Here's my extension to dabbrev-expand to support sub-string expansion.It works as expected, as far as I know. However I would find it even more useful if it supported in-symbol expansion similar to the behaviour of mdabbrev, which, by the way, is incomplete in terms of symbol-character and case-adjustment support. The pattern argument to dabbrev-substring-search, however, is only the pattern before point but for in-place expansions we need the pattern after point aswell. Why isn't this pattern available in hippie/dabbrev-expand and is there a preferred way to query it?
(defun dabbrev-substring-search (pattern &optional reverse limit syntax-context)
"Expand dabbrev substring. See:
http://www.emacswiki.org/cgi-bin/wiki/HippieExpand#toc5"
(let ((result ())
(regpat (cond ((not hippie-epxand-dabbrev-as-symbol)
(concat (regexp-quote pattern) W*))
;; ((eq (char-syntax (aref pattern 0)) ?_)
;; (concat (regexp-quote pattern)
;; "\\(\\sw\\|\\s_\\)*"))
(t
(concat "\\(?:"
Y<
"\\(" "\\(?:\\sw\\|\\s_\\)+" "\\)"
"\\(" (regexp-quote pattern) "\\)"
"\\(" "\\(?:\\sw\\|\\s_\\)*" "\\)"
Y>
"\\)"
"\\|"
"\\(?:"
Y<
"\\(" "\\(?:\\sw\\|\\s_\\)*" "\\)"
"\\(" (regexp-quote pattern) "\\)"
"\\(" "\\(?:\\sw\\|\\s_\\)+" "\\)"
Y>
"\\)"
)))))
(while (and (not result)
(if reverse
(re-search-backward regpat limit t)
(re-search-forward regpat limit t)))
(setq result (buffer-substring-no-properties (save-excursion
(goto-char (match-beginning 0))
;;(skip-syntax-backward "w_")
(point))
(match-end 0)))
(if (he-string-member result he-tried-table t)
(setq result nil))) ; ignore if bad prefix or already in table
(when nil
(when result
(let* ((p (point))
(end3 (match-end 3))
(beg2 (match-end 2))
(end2 (match-end 2))
(dummy (message "%s %s %s" end3 beg2 end2))
(beg (- end3 beg2)) ;begin offset from point
(end (- end3 end2))) ;end offset from point
(setq dabbrev-substring-match-region (cons beg end))
(hictx-generic (- p beg) (- p end) nil 'match 3))))
result))
;; Use: (dabbrev-substring-search "he")
(defun try-expand-dabbrev-substring-visible (old)
"Like `try-expand-dabbrev' but for visible part of buffer."
(interactive "P")
(let ((old-fun (symbol-function 'he-dabbrev-search)))
(fset 'he-dabbrev-search (symbol-function 'dabbrev-substring-search))
(unwind-protect (try-expand-dabbrev-visible old)
(fset 'he-dabbrev-search old-fun))))
(defun try-expand-dabbrev-substring (old)
"Like `try-expand-dabbrev' but for substring match."
(interactive "P")
(let ((old-fun (symbol-function 'he-dabbrev-search)))
(fset 'he-dabbrev-search (symbol-function 'dabbrev-substring-search))
(unwind-protect (try-expand-dabbrev old)
(fset 'he-dabbrev-search old-fun))))
(defun try-expand-dabbrev-substring-all-buffers (old)
"Like `try-expand-dabbrev-all-buffers' but for substring match."
(interactive "P")
(let ((old-fun (symbol-function 'he-dabbrev-search)))
(fset 'he-dabbrev-search (symbol-function 'dabbrev-substring-search))
(unwind-protect (try-expand-dabbrev-all-buffers old)
(fset 'he-dabbrev-search old-fun))))
which is activated for example using
(setq hippie-expand-try-functions-list
(append
'(
try-expand-dabbrev-substring-visible
try-expand-dabbrev-substring
try-expand-dabbrev-substring-all-buffers)))
This might or might not help. Like ordinary dabbrev, it works with the text before point, but candidate matching can be substring, regexp, or fuzzy (various kinds), in addition to prefix. Icicles - Dynamic Abbreviation
Related
In elisp, how can I get a destructuring bind for regex matches?
For example,
;; what is the equivalent of this with destructuring?
