;;; font-core.el --- Core interface to font-lock
;; Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
;; 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
;; Maintainer: FSF
;; Keywords: languages, faces
;; This file is part of GNU Emacs.
;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
;; This variable is used by mode packages that support Font Lock mode by
;; defining their own keywords to use for `font-lock-keywords'. (The mode
;; command should make it buffer-local and set it to provide the set up.)
(defvar font-lock-defaults nil
"Defaults for Font Lock mode specified by the major mode.
Defaults should be of the form:
(KEYWORDS [KEYWORDS-ONLY [CASE-FOLD [SYNTAX-ALIST [SYNTAX-BEGIN ...]]]])
KEYWORDS may be a symbol (a variable or function whose value is the keywords to
use for fontification) or a list of symbols. If KEYWORDS-ONLY is non-nil,
syntactic fontification (strings and comments) is not performed.
If CASE-FOLD is non-nil, the case of the keywords is ignored when fontifying.
If SYNTAX-ALIST is non-nil, it should be a list of cons pairs of the form
\(CHAR-OR-STRING . STRING) used to set the local Font Lock syntax table, for
keyword and syntactic fontification (see `modify-syntax-entry').
If SYNTAX-BEGIN is non-nil, it should be a function with no args used to move
backwards outside any enclosing syntactic block, for syntactic fontification.
Typical values are `beginning-of-line' (i.e., the start of the line is known to
be outside a syntactic block), or `beginning-of-defun' for programming modes or
`backward-paragraph' for textual modes (i.e., the mode-dependent function is
known to move outside a syntactic block). If nil, the beginning of the buffer
is used as a position outside of a syntactic block, in the worst case.
These item elements are used by Font Lock mode to set the variables
`font-lock-keywords-case-fold-search', `font-lock-syntax-table' and
Further item elements are alists of the form (VARIABLE . VALUE) and are in no
particular order. Each VARIABLE is made buffer-local before set to VALUE.
Currently, appropriate variables include `font-lock-mark-block-function'.
If this is non-nil, it should be a function with no args used to mark any
enclosing block of text, for fontification via \\[font-lock-fontify-block].
Typical values are `mark-defun' for programming modes or `mark-paragraph' for
textual modes (i.e., the mode-dependent function is known to put point and mark
around a text block relevant to that mode).
Other variables include that for syntactic keyword fontification,
`font-lock-syntactic-keywords' and those for buffer-specialized fontification
`font-lock-unfontify-region-function', and `font-lock-inhibit-thing-lock'.")
(defvar font-lock-defaults-alist nil
"Alist of fall-back Font Lock defaults for major modes.
Each item should be a list of the form:
(MAJOR-MODE . FONT-LOCK-DEFAULTS)
where MAJOR-MODE is a symbol and FONT-LOCK-DEFAULTS is a list of default
settings. See the variable `font-lock-defaults', which takes precedence.")
(make-obsolete-variable 'font-lock-defaults-alist 'font-lock-defaults)
(defvar font-lock-function 'font-lock-default-function
"A function which is called when `font-lock-mode' is toggled.
It will be passed one argument, which is the current value of
;; The mode for which font-lock was initialized, or nil if none.
"Toggle Font Lock mode.
With arg, turn Font Lock mode off if and only if arg is a non-positive
number; if arg is nil, toggle Font Lock mode; anything else turns Font
\(Font Lock is also known as \"syntax highlighting\".)
When Font Lock mode is enabled, text is fontified as you type it:
- Comments are displayed in `font-lock-comment-face';
- Strings are displayed in `font-lock-string-face';
- Certain other expressions are displayed in other faces according to the
value of the variable `font-lock-keywords'.
To customize the faces (colors, fonts, etc.) used by Font Lock for
fontifying different parts of buffer text, use \\[customize-face].
You can enable Font Lock mode in any major mode automatically by turning on in
the major mode's hook. For example, put in your ~/.emacs:
(add-hook 'c-mode-hook 'turn-on-font-lock)
Alternatively, you can use Global Font Lock mode to automagically turn on Font
Lock mode in buffers whose major mode supports it and whose major mode is one
of `font-lock-global-modes'. For example, put in your ~/.emacs:
Where major modes support different levels of fontification, you can use
the variable `font-lock-maximum-decoration' to specify which level you
generally prefer. When you turn Font Lock mode on/off the buffer is
fontified/defontified, though fontification occurs only if the buffer is
less than `font-lock-maximum-size'.
For example, to use maximum levels of fontification, put in your ~/.emacs:
(setq font-lock-maximum-decoration t)
To add your own highlighting for some major mode, and modify the highlighting
selected automatically via the variable `font-lock-maximum-decoration', you can
To fontify a buffer, without turning on Font Lock mode and regardless of buffer
size, you can use \\[font-lock-fontify-buffer].
To fontify a block (the function or paragraph containing point, or a number of
lines around point), perhaps because modification on the current line caused
syntactic change on other lines, you can use \\[font-lock-fontify-block].
See the variable `font-lock-defaults-alist' for the Font Lock mode default
settings. You can set your own default settings for some mode, by setting a
buffer local value for `font-lock-defaults', via its mode hook.
The above is the default behavior of `font-lock-mode'; you may specify
your own function which is called when `font-lock-mode' is toggled via
nil nil nil
;; Don't turn on Font Lock mode if we don't have a display (we're running a
;; batch job) or if the buffer is invisible (the name starts with a space).
(when (or noninteractive (eq (aref (buffer-name) 0) ?\ ))
(setq font-lock-mode nil))
(funcall font-lock-function font-lock-mode)
;; Arrange to unfontify this buffer if we change major mode later.
