(sentence-end-double-space, sentence-end-without-period): Move to paragraphs.

(fill-indent-according-to-mode): Change default to t.
(fill-context-prefix): Simplify control-flow and use a more
sophisticated merge that unifies both previous checks.
(fill-single-word-nobreak-p, fill-french-nobreak-p): New funs.
(fill-nobreak-predicate): Make it into a defcustom'd hook.
(fill-nobreak-p): New fun.
(fill-region-as-paragraph): Use it.
Handle `fill-indent-according-to-mode' slightly differently.
(fill-individual-paragraphs-prefix): Simplify the control-flow.
(fill-individual-paragraphs-citation): Fix.

1 files changed, 135 insertions, 141 deletions

diff --git a/lisp/textmodes/fill.el b/lisp/textmodes/fill.el
index f894b8d189d..48a4de776cf 100644
--- a/lisp/textmodes/fill.el
+++ b/lisp/textmodes/fill.el
@@ -38,28 +38,11 @@ A value of nil means that any change in indentation starts a new paragraph."
   :type 'boolean
   :group 'fill)
 
-(defcustom sentence-end-double-space t
-  "*Non-nil means a single space does not end a sentence.
-This is relevant for filling.  See also `sentence-end-without-period'
-and `colon-double-space'.
-
-If you change this, you should also change `sentence-end'.  See Info
-node `Sentences'."
-  :type 'boolean
-  :group 'fill)
-
 (defcustom colon-double-space nil
   "*Non-nil means put two spaces after a colon when filling."
   :type 'boolean
   :group 'fill)
 
-(defcustom sentence-end-without-period nil
-  "*Non-nil means a sentence will end without a period.
-For example, a sentence in Thai text ends with double space but
-without a period."
-  :type 'boolean
-  :group 'fill)
-
 (defvar fill-paragraph-function nil
   "Mode-specific function to fill a paragraph, or nil if there is none.
 If the function returns nil, then `fill-paragraph' does its normal work.")
@@ -123,7 +106,7 @@ This function is used when `adaptive-fill-regexp' does not match."
   :type '(choice (const nil) function)
   :group 'fill)
 
-(defvar fill-indent-according-to-mode nil
+(defvar fill-indent-according-to-mode t
   "Whether or not filling should try to use the major mode's indentation.")
 
 (defun current-fill-column ()
@@ -220,7 +203,6 @@ act as a paragraph-separator."
     (let ((firstline (point))
           first-line-prefix
           ;; Non-nil if we are on the second line.
-          at-second
           second-line-prefix
           start)
       (move-to-left-margin)
@@ -232,51 +214,47 @@ act as a paragraph-separator."
             ;; second-line-prefix from being used.
             (cond ;; ((looking-at paragraph-start) nil)
                   ((and adaptive-fill-regexp (looking-at adaptive-fill-regexp))
-                   (buffer-substring-no-properties start (match-end 0)))
+                   (match-string-no-properties 0))
                   (adaptive-fill-function (funcall adaptive-fill-function))))
       (forward-line 1)
-      (if (>= (point) to)
-          (goto-char firstline)
-        (setq at-second t)
+      (if (< (point) to)
+        (progn
         (move-to-left-margin)
         (setq start (point))
         (setq second-line-prefix
-              (cond ((looking-at paragraph-start) nil)
+              (cond ((looking-at paragraph-start) nil) ; can it happen ??  -sm
                     ((and adaptive-fill-regexp
                           (looking-at adaptive-fill-regexp))
                      (buffer-substring-no-properties start (match-end 0)))
                     (adaptive-fill-function
-                     (funcall adaptive-fill-function)))))
-      (if at-second
+                     (funcall adaptive-fill-function))))
           ;; If we get a fill prefix from the second line,
           ;; make sure it or something compatible is on the first line too.
-          (and second-line-prefix first-line-prefix
-               ;; If the first line has the second line prefix too, use it.
-               (if (or (string-match (concat "\\`"
-                                             (regexp-quote second-line-prefix)
-                                             "\\(\\'\\|[ \t]\\)")
-                                     first-line-prefix)
-                       ;; If the second line prefix is whitespace, use it.
-                       (string-match "\\`[ \t]+\\'" second-line-prefix))
-                   second-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)))
+          (when second-line-prefix
+            (unless first-line-prefix (setq first-line-prefix ""))
+
+            (if ;; If the non-whitespace chars match the first line,
+                ;; just use it (this subsumes the 2 previous checks).
+                ;; Used when first line is `/* ...' and second-line is
+                ;; ` * ...'.
+                (save-excursion
+                  (goto-char start)
+                  (looking-at
+                   (apply 'concat
+                          (mapcar (lambda (c)
+                                    (if (memq c '(?\t ?\ ))
+                                        ;; The number of chars might not
+                                        ;; match up if there's a mix of
+                                        ;; tabs and spaces.
+                                        "\\([ \t]*\\|.\\)"
+                                      (regexp-quote (string c))))
+                                  second-line-prefix))))
+                second-line-prefix
 