(with-temp-buffer
(save-excursion (insert "a b"))
(re-search-forward "\\(a\\) \\(b\\)")
(cons (match-string 1)
(match-string 2)))
;; trying to do something like the following
(with-temp-buffer
(save-excursion (insert "a b"))
(cl-destructuring-bind (a b) (re-search-forward "\\(a\\) \\(b\\)")
(cons a b)))
I was thinking I would have to write a macro to expand matches if there isn't another way.
Here is one way: you first extend pcase to accept a new re-match pattern, with a definition such as:
(pcase-defmacro re-match (re)
"Matches a string if that string matches RE.
RE should be a regular expression (a string).
It can use the special syntax \\(?VAR: to bind a sub-match
to variable VAR. All other subgroups will be treated as shy.
Multiple uses of this macro in a single `pcase' are not optimized
together, so don't expect lex-like performance. But in order for
such optimization to be possible in some distant future, back-references
are not supported."
(let ((start 0)
(last 0)
(new-re '())
(vars '())
(gn 0))
(while (string-match "\\\\(\\(?:\\?\\([-[:alnum:]]*\\):\\)?" re start)
(setq start (match-end 0))
(let ((beg (match-beginning 0))
(name (match-string 1 re)))
;; Skip false positives, either backslash-escaped or within [...].
(when (subregexp-context-p re start last)
(cond
((null name)
(push (concat (substring re last beg) "\\(?:") new-re))
((string-match "\\`[0-9]" name)
(error "Variable can't start with a digit: %S" name))
(t
(let* ((var (intern name))
(id (cdr (assq var vars))))
(unless id
(setq gn (1+ gn))
(setq id gn)
(push (cons var gn) vars))
(push (concat (substring re last beg) (format "\\(?%d:" id))
new-re))))
(setq last start))))
(push (substring re last) new-re)
(setq new-re (mapconcat #'identity (nreverse new-re) ""))
`(and (pred stringp)
(app (lambda (s)
(save-match-data
(when (string-match ,new-re s)
(vector ,#(mapcar (lambda (x) `(match-string ,(cdr x) s))
vars)))))
(,'\` [,#(mapcar (lambda (x) (list '\, (car x))) vars)])))))
and once that is done, you can use it as follows:
(pcase X
((re-match "\\(?var:[[:alpha:]]*\\)=\\(?val:.*\\)")
(cons var val)))
or
(pcase-let
(((re-match "\\(?var:[[:alpha:]]*\\)=\\(?val:.*\\)") X))
(cons var val))
This has not been heavily tested, and as mentioned in the docstring it doesn't work as efficiently as it (c|sh)ould when matching a string against various regexps at the same time. Also you only get the matched substrings, not their position. And finally, it applies the regexp search to a string, whereas in manny/most cases regexps searches are used in a buffer. But you may still find it useful.
I'm trying to add source blocks to the visibility cycling tree. Essentially I want a source block to be treated as a child of its heading. Consider the following org-mode document:
* Heading 1
** Heading 2
#+BEGIN_SRC R
print("hello world")
#+END_SRC
** Heading 3
I would like to be able to press TAB on heading one to cycle through the folding of the various parts including the source block. Currently org-mode does seem to have the facilities for folding the source block, because I can fold that if I go to #+BEGIN_SRC R and hit tab, but it doesnt seem to be being treated in the global cycling. Any suggestions to add it?
Thanks!
This is a slight modification of the code contained in the link mentioned in my first comment above: https://stackoverflow.com/a/21594242/2112489
All I did was replace the begin / end html regexp for the SRC regexp. Go ahead and give it a whirl and see if it is what you're looking for. I left my prior footnote modification in there.
(require 'org)
(defalias 'org-cycle-hide-drawers 'lawlist-block-org-cycle-hide-drawers)
(defun lawlist-block-org-cycle-hide-drawers (state)
"Re-hide all drawers, footnotes or html blocks after a visibility state change."
