Function: c-backward-sws
c-backward-sws is a byte-compiled function defined in cc-engine.el.gz.
Signature
(c-backward-sws)
Documentation
This function has :around advice: No documentation
Source Code
;; Defined in /usr/src/emacs/lisp/progmodes/cc-engine.el.gz
(defun c-backward-sws ()
;; Used by `c-backward-syntactic-ws' to implement the unbounded search.
;;
;; This function might do hidden buffer changes.
(let (;; `rung-pos' is set to a position as late as possible in the unmarked
;; part of the simple ws region.
(rung-pos (point)) next-rung-pos last-put-in-sws-pos
rung-is-marked simple-ws-beg cmt-skip-pos
(doc-line-join-here (concat c-doc-line-join-re "\\="))
attr-end)
;; Skip simple horizontal ws and do a quick check on the preceding
;; character to see if it's anything that can't end syntactic ws, so we can
;; bail out early in the majority of cases when there just are a few ws
;; chars. Newlines are complicated in the backward direction, so we can't
;; skip over them.
(c-skip-ws-chars-backward " \t\f ")
(when (and (not (bobp))
(save-excursion
(or (and
(memq (char-before) c-doc-line-join-end-ch) ; For speed.
(re-search-backward doc-line-join-here
(c-point 'bopl) t))
(and
(c-major-mode-is '(c-mode c++-mode))
(eq (char-before) ?\])
(eq (char-before (1- (point))) ?\])
(save-excursion
(and (c-go-list-backward)
(looking-at "\\[\\[")))
(setq attr-end (point)))
(progn
(backward-char)
(or (looking-at c-syntactic-ws-end)
(and c-opt-cpp-prefix
(looking-at c-symbol-char-key)
(progn (c-beginning-of-current-token)
(looking-at c-noise-macro-name-re))))))))
;; Try to find a rung position in the simple ws preceding point, so that
;; we can get a cache hit even if the last bit of the simple ws has
;; changed recently.
(setq simple-ws-beg (or attr-end ; After attribute.
(match-end 1) ; Noise macro, etc.
(match-end 0))) ; c-syntactic-ws-end
(c-skip-ws-chars-backward " \t\n\r\f\v ")
(if (setq rung-is-marked (text-property-any
(point) (min (1+ rung-pos) (point-max))
'c-is-sws t))
;; `rung-pos' will be the earliest marked position, which means that
;; there might be later unmarked parts in the simple ws region.
;; It's not worth the effort to fix that; the last part of the
;; simple ws is also typically edited often, so it could be wasted.
(goto-char (setq rung-pos rung-is-marked))
(goto-char simple-ws-beg))
(with-silent-modifications
(while
(progn
;; Each time round the next while form, we move back over a ladder
;; and append any simple WS preceding it, if possible joining with
;; the previous ladder.
(while
(when (and rung-is-marked
(not (bobp))
(get-text-property (1- (point)) 'c-in-sws))
;; The following search is the main reason that `c-in-sws'
;; and `c-is-sws' aren't combined to one property.
(goto-char (c-previous-single-property-change
(point) 'c-in-sws nil (point-min)))
(unless (get-text-property (point) 'c-is-sws)
;; If the `c-in-sws' region extended past the first
;; `c-is-sws' char we have to go forward a bit.
(goto-char (c-next-single-property-change
(point) 'c-is-sws)))
(c-debug-sws-msg
"c-backward-sws cached move %s <- %s (min %s)"
(point) rung-pos (point-min))
(setq rung-pos (point))
(if (and (< (min (c-skip-ws-chars-backward " \t\f\v ")
(progn
(setq simple-ws-beg (point))
(c-skip-ws-chars-backward " \t\n\r\f\v ")))
0)
(setq rung-is-marked
(text-property-any (point) rung-pos
'c-is-sws t)))
t
(goto-char simple-ws-beg)
nil))
;; We'll loop here if there is simple ws before the first rung.
;; That means that there's been some change in it and it's
;; possible that we've stepped into another ladder, so extend
;; the previous one to join with it if there is one, and try to
;; use the cache again.
(c-debug-sws-msg
"c-backward-sws extending rung with [%s..%s] (min %s)"
rung-is-marked rung-pos (point-min))
(unless (get-text-property (1- rung-pos) 'c-is-sws)
;; Remove any `c-in-sws' property from the last char of
;; the rung before we mark it with `c-is-sws', so that we
;; won't connect with the remains of a broken "ladder".
(c-remove-in-sws (1- rung-pos) rung-pos))
(c-put-is-sws rung-is-marked
rung-pos)
(c-put-in-sws rung-is-marked
(1- rung-pos))
(setq rung-pos rung-is-marked
last-put-in-sws-pos rung-pos))
(c-backward-comments)
(setq cmt-skip-pos (point))
(cond
((and c-opt-cpp-prefix
(/= cmt-skip-pos simple-ws-beg)
(c-beginning-of-macro))
;; Inside a cpp directive. See if it should be skipped over.
(let ((cpp-beg (point))
pause pos)
;; Move back over all line continuations and block comments in
;; the region skipped over by `c-backward-comments'. If we go
;; past it then we started inside the cpp directive.
(goto-char simple-ws-beg)
(beginning-of-line)
;; Note the similarity of the code here to some in
;; `c-beginning-of-macro'.
