Specify |
| 466 | @samp{--language=auto} to tell @code{etags} to resume guessing the |
| 467 | language from the file names and file contents. Specify |
| 468 | @samp{--language=none} to turn off language-specific processing |
| 469 | entirely; then @code{etags} recognizes tags by regexp matching alone |
| 470 | (@pxref{Etags Regexps}). |
| 471 | |
| 472 | The option @samp{--parse-stdin=@var{file}} is mostly useful when |
| 473 | calling @code{etags} from programs. It can be used (only once) in |
| 474 | place of a file name on the command line. @code{Etags} will read from |
| 475 | standard input and mark the produced tags as belonging to the file |
| 476 | @var{file}. |
| 477 | |
| 478 | @samp{etags --help} prints the list of the languages @code{etags} |
| 479 | knows, and the file name rules for guessing the language. It also prints |
| 480 | a list of all the available @code{etags} options, together with a short |
| 481 | explanation. If followed by one or more @samp{--language=@var{lang}} |
| 482 | options, prints detailed information about how tags are generated for |
| 483 | @var{lang}. |
| 484 | |
| 485 | @node Etags Regexps |
| 486 | @subsection Etags Regexps |
| 487 | |
| 488 | The @samp{--regex} option provides a general way of recognizing tags |
| 489 | based on regexp matching. You can freely intermix it with file names. |
| 490 | If you specify multiple @samp{--regex} options, all of them are used |
| 491 | in parallel, but each one applies only to the source files that follow |
| 492 | it. The syntax is: |
| 493 | |
| 494 | @smallexample |
| 495 | --regex=[@var{@{language@}}]/@var{tagregexp}/[@var{nameregexp}/]@var{modifiers} |
| 496 | @end smallexample |
| 497 | |
| 498 | The essential part of the option value is @var{tagregexp}, the |
| 499 | regexp for matching tags. It is always used anchored, that is, it |
| 500 | only matches at the beginning of a line. If you want to allow |
| 501 | indented tags, use a regexp that matches initial whitespace; start it |
| 502 | with @samp{[ \t]*}. |
| 503 | |
| 504 | In these regular expressions, @samp{\} quotes the next character, and |
| 505 | all the GCC character escape sequences are supported (@samp{\a} for |
| 506 | bell, @samp{\b} for back space, @samp{\d} for delete, @samp{\e} for |
| 507 | escape, @samp{\f} for formfeed, @samp{\n} for newline, @samp{\r} for |
| 508 | carriage return, @samp{\t} for tab, and @samp{\v} for vertical tab). |
| 509 | |
| 510 | Ideally, @var{tagregexp} should not match more characters than are |
| 511 | needed to recognize what you want to tag. If the syntax requires you |
| 512 | to write @var{tagregexp} so it matches more characters beyond the tag |
| 513 | itself, you should add a @var{nameregexp}, to pick out just the tag. |
| 514 | This will enable Emacs to find tags more accurately and to do |
| 515 | completion on tag names more reliably. You can find some examples |
| 516 | below. |
| 517 | |
| 518 | The @var{modifiers} are a sequence of zero or more characters that |
| 519 | modify the way @code{etags} does the matching. A regexp with no |
| 520 | modifiers is applied sequentially to each line of the input file, in a |
| 521 | case-sensitive way. The modifiers and their meanings are: |
| 522 | |
| 523 | @table @samp |
| 524 | @item i |
| 525 | Ignore case when matching this regexp. |
| 526 | @item m |
| 527 | Match this regular expression against the whole file, so that |
| 528 | multi-line matches are possible. |
| 529 | @item s |
| 530 | Match this regular expression against the whole file, and allow |
| 531 | @samp{.} in @var{tagregexp} to match newlines. |
| 532 | @end table |
| 533 | |
| 534 | The @samp{-R} option cancels all the regexps defined by preceding |
| 535 | @samp{--regex} options. It applies to the file names following it, as |
| 536 | you can see from the following example: |
| 537 | |
| 538 | @smallexample |
| 539 | etags --regex=/@var{reg1}/i voo.doo --regex=/@var{reg2}/m \ |
| 540 | bar.ber -R --lang=lisp los.er |
| 541 | @end smallexample |
| 542 | |
| 543 | @noindent |
| 544 | Here @code{etags} chooses the parsing language for @file{voo.doo} and |
| 545 | @file{bar.ber} according to their contents. @code{etags} also uses |
| 546 | @var{reg1} to recognize additional tags in @file{voo.doo}, and both |
| 547 | @var{reg1} and @var{reg2} to recognize additional tags in |
| 548 | @file{bar.ber}. @var{reg1} is checked against each line of |
| 549 | @file{voo.doo} and @file{bar.ber}, in a case-insensitive way, while |
| 550 | @var{reg2} is checked against the whole @file{bar.ber} file, |
| 551 | permitting multi-line matches, in a case-sensitive way. @code{etags} |
| 552 | uses only the Lisp tags rules, with no user-specified regexp matching, |
| 553 | to recognize tags in @file{los.er}. |
| 554 | |
| 555 | You can restrict a @samp{--regex} option to match only files of a |