(when
(and
(derived-mode-p 'org-mode)
(not (memq state '(overview folded contents))))
(save-excursion
(let* (
(globalp (memq state '(contents all)))
(beg (if globalp (point-min) (point)))
(end
(cond
(globalp
(point-max))
((eq state 'children)
(save-excursion (outline-next-heading) (point)))
(t (org-end-of-subtree t)) )))
(goto-char beg)
(while
(re-search-forward
".*\\[fn\\|^\\#\\+BEGIN_SRC.*$\\|^[ \t]*:PROPERTIES:[ \t]*$" end t)
(lawlist-org-flag t))))))
(defalias 'org-cycle-internal-local 'lawlist-block-org-cycle-internal-local)
(defun lawlist-block-org-cycle-internal-local ()
"Do the local cycling action."
(let ((goal-column 0) eoh eol eos has-children children-skipped struct)
(save-excursion
(if (org-at-item-p)
(progn
(beginning-of-line)
(setq struct (org-list-struct))
(setq eoh (point-at-eol))
(setq eos (org-list-get-item-end-before-blank (point) struct))
(setq has-children (org-list-has-child-p (point) struct)))
(org-back-to-heading)
(setq eoh (save-excursion (outline-end-of-heading) (point)))
(setq eos (save-excursion (1- (org-end-of-subtree t t))))
(setq has-children
(or
(save-excursion
(let ((level (funcall outline-level)))
(outline-next-heading)
(and
(org-at-heading-p t)
(> (funcall outline-level) level))))
(save-excursion
(org-list-search-forward (org-item-beginning-re) eos t)))))
(beginning-of-line 2)
(if (featurep 'xemacs)
(while
(and
(not (eobp))
(get-char-property (1- (point)) 'invisible))
(beginning-of-line 2))
(while
(and
(not (eobp))
(get-char-property (1- (point)) 'invisible))
(goto-char (next-single-char-property-change (point) 'invisible))
(and
(eolp)
(beginning-of-line 2))))
(setq eol (point)))
(cond
((= eos eoh)
(unless (org-before-first-heading-p)
(run-hook-with-args 'org-pre-cycle-hook 'empty))
(org-unlogged-message "EMPTY ENTRY")
(setq org-cycle-subtree-status nil)
(save-excursion
(goto-char eos)
(outline-next-heading)
(if (outline-invisible-p)
(org-flag-heading nil))))
((and
(or
(>= eol eos)
(not (string-match "\\S-" (buffer-substring eol eos))))
(or
has-children
(not (setq children-skipped
org-cycle-skip-children-state-if-no-children))))
(unless (org-before-first-heading-p)
(run-hook-with-args 'org-pre-cycle-hook 'children))
(if (org-at-item-p)
;; then
(org-list-set-item-visibility (point-at-bol) struct 'children)
;; else
(org-show-entry)
(org-with-limited-levels (show-children))
(when (eq org-cycle-include-plain-lists 'integrate)
(save-excursion
(org-back-to-heading)
(while (org-list-search-forward (org-item-beginning-re) eos t)
(beginning-of-line 1)
(let* (
(struct (org-list-struct))
(prevs (org-list-prevs-alist struct))
(end (org-list-get-bottom-point struct)))
(mapc (lambda (e) (org-list-set-item-visibility e struct 'folded))
(org-list-get-all-items (point) struct prevs))
(goto-char (if (< end eos) end eos)))))))
(org-unlogged-message "CHILDREN")
(save-excursion
(goto-char eos)
(outline-next-heading)
(if (outline-invisible-p)
(org-flag-heading nil)))
(setq org-cycle-subtree-status 'children)
(unless (org-before-first-heading-p)
(run-hook-with-args 'org-cycle-hook 'children)))
((or
children-skipped
(and
(eq last-command this-command)
(eq org-cycle-subtree-status 'children)))
(unless (org-before-first-heading-p)
(run-hook-with-args 'org-pre-cycle-hook 'subtree))
(outline-flag-region eoh eos nil)
(org-unlogged-message
(if children-skipped
"SUBTREE (NO CHILDREN)"
"SUBTREE"))
(setq org-cycle-subtree-status 'subtree)
(unless (org-before-first-heading-p)
(run-hook-with-args 'org-cycle-hook 'subtree)))
((eq org-cycle-subtree-status 'subtree)
(org-show-subtree)
(message "ALL")
(setq org-cycle-subtree-status 'all))
(t
(run-hook-with-args 'org-pre-cycle-hook 'folded)
(outline-flag-region eoh eos t)
(org-unlogged-message "FOLDED")
(setq org-cycle-subtree-status 'folded)
(unless (org-before-first-heading-p)
(run-hook-with-args 'org-cycle-hook 'folded))))))
(defun lawlist-org-flag (flag)
"When FLAG is non-nil, hide any of the following: html code block;
footnote; or, the properties drawer. Otherwise make it visible."
