Dear Nicolas Goaziou, Apparently my previous email was again refused by your mail server (I tried to add patch as attachment this time).
The patch is in https://gist.github.com/yantar92/6447754415457927293acda43a7fcaef This patch is actually one commit ahead of the patch in the email, fixing an issue when change function throws an error. I wrapped the call into with-demoted-errors to avoid potential data loss on error in future. Best, Ihor Ihor Radchenko <yanta...@gmail.com> writes: > Hi, > > [All the changes below are relative to commit ed0e75d24. Later commits > make it hard to distinguish between hidden headlines and drawers. I will > need to figure out a way to merge this branch with master. It does not > seem to be trivial.] > > I have finished a seemingly stable implementation of handling changes > inside drawer and block elements. For now, I did not bother with > 'modification-hooks and 'insert-in-font/behind-hooks, but simply used > before/after-change-functions. > > The basic idea is saving parsed org-elements before the modification > (with :begin and :end replaced by markers) and comparing them with the > versions of the same elements after the modification. > Any valid org element can be examined in such way by an arbitrary > function (see org-track-modification-elements) [1]. > > For now, I have implemented tracking changes in all the drawer and block > elements. If the contents of an element is changed and the element is > hidden, the contents remains hidden unless the change was done with > self-insert-command. If the begin/end line of the element was changed in > the way that the element changes the type or extends/shrinks, the > element contents is revealed. To illustrate: > > Case #1 (the element content is hidden): > > :PROPERTIES: > :ID: 279e797c-f4a7-47bb-80f6-e72ac6f3ec55 > :END: > > is changed to > > :ROPERTIES: > :ID: 279e797c-f4a7-47bb-80f6-e72ac6f3ec55 > :END: > > Text is revealed, because we have drawer in place of property-drawer > > Case #2 (the element content is hidden): > > :ROPERTIES: > :ID: 279e797c-f4a7-47bb-80f6-e72ac6f3ec55 > :END: > > is changed to > > :OPERTIES: > :ID: 279e797c-f4a7-47bb-80f6-e72ac6f3ec55 > :END: > > The text remains hidden since it is still a drawer. > > Case #3: (the element content is hidden): > > :FOO: > bar > tmp > :END: > > is changed to > > :FOO: > bar > :END: > tmp > :END: > > The text is revealed because the drawer contents shrank. > > Case #4: (the element content is hidden in both the drawers): > > :FOO: > bar > tmp > :END: > :BAR: > jjd > :END: > > is changed to > > :FOO: > bar > tmp > :BAR: > jjd > :END: > > The text is revealed in both the drawers because the drawers are merged > into a new drawer. > >> However, I think we can do better than that, and also fix the glitches >> from overlays. Here are two of them. Write the following drawer: >> >> :FOO: >> bar >> :END: >> >> fold it and delete the ":f". The overlay is still there, and you cannot >> remove it with TAB any more. Or, with the same initial drawer, from >> beginning of buffer, evaluate: >> >> (progn (re-search-forward ":END:") (replace-match "")) >> >> This is no longer a drawer: you just removed its closing line. Yet, the >> overlay is still there, and TAB is ineffective. > > I think the above examples cover what you described. > > Case #5 (the element content is hidden, point at <!>): > > :FOO:<!> > bar > tmp > :END: > > is changed (via self-insert-command) to > > :FOO:a<!> > bar > tmp > :END: > > The text is revealed. > > This last case sounds logical and might potentially replace > org-catch-invisible-edits. > > ------------------------------------------------------------------------ > > Some potential issues with the implementation: > > 1. org--after-element-change-function can called many times even for > trivial operations. For example (insert "\n" ":TEST:") seems to call it > two times already. This has two implications: (1) potential performance > degradation; (2) org-element library may not be able to parse the > changed element because its intermediate modified state may not match > the element syntax. Specifically, inserting