                  ;; Use the longest common substring of both prefixes,
                  ;; if there is one.
                  (fill-common-string-prefix first-line-prefix
-                                            second-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.
@@ -299,23 +277,75 @@ act as a paragraph-separator."
                                            (concat result "a"))))
                   result)))))))
 
-(defvar fill-nobreak-predicate nil
-  "If non-nil, a predicate for recognizing places not to break a line.
-The predicate is called with no arguments, with point at the place
-to be tested.  If it returns t, fill commands do not break the line there.")
+(defun fill-single-word-nobreak-p ()
+  "Don't break a line after the first or before the last word of a sentence."
+  (or (looking-at "[ \t]*\\sw+[ \t]*[.?!:][ \t]*$")
+      (save-excursion
+        (skip-chars-backward " \t")
+        (and (/= (skip-syntax-backward "w") 0)
+             (/= (skip-chars-backward " \t") 0)
+             (/= (skip-chars-backward ".?!:") 0)))))
+
+(defun fill-french-nobreak-p ()
+  "Return nil if French style allows breaking the line at point.
+This is used in `fill-nobreak-predicate' to prevent breaking lines just
+after an opening paren or just before a closing paren or a punctuation
+mark such as `?' or `:'.  It is common in French writing to put a space
+at such places, which would normally allow breaking the line at those
+places."
+  (or (looking-at "[ \t]*[])}»?!;:-]")
+      (save-excursion
+        (skip-chars-backward " \t")
+        (unless (bolp)
+          (backward-char 1)
+          (or (looking-at "[([{«]")
+              ;; Don't cut right after a single-letter word.
+              (and (memq (preceding-char) '(?\t ?\ ))
+                   (eq (char-syntax (following-char)) ?w)))))))
+
+(defcustom fill-nobreak-predicate nil
+  "List of predicates for recognizing places not to break a line.
+The predicates are called with no arguments, with point at the place to
+be tested.  If it returns t, fill commands do not break the line there."
+  :group 'fill
+  :type 'hook
+  :options '(fill-french-nobreak-p fill-single-word-nobreak-p))
+
+(defun fill-nobreak-p ()
+  "Return nil if breaking the line at point is allowed.
+Can be customized with the variable `fill-nobreak-predicate'."
+  (unless (bolp)
+    (or
+     ;; Don't break after a period followed by just one space.
+     ;; Move back to the previous place to break.
+     ;; The reason is that if a period ends up at the end of a
+     ;; line, further fills will assume it ends a sentence.
+     ;; If we now know it does not end a sentence, avoid putting
+     ;; it at the end of the line.
+     (and sentence-end-double-space
+          (save-excursion
+            (skip-chars-backward ". ")
+            (looking-at "\\. \\([^ ]\\|$\\)")))
+     ;; Another approach to the same problem.
+     (save-excursion
+       (skip-chars-backward ". ")
+       (and (looking-at "\\.")
+            (not (looking-at sentence-end))))
+     ;; Don't split a line if the rest would look like a new paragraph.
+     (unless use-hard-newlines
+       (save-excursion
+         (skip-chars-forward " \t") (looking-at paragraph-start)))
+     (run-hook-with-args-until-success 'fill-nobreak-predicate))))
 
 ;; Put `fill-find-break-point-function' property to charsets which
 ;; require special functions to find line breaking point.
-(let ((alist '((katakana-jisx0201 . kinsoku)
+(dolist (pair '((katakana-jisx0201 . kinsoku)
                (chinese-gb2312 . kinsoku)
                (japanese-jisx0208 . kinsoku)
                (japanese-jisx0212 . kinsoku)
                (chinese-big5-1 . kinsoku)
-               (chinese-big5-2 . kinsoku))))
-  (while alist
-    (put-charset-property (car (car alist)) 'fill-find-break-point-function
-                          (cdr (car alist)))
-    (setq alist (cdr alist))))
+                (chinese-big5-2 . kinsoku)))
+  (put-charset-property (car pair) 'fill-find-break-point-function (cdr pair)))
 
 (defun fill-find-break-point (limit)
   "Move point to a proper line breaking position of the current line.
@@ -403,6 +433,13 @@ space does not end a sentence, so don't break a line there."
 
