Re: Stepping Back: A Wealth Of Completion systems Re: [ELPA] New package: vertico

[Jean Louis <bugs@gnu.support>]

* Philip Kaludercic <philipk@posteo.net> [2021-04-07 22:14]:
> Daniel Mendler <mail@daniel-mendler.de> writes:
> 
> > On 4/7/21 6:20 PM, Philip Kaludercic wrote:
> >> Well that is because imenu presents the options in the minibuffer, and
> >> you have to go through the menu step-by-step. What I'm talking about is
> >> a direct hierarchical visualisation, that should be navigable with the
> >> intuitiveness of org-mode.
> >
> > This is a bit vague. If we have a tree structure one can have some
> > tree-like visualization (like the sidebar tree browsers) or have an 
> > outline like in org-mode. But how would you actually navigate quickly?
> > Using Avy-like keys? What if the structure does not fit on the screen 
> > easily, what if there are cycles, ...?
> 
> I'm still thinking about all of this, and have to find the time to
> implement a prototype. It might make sense to have a similar approach to
> completing-read, where a variable like completing-read-function can
> change everything.
> 
> A tree-like visualisation would probably make more sense, as long as it
> can be manipulated using the keyboard. I mentioned org-mode thinking of
> the org-cycle command, and how it allows you to hide and show
> subtrees.

When selecting items in tabulated-list-mode, all of them have the ID,
but some IDs have its type of being a Set or subtree. When subtree is
choosen a new frame appears with its nodes.

Similarly, completing-read could even now browse trees, it is matter
of recognizing which item belong to a tree to immediately offer
another completing-read with the nodes of the subtree. Subtrees cannot
be selected, but those nodes or candidates which are not subtrees they
can be selected.

I am using strings with IDs like "Selection candidate [123]" and that
is how I extract the ID of the item, then I can test for it if it is a
subtree or not and offer new completing read on that.

(defun string-cut-right-square-bracket-reference (s)
  "Returns the reference within square brackets on the end of S."
  (let* ((space (string-match " " (reverse s))))
    (if space
	(let* ((id (substring (reverse s) 0 space)))
	  (if (and (string-match "\\[" id)
		   (string-match "\\]" id))
	      (replace-regexp-in-string "\\[\\\|\\]" "" (reverse id))
	    nil))
      nil)))

(string-cut-right-square-bracket-reference "Selection candidate [123]") → "123"

(setq set '(10 20))
(setq collection-data '(("Candidate A" 10)
			("Candidate B" 11)
			("Candidate C" 20)
			("Candidate D" 12)
			("Candidate E" 13)
			("Candidate D" 14)))
(setq collection-verify collection-data)

(setq collection nil)

(while collection-data
  (let ((item (pop collection-data)))
    (push (format "%s [%s]" (car item) (cadr item)) collection)))

(completing-read "Choose item: " collection) → "Candidate A [10]"

Concept is here:

(defun completing-read-tree (prompt collection)
  (while (member (string-to-number
		  (string-cut-right-square-bracket-reference
		   (completing-read "Choose: " collection)))
		 set)
    (completing-read-tree prompt collection))) ;; at this point `collection'
					       ;; would be replaced
					       ;; with collection that
					       ;; belongs to
					       ;; particular set and
					       ;; browsing trees with
					       ;; completing read goes
					       ;; deeper and deeper. A
					       ;; key would be
					       ;; required to go back.


(completing-read-tree "Choose: " collection)

-- 
Jean

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