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Generalize prettify-symbols to arbitrary modes

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* lisp/progmodes/prog-mode.el
(prettify-symbols-default-compose-p): New function.
(prettify-symbols-compose-predicate): New variable.
(prettify-symbols--compose-symbol): Use it.
This commit is contained in:
Tassilo Horn 2015-08-20 09:58:28 +02:00
parent 760701ebe1
commit c88063faef
1 changed files with 31 additions and 16 deletions
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47
lisp/progmodes/prog-mode.el
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@ -133,26 +133,41 @@ Each element looks like (SYMBOL . CHARACTER), where the symbol
matching SYMBOL (a string, not a regexp) will be shown as
CHARACTER instead.")
(defun prettify-symbols-default-compose-p (start end _match)
"Return true iff the symbol MATCH should be composed.
The symbol starts at position START and ends at position END.
This is default `prettify-symbols-compose-predicate' which is
suitable for most programming languages such as C or Lisp."
;; Check that the chars should really be composed into a symbol.
(let* ((syntaxes-beg (if (memq (char-syntax (char-after start)) '(?w ?_))
'(?w ?_) '(?. ?\\)))
(syntaxes-end (if (memq (char-syntax (char-before end)) '(?w ?_))
'(?w ?_) '(?. ?\\))))
(not (or (memq (char-syntax (or (char-before start) ?\s)) syntaxes-beg)
(memq (char-syntax (or (char-after end) ?\s)) syntaxes-end)
(nth 8 (syntax-ppss))))))
(defvar-local prettify-symbols-compose-predicate
#'prettify-symbols-default-compose-p
"A predicate deciding if the currently matched symbol is to be composed.
The matched symbol is the car of one entry in `prettify-symbols-alist'.
The predicate receives the match's start and end position as well
as the match-string as arguments.")
(defun prettify-symbols--compose-symbol (alist)
"Compose a sequence of characters into a symbol.
Regexp match data 0 points to the chars."
;; Check that the chars should really be composed into a symbol.
(let* ((start (match-beginning 0))
(end (match-end 0))
(syntaxes-beg (if (memq (char-syntax (char-after start)) '(?w ?_))
'(?w ?_) '(?. ?\\)))
(syntaxes-end (if (memq (char-syntax (char-before end)) '(?w ?_))
'(?w ?_) '(?. ?\\)))
match)
(if (or (memq (char-syntax (or (char-before start) ?\s)) syntaxes-beg)
(memq (char-syntax (or (char-after end) ?\s)) syntaxes-end)
;; syntax-ppss could modify the match data (bug#14595)
(progn (setq match (match-string 0)) (nth 8 (syntax-ppss))))
;; No composition for you. Let's actually remove any composition
;; we may have added earlier and which is now incorrect.
(remove-text-properties start end '(composition))
;; That's a symbol alright, so add the composition.
(compose-region start end (cdr (assoc match alist)))))
(let ((start (match-beginning 0))
(end (match-end 0))
(match (match-string 0)))
(if (funcall prettify-symbols-compose-predicate start end match)
;; That's a symbol alright, so add the composition.
(compose-region start end (cdr (assoc match alist)))
;; No composition for you. Let's actually remove any
;; composition we may have added earlier and which is now
;; incorrect.
(remove-text-properties start end '(composition))))
;; Return nil because we're not adding any face property.
nil)