view etc/ETAGS.EBNF @ 4477:e34711681f30

Don't determine whether to call general device-type code at startup, rather decide in the device-specific code itself. lisp/ChangeLog addition: 2008-07-07 Aidan Kehoe <kehoea@parhasard.net> Patch to make it up to the device-specific code whether various Lisp functions should be called during device creation, not relying on the startup code to decide this. Also, rename initial-window-system to initial-device-type (which makes more sense in this scheme), always set it. * startup.el (command-line): Use initial-device-type, not initial-window-system; just call #'make-device, leave the special behaviour to be done the first time a console type is initialised to be decided on by the respective console code. * x-init.el (x-app-defaults-directory): Declare that it should be bound. (x-define-dead-key): Have the macro take a DEVICE argument. (x-initialize-compose): Have the function take a DEVICE argument, and use it when checking if various keysyms are available on the keyboard. (x-initialize-keyboard): Have the function take a DEVICE argument, allowing device-specific keyboard initialisation. (make-device-early-x-entry-point-called-p): New. (make-device-late-x-entry-point-called-p): New. Rename pre-x-win-initted, x-win-initted. (make-device-early-x-entry-point): Rename init-pre-x-win, take the call to make-x-device out (it should be called from the device-creation code, not vice-versa). (make-device-late-x-entry-point): Rename init-post-x-win, have it take a DEVICE argument, use that DEVICE argument when working out what device-specific things need doing. Don't use create-console-hook in core code. * x-win-xfree86.el (x-win-init-xfree86): Take a DEVICE argument; use it. * x-win-sun.el (x-win-init-sun): Take a DEVICE argument; use it. * mule/mule-x-init.el: Remove #'init-mule-x-win, an empty function. * tty-init.el (make-device-early-tty-entry-point-called-p): New. Rename pre-tty-win-initted. (make-device-early-tty-entry-point): New. Rename init-pre-tty-win. (make-frame-after-init-entry-point): New. Rename init-post-tty-win to better reflect when it's called. * gtk-init.el (gtk-early-lisp-options-file): New. Move this path to a documented variable. (gtk-command-switch-alist): Wrap the docstring to fewer than 79 columns. (make-device-early-gtk-entry-point-called-p): New. (make-device-late-gtk-entry-point-called-p): New. Renamed gtk-pre-win-initted, gtk-post-win-initted to these. (make-device-early-gtk-entry-point): New. (make-device-late-gtk-entry-point): New. Renamed init-pre-gtk-win, init-post-gtk-win to these. Have make-device-late-gtk-entry-point take a device argument, and use it; have make-device-early-gtk-entry-point load the GTK-specific startup code, instead of doing that in C. (init-gtk-win): Deleted, functionality moved to the GTK device creation code. (gtk-define-dead-key): Have it take a DEVICE argument; use this argument. (gtk-initialize-compose): Ditto. * coding.el (set-terminal-coding-system): Correct the docstring; the function isn't broken. src/ChangeLog addition: 2008-07-07 Aidan Kehoe <kehoea@parhasard.net> Patch to make it up to the device-specific code whether various Lisp functions should be called during device creation, not relying on the startup code to decide this. Also, rename initial-window-system to initial-device-type (which makes more sense in this scheme), always set it. * redisplay.c (Vinitial_device_type): New. (Vinitial_window_system): Removed. Rename initial-window-system to initial-device type, making it a stream if we're noninteractive. Update its docstring. * device-x.c (Qmake_device_early_x_entry_point, Qmake_device_late_x_entry_point): New. Rename Qinit_pre_x_win, Qinit_post_x_win. (x_init_device): Call #'make-device-early-x-entry-point earlier, now we rely on it to find the application class and the app-defaults directory. (x_finish_init_device): Call #'make-device-late-x-entry-point with the created device. (Vx_app_defaults_directory): Always make this available, to simplify code in x-init.el. * device-tty.c (Qmake_device_early_tty_entry_point): New. Rename Qinit_pre_tty_win, rename Qinit_post_tty_win and move to frame-tty.c as Qmake_frame_after_init_entry_point. (tty_init_device): Call #'make-device-early-tty-entry-point before doing anything. * frame-tty.c (Qmake_frame_after_init_entry_point): New. * frame-tty.c (tty_after_init_frame): Have it call the better-named #'make-frame-after-init-entry-point function instead of #'init-post-tty-win (since it's called after frame, not device, creation). * device-msw.c (Qmake_device_early_mswindows_entry_point, Qmake_device_late_mswindows_entry_point): New. Rename Qinit_pre_mswindows_win, Qinit_post_mswindows_win. (mswindows_init_device): Call #'make-device-early-mswindows-entry-point here, instead of having its predecessor call us. (mswindows_finish_init_device): Call #'make-device-early-mswindows-entry-point, for symmetry with the other device types (though it's an empty function). * device-gtk.c (Qmake_device_early_gtk_entry_point, Qmake_device_late_gtk_entry_point): New. Rename Qinit_pre_gtk_win, Qinit_post_gtk_win. (gtk_init_device): Call #'make-device-early-gtk-entry-point; don't load ~/.xemacs/gtk-options.el ourselves, leave that to lisp. (gtk_finish_init_device): Call #'make-device-late-gtk-entry-point with the created device as an argument.
author Aidan Kehoe <kehoea@parhasard.net>
date Wed, 09 Jul 2008 20:46:22 +0200
parents a827a51c3241
children 308d34e9f07d
line wrap: on
line source

