Re: Adding custom providers for thingatpt.el (was: [PATCH] Add support for 'thing-at-point' to get URL at point)

[Jim Porter <jporterbugs@gmail.com>]

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On 4/29/2024 11:14 AM, Ihor Radchenko wrote:
> Thanks!
> I have a small comment on the docstring of
> `forward-thing-provider-alist' - it refers to
> `thing-at-point-provider-alist', but the provides here are called with
> an argument N, unlike the providers in `thing-at-point-provider-alist'.

Fixed.

I've also added some helper functions for 'forward-thing' and 
'bounds-of-thing-at-point' when the "thing" is defined by a text 
property, and then used those helper functions for EWW and 
bug-reference-mode.

I've lightly tested this (and added a few automated regression tests), 
but there could be some bugs lurking in here...

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From ad8db930907cd760142fd6f035d97ce93ce8d850 Mon Sep 17 00:00:00 2001
From: Jim Porter <jporterbugs@gmail.com>
Date: Sun, 28 Apr 2024 21:19:53 -0700
Subject: [PATCH] Allow defining custom providers for more "thingatpt"
 functions

* lisp/thingatpt.el (forward-thing-provider-alist)
(bounds-of-thing-at-point-provider-alist): New variables...
(forward-thing, bounds-of-thing-at-point): ... use them.
(text-property-search-forward, text-property-search-backward)
(prop-match-beginning, prop-match-end): Declare.
(forward-thing-for-text-property)
(bounds-of-thing-at-point-for-text-property): New functions.

* lisp/net/eww.el (eww--bounds-of-url-at-point, eww--forward-url): New
functions...
(eww-mode): ... use them.

* lisp/progmodes/bug-reference.el
(bug-reference--bounds-of-url-at-point, bug-reference--forward-url): New
functions...
(bug-reference--init): ... use them.

* test/lisp/thingatpt-tests.el (thing-at-point-providers)
(forward-thing-providers, bounds-of-thing-at-point-providers): New
tests.

* etc/NEWS: Announce this change.
---
 etc/NEWS                        | 21 +++++++---
 lisp/net/eww.el                 | 14 +++++++
 lisp/progmodes/bug-reference.el | 22 +++++++++-
 lisp/thingatpt.el               | 71 ++++++++++++++++++++++++++++++---
 test/lisp/thingatpt-tests.el    | 36 +++++++++++++++++
 5 files changed, 153 insertions(+), 11 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 7efb4110bcd..394f75884c1 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1591,19 +1591,30 @@ of the currently existing keyboards macros using the new mode
 duplicating them, deleting them, and editing their counters, formats,
 and keys.
 
-** Miscellaneous
+** thingatpt.el
 
 ---
-*** Webjump now assumes URIs are HTTPS instead of HTTP.
-For links in 'webjump-sites' without an explicit URI scheme, it was
-previously assumed that they should be prefixed with "http://".  Such
-URIs are now prefixed with "https://" instead.
+*** New variables and functions for providing custom thingatpt implementations.
+The new variables 'bounds-of-thing-at-point-provider-alist' and
+'forward-thing-provider-alist' now allow defining custom implementations
+of 'bounds-of-thing-at-point' and 'forward-thing', respectively.  In
+addition, "things" defined by a text property can use the new functions
+'bounds-of-thing-at-point-for-text-property' and
+'forward-thing-for-text-property' to help implement these providers.
 
 ---
 *** 'bug-reference-mode' now supports 'thing-at-point'.
 Now, calling '(thing-at-point 'url)' when point is on a bug reference
 will return the URL for that bug.
 
+** Miscellaneous
+
+---
+*** Webjump now assumes URIs are HTTPS instead of HTTP.
+For links in 'webjump-sites' without an explicit URI scheme, it was
+previously assumed that they should be prefixed with "http://".  Such
+URIs are now prefixed with "https://" instead.
+
 +++
 *** New user option 'rcirc-log-time-format'
 This allows for rcirc logs to use a custom timestamp format, than the
diff --git a/lisp/net/eww.el b/lisp/net/eww.el
index 39ea964d47a..adabd8d8d8b 100644
--- a/lisp/net/eww.el
+++ b/lisp/net/eww.el
@@ -1321,6 +1321,12 @@ eww-mode
   (setq-local thing-at-point-provider-alist
               (append thing-at-point-provider-alist
                       '((url . eww--url-at-point))))
+  (setq-local bounds-of-thing-at-point-provider-alist
+              (append bounds-of-thing-at-point-provider-alist
+                      '((url . eww--bounds-of-url-at-point))))
+  (setq-local forward-thing-provider-alist
+              (append forward-thing-provider-alist
+                      '((url . eww--forward-url))))
   (setq-local bookmark-make-record-function #'eww-bookmark-make-record)
   (buffer-disable-undo)
   (setq-local shr-url-transformer #'eww--transform-url)
@@ -1351,6 +1357,14 @@ eww--url-at-point
   "`thing-at-point' provider function."
   (get-text-property (point) 'shr-url))
 
