Simplify erc-button movement commands

* etc/ERC-NEWS: Mention TAB being bound to new command `erc-tab' and
`erc-previous-button' now stopping at the start of buttons.
* lisp/erc/erc-button.el (erc-button-mode, erc-button-enable,
erc-button-disable): Add and remove `erc-button-next' to
`erc--tab-functions' hook, which is tantamount to binding the command
in the read-only area of an ERC buffer.
(erc-button-next-function): Deprecate and remove from client code path
because this module doesn't concern itself with prompt input and thus
no longer needs to conform to the `completion-at-point-functions'
interface.
(erc-button--prev-next-predicate-functions): New variable, a hook to
determine whether to continue searching for a button.  Other modules
should utilize this as needed.
(erc-button--end-of-button-p): Add function to serve as default value
for `erc-button--continue-predicate'.
(erc--button-next): Add generalized button-movement function.
(erc-button-next, erc-button-previous): Make `erc-button-previous'
behave more predictably by having it land at the beginning of buttons.
And remove roundabout appeal to HOF in `erc-button-next'.
(erc-button-previous-of-nick): New command to jump to previous
appearance of nick at point.
* lisp/erc/erc-fill.el (erc-fill-wrap, erc-fill-wrap-enable,
erc-fill-wrap-disable): Add and remove merge-related hookee from
`erc-button--prev-next-predicate-functions'.
(erc-fill--wrap-merged-button-p): New function to detect redundant
speakers.
* lisp/erc/erc.el (erc-complete-functions): Quote TAB in doc string.
(erc-mode-map): Bind `erc-tab' to TAB.
(erc--tab-functions, erc-tab): Add new command and hook to serve as
unified dispatch for TAB-related operations.  It calls `c-a-p' in the
input area and defers to module code in the read-only message area.
* test/lisp/erc/erc-button-tests.el: New file.
* test/lisp/erc/erc-fill-tests.el (erc-fill-tests--wrap-populate): Run
finalizer for transient keymap timer.
* test/lisp/erc/erc-tests.el
(erc-button--display-error-notice-with-keys): Move to new dedicated
test file for erc-button and fix expected behavior of
`erc-button-previous'.  (Bug#62834)

1 files changed, 9 insertions, 1 deletions

diff --git a/lisp/erc/erc-fill.el b/lisp/erc/erc-fill.el
index a56134d8188..bf995a5a5e6 100644
--- a/lisp/erc/erc-fill.el
+++ b/lisp/erc/erc-fill.el
@@ -300,7 +300,9 @@ of the minor-mode toggles as usual."
            (setq msg (concat msg (and msg " ")
                              (erc-fill--make-module-dependency-msg "button"))))
          (erc-with-server-buffer
-           (erc-button-mode +1))))
+           (erc-button-mode +1)))
+       (add-hook 'erc-button--prev-next-predicate-functions
+                 #'erc-fill--wrap-merged-button-p nil t))
      ;; Set local value of user option (can we avoid this somehow?)
      (unless (eq erc-fill-function #'erc-fill-wrap)
        (setq-local erc-fill-function #'erc-fill-wrap))
@@ -328,6 +330,8 @@ of the minor-mode toggles as usual."
    (kill-local-variable 'erc-fill--wrap-value)
    (kill-local-variable 'erc-fill-function)
    (kill-local-variable 'erc-fill--wrap-visual-keys)
+   (remove-hook 'erc-button--prev-next-predicate-functions
+                #'erc-fill--wrap-merged-button-p t)
    (remove-function (local 'erc-stamp--insert-date-function)
                     #'erc-fill--wrap-stamp-insert-prefixed-date)
    (visual-line-mode -1))
@@ -414,6 +418,10 @@ See `erc-fill-wrap-mode' for details."
                                `((space :width (- erc-fill--wrap-value ,len))
                                  (space :width erc-fill--wrap-value))))))
 
+;; FIXME use own text property to avoid false positives.
+(defun erc-fill--wrap-merged-button-p (point)
+  (equal "" (get-text-property point 'display)))
+
 ;; This is an experimental helper for third-party modules.  You could,
 ;; for example, use this to automatically resize the prefix to a
 ;; fraction of the window's width on some event change.  Another use