| 556 | given language by using the optional prefix @var{@{language@}}. |
| 557 | (@samp{etags --help} prints the list of languages recognized by |
| 558 | @code{etags}.) This is particularly useful when storing many |
| 559 | predefined regular expressions for @code{etags} in a file. The |
| 560 | following example tags the @code{DEFVAR} macros in the Emacs source |
| 561 | files, for the C language only: |
| 562 | |
| 563 | @smallexample |
| 564 | --regex='@{c@}/[ \t]*DEFVAR_[A-Z_ \t(]+"\([^"]+\)"/' |
| 565 | @end smallexample |
| 566 | |
| 567 | @noindent |
| 568 | When you have complex regular expressions, you can store the list of |
| 569 | them in a file. The following option syntax instructs @code{etags} to |
| 570 | read two files of regular expressions. The regular expressions |
| 571 | contained in the second file are matched without regard to case. |
| 572 | |
| 573 | @smallexample |
| 574 | --regex=@@@var{case-sensitive-file} --ignore-case-regex=@@@var{ignore-case-file} |
| 575 | @end smallexample |
| 576 | |
| 577 | @noindent |
| 578 | A regex file for @code{etags} contains one regular expression per |
| 579 | line. Empty lines, and lines beginning with space or tab are ignored. |
| 580 | When the first character in a line is @samp{@@}, @code{etags} assumes |
| 581 | that the rest of the line is the name of another file of regular |
| 582 | expressions; thus, one such file can include another file. All the |
| 583 | other lines are taken to be regular expressions. If the first |
| 584 | non-whitespace text on the line is @samp{--}, that line is a comment. |
| 585 | |
| 586 | For example, we can create a file called @samp{emacs.tags} with the |
| 587 | following contents: |
| 588 | |
| 589 | @smallexample |
| 590 | -- This is for GNU Emacs C source files |
| 591 | @{c@}/[ \t]*DEFVAR_[A-Z_ \t(]+"\([^"]+\)"/\1/ |
| 592 | @end smallexample |
| 593 | |
| 594 | @noindent |
| 595 | and then use it like this: |
| 596 | |
| 597 | @smallexample |
| 598 | etags --regex=@@emacs.tags *.[ch] */*.[ch] |
| 599 | @end smallexample |
| 600 | |
| 601 | Here are some more examples. The regexps are quoted to protect them |
| 602 | from shell interpretation. |
| 603 | |
| 604 | @itemize @bullet |
| 605 | |
| 606 | @item |
| 607 | Tag Octave files: |
| 608 | |
| 609 | @smallexample |
| 610 | etags --language=none \ |
| 611 | --regex='/[ \t]*function.*=[ \t]*\([^ \t]*\)[ \t]*(/\1/' \ |
| 612 | --regex='/###key \(.*\)/\1/' \ |
| 613 | --regex='/[ \t]*global[ \t].*/' \ |
| 614 | *.m |
| 615 | @end smallexample |
| 616 | |
| 617 | @noindent |
| 618 | Note that tags are not generated for scripts, so that you have to add |
| 619 | a line by yourself of the form @samp{###key @var{scriptname}} if you |
| 620 | want to jump to it. |
| 621 | |
| 622 | @item |
| 623 | Tag Tcl files: |
| 624 | |
| 625 | @smallexample |
| 626 | etags --language=none --regex='/proc[ \t]+\([^ \t]+\)/\1/' *.tcl |
| 627 | @end smallexample |
| 628 | |
| 629 | @item |
| 630 | Tag VHDL files: |
| 631 | |
| 632 | @smallexample |
| 633 | etags --language=none \ |
| 634 | --regex='/[ \t]*\(ARCHITECTURE\|CONFIGURATION\) +[^ ]* +OF/' \ |
| 635 | --regex='/[ \t]*\(ATTRIBUTE\|ENTITY\|FUNCTION\|PACKAGE\ |
| 636 | \( BODY\)?\|PROCEDURE\|PROCESS\|TYPE\)[ \t]+\([^ \t(]+\)/\3/' |
| 637 | @end smallexample |
| 638 | @end itemize |
| 639 | |
| 640 | @node Select Tags Table |
| 641 | @subsection Selecting a Tags Table |
| 642 | |
| 643 | @vindex tags-file-name |
| 644 | @findex visit-tags-table |
| 645 | Emacs has at any time one @dfn{selected} tags table, and all the commands |
| 646 | for working with tags tables use the selected one. To select a tags table, |
| 647 | type @kbd{M-x visit-tags-table}, which reads the tags table file name as an |
| 648 | argument. The name @file{TAGS} in the default directory is used as the |
| 649 | default file name. |
| 650 | |
| 651 | All this command does is store the file name in the variable |
| 652 | @code{tags-file-name}. Emacs does not actually read in the tags table |
| 653 | contents until you try to use them. Setting this variable yourself is just |
| 654 | as good as using @code{visit-tags-table}. The variable's initial value is |
| 655 | @code{nil}; that value tells all the commands for working with tags tables |
| 656 | that they must ask for a tags table file name to use. |
| 657 | |
| 658 | Using @code{visit-tags-table} when a tags table is already loaded |
| 659 | gives you a choice: you can add the new tags table to the current list |
| 660 | of tags tables, or start a new list. The tags commands use all the tags |
| 661 | tables in the current list. If you start a new list, the new tags table |
| 662 | is used @emph{instead} of others. If you add the new table to the |
| 663 | current list, it is used @emph{as well as} the others. When the tags |
| 664 | commands scan the list of tags tables, they don't always start at the |
