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(elisp)Font Lock Basics

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Font Lock Basics
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   There are several variables that control how Font Lock mode
highlights text.  But major modes should not set any of these variables
directly.  Instead, they should set `font-lock-defaults' as a
buffer-local variable.  The value assigned to this variable is used, if
and when Font Lock mode is enabled, to set all the other variables.

 - Variable: font-lock-defaults
     This variable is set by major modes, as a buffer-local variable, to
     specify how to fontify text in that mode.  The value should look
     like this:

          (KEYWORDS KEYWORDS-ONLY CASE-FOLD
           SYNTAX-ALIST SYNTAX-BEGIN OTHER-VARS...)

     The first element, KEYWORDS, indirectly specifies the value of
     `font-lock-keywords'.  It can be a symbol, a variable whose value
     is the list to use for `font-lock-keywords'.  It can also be a
     list of several such symbols, one for each possible level of
     fontification.  The first symbol specifies how to do level 1
     fontification, the second symbol how to do level 2, and so on.

     The second element, KEYWORDS-ONLY, specifies the value of the
     variable `font-lock-keywords-only'.  If this is non-`nil',
     syntactic fontification (of strings and comments) is not performed.

     The third element, CASE-FOLD, specifies the value of
     `font-lock-case-fold-search'.  If it is non-`nil', Font Lock mode
     ignores case when searching as directed by `font-lock-keywords'.

     If the fourth element, SYNTAX-ALIST, is non-`nil', it should be a
     list of cons cells of the form `(CHAR-OR-STRING . STRING)'.  These
     are used to set up a syntax table for fontification (Note: Syntax
     Table Functions).  The resulting syntax table is stored in
     `font-lock-syntax-table'.

     The fifth element, SYNTAX-BEGIN, specifies the value of
     `font-lock-beginning-of-syntax-function' (see below).

     All the remaining elements (if any) are collectively called
     OTHER-VARS.  Each of these elements should have the form
     `(VARIABLE . VALUE)'--which means, make VARIABLE buffer-local and
     then set it to VALUE.  You can use these OTHER-VARS to set other
     variables that affect fontification, aside from those you can
     control with the first five elements.