(comint-arguments): Rewrite for speed.

Don't keep parsing once we have enough args.

1 files changed, 28 insertions, 12 deletions

diff --git a/lisp/comint.el b/lisp/comint.el
index c18e84e70b2..b0135faf980 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -1043,18 +1043,34 @@ We assume whitespace separates arguments, except within quotes.
 Also, a run of one or more of a single character
 in `comint-delimiter-argument-list' is a separate argument.
 Argument 0 is the command name."
-  (let ((arg "\\(\\(\"[^\"]*\"\\|\'[^\']*\'\\|\`[^\`]*\`\\)\\|\\S \\)+")
-        (args ()) (pos 0) (str nil))
-    ;; We build a list of all the args.  Unnecessary, but more efficient, when
-    ;; ranges of args are required, than picking out one by one and recursing.
-    (while (string-match arg string pos)
-      (setq pos (match-end 0)
-            str (substring string (match-beginning 0) pos)
-            ;; (match-end 2) is non-nil if we found quotes.
-            args (if (match-end 2) (cons str args)
-                   (nconc (comint-delim-arg str) args))))
-    (let ((n (or nth (1- (length args))))
-          (m (if mth (1- (- (length args) mth)) 0)))
+  (let ((argpart "[^ \"'`]+\\|\\(\"[^\"]*\"\\|'[^']*'\\|`[^`]*`\\)")
+        (args ()) (pos 0)
+        (count 0)
+        beg str value quotes)
+    ;; Build a list of all the args until we have as many as we want.
+    (while (and (or (null mth) (<= count mth))
+                (string-match argpart string pos))
+      (if (and beg (= pos (match-beginning 0)))
+          ;; It's contiguous, part of the same arg.
+          (setq pos (match-end 0)
+                quotes (or quotes (match-beginning 1)))
+        ;; It's a new separate arg.
+        (if beg
+            ;; Put the previous arg, if there was one, onto ARGS.
+            (setq str (substring string beg pos)
+                  args (if quotes (cons str args)
+                         (nconc (comint-delim-arg str) args))
+                  count (1+ count)))
+        (setq quotes (match-beginning 1))
+        (setq beg (match-beginning 0))
+        (setq pos (match-end 0))))
+    (if beg
+        (setq str (substring string beg pos)
+              args (if quotes (cons str args)
+                     (nconc (comint-delim-arg str) args))
+              count (1+ count)))
+    (let ((n (or nth (1- count)))
+          (m (if mth (1- (- count mth)) 0)))
       (mapconcat
        (function (lambda (a) a)) (nthcdr n (nreverse (nthcdr m args))) " "))))