| 665 | beginning of the list; they start with the first tags table (if any) |
| 666 | that describes the current file, proceed from there to the end of the |
| 667 | list, and then scan from the beginning of the list until they have |
| 668 | covered all the tables in the list. |
| 669 | |
| 670 | @vindex tags-table-list |
| 671 | You can specify a precise list of tags tables by setting the variable |
| 672 | @code{tags-table-list} to a list of strings, like this: |
| 673 | |
| 674 | @c keep this on two lines for formatting in smallbook |
| 675 | @example |
| 676 | @group |
| 677 | (setq tags-table-list |
| 678 | '("~/emacs" "/usr/local/lib/emacs/src")) |
| 679 | @end group |
| 680 | @end example |
| 681 | |
| 682 | @noindent |
| 683 | This tells the tags commands to look at the @file{TAGS} files in your |
| 684 | @file{~/emacs} directory and in the @file{/usr/local/lib/emacs/src} |
| 685 | directory. The order depends on which file you are in and which tags |
| 686 | table mentions that file, as explained above. |
| 687 | |
| 688 | Do not set both @code{tags-file-name} and @code{tags-table-list}. |
| 689 | |
| 690 | @node Find Tag |
| 691 | @subsection Finding a Tag |
| 692 | |
| 693 | The most important thing that a tags table enables you to do is to find |
| 694 | the definition of a specific tag. |
| 695 | |
| 696 | @table @kbd |
| 697 | @item M-.@: @var{tag} @key{RET} |
| 698 | Find first definition of @var{tag} (@code{find-tag}). |
| 699 | @item C-u M-. |
| 700 | Find next alternate definition of last tag specified. |
| 701 | @item C-u - M-. |
| 702 | Go back to previous tag found. |
| 703 | @item C-M-. @var{pattern} @key{RET} |
| 704 | Find a tag whose name matches @var{pattern} (@code{find-tag-regexp}). |
| 705 | @item C-u C-M-. |
| 706 | Find the next tag whose name matches the last pattern used. |
| 707 | @item C-x 4 .@: @var{tag} @key{RET} |
| 708 | Find first definition of @var{tag}, but display it in another window |
| 709 | (@code{find-tag-other-window}). |
| 710 | @item C-x 5 .@: @var{tag} @key{RET} |
| 711 | Find first definition of @var{tag}, and create a new frame to select the |
| 712 | buffer (@code{find-tag-other-frame}). |
| 713 | @item M-* |
| 714 | Pop back to where you previously invoked @kbd{M-.} and friends. |
| 715 | @end table |
| 716 | |
| 717 | @kindex M-. |
| 718 | @findex find-tag |
| 719 | @kbd{M-.}@: (@code{find-tag}) is the command to find the definition of |
| 720 | a specified tag. It searches through the tags table for that tag, as a |
| 721 | string, and then uses the tags table info to determine the file that the |
| 722 | definition is in and the approximate character position in the file of |
| 723 | the definition. Then @code{find-tag} visits that file, moves point to |
| 724 | the approximate character position, and searches ever-increasing |
| 725 | distances away to find the tag definition. |
| 726 | |
| 727 | If an empty argument is given (just type @key{RET}), the balanced |
| 728 | expression in the buffer before or around point is used as the |
| 729 | @var{tag} argument. @xref{Expressions}. |
| 730 | |
| 731 | You don't need to give @kbd{M-.} the full name of the tag; a part |
| 732 | will do. This is because @kbd{M-.} finds tags in the table which |
| 733 | contain @var{tag} as a substring. However, it prefers an exact match |
| 734 | to a substring match. To find other tags that match the same |
| 735 | substring, give @code{find-tag} a numeric argument, as in @kbd{C-u |
| 736 | M-.}; this does not read a tag name, but continues searching the tags |
| 737 | table's text for another tag containing the same substring last used. |
| 738 | If you have a real @key{META} key, @kbd{M-0 M-.}@: is an easier |
| 739 | alternative to @kbd{C-u M-.}. |
| 740 | |
| 741 | @kindex C-x 4 . |
| 742 | @findex find-tag-other-window |
| 743 | @kindex C-x 5 . |
| 744 | @findex find-tag-other-frame |
| 745 | Like most commands that can switch buffers, @code{find-tag} has a |
| 746 | variant that displays the new buffer in another window, and one that |
| 747 | makes a new frame for it. The former is @kbd{C-x 4 .}, which invokes |
| 748 | the command @code{find-tag-other-window}. The latter is @kbd{C-x 5 .}, |
| 749 | which invokes @code{find-tag-other-frame}. |
| 750 | |
| 751 | To move back to places you've found tags recently, use @kbd{C-u - |
| 752 | M-.}; more generally, @kbd{M-.} with a negative numeric argument. This |
| 753 | command can take you to another buffer. @kbd{C-x 4 .} with a negative |
| 754 | argument finds the previous tag location in another window. |
| 755 | |
| 756 | @kindex M-* |
| 757 | @findex pop-tag-mark |
| 758 | @vindex find-tag-marker-ring-length |
| 759 | As well as going back to places you've found tags recently, you can go |
| 760 | back to places @emph{from where} you found them. Use @kbd{M-*}, which |
| 761 | invokes the command @code{pop-tag-mark}, for this. Typically you would |