     (or justify (setq justify (current-justification)))
 
+    ;; Never indent-according-to-mode with brain dead "indenting" functions.
+    (when (and fill-indent-according-to-mode
+               (memq indent-line-function
+                     '(indent-relative-maybe indent-relative
+                       indent-to-left-margin)))
+      (set (make-local-variable 'fill-indent-according-to-mode) nil))
+
     ;; Don't let Adaptive Fill mode alter the fill prefix permanently.
     (let ((fill-prefix fill-prefix))
       ;; Figure out how this paragraph is indented, if desired.
@@ -528,16 +565,7 @@ space does not end a sentence, so don't break a line there."
                 ;; further fills will assume it ends a sentence.
                 ;; If we now know it does not end a sentence,
                 ;; avoid putting it at the end of the line.
-                (while (and (> (point) linebeg)
-                            (or (and sentence-end-double-space
-                                     (> (point) (+ linebeg 2))
-                                     (eq (preceding-char) ?\ )
-                                     (not (eq (following-char) ?\ ))
-                                     (eq (char-after (- (point) 2)) ?\.)
-                                     (progn (forward-char -2) t))
-                                (and fill-nobreak-predicate
-                                     (funcall fill-nobreak-predicate)
-                                     (skip-chars-backward " \t"))))
+                (while (and (> (point) linebeg) (fill-nobreak-p))
                   (if (re-search-backward " \\|\\c|.\\|.\\c|" linebeg 0)
                       (forward-char 1)))
                 ;; If the left margin and fill prefix by themselves
@@ -553,18 +581,10 @@ space does not end a sentence, so don't break a line there."
                       (>= prefixcol (current-column)))
                     ;; Ok, skip at least one word or one \c| character.
                     ;; Meanwhile, don't stop at a period followed by one space.
-                    (let ((first t))
+                    (let ((fill-nobreak-predicate nil) ;to break sooner.
+                          (first t))
                       (move-to-column prefixcol)
-                      (while (and (not (eobp))
-                                  (or first
-                                      (and (not (bobp))
-                                           sentence-end-double-space
-                                           (save-excursion
-                                             (forward-char -1)
-                                             (and (looking-at "\\. ")
-                                                  (not (looking-at "\\.  ")))))
-                                      (and fill-nobreak-predicate
-                                           (funcall fill-nobreak-predicate))))
+                      (while (and (not (eobp)) (or first (fill-nobreak-p)))
                         ;; Find a breakable point while ignoring the
                         ;; following spaces.
                         (skip-chars-forward " \t")
@@ -579,7 +599,7 @@ space does not end a sentence, so don't break a line there."
                         (setq first nil)))
                   ;; Normally, move back over the single space between
                   ;; the words.
-                  (if (= (preceding-char) ?\ ) (forward-char -1))
+                  (skip-chars-backward " \t")
 
