diff options
| -rw-r--r-- | lisp/font-lock.el | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/lisp/font-lock.el b/lisp/font-lock.el index 0cad924f20..3496560cc7 100644 --- a/lisp/font-lock.el +++ b/lisp/font-lock.el @@ -976,7 +976,7 @@ The value of this variable is used when Font Lock mode is turned on." ;; multi-line strings and comments; regexps are not appropriate for the job.) (defvar font-lock-extend-after-change-region-function nil - "A function that determines the region to fontify after a change. + "A function that determines the region to refontify after a change. This variable is either nil, or is a function that determines the region to refontify after a change. @@ -985,7 +985,7 @@ Font-lock calls this function after each buffer change. The function is given three parameters, the standard BEG, END, and OLD-LEN from `after-change-functions'. It should return either a cons of the beginning -and end buffer positions \(in that order) of the region to fontify, or nil +and end buffer positions \(in that order) of the region to refontify, or nil \(which directs the caller to fontify a default region). This function should preserve the match-data. The region it returns may start or end in the middle of a line.") @@ -1044,6 +1044,12 @@ a very meaningful entity to highlight.") (defvar font-lock-beg) (defvar font-lock-end) (defvar font-lock-extend-region-functions '(font-lock-extend-region-wholelines + ;; This use of font-lock-multiline property is unreliable but is just + ;; a handy heuristic: in case you don't have a function that does + ;; /identification/ of multiline elements, you may still occasionally + ;; discover them by accident (or you may /identify/ them but not in all + ;; cases), in which case the font-lock-multiline property can help make + ;; sure you will properly *re*identify them during refontification. font-lock-extend-region-multiline) "Special hook run just before proceeding to fontify a region. This is used to allow major modes to help font-lock find safe buffer positions @@ -1177,6 +1183,12 @@ what properties to clear before refontifying a region.") end (max jit-lock-end (cdr region)))) ;; Then extend the region obeying font-lock-multiline properties, ;; indicating which part of the buffer needs to be refontified. + ;; !!! This is the *main* user of font-lock-multiline property !!! + ;; font-lock-after-change-function could/should also do that, but it + ;; doesn't need to because font-lock-default-fontify-region does + ;; it anyway. Here OTOH we have no guarantee that + ;; font-lock-default-fontify-region will be executed on this region + ;; any time soon. (when (and (> beg (point-min)) (get-text-property (1- beg) 'font-lock-multiline)) (setq beg (or (previous-single-property-change |