| 762 | find and study the definition of something with @kbd{M-.} and then |
| 763 | return to where you were with @kbd{M-*}. |
| 764 | |
| 765 | Both @kbd{C-u - M-.} and @kbd{M-*} allow you to retrace your steps to |
| 766 | a depth determined by the variable @code{find-tag-marker-ring-length}. |
| 767 | |
| 768 | @findex find-tag-regexp |
| 769 | @kindex C-M-. |
| 770 | The command @kbd{C-M-.} (@code{find-tag-regexp}) visits the tags that |
| 771 | match a specified regular expression. It is just like @kbd{M-.} except |
| 772 | that it does regexp matching instead of substring matching. |
| 773 | |
| 774 | @node Tags Search |
| 775 | @subsection Searching and Replacing with Tags Tables |
| 776 | @cindex search and replace in multiple files |
| 777 | @cindex multiple-file search and replace |
| 778 | |
| 779 | The commands in this section visit and search all the files listed in the |
| 780 | selected tags table, one by one. For these commands, the tags table serves |
| 781 | only to specify a sequence of files to search. |
| 782 | |
| 783 | @table @kbd |
| 784 | @item M-x tags-search @key{RET} @var{regexp} @key{RET} |
| 785 | Search for @var{regexp} through the files in the selected tags |
| 786 | table. |
| 787 | @item M-x tags-query-replace @key{RET} @var{regexp} @key{RET} @var{replacement} @key{RET} |
| 788 | Perform a @code{query-replace-regexp} on each file in the selected tags table. |
| 789 | @item M-, |
| 790 | Restart one of the commands above, from the current location of point |
| 791 | (@code{tags-loop-continue}). |
| 792 | @end table |
| 793 | |
| 794 | @findex tags-search |
| 795 | @kbd{M-x tags-search} reads a regexp using the minibuffer, then |
| 796 | searches for matches in all the files in the selected tags table, one |
| 797 | file at a time. It displays the name of the file being searched so you |
| 798 | can follow its progress. As soon as it finds an occurrence, |
| 799 | @code{tags-search} returns. |
| 800 | |
| 801 | @kindex M-, |
| 802 | @findex tags-loop-continue |
| 803 | Having found one match, you probably want to find all the rest. To find |
| 804 | one more match, type @kbd{M-,} (@code{tags-loop-continue}) to resume the |
| 805 | @code{tags-search}. This searches the rest of the current buffer, followed |
| 806 | by the remaining files of the tags table.@refill |
| 807 | |
| 808 | @findex tags-query-replace |
| 809 | @kbd{M-x tags-query-replace} performs a single |
| 810 | @code{query-replace-regexp} through all the files in the tags table. It |
| 811 | reads a regexp to search for and a string to replace with, just like |
| 812 | ordinary @kbd{M-x query-replace-regexp}. It searches much like @kbd{M-x |
| 813 | tags-search}, but repeatedly, processing matches according to your |
| 814 | input. @xref{Replace}, for more information on query replace. |
| 815 | |
| 816 | @vindex tags-case-fold-search |
| 817 | @cindex case-sensitivity and tags search |
| 818 | You can control the case-sensitivity of tags search commands by |
| 819 | customizing the value of the variable @code{tags-case-fold-search}. The |
| 820 | default is to use the same setting as the value of |
| 821 | @code{case-fold-search} (@pxref{Search Case}). |
| 822 | |
| 823 | It is possible to get through all the files in the tags table with a |
| 824 | single invocation of @kbd{M-x tags-query-replace}. But often it is |
| 825 | useful to exit temporarily, which you can do with any input event that |
| 826 | has no special query replace meaning. You can resume the query replace |
| 827 | subsequently by typing @kbd{M-,}; this command resumes the last tags |
| 828 | search or replace command that you did. |
| 829 | |
| 830 | The commands in this section carry out much broader searches than the |
| 831 | @code{find-tag} family. The @code{find-tag} commands search only for |
| 832 | definitions of tags that match your substring or regexp. The commands |
| 833 | @code{tags-search} and @code{tags-query-replace} find every occurrence |
| 834 | of the regexp, as ordinary search commands and replace commands do in |
| 835 | the current buffer. |
| 836 | |
| 837 | These commands create buffers only temporarily for the files that they |
| 838 | have to search (those which are not already visited in Emacs buffers). |
| 839 | Buffers in which no match is found are quickly killed; the others |
| 840 | continue to exist. |
| 841 | |
| 842 | It may have struck you that @code{tags-search} is a lot like |
| 843 | @code{grep}. You can also run @code{grep} itself as an inferior of |
| 844 | Emacs and have Emacs show you the matching lines one by one. This works |
| 845 | much like running a compilation; finding the source locations of the |
| 846 | @code{grep} matches works like finding the compilation errors. |
| 847 | @xref{Compilation}. |
| 848 | |
| 849 | @node List Tags |
| 850 | @subsection Tags Table Inquiries |
| 851 | |