new property into > :PROPERTIES: drawer inserts a newline at some point, which makes > org-element-at-point think that it is not a 'property-drawer, but just > 'drawer. > > For (1), I did not really do any workaround for now. One potential way > is making use of combine-after-change-calls (info:elisp#Change Hooks). > At least, within org source code. > > For (2), I have introduced org--property-drawer-modified-re to override > org-property-drawer-re in relevant *-change-function. This seems to work > for property drawers. However, I am not sure if similar problem may > happen in some border cases with ordinary drawers or blocks. > > 2. I have noticed that results of org-element-at-point and > org-element-parse-buffer are not always consistent. > In my tests, they returned different number of empty lines after drawers > (:post-blank and :end properties). I am not sure here if I did something > wrong in the code or if it is a real issue in org-element. > > For now, I simply called org-element-at-point with point at :begin > property of all the elements returned by org-element-parse buffer to > make things consistent. This indeed introduced overhead, but I do not > see other way to solve the inconsistency. > > 3. This implementation did not directly solve the previously observed > issue with two ellipsis displayed in folded drawer after adding hidden > text inside: > > :PROPERTY: ... --> :PROPERTY: ... ... > > For now, I just did > > (org-hide-drawer-toggle 'off) > (org-hide-drawer-toggle 'hide) > > to hide the second ellipsis, but I still don't understand why it is > happening. Is it some Emacs bug? I am not sure. > > 4. For some reason, before/after-change-functions do not seem to trigger > when adding note after todo state change. > > ------------------------------------------------------------------------ > > Further plans: > > 1. Investigate the issue with log notes. > 2. Try to change headings to use text properties as well. > > The current version of the patch (relative to commit ed0e75d24) is > attached. > > ------------------------------------------------------------------------ > > P.S. I have noticed an issue with hidden text on master (9bc0cc7fb) with > my personal config: > > For the following .org file: > > * TODO b > :PROPERTIES: > :CREATED: [2020-05-17 Sun 22:37] > :END: > > folded to > > * TODO b... > > Changing todo to DONE will be shown as > > * DONE b > CLOSED: [2020-05-17 Sun 22:54]...:LOGBOOK:... > > ------------------------------------------------------------------------ > > [1] If one wants to track changes in two elements types, where one is > always inside the other, it is not possible now. > > Best, > Ihor > > diff --git a/lisp/org-macs.el b/lisp/org-macs.el > index a02f713ca..4b0e23f6a 100644 > --- a/lisp/org-macs.el > +++ b/lisp/org-macs.el > @@ -682,7 +682,7 @@ When NEXT is non-nil, check the next line instead." > > > > -;;; Overlays > +;;; Overlays and text properties > > (defun org-overlay-display (ovl text &optional face evap) > "Make overlay OVL display TEXT with face FACE." > @@ -705,18 +705,44 @@ If DELETE is non-nil, delete all those overlays." > (delete (delete-overlay ov)) > (t (push ov found)))))) > > +(defun org--find-text-property-region (pos prop) > + "Find a region containing PROP text property around point POS." > + (let* ((beg (and (get-text-property pos prop) pos)) > + (end beg)) > + (when beg > + ;; when beg is the first point in the region, > `previous-single-property-change' > + ;; will return nil. > + (setq beg (or (previous-single-property-change pos prop) > + beg)) > + ;; when end is the last point in the region, > `next-single-property-change' > + ;; will return nil. > + (setq end (or (next-single-property-change pos prop) > + end)) > + (unless (= beg end) ; this should not happen > + (cons beg end))))) > + > (defun org-flag-region (from to flag spec) > "Hide or show lines from FROM to TO, according to FLAG. > SPEC is the invisibility spec, as a symbol." > - (remove-overlays from to 'invisible spec) > - ;; Use `front-advance' since text right before to the beginning of > - ;; the overlay belongs to the visible line