(add-hook 'change-major-mode-hook 'font-lock-change-mode nil t)
(remove-hook 'change-major-mode-hook 'font-lock-change-mode t))
(setq font-lock-mode-major-mode major-mode)))
;; Get rid of fontification for the old major mode.
;; We do this when changing major modes.
(defun font-lock-change-mode ()
(defun font-lock-defontify ()
"Clear out all `font-lock-face' properties in current buffer.
A major mode that uses `font-lock-face' properties might want to put
this function onto `change-major-mode-hook'."
(let ((modp (buffer-modified-p))
(remove-list-of-text-properties (point-min) (point-max)
(defun font-lock-default-function (mode)
;; Turn on Font Lock mode.
(set (make-local-variable 'char-property-alias-alist)
;; Add `font-lock-face' as an alias for the `face' property.
(let ((elt (assq 'face char-property-alias-alist)))
(unless (memq 'font-lock-face (cdr elt))
(setcdr elt (nconc (cdr elt) (list 'font-lock-face))))
(push (list 'face 'font-lock-face) char-property-alias-alist))))
;; Turn off Font Lock mode.
;; Remove `font-lock-face' as an alias for the `face' property.
(set (make-local-variable 'char-property-alias-alist)
(let ((elt (assq 'face char-property-alias-alist)))
(setcdr elt (remq 'font-lock-face (cdr elt)))
(when (null (cdr elt))
(delq elt char-property-alias-alist))))))
;; Only do hard work if the mode has specified stuff in
(when (or font-lock-defaults
(if (boundp 'font-lock-keywords) font-lock-keywords)
(cdr (assq major-mode font-lock-defaults-alist)))
(not (eq font-lock-mode-major-mode major-mode))))
(defun turn-on-font-lock ()
"Turn on Font Lock mode (only if the terminal can display it)."
;;; Global Font Lock mode.
;; A few people have hassled in the past for a way to make it easier to turn on
;; Font Lock mode, without the user needing to know for which modes s/he has to
;; turn it on, perhaps the same way hilit19.el/hl319.el does. I've always
;; balked at that way, as I see it as just re-moulding the same problem in
;; another form. That is; some person would still have to keep track of which
;; modes (which may not even be distributed with Emacs) support Font Lock mode.
;; The list would always be out of date. And that person might have to be me.
;; In a previous discussion the following hack came to mind. It is a gross
;; hack, but it generally works. We use the convention that major modes start
;; by calling the function `kill-all-local-variables', which in turn runs
;; functions on the hook variable `change-major-mode-hook'. We attach our
;; function `font-lock-change-major-mode' to that hook. Of course, when this
;; hook is run, the major mode is in the process of being changed and we do not
;; know what the final major mode will be. So, `font-lock-change-major-mode'
;; only (a) notes the name of the current buffer, and (b) adds our function
;; `turn-on-font-lock-if-enabled' to the hook variables
;; `after-change-major-mode-hook' and `post-command-hook' (for modes
;; that do not yet run `after-change-major-mode-hook'). By the time
;; the functions on the first of these hooks to be run are run, the new major
;; mode is assumed to be in place. This way we get a Font Lock function run
;; when a major mode is turned on, without knowing major modes or their hooks.
;; Naturally this requires that major modes run `kill-all-local-variables'
;; and `after-change-major-mode-hook', as they are supposed to. For modes
;; that do not run `after-change-major-mode-hook' yet, `post-command-hook'
;; takes care of things if the mode is set directly or indirectly by
;; an interactive command; however, problems can occur if the mode is
;; set by a timer or process: in that case, proper handling of Font Lock mode
;; may be delayed until the next interactive command.
;; User interface.
;; Although Global Font Lock mode is a pseudo-mode, I think that the user
;; interface should conform to the usual Emacs convention for modes, i.e., a
;; command to toggle the feature (`global-font-lock-mode') with a variable for
;; finer control of the mode's behaviour (`font-lock-global-modes').
;; The feature should not be enabled by loading font-lock.el, since other
;; mechanisms for turning on Font Lock mode, such as M-x font-lock-mode RET or
;; (add-hook 'c-mode-hook 'turn-on-font-lock), would cause Font Lock mode to be
;; turned on everywhere. That would not be intuitive or informative because
;; loading a file tells you nothing about the feature or how to control it. It
;; would also be contrary to the Principle of Least Surprise. sm.
(defcustom font-lock-global-modes t
"*Modes for which Font Lock mode is automagically turned on.
Global Font Lock mode is controlled by the command `global-font-lock-mode'.
If nil, means no modes have Font Lock mode automatically turned on.
If t, all modes that support Font Lock mode have it automatically turned on.
If a list, it should be a list of `major-mode' symbol names for which Font Lock
mode should be automatically turned on. The sense of the list is negated if it
begins with `not'. For example:
means that Font Lock mode is turned on for buffers in C and C++ modes only."
:type '(choice (const :tag "none" nil)
(const :tag "all" t)
(set :menu-tag "mode specific" :tag "modes"
(const :tag "Except" not)
(repeat :inline t (symbol :tag "mode"))))
(defun turn-on-font-lock-if-enabled ()
(unless (and (eq (car-safe font-lock-global-modes) 'not)
(memq major-mode (cdr font-lock-global-modes)))
:init-value (not (or noninteractive emacs-basic-display))
;;; End of Global Font Lock mode.
;; arch-tag: f8c286e1-02f7-41d9-b89b-1b67780aed71
;;; font-core.el ends here