| 852 | @table @kbd |
| 853 | @item M-x list-tags @key{RET} @var{file} @key{RET} |
| 854 | Display a list of the tags defined in the program file @var{file}. |
| 855 | @item M-x tags-apropos @key{RET} @var{regexp} @key{RET} |
| 856 | Display a list of all tags matching @var{regexp}. |
| 857 | @end table |
| 858 | |
| 859 | @findex list-tags |
| 860 | @kbd{M-x list-tags} reads the name of one of the files described by |
| 861 | the selected tags table, and displays a list of all the tags defined in |
| 862 | that file. The ``file name'' argument is really just a string to |
| 863 | compare against the file names recorded in the tags table; it is read as |
| 864 | a string rather than as a file name. Therefore, completion and |
| 865 | defaulting are not available, and you must enter the file name the same |
| 866 | way it appears in the tags table. Do not include a directory as part of |
| 867 | the file name unless the file name recorded in the tags table includes a |
| 868 | directory. |
| 869 | |
| 870 | @findex tags-apropos |
| 871 | @vindex tags-apropos-verbose |
| 872 | @kbd{M-x tags-apropos} is like @code{apropos} for tags |
| 873 | (@pxref{Apropos}). It finds all the tags in the selected tags table |
| 874 | whose entries match @var{regexp}, and displays them. If the variable |
| 875 | @code{tags-apropos-verbose} is non-@code{nil}, it displays the names |
| 876 | of the tags files together with the tag names. |
| 877 | |
| 878 | @vindex tags-tag-face |
| 879 | @vindex tags-apropos-additional-actions |
| 880 | You can customize the appearance of the output with the face |
| 881 | @code{tags-tag-face}. You can display additional output with @kbd{M-x |
| 882 | tags-apropos} by customizing the variable |
| 883 | @code{tags-apropos-additional-actions}---see its documentation for |
| 884 | details. |
| 885 | |
| 886 | You can also use the collection of tag names to complete a symbol |
| 887 | name in the buffer. @xref{Symbol Completion}. |
| 888 | |
| 889 | @node Emerge |
| 890 | @section Merging Files with Emerge |
| 891 | @cindex Emerge |
| 892 | @cindex merging files |
| 893 | |
| 894 | It's not unusual for programmers to get their signals crossed and modify |
| 895 | the same program in two different directions. To recover from this |
| 896 | confusion, you need to merge the two versions. Emerge makes this |
| 897 | easier. See also @ref{Comparing Files}, for commands to compare |
| 898 | in a more manual fashion, and @ref{Top, Ediff,, ediff, The Ediff Manual}. |
| 899 | |
| 900 | @menu |
| 901 | * Overview of Emerge:: How to start Emerge. Basic concepts. |
| 902 | * Submodes of Emerge:: Fast mode vs. Edit mode. |
| 903 | Skip Prefers mode and Auto Advance mode. |
| 904 | * State of Difference:: You do the merge by specifying state A or B |
| 905 | for each difference. |
| 906 | * Merge Commands:: Commands for selecting a difference, |
| 907 | changing states of differences, etc. |
| 908 | * Exiting Emerge:: What to do when you've finished the merge. |
| 909 | * Combining in Emerge:: How to keep both alternatives for a difference. |
| 910 | * Fine Points of Emerge:: Misc. |
| 911 | @end menu |
| 912 | |
| 913 | @node Overview of Emerge |
| 914 | @subsection Overview of Emerge |
| 915 | |
| 916 | To start Emerge, run one of these four commands: |
| 917 | |
| 918 | @table @kbd |
| 919 | @item M-x emerge-files |
| 920 | @findex emerge-files |
| 921 | Merge two specified files. |
| 922 | |
| 923 | @item M-x emerge-files-with-ancestor |
| 924 | @findex emerge-files-with-ancestor |
| 925 | Merge two specified files, with reference to a common ancestor. |
| 926 | |
| 927 | @item M-x emerge-buffers |
| 928 | @findex emerge-buffers |
| 929 | Merge two buffers. |
| 930 | |
| 931 | @item M-x emerge-buffers-with-ancestor |
| 932 | @findex emerge-buffers-with-ancestor |
| 933 | Merge two buffers with reference to a common ancestor in a third |
| 934 | buffer. |
| 935 | @end table |
| 936 | |
| 937 | @cindex merge buffer (Emerge) |
| 938 | @cindex A and B buffers (Emerge) |
| 939 | The Emerge commands compare two files or buffers, and display the |
| 940 | comparison in three buffers: one for each input text (the @dfn{A buffer} |
| 941 | and the @dfn{B buffer}), and one (the @dfn{merge buffer}) where merging |
| 942 | takes place. The merge buffer shows the full merged text, not just the |
| 943 | differences. Wherever the two input texts differ, you can choose which |
| 944 | one of them to include in the merge buffer. |
| 945 | |
| 946 | The Emerge commands that take input from existing buffers use only the |
| 947 | accessible portions of those buffers, if they are narrowed |
| 948 | (@pxref{Narrowing}). |
| 949 | |
| 950 | If a common ancestor version is available, from which the two texts to |
| 951 | be merged were both derived, Emerge can use it to guess which |
| 952 | alternative is right. Wherever one current version agrees with the |
