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Commit 171a7d5d authored by Colin Walters's avatar Colin Walters
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(truncate-string-to-width): New optional argument `ellipsis'. Add 

commented-out test suite, and change coding to iso-2022-7bit.
parent a7c4d9c8
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lisp/international/mule-util.el
View file @ 171a7d5d
......@@ -84,23 +84,38 @@ TYPE should be `list' or `vector'."
string)
;;;###autoload
(defun truncate-string-to-width (str end-column &optional start-column padding)
(defun truncate-string-to-width (str end-column
&optional start-column padding ellipsis)
"Truncate string STR to end at column END-COLUMN.
The optional 3rd arg START-COLUMN, if non-nil, specifies
the starting column; that means to return the characters occupying
columns START-COLUMN ... END-COLUMN of STR.
The optional 4th arg PADDING, if non-nil, specifies a padding character
to add at the end of the result if STR doesn't reach column END-COLUMN,
or if END-COLUMN comes in the middle of a character in STR.
PADDING is also added at the beginning of the result
if column START-COLUMN appears in the middle of a character in STR.
The optional 3rd arg START-COLUMN, if non-nil, specifies the starting
column; that means to return the characters occupying columns
START-COLUMN ... END-COLUMN of STR. Both END-COLUMN and START-COLUMN
are specified in terms of character display width in the current
buffer; see also `char-width'.
The optional 4th arg PADDING, if non-nil, specifies a padding
character (which should have a display width of 1) to add at the end
of the result if STR doesn't reach column END-COLUMN, or if END-COLUMN
comes in the middle of a character in STR. PADDING is also added at
the beginning of the result if column START-COLUMN appears in the
middle of a character in STR.
If PADDING is nil, no padding is added in these cases, so
the resulting string may be narrower than END-COLUMN."
the resulting string may be narrower than END-COLUMN.
If ELLIPSIS is non-nil, it should be a string which will replace the
end of STR (including any padding) if it extends beyond END-COLUMN,
unless the display width of STR is equal to or less than the display
width of ELLIPSIS. If it is non-nil and not a string, then ELLIPSIS
defaults to \"...\"."
(or start-column
(setq start-column 0))
(let ((len (length str))
(when (and ellipsis (not (stringp ellipsis)))
(setq ellipsis "..."))
(let ((str-len (length str))
(str-width (string-width str))
(ellipsis-len (if ellipsis (length ellipsis) 0))
(ellipsis-width (if ellipsis (string-width ellipsis) 0))
(idx 0)
(column 0)
(head-padding "") (tail-padding "")
......@@ -110,14 +125,17 @@ the resulting string may be narrower than END-COLUMN."
(setq ch (aref str idx)
column (+ column (char-width ch))
idx (1+ idx)))
(args-out-of-range (setq idx len)))
(args-out-of-range (setq idx str-len)))
(if (< column start-column)
(if padding (make-string end-column padding) "")
(if (and padding (> column start-column))
(setq head-padding (make-string (- column start-column) padding)))
(when (and padding (> column start-column))
(setq head-padding (make-string (- column start-column) padding)))
(setq from-idx idx)
(if (< end-column column)
(setq idx from-idx)
(when (>= end-column column)
(if (and (< end-column str-width)
(> str-width ellipsis-width))
(setq end-column (- end-column ellipsis-width))
(setq ellipsis ""))
(condition-case nil
(while (< column end-column)
(setq last-column column
......@@ -125,15 +143,67 @@ the resulting string may be narrower than END-COLUMN."