than to the contents. > - (when flag > - (let ((o (make-overlay from to nil 'front-advance))) > - (overlay-put o 'evaporate t) > - (overlay-put o 'invisible spec) > - (overlay-put o 'isearch-open-invisible #'delete-overlay)))) > - > + (pcase spec > + ('outline > + (remove-overlays from to 'invisible spec) > + ;; Use `front-advance' since text right before to the beginning of > + ;; the overlay belongs to the visible line than to the contents. > + (when flag > + (let ((o (make-overlay from to nil 'front-advance))) > + (overlay-put o 'evaporate t) > + (overlay-put o 'invisible spec) > + (overlay-put o 'isearch-open-invisible #'delete-overlay)))) > + (_ > + ;; Use text properties instead of overlays for speed. > + ;; Overlays are too slow (Emacs Bug#35453). > + (with-silent-modifications > + (remove-text-properties from to '(invisible nil)) > + (when flag > + (put-text-property from to 'rear-non-sticky nil) > + (put-text-property from to 'front-sticky t) > + (put-text-property from to 'invisible spec)))))) > > > ;;; Regexp matching > diff --git a/lisp/org.el b/lisp/org.el > index 96e7384f3..1bf90edae 100644 > --- a/lisp/org.el > +++ b/lisp/org.el > @@ -114,6 +114,7 @@ Stars are put in group 1 and the trimmed body in group > 2.") > (declare-function cdlatex-math-symbol "ext:cdlatex") > (declare-function Info-goto-node "info" (nodename &optional fork > strict-case)) > (declare-function isearch-no-upper-case-p "isearch" (string regexp-flag)) > +(declare-function isearch-filter-visible "isearch" (beg end)) > (declare-function org-add-archive-files "org-archive" (files)) > (declare-function org-agenda-entry-get-agenda-timestamp "org-agenda" (pom)) > (declare-function org-agenda-list "org-agenda" (&optional arg start-day span > with-hour)) > @@ -192,6 +193,9 @@ Stars are put in group 1 and the trimmed body in group > 2.") > > (defvar ffap-url-regexp) > (defvar org-element-paragraph-separate) > +(defvar org-element-all-objects) > +(defvar org-element-all-elements) > +(defvar org-element-greater-elements) > (defvar org-indent-indentation-per-level) > (defvar org-radio-target-regexp) > (defvar org-target-link-regexp) > @@ -4737,6 +4741,153 @@ This is for getting out of special buffers like > capture.") > (defun org-before-change-function (_beg _end) > "Every change indicates that a table might need an update." > (setq org-table-may-need-update t)) > + > +(defvar-local org--modified-elements nil > + "List of unmodified versions of recently modified elements. > + > +The :begin and :end element properties contain markers instead of > positions.") > + > +(defvar org--property-drawer-modified-re (concat (replace-regexp-in-string > "\\$$" "\n" org-property-start-re) > + "\\(?:.*\n\\)*?" > + (replace-regexp-in-string > "^\\^" "" org-property-end-re)) > + "Matches entire property drawer, including its state during modification. > + > +This should be different from `org-property-drawer-re' because > +property drawer may contain empty or incomplete lines in the middle of > +modification.") > + > +(defun org--drawer-or-block-change-function (el) > + "Update visibility of changed drawer/block EL. > + > +If text was added to hidden drawer/block, > +make sure that the text is also hidden, unless > +the change was done by `self-insert-command'. > +If the modification destroyed the drawer/block, > +reveal the hidden text in former drawer/block." > + (save-match-data > + (save-excursion > + (save-restriction > + (goto-char (org-element-property :begin el)) > + (let* ((newel (org-element-at-point)) > + (spec (if (string-match-p "block" (symbol-name > (org-element-type el))) > + 'org-hide-block > + (if (string-match-p "drawer" (symbol-name > (org-element-type el))) > + 'org-hide-drawer > + t)))) > + (if (and (equal (org-element-type el) (org-element-type newel)) > + (equal (marker-position (org-element-property :begin el)) > + (org-element-property :begin newel)) > + (equal (marker-position (org-element-property :end el)) > + (org-element-property :end newel))) > + (when (text-property-any (marker-position (org-element-property > :begin el)) > + (marker-position (org-element-property > :end el)) > + 