Commit 8c9dbabe authored by Karl Heuer's avatar Karl Heuer
Browse files

(compare-windows): Make more efficient use of

result from compare-buffer-substrings.
parent 49683a13
......@@ -64,11 +64,13 @@ The variable `compare-windows-whitespace' controls how whitespace is skipped.
If `compare-ignore-case' is non-nil, changes in case are also ignored."
(interactive "P")
(let* (p1 p2 maxp1 maxp2 b1 b2 w2
success size
(progress 1)
(opoint1 (point))
(skip-whitespace (if ignore-whitespace
(skip-func (if ignore-whitespace
(if (stringp compare-windows-whitespace)
(setq p1 (point) b1 (current-buffer))
(setq w2 (next-window (selected-window)))
(if (eq w2 (selected-window))
......@@ -83,58 +85,34 @@ If `compare-ignore-case' is non-nil, changes in case are also ignored."
(setq maxp2 (point-max)))
(setq success t)
(while success
(setq success nil)
;; if interrupted, show how far we've gotten
(goto-char p1)
(set-window-point w2 p2)
(while (> progress 0)
;; If both buffers have whitespace next to point,
;; optionally skip over it.
(and skip-whitespace
(and skip-func
(let (p1a p2a w1 w2 result1 result2)
(setq result1
(if (stringp skip-whitespace)
(compare-windows-skip-whitespace opoint1)
(funcall skip-whitespace opoint1)))
(setq result1 (funcall skip-func opoint1))
(setq p1a (point))
(set-buffer b2)
(goto-char p2)
(setq result2
(if (stringp skip-whitespace)
(compare-windows-skip-whitespace opoint2)
(funcall skip-whitespace opoint2)))
(setq result2 (funcall skip-func opoint2))
(setq p2a (point))
(if (or (stringp skip-whitespace)
(and result1 result2 (eq result1 result2)))
(setq p1 p1a
p2 p2a)))))
;; Try advancing comparing 1000 chars at a time.
;; When that fails, go 500 chars at a time, and so on.
(let ((size 1000)
(let ((size (min (- maxp1 p1) (- maxp2 p2)))
(case-fold-search compare-ignore-case))
(while (> size 0)
(setq success-1 t)
;; Try comparing SIZE chars at a time, repeatedly, till that fails.
(while success-1
(setq size (min size (- maxp1 p1) (- maxp2 p2)))
(setq success-1
(and (> size 0)
(= 0 (compare-buffer-substrings b2 p2 (+ size p2)
b1 p1 (+ size p1)))))
(if success-1
(setq p1 (+ p1 size) p2 (+ p2 size)
success t)))
;; If SIZE chars don't match, try fewer.
(setq size (/ size 2)))))
(goto-char p1)
(set-window-point w2 p2)
(setq progress (compare-buffer-substrings b2 p2 (+ size p2)
b1 p1 (+ size p1)))
(setq progress (if (zerop progress) size (1- (abs progress))))
(setq p1 (+ p1 progress) p2 (+ p2 progress)))
;; Advance point now rather than later, in case we're interrupted.
(goto-char p1)
(set-window-point w2 p2))
(if (= (point) opoint1)
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