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312 lines
14 KiB
EmacsLisp
312 lines
14 KiB
EmacsLisp
;;; font-core.el --- Core interface to font-lock
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;; Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
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;; 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
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;; Maintainer: FSF
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;; Keywords: languages, faces
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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;;; Code:
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;; This variable is used by mode packages that support Font Lock mode by
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;; defining their own keywords to use for `font-lock-keywords'. (The mode
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;; command should make it buffer-local and set it to provide the set up.)
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(defvar font-lock-defaults nil
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"Defaults for Font Lock mode specified by the major mode.
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Defaults should be of the form:
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(KEYWORDS [KEYWORDS-ONLY [CASE-FOLD [SYNTAX-ALIST [SYNTAX-BEGIN ...]]]])
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KEYWORDS may be a symbol (a variable or function whose value is the keywords
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to use for fontification) or a list of symbols (specifying different levels
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of fontification).
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If KEYWORDS-ONLY is non-nil, syntactic fontification (strings and
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comments) is not performed.
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If CASE-FOLD is non-nil, the case of the keywords is ignored when fontifying.
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If SYNTAX-ALIST is non-nil, it should be a list of cons pairs of the form
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\(CHAR-OR-STRING . STRING) used to set the local Font Lock syntax table, for
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keyword and syntactic fontification (see `modify-syntax-entry').
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If SYNTAX-BEGIN is non-nil, it should be a function with no args used to move
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backwards outside any enclosing syntactic block, for syntactic fontification.
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Typical values are `beginning-of-line' (i.e., the start of the line is known to
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be outside a syntactic block), or `beginning-of-defun' for programming modes or
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`backward-paragraph' for textual modes (i.e., the mode-dependent function is
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known to move outside a syntactic block). If nil, the beginning of the buffer
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is used as a position outside of a syntactic block, in the worst case.
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\(See also Info node `(elisp)Font Lock Basics'.)
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These item elements are used by Font Lock mode to set the variables
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`font-lock-keywords', `font-lock-keywords-only',
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`font-lock-keywords-case-fold-search', `font-lock-syntax-table' and
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`font-lock-beginning-of-syntax-function', respectively.
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Further item elements are alists of the form (VARIABLE . VALUE) and are in no
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particular order. Each VARIABLE is made buffer-local before set to VALUE.
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Currently, appropriate variables include `font-lock-mark-block-function'.
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If this is non-nil, it should be a function with no args used to mark any
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enclosing block of text, for fontification via \\[font-lock-fontify-block].
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Typical values are `mark-defun' for programming modes or `mark-paragraph' for
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textual modes (i.e., the mode-dependent function is known to put point and mark
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around a text block relevant to that mode).
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Other variables include that for syntactic keyword fontification,
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`font-lock-syntactic-keywords' and those for buffer-specialized fontification
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functions, `font-lock-fontify-buffer-function',
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`font-lock-unfontify-buffer-function', `font-lock-fontify-region-function',
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`font-lock-unfontify-region-function', and `font-lock-inhibit-thing-lock'.")
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(make-variable-buffer-local 'font-lock-defaults)
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(defvar font-lock-defaults-alist nil
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"Alist of fall-back Font Lock defaults for major modes.
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Each item should be a list of the form:
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(MAJOR-MODE . FONT-LOCK-DEFAULTS)
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where MAJOR-MODE is a symbol and FONT-LOCK-DEFAULTS is a list of default
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settings. See the variable `font-lock-defaults', which takes precedence.")
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(make-obsolete-variable 'font-lock-defaults-alist 'font-lock-defaults "21.1")
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(defvar font-lock-function 'font-lock-default-function
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"A function which is called when `font-lock-mode' is toggled.
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It will be passed one argument, which is the current value of
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`font-lock-mode'.")
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;; The mode for which font-lock was initialized, or nil if none.
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(defvar font-lock-mode-major-mode)
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(define-minor-mode font-lock-mode
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"Toggle Font Lock mode.
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With arg, turn Font Lock mode off if and only if arg is a non-positive
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number; if arg is nil, toggle Font Lock mode; anything else turns Font
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Lock on.
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\(Font Lock is also known as \"syntax highlighting\".)
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When Font Lock mode is enabled, text is fontified as you type it:
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- Comments are displayed in `font-lock-comment-face';
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- Strings are displayed in `font-lock-string-face';
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- Certain other expressions are displayed in other faces according to the
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value of the variable `font-lock-keywords'.
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To customize the faces (colors, fonts, etc.) used by Font Lock for
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fontifying different parts of buffer text, use \\[customize-face].