(setq pause (point))
(while
(progn
(while (and (> (point) cmt-skip-pos)
(progn (backward-char)
(eq (char-before) ?\\)))
(beginning-of-line))
(setq pos (point))
(when (and c-last-c-comment-end-on-line-re
(re-search-forward
c-last-c-comment-end-on-line-re pause t))
(goto-char (match-end 1))
(if (c-backward-single-comment)
(progn
(beginning-of-line)
(setq pause (point)))
(goto-char pos)
nil))))
(if (< (point) cmt-skip-pos)
;; Don't move past the cpp directive if we began inside
;; it. Note that the position at the end of the last line
;; of the macro is also considered to be within it.
(progn (goto-char cmt-skip-pos)
nil)
;; It's worthwhile to spend a little bit of effort on finding
;; the end of the macro, to get a good `simple-ws-beg'
;; position for the cache. Note that `c-backward-comments'
;; could have stepped over some comments before going into
;; the macro, and then `simple-ws-beg' must be kept on the
;; same side of those comments.
(goto-char simple-ws-beg)
(c-skip-ws-chars-backward " \t\n\r\f\v ")
(if (eq (char-before) ?\\)
(forward-char))
(forward-line 1)
(if (< (point) simple-ws-beg)
;; Might happen if comments after the macro were skipped
;; over.
(setq simple-ws-beg (point)))
(goto-char cpp-beg)
t)))
((/= (save-excursion
(c-skip-ws-chars-forward " \t\n\r\f\v " simple-ws-beg)
(setq next-rung-pos (point)))
simple-ws-beg)
;; Skipped over comments. Must put point at the end of
;; the simple ws at point since we might be after a line
;; comment or cpp directive that's been partially
;; narrowed out, and we can't risk marking the simple ws
;; at the end of it.
(goto-char next-rung-pos)
t)
((and c-opt-cpp-prefix
(save-excursion
(and (< (skip-syntax-backward "w_") 0)
(progn (setq next-rung-pos (point))
(looking-at c-noise-macro-name-re)))))
;; Skipped over a noise macro
(goto-char next-rung-pos)
t)
((and (c-major-mode-is '(c-mode c++-mode))
(eq (char-before) ?\])
(eq (char-before (1- (point))) ?\])
(save-excursion
(and (c-go-list-backward)
(setq next-rung-pos (point))
(looking-at "\\[\\["))))
(goto-char next-rung-pos)
t)
((and
(memq (char-before) c-doc-line-join-end-ch) ; For speed.
(re-search-backward doc-line-join-here (c-point 'bopl) t)))))
;; We've searched over a piece of non-white syntactic ws. See if this
;; can be cached.
(setq next-rung-pos (point))
(c-skip-ws-chars-backward " \t\f\v ")
(if (or
;; Cache if we started either from a marked rung or from a
;; completely uncached position.
rung-is-marked
(not (get-text-property (1- simple-ws-beg) 'c-in-sws))
;; Cache if there's a marked rung in the encountered simple ws.
(save-excursion
(c-skip-ws-chars-backward " \t\n\r\f\v ")
(text-property-any (point) (min (1+ next-rung-pos) (point-max))
'c-is-sws t)))
(progn
(c-debug-sws-msg
"c-backward-sws caching [%s..%s] - [%s..%s] (min %s)"
(point) (1+ next-rung-pos)
simple-ws-beg (min (1+ rung-pos) (point-max))
(point-min))
;; Remove the properties for any nested ws that might be cached.
;; Only necessary for `c-is-sws' since `c-in-sws' will be set
;; anyway.
(c-remove-is-sws (1+ next-rung-pos) simple-ws-beg)
(unless (and rung-is-marked (= simple-ws-beg rung-pos))
(let ((rung-end-pos (min (1+ rung-pos) (point-max))))
(unless (get-text-property (1- rung-end-pos) 'c-is-sws)
;; Remove any `c-in-sws' property from the last char of
;; the rung before we mark it with `c-is-sws', so that we
;; won't connect with the remains of a broken "ladder".
(c-remove-in-sws (1- rung-end-pos) rung-end-pos))
(c-put-is-sws simple-ws-beg
rung-end-pos)
(setq rung-is-marked t)))
(c-put-in-sws (setq simple-ws-beg (point)
last-put-in-sws-pos simple-ws-beg)
rung-pos)
(c-put-is-sws (setq rung-pos simple-ws-beg)
(1+ next-rung-pos)))
(c-debug-sws-msg
"c-backward-sws not caching [%s..%s] - [%s..%s] (min %s)"
(point) (1+ next-rung-pos)
simple-ws-beg (min (1+ rung-pos) (point-max))
(point-min))
(setq rung-pos next-rung-pos
simple-ws-beg (point))
))
;; Make sure that the newly marked `c-in-sws' region doesn't connect to
;; another one before the point (which might occur when editing inside a
;; comment or macro).
(when (eq last-put-in-sws-pos (point))
(cond ((< (point-min) last-put-in-sws-pos)
(c-debug-sws-msg
"c-backward-sws clearing at %s for cache separation"
(1- last-put-in-sws-pos))
(c-remove-in-sws (1- last-put-in-sws-pos)
last-put-in-sws-pos))
((> (point-min) 1)
;; If at bob and the buffer is narrowed, we have to clear the
;; character we're standing on instead since there might be a
;; `c-in-sws' before (point-min). In this case it's necessary
;; to clear both properties.
(c-debug-sws-msg
"c-backward-sws clearing thoroughly at %s for cache separation"
last-put-in-sws-pos)
(c-remove-is-and-in-sws last-put-in-sws-pos
(1+ last-put-in-sws-pos)))))
))))