From 3b5f728bffb043d623874db29869cc3adf117e43 Mon Sep 17 00:00:00 2001
From: Tassilo Horn <tsdh@gnu.org>
Date: Thu, 7 May 2020 09:53:54 +0200
Subject: [PATCH] Refactor browse-url handler selection into separate function.

* lisp/net/browse-url.el (browse-url-select-handler): New function.
(browse-url): Use it.
* lisp/dnd.el (dnd-handle-one-url): Use it.
---
 lisp/dnd.el            | 19 ++++----------
 lisp/net/browse-url.el | 57 +++++++++++++++++++++++-------------------
 2 files changed, 36 insertions(+), 40 deletions(-)

diff --git a/lisp/dnd.el b/lisp/dnd.el
index b649e725f25..c185794d6ea 100644
--- a/lisp/dnd.el
+++ b/lisp/dnd.el
@@ -92,7 +92,6 @@ If no match is found here, `browse-url-handlers' and
 If no match is found, just call `dnd-insert-text'.  WINDOW is
 where the drop happened, ACTION is the action for the drop, URL
 is what has been dropped.  Returns ACTION."
-  (require 'browse-url)
   (let (ret)
     (or
      (catch 'done
@@ -102,19 +101,11 @@ is what has been dropped.  Returns ACTION."
 	   (throw 'done t)))
        nil)
      (catch 'done
-       (defvar browse-url-handlers) ;; Not autoloaded.
-       (dolist (bf (append
-                    ;; The alist choice of browse-url-browser-function
-                    ;; is deprecated since 28.1, so the (unless ...)
-                    ;; can be removed at some point in time.
-                    (unless (functionp browse-url-browser-function)
-                      browse-url-browser-function)
-                    browse-url-handlers
-                    browse-url-default-handlers))
-	 (when (string-match (car bf) url)
-	   (setq ret 'private)
-	   (funcall (cdr bf) url action)
-	   (throw 'done t)))
+       (let ((browser (browse-url-select-handler url)))
+         (when browser
+           (setq ret 'private)
+           (funcall browser url action)
+           (throw 'done t)))
        nil)
      (progn
        (dnd-insert-text window action url)
diff --git a/lisp/net/browse-url.el b/lisp/net/browse-url.el
index 67dc4cd231b..b34665358ca 100644
--- a/lisp/net/browse-url.el
+++ b/lisp/net/browse-url.el
@@ -635,6 +635,32 @@ match, the URL is opened using the value of
                 :value-type (function :tag "Handler"))
   :version "28.1")
 
+;;;###autoload
+(defun browse-url-select-handler (url)
+  "Return a handler suitable for browsing URL.
+This searches `browse-url-handlers', and
+`browse-url-default-handlers' for a matching handler.  Return nil
+if no handler is found.
+
+Currently, it also consults `browse-url-browser-function' first
+if it is set to an alist, although this usage is deprecated since
+Emacs 28.1 and will be removed in a future release."
+  (catch 'custom-url-handler
+    (dolist (regex-handler
+             (append
+              ;; The alist choice of browse-url-browser-function
+              ;; is deprecated since 28.1, so the (unless ...)
+              ;; can be removed at some point in time.
+              (when (and (consp browse-url-browser-function)
+	                 (not (functionp browse-url-browser-function)))
+                (warn "Having `browse-url-browser-function' set to an
+alist is deprecated.  Use `browse-url-handlers' instead.")
+                browse-url-browser-function)
+              browse-url-handlers
+              browse-url-default-handlers))
+      (when (string-match-p (car regex-handler) url)
+        (throw 'custom-url-handler (cdr regex-handler))))))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; URL encoding
 
@@ -828,14 +854,8 @@ If ARGS are omitted, the default is to pass
              (not (string-match "\\`[a-z]+:" url)))
     (setq url (expand-file-name url)))
   (let ((process-environment (copy-sequence process-environment))
-	(function
-         (catch 'custom-url-handler
-           (dolist (regex-handler (append browse-url-handlers
-                                          browse-url-default-handlers))
-             (when (string-match-p (car regex-handler) url)
-               (throw 'custom-url-handler (cdr regex-handler))))
-           ;; No special handler found.
-           browse-url-browser-function))
+	(function (or (browse-url-select-handler url)
+                      browse-url-browser-function))
 	;; Ensure that `default-directory' exists and is readable (bug#6077).
 	(default-directory (or (unhandled-file-name-directory default-directory)
 			       (expand-file-name "~/"))))
@@ -844,24 +864,9 @@ If ARGS are omitted, the default is to pass
     ;; which may not even exist any more.
     (if (stringp (frame-parameter nil 'display))
         (setenv "DISPLAY" (frame-parameter nil 'display)))
-    (if (and (consp function)
-	     (not (functionp function)))
-	;; The `function' can be an alist; look down it for first
-	;; match and apply the function (which might be a lambda).
-	;; However, this usage is deprecated as of Emacs 28.1.
-        (progn
-          (warn "Having `browse-url-browser-function' set to an
-alist is deprecated.  Use `browse-url-handlers' instead.")
-          (catch 'done
-	    (dolist (bf function)
-	      (when (string-match (car bf) url)
-	        (apply (cdr bf) url args)
-	        (throw 'done t)))
-	    (error "No browse-url-browser-function matching URL %s"
-	           url)))
-      ;; Unbound symbols go down this leg, since void-function from
-      ;; apply is clearer than wrong-type-argument from dolist.
-      (apply function url args))))
+    (if (functionp nil)
+        (apply function url args)
+      (error "No suitable browser for URL %s" url))))
 
 ;;;###autoload
 (defun browse-url-at-point (&optional arg)
-- 
2.39.5