| 953 | ancestor, Emerge presumes that the other current version is a deliberate |
| 954 | change which should be kept in the merged version. Use the |
| 955 | @samp{with-ancestor} commands if you want to specify a common ancestor |
| 956 | text. These commands read three file or buffer names---variant A, |
| 957 | variant B, and the common ancestor. |
| 958 | |
| 959 | After the comparison is done and the buffers are prepared, the |
| 960 | interactive merging starts. You control the merging by typing special |
| 961 | @dfn{merge commands} in the merge buffer. The merge buffer shows you a |
| 962 | full merged text, not just differences. For each run of differences |
| 963 | between the input texts, you can choose which one of them to keep, or |
| 964 | edit them both together. |
| 965 | |
| 966 | The merge buffer uses a special major mode, Emerge mode, with commands |
| 967 | for making these choices. But you can also edit the buffer with |
| 968 | ordinary Emacs commands. |
| 969 | |
| 970 | At any given time, the attention of Emerge is focused on one |
| 971 | particular difference, called the @dfn{selected} difference. This |
| 972 | difference is marked off in the three buffers like this: |
| 973 | |
| 974 | @example |
| 975 | vvvvvvvvvvvvvvvvvvvv |
| 976 | @var{text that differs} |
| 977 | ^^^^^^^^^^^^^^^^^^^^ |
| 978 | @end example |
| 979 | |
| 980 | @noindent |
| 981 | Emerge numbers all the differences sequentially and the mode |
| 982 | line always shows the number of the selected difference. |
| 983 | |
| 984 | Normally, the merge buffer starts out with the A version of the text. |
| 985 | But when the A version of a difference agrees with the common ancestor, |
| 986 | then the B version is initially preferred for that difference. |
| 987 | |
| 988 | Emerge leaves the merged text in the merge buffer when you exit. At |
| 989 | that point, you can save it in a file with @kbd{C-x C-w}. If you give a |
| 990 | numeric argument to @code{emerge-files} or |
| 991 | @code{emerge-files-with-ancestor}, it reads the name of the output file |
| 992 | using the minibuffer. (This is the last file name those commands read.) |
| 993 | Then exiting from Emerge saves the merged text in the output file. |
| 994 | |
| 995 | Normally, Emerge commands save the output buffer in its file when you |
| 996 | exit. If you abort Emerge with @kbd{C-]}, the Emerge command does not |
| 997 | save the output buffer, but you can save it yourself if you wish. |
| 998 | |
| 999 | @node Submodes of Emerge |
| 1000 | @subsection Submodes of Emerge |
| 1001 | |
| 1002 | You can choose between two modes for giving merge commands: Fast mode |
| 1003 | and Edit mode. In Fast mode, basic merge commands are single |
| 1004 | characters, but ordinary Emacs commands are disabled. This is |
| 1005 | convenient if you use only merge commands. In Edit mode, all merge |
| 1006 | commands start with the prefix key @kbd{C-c C-c}, and the normal Emacs |
| 1007 | commands are also available. This allows editing the merge buffer, but |
| 1008 | slows down Emerge operations. |
| 1009 | |
| 1010 | Use @kbd{e} to switch to Edit mode, and @kbd{C-c C-c f} to switch to |
| 1011 | Fast mode. The mode line indicates Edit and Fast modes with @samp{E} |
| 1012 | and @samp{F}. |
| 1013 | |
| 1014 | Emerge has two additional submodes that affect how particular merge |
| 1015 | commands work: Auto Advance mode and Skip Prefers mode. |
| 1016 | |
| 1017 | If Auto Advance mode is in effect, the @kbd{a} and @kbd{b} commands |
| 1018 | advance to the next difference. This lets you go through the merge |
| 1019 | faster as long as you simply choose one of the alternatives from the |
| 1020 | input. The mode line indicates Auto Advance mode with @samp{A}. |
| 1021 | |
| 1022 | If Skip Prefers mode is in effect, the @kbd{n} and @kbd{p} commands |
| 1023 | skip over differences in states prefer-A and prefer-B (@pxref{State of |
| 1024 | Difference}). Thus you see only differences for which neither version |
| 1025 | is presumed ``correct.'' The mode line indicates Skip Prefers mode with |
| 1026 | @samp{S}. |
| 1027 | |
| 1028 | @findex emerge-auto-advance-mode |
| 1029 | @findex emerge-skip-prefers-mode |
| 1030 | Use the command @kbd{s a} (@code{emerge-auto-advance-mode}) to set or |
| 1031 | clear Auto Advance mode. Use @kbd{s s} |
| 1032 | (@code{emerge-skip-prefers-mode}) to set or clear Skip Prefers mode. |
| 1033 | These commands turn on the mode with a positive argument, turns it off |
| 1034 | with a negative or zero argument, and toggle the mode with no argument. |
| 1035 | |
| 1036 | @node State of Difference |
| 1037 | @subsection State of a Difference |
| 1038 | |
| 1039 | In the merge buffer, a difference is marked with lines of @samp{v} and |
| 1040 | @samp{^} characters. Each difference has one of these seven states: |
| 1041 | |
| 1042 | @table @asis |