ch (aref str idx)
column (+ column (char-width ch))
idx (1+ idx)))
(args-out-of-range (setq idx len)))
(if (> column end-column)
(setq column last-column idx last-idx))
(if (and padding (< column end-column))
(setq tail-padding (make-string (- end-column column) padding))))
(setq str (substring str from-idx idx))
(if padding
(concat head-padding str tail-padding)
str))))
(args-out-of-range (setq idx str-len)))
(when (> column end-column)
(setq column last-column
idx last-idx))
(when (and padding (< column end-column))
(setq tail-padding (make-string (- end-column column) padding))))
(concat head-padding (substring str from-idx idx)
tail-padding ellipsis))))
;;; Test suite for truncate-string-to-width
;; (dolist (test '((("" 0) . "")
;; (("x" 1) . "x")
;; (("xy" 1) . "x")
;; (("xy" 2 1) . "y")
;; (("xy" 0) . "")
;; (("xy" 3) . "xy")
;; (("$AVP(B" 0) . "")
;; (("$AVP(B" 1) . "")
;; (("$AVP(B" 2) . "$AVP(B")
;; (("$AVP(B" 1 nil ? ) . " ")
;; (("$AVPND(B" 3 1 ? ) . " ")
;; (("x$AVP(Bx" 2) . "x")
;; (("x$AVP(Bx" 3) . "x$AVP(B")
;; (("x$AVP(Bx" 3) . "x$AVP(B")
;; (("x$AVP(Bx" 4 1) . "$AVP(Bx")
;; (("kor$(CGQ(Be$(C1[(Ban" 8 1 ? ) . "or$(CGQ(Be$(C1[(B")
;; (("kor$(CGQ(Be$(C1[(Ban" 7 2 ? ) . "r$(CGQ(Be ")
;; (("" 0 nil nil "...") . "")
;; (("x" 3 nil nil "...") . "x")
;; (("$AVP(B" 3 nil nil "...") . "$AVP(B")
;; (("foo" 3 nil nil "...") . "foo")
;; (("foo" 2 nil nil "...") . "fo") ;; XEmacs failure?
;; (("foobar" 6 0 nil "...") . "foobar")
;; (("foobarbaz" 6 nil nil "...") . "foo...")
;; (("foobarbaz" 7 2 nil "...") . "ob...")
;; (("foobarbaz" 9 3 nil "...") . "barbaz")
;; (("$B$3(Bh$B$s(Be$B$K(Bl$B$A(Bl$B$O(Bo" 15 1 ? t) . " h$B$s(Be$B$K(Bl$B$A(Bl$B$O(Bo")
;; (("$B$3(Bh$B$s(Be$B$K(Bl$B$A(Bl$B$O(Bo" 14 1 ? t) . " h$B$s(Be$B$K(Bl$B$A(B...")
;; (("x" 3 nil nil "$(0GnM$(B") . "x")
;; (("$AVP(B" 2 nil nil "$(0GnM$(B") . "$AVP(B")
;; (("$AVP(B" 1 nil ?x "$(0GnM$(B") . "x") ;; XEmacs error
;; (("$AVPND(B" 3 nil ? "$(0GnM$(B") . "$AVP(B ") ;; XEmacs error
;; (("foobarbaz" 4 nil nil "$(0GnM$(B") . "$(0GnM$(B")
;; (("foobarbaz" 5 nil nil "$(0GnM$(B") . "f$(0GnM$(B")
;; (("foobarbaz" 6 nil nil "$(0GnM$(B") . "fo$(0GnM$(B")
;; (("foobarbaz" 8 3 nil "$(0GnM$(B") . "b$(0GnM$(B")
;; (("$B$3(Bh$B$s(Be$B$K(Bl$B$A(Bl$B$O(Bo" 14 4 ?x "$BF|K\8l(B") . "xe$B$KF|K\8l(B")
;; (("$B$3(Bh$B$s(Be$B$K(Bl$B$A(Bl$B$O(Bo" 13 4 ?x "$BF|K\8l(B") . "xex$BF|K\8l(B")
;; ))
;; (let (ret)
;; (condition-case e
;; (setq ret (apply #'truncate-string-to-width (car test)))
;; (error (setq ret e)))
;; (unless (equal ret (cdr test))
;; (error "%s: expected %s, got %s"
;; (prin1-to-string (cons 'truncate-string-to-width (car test)))
;; (prin1-to-string (cdr test))
;; (if (consp ret)
;; (format "error: %s: %s" (car ret)
;; (prin1-to-string (cdr ret)))
;; (prin1-to-string ret))))))
;;; For backward compatibility ...
;;;###autoload
......@@ -300,4 +370,8 @@ language environment LANG-ENV."
(provide 'mule-util)
;; Local Variables:
;; coding: iso-2022-7bit
;; End:
;;; mule-util.el ends here
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