consult-xref-history

[jdtsmith]

I saw this implemented somewhere and can't find it again. I always get lost in the xref mark stack as you jump to various definitions. It would be great to have a M-x consult-xref-history that presented the xref history stack and where you are within it, similar to consult-mark. Note that the xref--history is a cons of two stacks, backwards and forwards, and can be global or window-local.

[minad]

This should be simple to add. Both consult-mark and consult-global-mark can take a list of markers. Would it be sufficient to wrap one of those?

[jdtsmith]

I think the only difference would be indicating where you are in the stack.

[hmelman]

Probably this https://takeonrules.com/2024/06/08/adding-a-consult-function-for-visualizing-xref/

[jdtsmith]

That's the one! Thanks.

[jdtsmith]

I found myself again wishing for a consult-xref-history. This works "OK":

(defvar consult--xref-history nil
  "History for the `consult-recent-xref' results.")

(defun consult-recent-xref (&optional markers)
  "Jump to a marker in MARKERS list (defaults to `xref--history'.

The command supports preview of the currently selected marker position.
The symbol at point is added to the future history."
  (interactive)
  (consult--read
   (consult--global-mark-candidates
    (or markers (flatten-list xref--history)))
   :prompt "Go to Xref: "
   ;; :annotate (consult--line-prefix)  ;; broken
   :category 'consult-location
   :sort nil
   :require-match t
   :lookup #'consult--lookup-location
   :history '(:input consult--xref-history)
   :add-history (thing-at-point 'symbol)
   :state (consult--jump-state)))

But it has a few flaws. For some reason, random individual characters are pre-highlighted, even when nothing is entered at the prompt:

Also, it would be better if the initially selected marker were the current position in xref history not the most recent older one. Right now invoking consult-recent-xref jumps you immediately to one position prior in history.

The "current" position can be determined by the contents of xref--history, which is a compound list, à la:

(BACKWARD-STACK . FORWARD-STACK) of markers to visited Xref locations.

I.e. if BACKWARD-STACK is nil, you are at the (oldest) beginning of history. If FORWARD-STACK is nil you are at the (newest) end of xref history. Note that the current marker-position is popped off and pushed upon each xref navigation.

So I tried something like:

(defun consult-recent-xref (&optional markers)
  "Jump to a marker in MARKERS list (defaults to `xref--history'.

The command supports preview of the currently selected marker position.
The symbol at point is added to the future history."
  (interactive)
  (let* ((history (xref--get-history))
         (mrk (list (point-marker)))
         (flat (append (reverse (car history)) mrk (cdr history))))
   (consult--read
    (consult--global-mark-candidates (or markers flat))
    :prompt "Go to Xref: "
    ;; :annotate (consult--line-prefix)
    :category 'consult-location
    :default (car (consult--global-mark-candidates mrk))
    :sort nil
    :require-match t
    :lookup #'consult--lookup-location
    :history '(:input consult--xref-history)
    :add-history (thing-at-point 'symbol)
    :state (consult--jump-state))))

But this moves the "default selection" to the top (in vertico), where I'd prefer to keep it sorted as-is and have the currently selected candidate fall in its natural location. Is there a way to tell consult to lay out a series of candidates and pre-select a specific one, in place? BTW, a :default-index would be nice to have so you don't have to format your chosen candidate.

But then even with the default candidate selection solved, consult does not maintain the xref--history in the format above, it just blindly visits the markers. So perhaps a custom state function is what is needed. It could update the xref--history list upon successful return to look again like (BACKWARD-STACK . FORWARD-STACK).

[oantolin]

For some reason, random individual characters are pre-highlighted, even when nothing is entered at the prompt

Don't those indicate which point position is the one in the xref history? I think the history is of specific point locations, not merely lines.

[jdtsmith]

Oh good point, that must be right. If there's a way to select candidate N in position N I can look at implementing a state tracker to respect the backward/forward xref--history correctly. Though maybe "history with a known current position" is a generic enough concept to deserve a special state function, e.g. for winner-undo/redo?