Some work in progress on a more efficient way to fontify a region as Clojure code

1 files changed, 37 insertions, 0 deletions

diff --git a/cider-util.el b/cider-util.el
index 9af18cb5..04b1fbba 100644
--- a/cider-util.el
+++ b/cider-util.el
@@ -87,6 +87,43 @@ Unless you specify a BUFFER it will default to the current one."
   "Font-lock STRING as Clojure code."
   (cider-font-lock-as 'clojure-mode string))
 
+;; More efficient way to fontify a region, without having to delete it
+;; Unfortunately still needs work, since the font-locking code in clojure-mode
+;; is pretty convoluted
+(defun cider-fontify-region
+  (beg end keywords syntax-table syntactic-keywords syntax-propertize-fn)
+  "Fontify a region between BEG and END using another mode's fontification.
+
+KEYWORDS, SYNTAX-TABLE, SYNTACTIC-KEYWORDS and
+SYNTAX-PROPERTIZE-FN are the values of that mode's
+`font-lock-keywords', `font-lock-syntax-table',
+`font-lock-syntactic-keywords', and `syntax-propertize-function'
+respectively."
+  (save-excursion
+    (save-match-data
+      (let ((font-lock-keywords keywords)
+            (font-lock-syntax-table syntax-table)
+            (font-lock-syntactic-keywords syntactic-keywords)
+            (syntax-propertize-function syntax-propertize-fn)
+            (font-lock-multiline 'undecided)
+            (font-lock-dont-widen t)
+            font-lock-keywords-only
+            font-lock-extend-region-functions
+            font-lock-keywords-case-fold-search)
+        (save-restriction
+          (narrow-to-region (1- beg) end)
+          ;; font-lock-fontify-region apparently isn't inclusive,
+          ;; so we have to move the beginning back one char
+          (font-lock-fontify-region (1- beg) end))))))
+
+(defun cider-fontify-region-as-clojure (beg end)
+  "Use Clojure's font-lock variables to fontify the region between BEG and END."
+  (cider-fontify-region beg end
+                        clojure-font-lock-keywords
+                        clojure-mode-syntax-table
+                        nil
+                        nil))
+
 (defun cider-format-pprint-eval (form)
   "Return a string of Clojure code that will eval and pretty-print FORM."
   (format "(let [x %s] (clojure.pprint/pprint x) x)" form))