                   (if enable-multibyte-characters
                       ;; If we are going to break the line after or
@@ -613,17 +633,9 @@ space does not end a sentence, so don't break a line there."
                                                           0 nchars)))))))
                     ;; Ok, skip at least one word.  But
                     ;; don't stop at a period followed by just one space.
-                    (let ((first t))
-                      (while (and (not (eobp))
-                                  (or first
-                                      (and (not (bobp))
-                                           sentence-end-double-space
-                                           (save-excursion
-                                             (forward-char -1)
-                                             (and (looking-at "\\. ")
-                                                  (not (looking-at "\\.  ")))))
-                                      (and fill-nobreak-predicate
-                                           (funcall fill-nobreak-predicate))))
+                    (let ((fill-nobreak-predicate nil) ;to break sooner.
+                          (first t))
+                      (while (and (not (eobp)) (or first (fill-nobreak-p)))
                         ;; Find a breakable point while ignoring the
                         ;; following spaces.
                         (skip-chars-forward " \t")
@@ -656,10 +668,7 @@ space does not end a sentence, so don't break a line there."
                   (set-text-properties (1- (point)) (point)
                                        (text-properties-at (point)))
                   (if (or fill-prefix
-                          (not fill-indent-according-to-mode)
-                          (memq indent-line-function
-                                ;; Brain dead "indenting" functions.
-                                '(indent-relative-maybe indent-relative)))
+                          (not fill-indent-according-to-mode))
                       (indent-to-left-margin)
                     (indent-according-to-mode))
                   ;; Insert the fill prefix after indentation.
@@ -799,8 +808,7 @@ space does not end a sentence, so don't break a line there."
   "*Method of justifying text not otherwise specified.
 Possible values are `left', `right', `full', `center', or `none'.
 The requested kind of justification is done whenever lines are filled.
-The `justification' text-property  can locally override this variable.
-This variable automatically becomes buffer-local when set in any fashion."
+The `justification' text-property can locally override this variable."
   :type '(choice (const left)
                  (const right)
                  (const full)
@@ -1226,61 +1234,47 @@ Also, if CITATION-REGEXP is non-nil,  don't fill header lines."
             (fill-region-as-paragraph start (point) justify)
             (if (and (bolp) (not had-newline))
                 (delete-char -1))))))))
-
 (defun fill-individual-paragraphs-prefix (citation-regexp)
-  (or (let ((adaptive-fill-first-line-regexp "")
-            just-one-line-prefix
-            two-lines-prefix
-            one-line-citation-part
-            two-lines-citation-part
-            adjusted-two-lines-citation-part)
-        (setq just-one-line-prefix
-              (fill-context-prefix
-               (point)
-               (line-beginning-position 2)))
-        (setq two-lines-prefix
-              (fill-context-prefix
-               (point)
-               (line-beginning-position 3)))
-        (when just-one-line-prefix
-          (setq one-line-citation-part
-                (if citation-regexp
-                    (fill-individual-paragraphs-citation just-one-line-prefix
-                                                         citation-regexp)
-                  just-one-line-prefix)))
-        (when two-lines-prefix
-          (setq two-lines-citation-part
-                (if citation-regexp
-                    (fill-individual-paragraphs-citation two-lines-prefix
-                                                         citation-regexp)
-                  just-one-line-prefix))
-          (or two-lines-citation-part (setq two-lines-citation-part ""))
-          (setq adjusted-two-lines-citation-part
-                (substring two-lines-citation-part 0
-                           (string-match "[ \t]*\\'"
-                                         two-lines-citation-part))))
+  (let* ((adaptive-fill-first-line-regexp ".*")
+         (just-one-line-prefix
+          ;; Accept any prefix rather than just the ones matched by
+          ;; adaptive-fill-first-line-regexp.
+          (fill-context-prefix (point) (line-beginning-position 2)))
+         (two-lines-prefix
+          (fill-context-prefix (point) (line-beginning-position 3))))
+    (if (not just-one-line-prefix)
+        (buffer-substring
+         (point) (save-excursion (skip-chars-forward " \t") (point)))
         ;; See if the citation part of JUST-ONE-LINE-PREFIX
         ;; is the same as that of TWO-LINES-PREFIX,
         ;; except perhaps with longer whitespace.
-        (if (and just-one-line-prefix
-                 two-lines-prefix
+      (if (and just-one-line-prefix two-lines-prefix
+               (let* ((one-line-citation-part
+                       (fill-individual-paragraphs-citation
+                        just-one-line-prefix citation-regexp))
+                      (two-lines-citation-part
+                       (fill-individual-paragraphs-citation
+                        two-lines-prefix citation-regexp))
+                      (adjusted-two-lines-citation-part
+                       (substring two-lines-citation-part 0
+                                  (string-match "[ \t]*\\'"
+                                                two-lines-citation-part))))
+                 (and
                  (string-match (concat "\\`"
                                        (regexp-quote
                                         adjusted-two-lines-citation-part)
                                        "[ \t]*\\'")
                                one-line-citation-part)
                  (>= (string-width one-line-citation-part)
-                     (string-width two-lines-citation-part)))
+                      (string-width two-lines-citation-part)))))
             two-lines-prefix
-          just-one-line-prefix))
-      (buffer-substring 
-       (point)
-       (save-excursion (skip-chars-forward " \t")
-                       (point)))))
+        just-one-line-prefix))))
 
 (defun fill-individual-paragraphs-citation (string citation-regexp)
-  (string-match citation-regexp
-                string)
-  (match-string 0 string))  
+  (if citation-regexp
+      (if (string-match citation-regexp string)
+          (match-string 0 string)
+        "")
+    string))
 
 ;;; fill.el ends here