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You can enable Font Lock mode in any major mode automatically by turning on in
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the major mode's hook. For example, put in your ~/.emacs:
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(add-hook 'c-mode-hook 'turn-on-font-lock)
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Alternatively, you can use Global Font Lock mode to automagically turn on Font
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Lock mode in buffers whose major mode supports it and whose major mode is one
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of `font-lock-global-modes'. For example, put in your ~/.emacs:
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(global-font-lock-mode t)
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Where major modes support different levels of fontification, you can use
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the variable `font-lock-maximum-decoration' to specify which level you
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generally prefer. When you turn Font Lock mode on/off the buffer is
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fontified/defontified, though fontification occurs only if the buffer is
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less than `font-lock-maximum-size'.
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To add your own highlighting for some major mode, and modify the highlighting
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selected automatically via the variable `font-lock-maximum-decoration', you can
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use `font-lock-add-keywords'.
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To fontify a buffer, without turning on Font Lock mode and regardless of buffer
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size, you can use \\[font-lock-fontify-buffer].
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To fontify a block (the function or paragraph containing point, or a number of
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lines around point), perhaps because modification on the current line caused
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syntactic change on other lines, you can use \\[font-lock-fontify-block].
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See the variable `font-lock-defaults-alist' for the Font Lock mode default
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settings. You can set your own default settings for some mode, by setting a
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buffer local value for `font-lock-defaults', via its mode hook.
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The above is the default behavior of `font-lock-mode'; you may specify
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your own function which is called when `font-lock-mode' is toggled via
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`font-lock-function'. "
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nil nil nil
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;; Don't turn on Font Lock mode if we don't have a display (we're running a
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;; batch job) or if the buffer is invisible (the name starts with a space).
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(when (or noninteractive (eq (aref (buffer-name) 0) ?\s))
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(setq font-lock-mode nil))
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(funcall font-lock-function font-lock-mode)
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;; Arrange to unfontify this buffer if we change major mode later.
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(if font-lock-mode
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(add-hook 'change-major-mode-hook 'font-lock-change-mode nil t)
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(remove-hook 'change-major-mode-hook 'font-lock-change-mode t))
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(when font-lock-mode
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(setq font-lock-mode-major-mode major-mode)))
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;; Get rid of fontification for the old major mode.
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;; We do this when changing major modes.
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(defun font-lock-change-mode ()
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(font-lock-mode -1))
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(defun font-lock-defontify ()
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"Clear out all `font-lock-face' properties in current buffer.
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A major mode that uses `font-lock-face' properties might want to put
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this function onto `change-major-mode-hook'."
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(let ((modp (buffer-modified-p))
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(inhibit-read-only t))
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(save-restriction
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(widen)
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(remove-list-of-text-properties (point-min) (point-max)
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'(font-lock-face)))
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(restore-buffer-modified-p modp)))
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(defvar font-lock-set-defaults)
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(defun font-lock-default-function (mode)
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;; Turn on Font Lock mode.
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(when mode
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(set (make-local-variable 'char-property-alias-alist)
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(copy-tree char-property-alias-alist))
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;; Add `font-lock-face' as an alias for the `face' property.
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(let ((elt (assq 'face char-property-alias-alist)))
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(if elt
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(unless (memq 'font-lock-face (cdr elt))
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(setcdr elt (nconc (cdr elt) (list 'font-lock-face))))
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(push (list 'face 'font-lock-face) char-property-alias-alist))))
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;; Turn off Font Lock mode.
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(unless mode
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;; Remove `font-lock-face' as an alias for the `face' property.
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(set (make-local-variable 'char-property-alias-alist)
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(copy-tree char-property-alias-alist))
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(let ((elt (assq 'face char-property-alias-alist)))
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(when elt
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(setcdr elt (remq 'font-lock-face (cdr elt)))
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(when (null (cdr elt))
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(setq char-property-alias-alist
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(delq elt char-property-alias-alist))))))
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;; Only do hard work if the mode has specified stuff in
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;; `font-lock-defaults'.
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(when (or font-lock-defaults
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(if (boundp 'font-lock-keywords) font-lock-keywords)
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(with-no-warnings
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(cdr (assq major-mode font-lock-defaults-alist)))
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(and mode
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(boundp 'font-lock-set-defaults)
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font-lock-set-defaults
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font-lock-mode-major-mode
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(not (eq font-lock-mode-major-mode major-mode))))
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(font-lock-mode-internal mode)))
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(defun turn-on-font-lock ()
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"Turn on Font Lock mode (only if the terminal can display it)."