-*- indented-text -*-

See the end of this file for copyright information.

This file contains two sections:

1) An EBNF (Extended Backus-Naur Form) description of the format of
    the tags file created by etags.c and interpreted by etags.el;
2) A discussion of tag names and implicit tag names.

====================== 1) EBNF tag file description =====================

Productions created from current behaviour to aid extensions
Francesco Potorti` <pot@gnu.org> 2002
----------------

FF ::= #x0c				   /* tag section starter */

LF ::= #x0a				   /* line terminator */

DEL ::= #x7f				   /* pattern terminator */

SOH ::= #x01				   /* name terminator */

regchar ::= [^#x0a#x0c#x7f]		   /* regular character */

regstring ::= { regchar }		   /* regular string */

unsint ::= [0-9] { [0-9] }		   /* non-negative integer */



tagfile ::= { tagsection }		   /* a tags file */

tagsection ::= FF LF ( includesec | regularsec ) LF

includesec ::= filename ",include" [ LF fileprop ]

regularsec ::= filename "," [ unsint ] [ LF fileprop ] { LF tag }

filename ::= regchar regstring		   /* a file name */

fileprop ::= "(" regstring ")"		   /* an elisp alist */

tag ::= directtag | patterntag

directtag ::= DEL realposition		   /* no pattern */

patterntag ::= pattern DEL [ tagname SOH ] position

pattern ::= regstring			   /* a tag pattern */

tagname ::= regchar regstring		   /* a tag name */

position ::= realposition | "," 	   /* charpos,linepos */

realposition ::= "," unsint | unsint "," | unsint "," unsint

==================== end of EBNF tag file description ====================



======================= 2) discussion of tag names =======================

- WHAT ARE TAG NAMES
Tag lines in a tags file are usually made from the above defined pattern
and by an optional tag name.  The pattern is a string that is searched
in the source file to find the tagged line.

- WHY TAG NAMES ARE GOOD
When a user looks for a tag, Emacs first compares the tag with the tag
names contained in the tags file.  If no match is found, Emacs compares
the tag with the patterns.  The tag name is then the preferred way to
look for tags in the tags file, because when the tag name is present
Emacs can find a tag faster and more accurately.  These tag names are
part of tag lines in the tags file, so we call them "explicit".

- WHY IMPLICIT TAG NAMES ARE EVEN BETTER
When a tag line has no name, but a name can be deduced from the pattern,
we say that the tag line has an implicit tag name.  Often tag names are
redundant; this happens when the name of a tag is an easily guessable
substring of the tag pattern.  We define a set of rules to decide
whether it is possible to deduce the tag name from the pattern, and make
an unnamed tag in those cases.  The name deduced from the pattern of an
unnamed tag is the implicit name of that tag.
  When the user looks for a tag, and Emacs finds no explicit tag names
that match it, Emacs then looks for an tag whose implicit tag name
matches the request.  etags.c uses implicit tag names when possible, in
order to reduce the size of the tags file.
  An implicit tag name is deduced from the pattern by discarding the
last character if it is one of ` \f\t\n\r()=,;', then taking all the
rightmost consecutive characters in the pattern which are not one of
those.

===================== end of discussion of tag names =====================

Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007
Free Software Foundation, Inc.

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