(save-excursion
(beginning-of-line 1)
(cond
((looking-at ".*\\[fn")
(let* (
(begin (match-end 0))
end-footnote)
(if (re-search-forward "\\]"
(save-excursion (outline-next-heading) (point)) t)
(progn
(setq end-footnote (point))
(outline-flag-region begin end-footnote flag))
(user-error "Error beginning at point %s." begin))))
((looking-at "^\\#\\+BEGIN_SRC.*$\\|^[ \t]*:PROPERTIES:[ \t]*$")
(let* ((begin (match-end 0)))
(if (re-search-forward "^\\#\\+END_SRC.*$\\|^[ \t]*:END:"
(save-excursion (outline-next-heading) (point)) t)
(outline-flag-region begin (point-at-eol) flag)
(user-error "Error beginning at point %s." begin)))))))
(defun lawlist-toggle-block-visibility ()
"For this function to work, the cursor must be on the same line as the regexp."
(interactive)
(if
(save-excursion
(beginning-of-line 1)
(looking-at
".*\\[fn\\|^\\#\\+BEGIN_SRC.*$\\|^[ \t]*:PROPERTIES:[ \t]*$"))
(lawlist-org-flag (not (get-char-property (match-end 0) 'invisible)))
(message "Sorry, you are not on a line containing the beginning regexp.")))
I'm writing a minor mode for emacs which, at the very least, will calculate a numeric value for each line in a buffer. I want to display this visually, preferable neatly before each line.
I know some minor modes draw to the fringe, and I know overlays are an option too (are these related?), but I can't find a good example of what I want anywhere.
Basically, I want to have something like the line numbers from linum-mode, but they will need to change every time the buffer is modified (actually, only whenever the line they're on changes). Something like a character counter for each line would be a good example. And I'd like it to not break linum-mode, but not depend on it, etc, if possible.
Here is a quick example of one way to put an overlay after linum-mode numbers and before the line of text. I will need to give some thought about right-alignment of the character count.
NOTE: This method contemplates that the linum-mode numbers are generated before the code that follows in this example. If the post-command-hook or the widow-scroll-functions hook is used to implement this proposed method, then those additions to the hooks would need to follow in time subsequently to the linum-mode functions attached to those same hooks.
The following example could be implemented with the post-command-hook and the window-scroll-functions hook. See the following link for an example of how to determine window-start and window-end before a redisplay occurs: https://stackoverflow.com/a/24216247/2112489
EDIT: Added right-alignment of character count -- contemplates a maximum of three digits (i.e., up to 999 characters per line). The text after the character count overlays are now left-aligned.
(save-excursion
(let* (
(window-start (window-start))
(window-end (window-end)))
(goto-char window-end)
(while (re-search-backward "\n" window-start t)
(let* (
(pbol (point-at-bol))
(peol (point-at-eol))
(raw-char-count (abs (- peol pbol)))
(starting-column
(propertize (char-to-string ?\uE001)
'display
`((space :align-to 1)
(space :width 0))))
(colored-char-count
(propertize (number-to-string raw-char-count)
'face '(:background "gray50" :foreground "black")
'cursor t))
(one-spacer
(propertize (char-to-string ?\uE001)
'display
`((space :width 1))))
(two-spacers
(propertize (char-to-string ?\uE001)
'display
`((space :width 2))))
(final-char-count
(cond
((and
(< raw-char-count 100)
(> raw-char-count 9))
(concat one-spacer colored-char-count))
((< raw-char-count 10)
(concat two-spacers colored-char-count))
(t colored-char-count))) )
(overlay-put (make-overlay pbol pbol)
'before-string
(concat starting-column final-char-count two-spacers) )))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; M-x char-count-mode
(defvar char-count-p nil
"When `char-count-p` is non-`nil`, the overlays are present.")
(make-variable-buffer-local 'char-count-p)
(defvar char-count-this-command nil
"This local variable is set within the `post-command-hook`; and,
is also used by the `window-scroll-functions` hook.")