+(defun eww--bounds-of-url-at-point ()
+  "`bounds-of-thing-at-point' provider function."
+  (bounds-of-thing-at-point-for-text-property 'shr-url))
+
+(defun eww--forward-url (n)
+  "`forward-thing' provider function."
+  (forward-thing-for-text-property 'shr-url n))
+
 ;;;###autoload
 (defun eww-browse-url (url &optional new-window)
   "Ask the EWW browser to load URL.
diff --git a/lisp/progmodes/bug-reference.el b/lisp/progmodes/bug-reference.el
index 977a3d72cb7..bfc22fb10d2 100644
--- a/lisp/progmodes/bug-reference.el
+++ b/lisp/progmodes/bug-reference.el
@@ -660,17 +660,37 @@ bug-reference--url-at-point
   "`thing-at-point' provider function."
   (get-char-property (point) 'bug-reference-url))
 
+(defun bug-reference--bounds-of-url-at-point ()
+  "`bounds-of-thing-at-point' provider function."
+  (bounds-of-thing-at-point-for-text-property 'bug-reference-url))
+
+(defun bug-reference--forward-url (n)
+  "`forward-thing' provider function."
+  (forward-thing-for-text-property 'bug-reference-url n))
+
 (defun bug-reference--init (enable)
   (if enable
       (progn
         (jit-lock-register #'bug-reference-fontify)
         (setq-local thing-at-point-provider-alist
                     (append thing-at-point-provider-alist
-                            '((url . bug-reference--url-at-point)))))
+                            '((url . bug-reference--url-at-point))))
+        (setq-local bounds-of-thing-at-point-provider-alist
+                    (append bounds-of-thing-at-point-provider-alist
+                            '((url . bug-reference--bounds-of-url-at-point))))
+        (setq-local forward-thing-provider-alist
+                    (append forward-thing-provider-alist
+                            '((url . bug-reference--forward-url)))))
     (jit-lock-unregister #'bug-reference-fontify)
     (setq thing-at-point-provider-alist
           (delete '((url . bug-reference--url-at-point))
                   thing-at-point-provider-alist))
+    (setq bounds-of-thing-at-point-provider-alist
+          (delete '((url . bug-reference--bounds-of-url-at-point))
+                  bounds-of-thing-at-point-provider-alist))
+    (setq forward-thing-provider-alist
+          (delete '((url . bug-reference--forward-url))
+                  forward-thing-provider-alist))
     (save-restriction
       (widen)
       (bug-reference-unfontify (point-min) (point-max)))))
diff --git a/lisp/thingatpt.el b/lisp/thingatpt.el
index 7896ad984df..dad71a4ca94 100644
--- a/lisp/thingatpt.el
+++ b/lisp/thingatpt.el
@@ -75,6 +75,27 @@ thing-at-point-provider-alist
 `existing-filename', `url', `email', `uuid', `word', `sentence',
 `whitespace', `line', `face' and `page'.")
 
+(defvar forward-thing-provider-alist nil
+  "Alist of providers for moving forward to the end of a \"thing\".
+This variable can be set globally, or appended to buffer-locally by
+modes, to provide functions that will move forward to the end of a
+\"thing\" at point.  Each function should take a single argument N, the
+number of \"things\" to move forward past.  The first provider for the
+\"thing\" that returns a non-nil value wins.
+
+You can use this variable in much the same way as
+`thing-at-point-provider-alist' (which see).")
+
+(defvar bounds-of-thing-at-point-provider-alist nil
+  "Alist of providers to return the bounds of a \"thing\" at point.
+This variable can be set globally, or appended to buffer-locally by
+modes, to provide functions that will return the bounds of a \"thing\"
+at point.  The first provider for the \"thing\" that returns a non-nil
+value wins.
+
+You can use this variable in much the same way as
+`thing-at-point-provider-alist' (which see).")
+
 ;; Basic movement
 
 ;;;###autoload
@@ -84,11 +105,16 @@ forward-thing
 Possibilities include `symbol', `list', `sexp', `defun', `number',
 `filename', `url', `email', `uuid', `word', `sentence', `whitespace',
 `line', and `page'."
-  (let ((forward-op (or (get thing 'forward-op)
-			(intern-soft (format "forward-%s" thing)))))
-    (if (functionp forward-op)
-	(funcall forward-op (or n 1))
-      (error "Can't determine how to move over a %s" thing))))
+  (setq n (or n 1))
+  (or (seq-some (lambda (elt)
+                  (and (eq (car elt) thing)
+                       (funcall (cdr elt) n)))
+                forward-thing-provider-alist)
+      (let ((forward-op (or (get thing 'forward-op)
+			    (intern-soft (format "forward-%s" thing)))))
+        (if (functionp forward-op)
+	    (funcall forward-op n)
+          (error "Can't determine how to move over a %s" thing)))))
 
