Make syntax.c call syntax-propertize on demand

* lisp/emacs-lisp/syntax.el (syntax--jit-propertize): New function.
(parse-sexp-propertize-function): Use it.
(syntax-propertize): Disable parse-sexp-propertize-function.

* src/syntax.c (parse_sexp_propertize, update_syntax_table_forward):
New functions.
(syms_of_syntax): New vars `parse-sexp-propertize-done' and
`parse-sexp-propertize-function'.

* src/syntax.h (struct gl_state_s): Add `e_property_truncated' field.
(UPDATE_SYNTAX_TABLE_FORWARD): Use update_syntax_table_forward.
(SETUP_BUFFER_SYNTAX_TABLE): Set e_property_truncated.

* lisp/progmodes/elisp-mode.el (elisp-byte-code-syntax-propertize):
Don't assume `point' is set.

1 files changed, 15 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/syntax.el b/lisp/emacs-lisp/syntax.el
index 05dd7d57503..6c9cba3e563 100644
--- a/lisp/emacs-lisp/syntax.el
+++ b/lisp/emacs-lisp/syntax.el
@@ -297,7 +297,10 @@ The return value is a function suitable for `syntax-propertize-function'."
     (set (make-local-variable 'parse-sexp-lookup-properties) t)
     (save-excursion
       (with-silent-modifications
+        (make-local-variable 'parse-sexp-propertize-done) ;Just in case!
         (let* ((start (max syntax-propertize--done (point-min)))
+               ;; Avoid recursion!
+               (parse-sexp-propertize-done most-positive-fixnum)
                (end (max pos
                          (min (point-max)
                               (+ start syntax-propertize-chunk-size))))
@@ -324,6 +327,18 @@ The return value is a function suitable for `syntax-propertize-function'."
                                   '(syntax-table nil syntax-multiline nil))
           (funcall syntax-propertize-function start end))))))
 
+;;; Link syntax-propertize with the new parse-sexp-propertize.
+
+(setq-default parse-sexp-propertize-function #'syntax--jit-propertize)
+(defun syntax--jit-propertize (charpos)
+  (if (not syntax-propertize-function)
+      (setq parse-sexp-propertize-done (1+ (point-max)))
+    (syntax-propertize charpos)
+    (setq parse-sexp-propertize-done
+          (if (= (point-max) syntax-propertize--done)
+              (1+ (point-max))
+            syntax-propertize--done))))
+
 ;;; Incrementally compute and memoize parser state.
 
 (defsubst syntax-ppss-depth (ppss)