(make-variable-buffer-local 'char-count-this-command)
(defvar char-count-overlay-list nil
"List used to store overlays until they are removed.")
(make-variable-buffer-local 'char-count-overlay-list)
(defun char-count-post-command-hook ()
"Doc-string."
(setq char-count-this-command this-command)
(character-count-function))
(defun character-count-window-scroll-functions (win _start)
"Doc-string."
(character-count-function))
(defun equal-including-properties--remove-overlays (beg end name val)
"Remove the overlays using `equal`, instead of `eq`."
(when (and beg end name val)
(overlay-recenter end)
(dolist (o (overlays-in beg end))
(when (equal-including-properties (overlay-get o name) val)
(delete-overlay o)))))
(defun character-count-function ()
"Doc-string for the character-count-function."
(when
(and
char-count-mode
char-count-this-command
(window-live-p (get-buffer-window (current-buffer)))
(not (minibufferp))
(pos-visible-in-window-p (point)
(get-buffer-window (current-buffer) (selected-frame)) t) )
(remove-char-count-overlays)
(save-excursion
(let* (
counter
(selected-window (selected-window))
(window-start (window-start selected-window))
(window-end (window-end selected-window t)) )
(goto-char window-end)
(catch 'done
(while t
(when counter
(re-search-backward "\n" window-start t))
(when (not counter)
(setq counter t))
(let* (
(pbol (point-at-bol))
(peol (point-at-eol))
(raw-char-count (abs (- peol pbol)))
(starting-column
(propertize (char-to-string ?\uE001)
'display
`((space :align-to 1) (space :width 0))))
(colored-char-count
(propertize (number-to-string raw-char-count)
'face '(:background "gray50" :foreground "black")))
(one-spacer
(propertize (char-to-string ?\uE001)
'display
`((space :width 1))))
(two-spacers
(propertize (char-to-string ?\uE001)
'display
`((space :width 2))))
(final-char-count
(cond
((and
(< raw-char-count 100)
(> raw-char-count 9))
(concat one-spacer colored-char-count))
((< raw-char-count 10)
(concat two-spacers colored-char-count))
(t colored-char-count)))
(ov-string (concat starting-column final-char-count two-spacers)) )
(push ov-string char-count-overlay-list)
(overlay-put (make-overlay pbol pbol) 'before-string ov-string)
(when (<= pbol window-start)
(throw 'done nil)) )))
(setq char-count-p t)))
(setq char-count-this-command nil) ))
(defun remove-char-count-overlays ()
(when char-count-p
(require 'cl)
(setq char-count-overlay-list
(remove-duplicates char-count-overlay-list
:test (lambda (x y) (or (null y) (equal-including-properties x y)))
:from-end t))
(dolist (description char-count-overlay-list)
(equal-including-properties--remove-overlays (point-min) (point-max) 'before-string description))
(setq char-count-p nil) ))
(defun turn-off-char-count-mode ()
(char-count-mode -1))
(define-minor-mode char-count-mode
"A minor-mode that places the character count at the beginning of the line."
:init-value nil
:lighter " Char-Count"
:keymap nil
:global nil
:group nil
(cond
(char-count-mode
(setq scroll-conservatively 101)
(add-hook 'post-command-hook 'char-count-post-command-hook t t)
(add-hook 'window-scroll-functions
'character-count-window-scroll-functions t t)
(add-hook 'change-major-mode-hook 'turn-off-char-count-mode nil t)
(message "Turned ON `char-count-mode`."))
(t
(remove-char-count-overlays)
(remove-hook 'post-command-hook 'char-count-post-command-hook t)
(remove-hook 'window-scroll-functions
'character-count-window-scroll-functions t)
(remove-hook 'change-major-mode-hook 'turn-off-char-count-mode t)
(kill-local-variable 'scroll-conservatively)
(message "Turned OFF `char-count-mode`.") )))
(provide 'char-count)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
I'd like to be able to toggle the case of the letter under the point. To that end, I wrote this:
(defun toggle-case-next-letter ()
"Toggles the case of the next letter, then moves the point forward one character"
(interactive)
(let* ((p (point))
(upcased (upcasep (char-after)))
(f (if upcased 'downcase-region 'upcase-region)))
(progn
(f p (+ 1 p))
(forward-char))))
However, when I run it (I've bound it to M-#), I get progn: Symbol's function definition is void: f. I assume this means f isn't bound, but I'm not sure.