| 1043 | @item A |
| 1044 | The difference is showing the A version. The @kbd{a} command always |
| 1045 | produces this state; the mode line indicates it with @samp{A}. |
| 1046 | |
| 1047 | @item B |
| 1048 | The difference is showing the B version. The @kbd{b} command always |
| 1049 | produces this state; the mode line indicates it with @samp{B}. |
| 1050 | |
| 1051 | @item default-A |
| 1052 | @itemx default-B |
| 1053 | The difference is showing the A or the B state by default, because you |
| 1054 | haven't made a choice. All differences start in the default-A state |
| 1055 | (and thus the merge buffer is a copy of the A buffer), except those for |
| 1056 | which one alternative is ``preferred'' (see below). |
| 1057 | |
| 1058 | When you select a difference, its state changes from default-A or |
| 1059 | default-B to plain A or B. Thus, the selected difference never has |
| 1060 | state default-A or default-B, and these states are never displayed in |
| 1061 | the mode line. |
| 1062 | |
| 1063 | The command @kbd{d a} chooses default-A as the default state, and @kbd{d |
| 1064 | b} chooses default-B. This chosen default applies to all differences |
| 1065 | which you haven't ever selected and for which no alternative is preferred. |
| 1066 | If you are moving through the merge sequentially, the differences you |
| 1067 | haven't selected are those following the selected one. Thus, while |
| 1068 | moving sequentially, you can effectively make the A version the default |
| 1069 | for some sections of the merge buffer and the B version the default for |
| 1070 | others by using @kbd{d a} and @kbd{d b} between sections. |
| 1071 | |
| 1072 | @item prefer-A |
| 1073 | @itemx prefer-B |
| 1074 | The difference is showing the A or B state because it is |
| 1075 | @dfn{preferred}. This means that you haven't made an explicit choice, |
| 1076 | but one alternative seems likely to be right because the other |
| 1077 | alternative agrees with the common ancestor. Thus, where the A buffer |
| 1078 | agrees with the common ancestor, the B version is preferred, because |
| 1079 | chances are it is the one that was actually changed. |
| 1080 | |
| 1081 | These two states are displayed in the mode line as @samp{A*} and @samp{B*}. |
| 1082 | |
| 1083 | @item combined |
| 1084 | The difference is showing a combination of the A and B states, as a |
| 1085 | result of the @kbd{x c} or @kbd{x C} commands. |
| 1086 | |
| 1087 | Once a difference is in this state, the @kbd{a} and @kbd{b} commands |
| 1088 | don't do anything to it unless you give them a numeric argument. |
| 1089 | |
| 1090 | The mode line displays this state as @samp{comb}. |
| 1091 | @end table |
| 1092 | |
| 1093 | @node Merge Commands |
| 1094 | @subsection Merge Commands |
| 1095 | |
| 1096 | Here are the Merge commands for Fast mode; in Edit mode, precede them |
| 1097 | with @kbd{C-c C-c}: |
| 1098 | |
| 1099 | @table @kbd |
| 1100 | @item p |
| 1101 | Select the previous difference. |
| 1102 | |
| 1103 | @item n |
| 1104 | Select the next difference. |
| 1105 | |
| 1106 | @item a |
| 1107 | Choose the A version of this difference. |
| 1108 | |
| 1109 | @item b |
| 1110 | Choose the B version of this difference. |
| 1111 | |
| 1112 | @item C-u @var{n} j |
| 1113 | Select difference number @var{n}. |
| 1114 | |
| 1115 | @item . |
| 1116 | Select the difference containing point. You can use this command in the |
| 1117 | merge buffer or in the A or B buffer. |
| 1118 | |
| 1119 | @item q |
| 1120 | Quit---finish the merge. |
| 1121 | |
| 1122 | @item C-] |
| 1123 | Abort---exit merging and do not save the output. |
| 1124 | |
| 1125 | @item f |
| 1126 | Go into Fast mode. (In Edit mode, this is actually @kbd{C-c C-c f}.) |
| 1127 | |
| 1128 | @item e |
| 1129 | Go into Edit mode. |
| 1130 | |
| 1131 | @item l |
| 1132 | Recenter (like @kbd{C-l}) all three windows. |
| 1133 | |
| 1134 | @item - |
| 1135 | Specify part of a prefix numeric argument. |
| 1136 | |
| 1137 | @item @var{digit} |
| 1138 | Also specify part of a prefix numeric argument. |
| 1139 | |
| 1140 | @item d a |
| 1141 | Choose the A version as the default from here down in |
| 1142 | the merge buffer. |
| 1143 | |
| 1144 | @item d b |
| 1145 | Choose the B version as the default from here down in |
| 1146 | the merge buffer. |
| 1147 | |
| 1148 | @item c a |
| 1149 | Copy the A version of this difference into the kill ring. |
| 1150 | |
| 1151 | @item c b |
| 1152 | Copy the B version of this difference into the kill ring. |
| 1153 | |
| 1154 | @item i a |
| 1155 | Insert the A version of this difference at point. |
| 1156 | |
| 1157 | @item i b |
| 1158 | Insert the B version of this difference at point. |
| 1159 | |
| 1160 | @item m |
| 1161 | Put point and mark around the difference. |
| 1162 | |
| 1163 | @item ^ |
| 1164 | Scroll all three windows down (like @kbd{M-v}). |
| 1165 | |