 ;; General routines
 
@@ -106,6 +132,10 @@ bounds-of-thing-at-point
 Return a cons cell (START . END) giving the start and end
 positions of the thing found."
   (cond
+   ((seq-some (lambda (elt)
+                (and (eq (car elt) thing)
+                     (funcall (cdr elt))))
+                bounds-of-thing-at-point-provider-alist))
    ((get thing 'bounds-of-thing-at-point)
     (funcall (get thing 'bounds-of-thing-at-point)))
    ;; If the buffer is totally empty, give up.
@@ -775,4 +805,35 @@ list-at-point
       (goto-char (or (nth 8 ppss) (point)))
       (form-at-point 'list 'listp))))
 
+(autoload 'text-property-search-forward "text-property-search")
+(autoload 'text-property-search-backward "text-property-search")
+(autoload 'prop-match-beginning "text-property-search")
+(autoload 'prop-match-end "text-property-search")
+
+(defun forward-thing-for-text-property (property n)
+  "Move forward to the end of the Nth next \"thing\".
+Each \"thing\" is a region of text with the specified text PROPERTY set."
+  (let ((search-func (if (> n 0) #'text-property-search-forward
+                       #'text-property-search-backward))
+        (pos-func (if (> n 0) #'prop-match-end #'prop-match-beginning))
+        (limit (if (> n 0) (point-max) (point-min))))
+    (catch 'done
+      (dotimes (_ (abs n))
+        (if-let ((match (funcall search-func property)))
+            (goto-char (funcall pos-func match))
+          (goto-char limit)
+          (throw 'done t))))
+    ;; Return non-nil.
+    t))
+
+(defun bounds-of-thing-at-point-for-text-property (property)
+  "Determine the start and end buffer locations for the \"thing\" at point.
+The \"thing\" is a region of text with the specified text PROPERTY set."
+  (when (get-text-property (point) property)
+    (cons (or (previous-single-property-change
+               (min (1+ (point)) (point-max)) property)
+              (point-min))
+          (or (next-single-property-change (point) property)
+              (point-max)))))
+
 ;;; thingatpt.el ends here
diff --git a/test/lisp/thingatpt-tests.el b/test/lisp/thingatpt-tests.el
index e50738f1122..26e20f58be7 100644
--- a/test/lisp/thingatpt-tests.el
+++ b/test/lisp/thingatpt-tests.el
@@ -258,4 +258,40 @@ test-numbers-hex-c
   (should (equal (test--number "0xf00" 2) 3840))
   (should (equal (test--number "0xf00" 3) 3840)))
 
+(ert-deftest thing-at-point-providers ()
+  (with-temp-buffer
+    (setq-local thing-at-point-provider-alist
+                `((url . ,(lambda () (get-text-property (point) 'my-url)))))
+    (insert (propertize "hello" 'my-url "test"))
+    (goto-char (point-min))
+    (should (equal (thing-at-point 'url) "test"))
+    (should (equal (thing-at-point 'word) "hello"))))
+
+(ert-deftest forward-thing-providers ()
+  (with-temp-buffer
+    (setq-local forward-thing-provider-alist
+                `((url . ,(lambda (n)
+                            (forward-thing-for-text-property 'my-url n)))))
+    (insert (propertize "foo" 'my-url "test") "bar")
+    (goto-char (point-min))
+    (should (eq (save-excursion (forward-thing 'url) (point)) 4))
+    (should (eq (save-excursion (forward-thing 'word) (point)) 7))))
+
+(ert-deftest bounds-of-thing-at-point-providers ()
+  (with-temp-buffer
+    (setq-local bounds-of-thing-at-point-provider-alist
+                `((url . ,(lambda ()
+                            (bounds-of-thing-at-point-for-text-property
+                             'my-url)))))
+    (insert (propertize "foo" 'my-url "test") "bar")
+    (goto-char (point-min))
+    ;; Look for a "URL", using our provider above.
+    (should (equal (bounds-of-thing-at-point 'url) '(1 . 4)))
+    (should (eq (save-excursion (beginning-of-thing 'url)) 1))
+    (should (eq (save-excursion (end-of-thing 'url)) 4))
+    ;; Look for a word, which should *not* use our provider above.
+    (should (equal (bounds-of-thing-at-point 'word) '(1 . 7)))
+    (should (eq (save-excursion (beginning-of-thing 'word)) 1))
+    (should (eq (save-excursion (end-of-thing 'word)) 7))))
+
 ;;; thingatpt-tests.el ends here
-- 
2.25.1