'invisible spec) > + (if (memq this-command '(self-insert-command)) > + ;; reveal if change was made by typing > + (org-hide-drawer-toggle 'off) > + ;; re-hide the inserted text > + ;; FIXME: opening the drawer before hiding should not be > needed here > + (org-hide-drawer-toggle 'off) ; this is needed to avoid > showing double ellipsis > + (org-hide-drawer-toggle 'hide))) > + ;; The element was destroyed. Reveal everything. > + (org-flag-region (marker-position (org-element-property :begin > el)) > + (marker-position (org-element-property :end el)) > + nil spec) > + (org-flag-region (org-element-property :begin newel) > + (org-element-property :end newel) > + nil spec))))))) > + > +(defvar org-track-modification-elements (list (cons 'center-block > #'org--drawer-or-block-change-function) > + (cons 'drawer > #'org--drawer-or-block-change-function) > + (cons 'dynamic-block > #'org--drawer-or-block-change-function) > + (cons 'property-drawer > #'org--drawer-or-block-change-function) > + (cons 'quote-block > #'org--drawer-or-block-change-function) > + (cons 'special-block > #'org--drawer-or-block-change-function)) > + "Alist of elements to be tracked for modifications. > +Each element of the alist is a cons of an element from > +`org-element-all-elements' and the function used to handle the > +modification. > +The function must accept a single argument - parsed element before > +modificatin with :begin and :end properties containing markers.") > + > +(defun org--find-elements-in-region (beg end elements &optional > include-partial) > + "Find all elements from ELEMENTS list in region BEG . END. > +All the listed elements must be resolvable by `org-element-at-point'. > +Include elements if they are partially inside region when INCLUDE-PARTIAL is > non-nil." > + (when include-partial > + (org-with-point-at beg > + (when-let ((new-beg (org-element-property :begin > + (org-element-lineage > (org-element-at-point) > + elements > + 'with-self)))) > + (setq beg new-beg)) > + (when (memq 'headline elements) > + (when-let ((new-beg (ignore-error user-error (org-back-to-heading > 'include-invisible)))) > + (setq beg new-beg)))) > + (org-with-point-at end > + (when-let ((new-end (org-element-property :end > + (org-element-lineage > (org-element-at-point) > + elements > + 'with-self)))) > + (setq end new-end)) > + (when (memq 'headline elements) > + (when-let ((new-end (org-with-limited-levels (outline-next-heading)))) > + (setq end (1- new-end)))))) > + (save-excursion > + (save-restriction > + (narrow-to-region beg end) > + (let (has-object has-element has-greater-element granularity) > + (dolist (el elements) > + (when (memq el org-element-all-objects) (setq has-object t)) > + (when (memq el org-element-all-elements) (setq has-element t)) > + (when (memq el org-element-greater-elements) (setq > has-greater-element t))) > + (if has-object > + (setq granularity 'object) > + (if has-greater-element > + (setq granularity 'greater-element) > + (if has-element > + (setq granularity 'element) > + (setq granularity 'headline)))) > + (org-element-map (org-element-parse-buffer granularity) elements > #'identity))))) > + > +(defun org--before-element-change-function (beg end) > + "Register upcoming element modifications in `org--modified-elements' for > all elements interesting with BEG END." > + (let ((org-property-drawer-re org--property-drawer-modified-re)) > + (save-match-data > + (save-excursion > + (save-restriction > + (dolist (el (org--find-elements-in-region beg > + end > + (mapcar #'car > org-track-modification-elements) > + 'include-partial)) > + ;; `org-element-at-point' is not consistent with results > + ;; of `org-element-parse-buffer' for :post-blank and :end > + ;; Using `org-element-at-point to keep consistent > + ;; parse results with `org--after-element-change-function' > + (let* ((el (org-with-point-at (org-element-property :begin el) > + (org-element-at-point))) > + (beg-marker (copy-marker (org-element-property :begin el) > 't)) > + (end-marker (copy-marker (org-element-property :end el) 't))) > + (when (and (marker-position beg-marker) (marker-position > end-marker)) > + (org-element-put-property el :begin beg-marker) > + (org-element-put-property el :end end-marker) > + (add-to-list 'org--modified-elements el))))))))) > + > +;; FIXME: this function may be called many times during routine modifications > +;; The normal way to avoid this is `combine-after-change-calls' - not > +;; the case in most org primitives. > +(defun org--after-element-change-function (&rest _) > + "Handle changed elements from `org--modified-elements'." > + (let ((org-property-drawer-re org--property-drawer-modified-re)) > + (dolist (el org--modified-elements) > + (save-match-data > + (save-excursion > + (save-restriction > + (let* ((type (org-element-type el)) > + (change-func (alist-get type > org-track-modification-elements))) > + (funcall (symbol-function change-func) el))))))) > + (setq org--modified-elements nil)) > + > (defvar org-mode-map) > (defvar org-inhibit-startup-visibility-stuff nil) ; Dynamically-scoped param. > (defvar org-agenda-keep-modes nil) ; Dynamically-scoped param. > @@ -4818,6 +4969,9 @@ The following commands are available: > ;; Activate before-change-function > (setq-local org-table-may-need-update t) > (add-hook 'before-change-functions 'org-before-change-function nil 'local) > + (add-hook 'before-change-functions 'org--before-element-change-function > nil 'local) > + ;; Activate after-change-function > + (add-hook 'after-change-functions 'org--after-element-change-function nil > 'local) > ;; Check for running clock before killing a buffer > (add-hook 'kill-buffer-hook 'org-check-running-clock nil 'local) > ;; Initialize macros templates. > @@ -4869,6 +5023,10 @@ The following commands are available: > (setq-local outline-isearch-open-invisible-function > (lambda (&rest _) (org-show-context 'isearch))) > > + ;; Make isearch search in blocks hidden via text properties > + (setq-local isearch-filter-predicate #'org--isearch-filter-predicate) > + (add-hook 'isearch-mode-end-hook #'org--clear-isearch-overlays nil 'local) > + > ;; Setup the pcomplete hooks > (setq-local pcomplete-command-completion-function #'org-pcomplete-initial) > (setq-local pcomplete-command-name-function #'org-command-at-point) > @@ -5859,9 +6017,26 @@ If TAG is a number, get the corresponding match group." > (inhibit-modification-hooks t) > deactivate-mark buffer-file-name buffer-file-truename) > (decompose-region beg end) > + ;; do not remove invisible text properties specified by > + ;; 'org-hide-block and 'org-hide-drawer (but remove 'org-link) > + ;; this is needed to keep the drawers and blocks hidden unless > + ;; they are toggled by user > + ;; Note: The below may be too specific and create troubles > + ;; if more invisibility specs are added to org in future > + (let ((pos beg) > + next spec) > + (while (< pos end) > + (setq next (next-single-property-change pos 'invisible nil end) > + spec (get-text-property pos 'invisible)) > + (unless (memq spec (list 'org-hide-block > + 'org-hide-drawer)) > + (remove-text-properties pos next '(invisible t))) > + (setq pos next))) > (remove-text-properties beg end > '(mouse-face t keymap t org-linked-text t > - invisible t intangible t > + ;; Do not remove all invisible during > fontification > + ;; invisible t > + intangible t > org-emphasis t)) > (org-remove-font-lock-display-properties beg end))) > > @@ -6666,8 +6841,13 @@ information." > ;; expose it. > (dolist (o (overlays-at (point))) > (when (memq (overlay-get o 'invisible) > - '(org-hide-block org-hide-drawer outline)) > + '(outline)) > (delete-overlay o))) > + (when (memq (get-text-property (point) 'invisible) > + '(org-hide-block org-hide-drawer)) > + (let ((spec (get-text-property (point) 'invisible)) > + (region (org--find-text-property-region (point) 'invisible))) > + (org-flag-region (car region) (cdr region) nil spec))) > (unless (org-before-first-heading-p) > (org-with-limited-levels > (cl-case detail > @@ -20902,6 +21082,79 @@ Started from `gnus-info-find-node'." > (t default-org-info-node)))))) > > > + > +;;; Make isearch search in some text hidden via text propertoes > + > +(defvar org--isearch-overlays nil > + "List of overlays temporarily