| 1166 | @item v |
| 1167 | Scroll all three windows up (like @kbd{C-v}). |
| 1168 | |
| 1169 | @item < |
| 1170 | Scroll all three windows left (like @kbd{C-x <}). |
| 1171 | |
| 1172 | @item > |
| 1173 | Scroll all three windows right (like @kbd{C-x >}). |
| 1174 | |
| 1175 | @item | |
| 1176 | Reset horizontal scroll on all three windows. |
| 1177 | |
| 1178 | @item x 1 |
| 1179 | Shrink the merge window to one line. (Use @kbd{C-u l} to restore it |
| 1180 | to full size.) |
| 1181 | |
| 1182 | @item x c |
| 1183 | Combine the two versions of this difference (@pxref{Combining in |
| 1184 | Emerge}). |
| 1185 | |
| 1186 | @item x f |
| 1187 | Show the names of the files/buffers Emerge is operating on, in a Help |
| 1188 | window. (Use @kbd{C-u l} to restore windows.) |
| 1189 | |
| 1190 | @item x j |
| 1191 | Join this difference with the following one. |
| 1192 | (@kbd{C-u x j} joins this difference with the previous one.) |
| 1193 | |
| 1194 | @item x s |
| 1195 | Split this difference into two differences. Before you use this |
| 1196 | command, position point in each of the three buffers at the place where |
| 1197 | you want to split the difference. |
| 1198 | |
| 1199 | @item x t |
| 1200 | Trim identical lines off the top and bottom of the difference. |
| 1201 | Such lines occur when the A and B versions are |
| 1202 | identical but differ from the ancestor version. |
| 1203 | @end table |
| 1204 | |
| 1205 | @node Exiting Emerge |
| 1206 | @subsection Exiting Emerge |
| 1207 | |
| 1208 | The @kbd{q} command (@code{emerge-quit}) finishes the merge, storing |
| 1209 | the results into the output file if you specified one. It restores the |
| 1210 | A and B buffers to their proper contents, or kills them if they were |
| 1211 | created by Emerge and you haven't changed them. It also disables the |
| 1212 | Emerge commands in the merge buffer, since executing them later could |
| 1213 | damage the contents of the various buffers. |
| 1214 | |
| 1215 | @kbd{C-]} aborts the merge. This means exiting without writing the |
| 1216 | output file. If you didn't specify an output file, then there is no |
| 1217 | real difference between aborting and finishing the merge. |
| 1218 | |
| 1219 | If the Emerge command was called from another Lisp program, then its |
| 1220 | return value is @code{t} for successful completion, or @code{nil} if you |
| 1221 | abort. |
| 1222 | |
| 1223 | @node Combining in Emerge |
| 1224 | @subsection Combining the Two Versions |
| 1225 | |
| 1226 | Sometimes you want to keep @emph{both} alternatives for a particular |
| 1227 | difference. To do this, use @kbd{x c}, which edits the merge buffer |
| 1228 | like this: |
| 1229 | |
| 1230 | @example |
| 1231 | @group |
| 1232 | #ifdef NEW |
| 1233 | @var{version from A buffer} |
| 1234 | #else /* not NEW */ |
| 1235 | @var{version from B buffer} |
| 1236 | #endif /* not NEW */ |
| 1237 | @end group |
| 1238 | @end example |
| 1239 | |
| 1240 | @noindent |
| 1241 | @vindex emerge-combine-versions-template |
| 1242 | While this example shows C preprocessor conditionals delimiting the two |
| 1243 | alternative versions, you can specify the strings to use by setting |
| 1244 | the variable @code{emerge-combine-versions-template} to a string of your |
| 1245 | choice. In the string, @samp{%a} says where to put version A, and |
| 1246 | @samp{%b} says where to put version B. The default setting, which |
| 1247 | produces the results shown above, looks like this: |
| 1248 | |
| 1249 | @example |
| 1250 | @group |
| 1251 | "#ifdef NEW\n%a#else /* not NEW */\n%b#endif /* not NEW */\n" |
| 1252 | @end group |
| 1253 | @end example |
| 1254 | |
| 1255 | @node Fine Points of Emerge |
| 1256 | @subsection Fine Points of Emerge |
| 1257 | |
| 1258 | During the merge, you mustn't try to edit the A and B buffers yourself. |
| 1259 | Emerge modifies them temporarily, but ultimately puts them back the way |
| 1260 | they were. |
| 1261 | |
| 1262 | You can have any number of merges going at once---just don't use any one |
| 1263 | buffer as input to more than one merge at once, since the temporary |
| 1264 | changes made in these buffers would get in each other's way. |
| 1265 | |
| 1266 | Starting Emerge can take a long time because it needs to compare the |
| 1267 | files fully. Emacs can't do anything else until @code{diff} finishes. |
| 1268 | Perhaps in the future someone will change Emerge to do the comparison in |
| 1269 | the background when the input files are large---then you could keep on |
| 1270 | doing other things with Emacs until Emerge is ready to accept |
| 1271 | commands. |
| 1272 | |
| 1273 | @vindex emerge-startup-hook |
| 1274 | After setting up the merge, Emerge runs the hook |
| 1275 | @code{emerge-startup-hook} (@pxref{Hooks}). |
| 1276 | |
| 1277 | @ignore |
| 1278 | arch-tag: b9d83dfb-82ea-4ff6-bab5-05a3617091fb |
| 1279 | @end ignore |