Use `org-strip-quote' when possible

* lisp/org-macs.el (org-unbracket-string):
(org-strip-quotes): Allow nil values.
* lisp/org-lint.el (org-lint-wrong-include-link-parameter):
* lisp/org-macro.el (org-macro--collect-macros):
* lisp/org.el (org--setup-collect-keywords):
(org-edit-special):
* lisp/ox.el (org-export--get-inbuffer-options):
(org-export--list-bound-variables):
(org-export-expand-include-keyword): Use `org-strip-quote' instead of
`org-unbracket-string' whenever possible.

lisp/org-lint.el

@@ -589,7 +589,7 @@ Use :header-args: instead"
 	       (path
 		(and (string-match "^\\(\".+\"\\|\\S-+\\)[ \t]*" value)
 		     (save-match-data
-		       (org-unbracket-string "\"" "\"" (match-string 1 value))))))
+		       (org-strip-quotes (match-string 1 value))))))
 	  (if (not path)
 	      (list (org-element-property :post-affiliated k)
 		    "Missing location argument in INCLUDE keyword")

lisp/org-macro.el

@@ -110,7 +110,7 @@ Return an alist containing all macro templates found."
 				 (if old-cell (setcdr old-cell template)
 				   (push (cons name template) templates))))
 			   ;; Enter setup file.
-			   (let* ((uri (org-unbracket-string "\"" "\"" (org-trim val)))
+			   (let* ((uri (org-strip-quotes (org-trim val)))
 				  (uri-is-url (org-file-url-p uri))
 				  (uri (if uri-is-url
 					   uri

lisp/org-macs.el

@@ -899,14 +899,17 @@ Otherwise return nil."
 (defun org-unbracket-string (pre post string)
   "Remove PRE/POST from the beginning/end of STRING.
 Both PRE and POST must be pre-/suffixes of STRING, or neither is
-removed."
-  (if (and (string-prefix-p pre string)
-	   (string-suffix-p post string))
-      (substring string (length pre) (- (length post)))
-    string))
+removed.  Return the new string.  If STRING is nil, return nil."
+  (declare (indent 2))
+  (and string
+       (if (and (string-prefix-p pre string)
+		(string-suffix-p post string))
+	   (substring string (length pre) (- (length post)))
+	 string)))
 
 (defun org-strip-quotes (string)
-  "Strip double quotes from around a string, if applicable."
+  "Strip double quotes from around STRING, if applicable.
+If STRING is nil, return nil."
   (org-unbracket-string "\"" "\"" string))
 
 (defsubst org-current-line-string (&optional to-here)

lisp/org.el

@@ -5173,8 +5173,7 @@ Return value contains the following keys: `archive', `category',
 	      ((equal key "SETUPFILE")
 	       (unless buffer-read-only ; Do not check in Gnus messages.
 		 (let ((f (and (org-string-nw-p value)
-			       (expand-file-name
-				(org-unbracket-string "\"" "\"" value)))))
+			       (expand-file-name (org-strip-quotes value)))))
 		   (when (and f (file-readable-p f) (not (member f files)))
 		     (with-temp-buffer
 		       (setq default-directory (file-name-directory f))
@@ -20084,28 +20083,27 @@ Otherwise, return a user error."
 		(params (nth 2 info))
 		(session (cdr (assq :session params))))
 	   (if (not session) (org-edit-src-code)
-	     ;; At a src-block with a session and function called with
-	     ;; an ARG: switch to the buffer related to the inferior
-	     ;; process.
+	     ;; At a source block with a session and function called
+	     ;; with an ARG: switch to the buffer related to the
+	     ;; inferior process.
 	     (switch-to-buffer
 	      (funcall (intern (concat "org-babel-prep-session:" lang))
 		       session params))))))
       (`keyword
-       (if (member (org-element-property :key element) '("INCLUDE" "SETUPFILE"))
-           (org-open-link-from-string
-	    (format "[[%s]]"
-		    (expand-file-name
-		     (let ((value (org-element-property :value element)))
-		       (cond ((org-file-url-p value)
-			      (user-error "The file is specified as a URL, cannot be edited"))
-			     ((not (org-string-nw-p value))
-			      (user-error "No file to edit"))
-			     ((string-match "\\`\"\\(.*?\\)\"" value)
-			      (match-string 1 value))
-			     ((string-match "\\`[^ \t\"]\\S-*" value)
-			      (match-string 0 value))
-			     (t (user-error "No valid file specified")))))))
-         (user-error "No special environment to edit here")))
+       (unless (member (org-element-property :key element)
+		       '("INCLUDE" "SETUPFILE"))
+	 (user-error "No special environment to edit here"))
+       (org-open-link-from-string
+	(format "[[%s]]"
+		(expand-file-name
+		 (let ((value (org-strip-quotes
+			       (org-element-property :value element))))
+		   (cond
+		    ((not (org-string-nw-p value))
+		     (user-error "No file to edit"))
+		    ((org-file-url-p value)
+		     (user-error "Files located with a URL cannot be edited"))
+		    (t value)))))))
       (`table
        (if (eq (org-element-property :type element) 'table.el)
            (org-edit-table.el)

lisp/ox.el

@@ -1499,7 +1499,7 @@ Assume buffer is in Org mode.  Narrowing, if any, is ignored."
 			 (cond
 			  ;; Options in `org-export-special-keywords'.
 			  ((equal key "SETUPFILE")
-			   (let* ((uri (org-unbracket-string "\"" "\"" (org-trim val)))
+			   (let* ((uri (org-strip-quotes (org-trim val)))
 				  (uri-is-url (org-file-url-p uri))
 				  (uri (if uri-is-url
 					   uri
@@ -1650,7 +1650,7 @@ an alist where associations are (VARIABLE-NAME VALUE)."
 				      "BIND")
 			       (push (read (format "(%s)" val)) alist)
 			     ;; Enter setup file.
-			     (let* ((uri (org-unbracket-string "\"" "\"" val))
+			     (let* ((uri (org-strip-quotes val))
 				    (uri-is-url (org-file-url-p uri))
 				    (uri (if uri-is-url
 					     uri
@@ -3283,8 +3283,8 @@ storing and resolving footnotes.  It is created automatically."
 		   (ind (current-indentation))
 		   location
 		   (file
-		    (and (string-match
-			  "^\\(\".+?\"\\|\\S-+\\)\\(?:\\s-+\\|$\\)" value)
+		    (and (string-match "^\\(\".+?\"\\|\\S-+\\)\\(?:\\s-+\\|$\\)"
+				       value)
 			 (prog1
 			     (save-match-data
 			       (let ((matched (match-string 1 value)))
@@ -3293,9 +3293,8 @@ storing and resolving footnotes.  It is created automatically."
 				   (setq location (match-string 2 matched))
 				   (setq matched
 					 (replace-match "" nil nil matched 1)))
-				 (expand-file-name
-				  (org-unbracket-string "\"" "\"" matched)
-				  dir)))
+				 (expand-file-name (org-strip-quotes matched)
+						   dir)))
 			   (setq value (replace-match "" nil nil value)))))
 		   (only-contents
 		    (and (string-match ":only-contents *\\([^: \r\t\n]\\S-*\\)?"