created during isearch. > +This is used to allow searching in regions hidden via text properties. > +As for [2020-05-09 Sat], Isearch only has special handling of hidden > overlays. > +Any text hidden via text properties is not revealed even if > `search-invisible' > +is set to 't.") > + > +;; Not sure if it needs to be a user option > +;; One might want to reveal hidden text in, for example, hidden parts of the > links. > +;; Currently, hidden text in links is never revealed by isearch. > +(defvar org-isearch-specs '(org-hide-block > + org-hide-drawer) > + "List of text invisibility specs to be searched by isearch. > +By default ([2020-05-09 Sat]), isearch does not search in hidden text, > +which was made invisible using text properties. Isearch will be forced > +to search in hidden text with any of the listed 'invisible property value.") > + > +(defun org--create-isearch-overlays (beg end) > + "Replace text property invisibility spec by overlays between BEG and END. > +All the regions with invisibility text property spec from > +`org-isearch-specs' will be changed to use overlays instead > +of text properties. The created overlays will be stored in > +`org--isearch-overlays'." > + (let ((pos beg)) > + (while (< pos end) > + (when-let* ((spec (get-text-property pos 'invisible)) > + (spec (memq spec org-isearch-specs)) > + (region (org--find-text-property-region pos 'invisible))) > + ;; Changing text properties is considered buffer modification. > + ;; We do not want it here. > + (with-silent-modifications > + ;; The overlay is modelled after `org-flag-region' [2020-05-09 Sat] > + ;; overlay for 'outline blocks. > + (let ((o (make-overlay (car region) (cdr region) nil > 'front-advance))) > + (overlay-put o 'evaporate t) > + (overlay-put o 'invisible spec) > + ;; `delete-overlay' here means that spec information will be lost > + ;; for the region. The region will remain visible. > + (overlay-put o 'isearch-open-invisible #'delete-overlay) > + (push o org--isearch-overlays)) > + (remove-text-properties (car region) (cdr region) '(invisible nil)))) > + (setq pos (next-single-property-change pos 'invisible nil end))))) > + > +(defun org--isearch-filter-predicate (beg end) > + "Return non-nil if text between BEG and END is deemed visible by Isearch. > +This function is intended to be used as `isearch-filter-predicate'. > +Unlike `isearch-filter-visible', make text with 'invisible text property > +value listed in `org-isearch-specs' visible to Isearch." > + (org--create-isearch-overlays beg end) ;; trick isearch by creating > overlays in place of invisible text > + (isearch-filter-visible beg end)) > + > +(defun org--clear-isearch-overlay (ov) > + "Convert OV region back into using text properties." > + (when-let ((spec (overlay-get ov 'invisible))) ;; ignore deleted overlays > + ;; Changing text properties is considered buffer modification. > + ;; We do not want it here. > + (with-silent-modifications > + (put-text-property (overlay-start ov) (overlay-end ov) 'invisible > spec))) > + (when (member ov isearch-opened-overlays) > + (setq isearch-opened-overlays (delete ov isearch-opened-overlays))) > + (delete-overlay ov)) > + > +(defun org--clear-isearch-overlays () > + "Convert overlays from `org--isearch-overlays' back into using text > properties." > + (when org--isearch-overlays > + (mapc #'org--clear-isearch-overlay org--isearch-overlays) > + (setq org--isearch-overlays nil))) > + > + > + > ;;; Finish up > > (add-hook 'org-mode-hook ;remove overlays when changing major mode > > > Nicolas Goaziou <m...@nicolasgoaziou.fr> writes: > >> Ihor Radchenko <yanta...