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(fill-common-string-prefix): New function.

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(fill-context-prefix): Use the longest common substring of both
prefixes, if there is one.
This commit is contained in:
Gerd Moellmann 2000-01-11 21:42:12 +00:00
parent 7fbc46a0a2
commit 7190ab8737
1 changed files with 27 additions and 7 deletions
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34
lisp/textmodes/fill.el
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@ -185,6 +185,15 @@ Remove indentation from each line."
;; of the line and wants it to stay at the end of the line.
(insert-before-markers-and-inherit ? )))))
(defun fill-common-string-prefix (s1 s2)
"Return the longest common prefix of strings S1 and S2, or nil if none."
(let ((cmp (compare-strings s1 nil nil s2 nil nil)))
(if (eq cmp t)
s1
(setq cmp (1- (abs cmp)))
(unless (zerop cmp)
(substring s1 0 cmp)))))
(defun fill-context-prefix (from to &optional first-line-regexp)
"Compute a fill prefix from the text between FROM and TO.
This uses the variables `adaptive-fill-regexp' and `adaptive-fill-function'
@ -233,13 +242,24 @@ act as a paragraph-separator."
;; If the second line prefix is whitespace, use it.
(string-match "\\`[ \t]+\\'" second-line-prefix))
second-line-prefix
;; If the second line has the first line prefix,
;; plus whitespace, use the part that the first line shares.
(if (string-match (concat "\\`"
(regexp-quote first-line-prefix)
"[ \t]*\\'")
second-line-prefix)
first-line-prefix)))
;; If using the common prefix of first-line-prefix
;; and second-line-prefix leads to problems, consider
;; to restore the code below that's commented out,
;; and document why a common prefix cannot be used.
; ;; If the second line has the first line prefix,
; ;; plus whitespace, use the part that the first line shares.
; (if (string-match (concat "\\`"
; (regexp-quote first-line-prefix)
; "[ \t]*\\'")
; second-line-prefix)
; first-line-prefix)))
;; Use the longest common substring of both prefixes,
;; if there is one.
(fill-common-string-prefix first-line-prefix
second-line-prefix)))
;; If we get a fill prefix from a one-line paragraph,
;; maybe change it to whitespace,
;; and check that it isn't a paragraph starter.