Upcasep is defined as:
(defun upcasep (c) (eq c (upcase c)))
Is the problem in the let binding, or something else? (Also, if there's a better way to do this, that'd be nice as well).
Note that originally I had (upcased (upcasep (buffer-substring-no-properties p (+ 1 p)))), which I've corrected to (upcased (upcasep (char-after)), because using upcasep as defined above is always nil for strings (so I couldn't downcase again).
You've got a typical case of lisp-1 / lisp-2 confusion. Here's a fix (just a funcall):
(defun toggle-case-next-letter ()
"Toggles the case of the next letter, then moves the point forward one character"
(interactive)
(let* ((p (point))
(upcased (char-upcasep (buffer-substring-no-properties p (+ 1 p))))
(f (if upcased 'downcase-region 'upcase-region)))
(progn
(funcall f p (+ 1 p))
(forward-char))))
And here's what I have:
(global-set-key (kbd "C->") 'upcase-word-toggle)
(global-set-key (kbd "C-z") 'capitalize-word-toggle)
(defun char-upcasep (letter)
(eq letter (upcase letter)))
(defun capitalize-word-toggle ()
(interactive)
(let ((start (car
(save-excursion
(backward-word)
(bounds-of-thing-at-point 'symbol)))))
(if start
(save-excursion
(goto-char start)
(funcall
(if (char-upcasep (char-after))
'downcase-region
'upcase-region)
start (1+ start)))
(capitalize-word -1))))
(defun upcase-word-toggle ()
(interactive)
(let ((bounds (bounds-of-thing-at-point 'symbol))
beg end
regionp)
(if (eq this-command last-command)
(setq regionp (get this-command 'regionp))
(put this-command 'regionp nil))
(cond
((or (region-active-p) regionp)
(setq beg (region-beginning)
end (region-end))
(put this-command 'regionp t))
(bounds
(setq beg (car bounds)
end (cdr bounds)))
(t
(setq beg (point)
end (1+ beg))))
(save-excursion
(goto-char (1- beg))
(and (re-search-forward "[A-Za-z]" end t)
(funcall (if (char-upcasep (char-before))
'downcase-region
'upcase-region)
beg end)))))
I couldn't get #abo-abo's answer working for me but using his comments I was able to google better and found the following at http://chneukirchen.org/dotfiles/.emacs
(defun chris2-toggle-case ()
(interactive)
(let ((char (following-char)))
(if (eq char (upcase char))
(insert-char (downcase char) 1 t)
(insert-char (upcase char) 1 t)))
(delete-char 1 nil)
(backward-char))
(global-set-key (kbd "M-#") 'chris2-toggle-case)
This answers the original question if you remove (backward-char).
I realize this is a very old question, but having stumbled upon the same problem recently, I'd like to suggest a simpler solution.
I start with a pure function for toggling character case, based on char code property inspection:
(cl-defun toggle-char-case (c)
(cl-case (get-char-code-property c 'general-category)
(Lu (downcase c))
(Ll (upcase c))
(t c)))
I then use it from within an interactive function operating at point:
(cl-defun toggle-char-case-at-point ()
(interactive)
(let ((new (toggle-char-case (char-after))))
(delete-char 1)
(insert new)))
I then bound this interactive function to a keybinding of my choice:
(global-set-key (kbd "C-M-c") 'toggle-char-case-at-point)
The way this function operates is, after toggling the case it advances the point by one. So calling it repeatedly will toggle the cases of a sequence of chars. One could make it keep the point unchanged - that would require adding (backward-char) to the body.
How can I toggle the case of letters (switch uppercase letters to lowercase and lowercase letters to uppercase) of a region's text in Emacs?
There are listed commands for conversion but nothing for toggling.
Example:
PLease toggLE MY LETTER case
should become:
plEASE TOGGle my letter CASE
You can do it with a regexp substitution:
M-x replace-regexp RET
\([[:upper:]]+\)?\([[:lower:]]+\)? RET
\,(concat (downcase (or \1 "")) (upcase (or \2 ""))) RET
It's up to you to bind a key to this.