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(unless font-lock-mode
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(font-lock-mode)))
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;;; Global Font Lock mode.
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;; A few people have hassled in the past for a way to make it easier to turn on
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;; Font Lock mode, without the user needing to know for which modes s/he has to
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;; turn it on, perhaps the same way hilit19.el/hl319.el does. I've always
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;; balked at that way, as I see it as just re-moulding the same problem in
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;; another form. That is; some person would still have to keep track of which
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;; modes (which may not even be distributed with Emacs) support Font Lock mode.
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;; The list would always be out of date. And that person might have to be me.
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;; Implementation.
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;;
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;; In a previous discussion the following hack came to mind. It is a gross
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;; hack, but it generally works. We use the convention that major modes start
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;; by calling the function `kill-all-local-variables', which in turn runs
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;; functions on the hook variable `change-major-mode-hook'. We attach our
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;; function `font-lock-change-major-mode' to that hook. Of course, when this
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;; hook is run, the major mode is in the process of being changed and we do not
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;; know what the final major mode will be. So, `font-lock-change-major-mode'
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;; only (a) notes the name of the current buffer, and (b) adds our function
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;; `turn-on-font-lock-if-desired' to the hook variables
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;; `after-change-major-mode-hook' and `post-command-hook' (for modes
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;; that do not yet run `after-change-major-mode-hook'). By the time
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;; the functions on the first of these hooks to be run are run, the new major
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;; mode is assumed to be in place. This way we get a Font Lock function run
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;; when a major mode is turned on, without knowing major modes or their hooks.
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;;
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;; Naturally this requires that major modes run `kill-all-local-variables'
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;; and `after-change-major-mode-hook', as they are supposed to. For modes
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;; that do not run `after-change-major-mode-hook' yet, `post-command-hook'
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;; takes care of things if the mode is set directly or indirectly by
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;; an interactive command; however, problems can occur if the mode is
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;; set by a timer or process: in that case, proper handling of Font Lock mode
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;; may be delayed until the next interactive command.
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;; User interface.
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;;
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;; Although Global Font Lock mode is a pseudo-mode, I think that the user
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;; interface should conform to the usual Emacs convention for modes, i.e., a
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;; command to toggle the feature (`global-font-lock-mode') with a variable for
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;; finer control of the mode's behavior (`font-lock-global-modes').
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;;
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;; The feature should not be enabled by loading font-lock.el, since other
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;; mechanisms for turning on Font Lock mode, such as M-x font-lock-mode RET or
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;; (add-hook 'c-mode-hook 'turn-on-font-lock), would cause Font Lock mode to be
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;; turned on everywhere. That would not be intuitive or informative because
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;; loading a file tells you nothing about the feature or how to control it. It
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;; would also be contrary to the Principle of Least Surprise. sm.
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(defcustom font-lock-global-modes t
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"Modes for which Font Lock mode is automagically turned on.
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Global Font Lock mode is controlled by the command `global-font-lock-mode'.
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If nil, means no modes have Font Lock mode automatically turned on.
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If t, all modes that support Font Lock mode have it automatically turned on.
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If a list, it should be a list of `major-mode' symbol names for which Font Lock
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mode should be automatically turned on. The sense of the list is negated if it
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begins with `not'. For example:
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(c-mode c++-mode)
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means that Font Lock mode is turned on for buffers in C and C++ modes only."
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:type '(choice (const :tag "none" nil)
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(const :tag "all" t)
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(set :menu-tag "mode specific" :tag "modes"
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:value (not)
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(const :tag "Except" not)
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(repeat :inline t (symbol :tag "mode"))))
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:group 'font-lock)
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(defun turn-on-font-lock-if-desired ()
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(when (cond ((eq font-lock-global-modes t)
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t)
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((eq (car-safe font-lock-global-modes) 'not)
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(not (memq major-mode (cdr font-lock-global-modes))))
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(t (memq major-mode (cdr font-lock-global-modes))))
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(let (inhibit-quit)
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(turn-on-font-lock))))
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(define-globalized-minor-mode global-font-lock-mode
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font-lock-mode turn-on-font-lock-if-desired
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:extra-args (dummy)
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:initialize 'custom-initialize-safe-default
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:init-value (not (or noninteractive emacs-basic-display))
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:group 'font-lock
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:version "22.1")
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;;; End of Global Font Lock mode.
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(provide 'font-core)
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;; arch-tag: f8c286e1-02f7-41d9-b89b-1b67780aed71
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;;; font-core.el ends here
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