@gmail.com> writes: >> >>> This should be better: >>> https://gist.github.com/yantar92/e37c2830d3bb6db8678b14424286c930 >> >> Thank you. >> >>> This might get tricky in the following case: >>> >>> :PROPERTIES: >>> :CREATED: [2020-04-13 Mon 22:31] >>> <region-beginning> >>> :SHOWFROMDATE: 2020-05-11 >>> :ID: e05e3b33-71ba-4bbc-abba-8a92c565ad34 >>> :END: >>> >>> <many subtrees in between> >>> >>> :PROPERTIES: >>> :CREATED: [2020-04-27 Mon 13:50] >>> <region-end> >>> :ID: b2eef49f-1c5c-4ff1-8e10-80423c8d8532 >>> :ATTACH_DIR_INHERIT: t >>> :END: >>> >>> If the text in the region is replaced by something else, <many subtrees >>> in between> should not be fully hidden. We cannot simply look at the >>> 'invisible property before and after the changed region. >> >> Be careful: "replaced by something else" is ambiguous. "Replacing" is an >> unlikely change: you would need to do >> >> (setf (buffer-substring x y) "foo") >> >> We can safely assume this will not happen. If it does, we can accept the >> subsequent glitch. >> >> Anyway it is less confusing to think in terms of deletion and insertion. >> In the case above, you probably mean "the region is deleted then >> something else is inserted", or the other way. So there are two actions >> going on, i.e., `after-change-functions' are called twice. >> >> In particular the situation you foresee /cannot happen/ with an >> insertion. Text is inserted at a single point. Let's assume this is in >> the first drawer. Once inserted, both text before and after the new text >> were part of the same drawer. Insertion introduces other problems, >> though. More on this below. >> >> It is true the deletion can produce the situation above. But in this >> case, there is nothing to do, you just merged two drawers into a single >> one, which stays invisible. Problem solved. >> >> IOW, big changes like the one you describe are not an issue. I think the >> "check if previous and next parts match" trick gives us roughly the same >> functionality, and the same glitches, as overlays. >> >> However, I think we can do better than that, and also fix the glitches >> from overlays. Here are two of them. Write the following drawer: >> >> :FOO: >> bar >> :END: >> >> fold it and delete the ":f". The overlay is still there, and you cannot >> remove it with TAB any more. Or, with the same initial drawer, from >> beginning of buffer, evaluate: >> >> (progn (re-search-forward ":END:") (replace-match "")) >> >> This is no longer a drawer: you just removed its closing line. Yet, the >> overlay is still there, and TAB is ineffective. >> >> Here's an idea to develop that would make folding more robust, and still >> fast. >> >> Each syntactical element has a "sensitive part", a particular area that >> can change the nature of the element when it is altered. Luckily drawers >> (and blocks) are sturdy. For a drawer, there are three things to check: >> >> 1. the opening line must match org-drawer-regexp >> 2. the closing line must match org-property-end-re (case ignored) >> 3. between those, you must not insert text match org-property-end-re or >> org-outline-regexp-bol >> >> Obviously, point 3 needs not be checked during deletion. >> >> Instead of `after-change-functions', we may use `modification-hooks' for >> deletions, and `insert-behind-hooks' for insertions. For example, we >> might add modification-hooks property to both opening and closing line, >> and `insert-behind-hooks' on all the drawer. If any of the 3 points >> above is verified, we remove all properties. >> >> Note that if we can implement something robust with text properties, we >> might use them for headlines too, for another significant speed-up. >> >> WDYT? >> >>> I think that using fontification (something similar to >>> org-fontify-drawers) instead of after-change-functions should be >>> faster. >> >> I don't think it would be faster. With `after-change-functions', >> `modification-hooks' or `insert-behind-hook', we know exactly where the >> change happened. Fontification is fuzzier. It is not instantaneous >> either. >> >> It is an option only if we cannot do something fast and accurate with >> `after-change-functions', IMO. >> > > -- > Ihor Radchenko, > PhD, > Center for Advancing Materials Performance from the Nanoscale (CAMP-nano) > State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong > University, Xi'an, China > Email: yanta...@gmail.com, ihor_radche...@alumni.sutd.edu.sg -- Ihor Radchenko, PhD, Center for Advancing Materials Performance from the Nanoscale (CAMP-nano) State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China Email: yanta...@gmail.com, ihor_radche...@alumni.sutd.edu.sg