I wrote it for you; it did not have thorough testing, but it appears to do what you seek.
The logic behind it is to loop over every single character in the text. If the character is equal to the character in downcase, append it to the return string in upcase. If not, append it in downcase. At the end, delete region and insert the return string.
It works immediate on a page of text, though I'd be wary to use it on huge texts (should be fine still).
(defun toggle-case ()
(interactive)
(when (region-active-p)
(let ((i 0)
(return-string "")
(input (buffer-substring-no-properties (region-beginning) (region-end))))
(while (< i (- (region-end) (region-beginning)))
(let ((current-char (substring input i (+ i 1))))
(if (string= (substring input i (+ i 1)) (downcase (substring input i (+ i 1))))
(setq return-string
(concat return-string (upcase (substring input i (+ i 1)))))
(setq return-string
(concat return-string (downcase (substring input i (+ i 1)))))))
(setq i (+ i 1)))
(delete-region (region-beginning) (region-end))
(insert return-string))))
Commands upcase-region, downcase-region, andcapitalize-region are not toggles, and are perhaps the "conversion" commands you referred to. Here is a command that cycles among them.
(defvar cycle-region-capitalization-last 'upper)
(defun cycle-region-capitalization (&optional msgp)
"Cycle the region text among uppercase, lowercase and capitalized (title case)."
(interactive "p")
(setq cycle-region-capitalization-last
(case cycle-region-capitalization-last
(upper (call-interactively #'downcase-region) 'lower)
(lower (call-interactively #'capitalize-region) 'title)
(title (call-interactively #'upcase-region) 'upper)))
(when msgp (message "Region is now %scase" cycle-region-capitalization-last)))
If you mean letter case, then this function works nicely: http://ergoemacs.org/emacs/modernization_upcase-word.html
(defun toggle-letter-case ()
"Toggle the letter case of current word or text selection.
Toggles between: “all lower”, “Init Caps”, “ALL CAPS”."
(interactive)
(let (p1 p2 (deactivate-mark nil) (case-fold-search nil))
(if (region-active-p)
(setq p1 (region-beginning) p2 (region-end))
(let ((bds (bounds-of-thing-at-point 'word) ) )
(setq p1 (car bds) p2 (cdr bds)) ) )
(when (not (eq last-command this-command))
(save-excursion
(goto-char p1)
(cond
((looking-at "[[:lower:]][[:lower:]]") (put this-command 'state "all lower"))
((looking-at "[[:upper:]][[:upper:]]") (put this-command 'state "all caps") )
((looking-at "[[:upper:]][[:lower:]]") (put this-command 'state "init caps") )
((looking-at "[[:lower:]]") (put this-command 'state "all lower"))
((looking-at "[[:upper:]]") (put this-command 'state "all caps") )
(t (put this-command 'state "all lower") ) ) ) )
(cond
((string= "all lower" (get this-command 'state))
(upcase-initials-region p1 p2) (put this-command 'state "init caps"))
((string= "init caps" (get this-command 'state))
(upcase-region p1 p2) (put this-command 'state "all caps"))
((string= "all caps" (get this-command 'state))
(downcase-region p1 p2) (put this-command 'state "all lower")) )
) )
I liked the other answer's technique of comparing this-command and last-command,
so I've incorporated it into my old function. Here's the result:
(defun upcase-word-toggle ()
(interactive)
(let ((bounds (bounds-of-thing-at-point 'symbol))
beg end
regionp)
(if (eq this-command last-command)
(setq regionp (get this-command 'regionp))
(put this-command 'regionp nil))
(cond
((or (region-active-p) regionp)
(setq beg (region-beginning)
end (region-end))
(put this-command 'regionp t))
(bounds
(setq beg (car bounds)
end (cdr bounds)))
(t
(setq beg (point)
end (1+ beg))))
(save-excursion
(goto-char (1- beg))
(and (re-search-forward "[A-Za-z]" end t)
(funcall (if (char-upcasep (char-after))
'downcase-region
'upcase-region)
beg end)))))
(defun char-upcasep (letter)
(eq letter (upcase letter)))
(global-set-key (kbd "C->") 'upcase-word-toggle)