(feat): allow setting #+roam_alias and #+roam_tag on multiple lines (#1540)

This brings them more in line with how other Org keywords, such as
\#+PROPERTY, are declared.

Previously

    #+roam_alias: abc def
    #+roam_alias: ghi

would result in only the last one ("ghi") being extracted. Now ("abc"
"def" "ghi") are all extracted (in that order).

* org-roam.el (org-roam--extract-tags-prop, org-roam--extract-titles-alias): Accept and return all values in a list, not just from one line.
(org-roam--extract-prop-as-list): New function. List prop extraction refactored from `org-roam--extract-tags-prop` and `org-roam--extract-titles-alias`

* tests/test-org-roam.el: Add tests for defining tags and aliases in multiple lines

CHANGELOG.md

@@ -9,6 +9,7 @@
 ### Changed
 - [#1352](https://github.com/org-roam/org-roam/pull/1352) prefer lower-case for roam_tag and roam_alias in interactive commands
 - [#1513](https://github.com/org-roam/org-roam/pull/1513) replaced hardcoded "svg" with defcustom org-roam-graph-filetype 
+- [#1540](https://github.com/org-roam/org-roam/pull/1540) allow `roam_tag` and `roam_alias` to be specified on multiple lines
 
 ### Fixed
 - [#1281](https://github.com/org-roam/org-roam/pull/1281) fixed idle-timer not instantiated on `org-roam-mode`

org-roam.el

@@ -559,6 +559,28 @@ any), and Org keywords. Org keywords take precedence."
    (org-roam--extract-global-props-keyword props)
    (org-roam--extract-global-props-drawer props)))
 
+(defun org-roam--extract-prop-as-list (prop)
+  "Extract PROP from the current Org buffer as a list.
+
+This is the common logic behind the extraction of roam_tags and
+roam_alias."
+  ;; Values are split in two ways:
+  ;; 1. with spaces and double quotes:
+  ;;     #+prop: a b c \"quoted string\"
+  ;;     -> '(\"a\" \"b\" \"c\" \"quoted string\")
+  ;; 2. and/or with multiple lines:
+  ;;     #+prop: a b
+  ;;     #+prop: c d
+  ;;     -> '(\"a\" \"b\" \"c\" \"d\")
+  (--> (org-roam--extract-global-props (list prop))
+    ;; so that the returned order is the same as in the buffer
+    nreverse
+    ;; '(("ROAM_TAGS" . "a b") ("ROAM_TAGS" . "c d"))
+    ;; -> '("a b" "c d")
+    (mapcar #'cdr it)
+    (mapcar #'split-string-and-unquote it)
+    ;; We have a list of lists at this point. Join them.
+    (apply #'append it)))
 
 (defun org-roam--get-outline-path ()
   "Return the outline path to the current entry.
@@ -667,18 +689,15 @@ If FILE-PATH is nil, use the current file."
 (defun org-roam--extract-titles-alias ()
   "Return the aliases from the current buffer.
 Reads from the \"roam_alias\" property."
-  (let* ((prop (org-roam--extract-global-props '("ROAM_ALIAS")))
-         (aliases (or (cdr (assoc "ROAM_ALIAS" prop))
-                      "")))
   (condition-case nil
-        (split-string-and-unquote aliases)
+      (org-roam--extract-prop-as-list "ROAM_ALIAS")
     (error
      (progn
        (lwarn '(org-roam) :error
               "Failed to parse aliases for buffer: %s. Skipping"
               (or org-roam-file-name
                   (buffer-file-name)))
-         nil)))))
+       nil))))
 
 (defun org-roam--extract-titles-headline ()
   "Return the first headline of the current buffer."
@@ -735,17 +754,15 @@ tag."
 
 (defun org-roam--extract-tags-prop (_file)
   "Extract tags from the current buffer's \"#roam_tags\" global property."
-  (let* ((prop (or (cdr (assoc "ROAM_TAGS" (org-roam--extract-global-props '("ROAM_TAGS"))))
-                   "")))
   (condition-case nil
-        (split-string-and-unquote prop)
+      (org-roam--extract-prop-as-list "ROAM_TAGS")
     (error
      (progn
        (lwarn '(org-roam) :error
               "Failed to parse tags for buffer: %s. Skipping"
               (or org-roam-file-name
                   (buffer-file-name)))
-         nil)))))
+       nil))))
 
 (defun org-roam--extract-tags-vanilla (_file)
   "Extract vanilla `org-mode' tags.

tests/roam-files/tags/tag.org

@@ -1,4 +1,5 @@
 #+roam_tags: "t1" "t2 with space" t3
+#+roam_tags: "t4 second-line"
 #+title: Tags
 
 This file is used to test functionality for =(org-roam--extract-tags)=

tests/roam-files/titles/aliases.org

@@ -1 +1,2 @@
 #+roam_alias: "roam" "alias"
+#+roam_alias: "second" "line"

tests/test-org-roam.el

@@ -126,7 +126,7 @@
       (expect (test #'org-roam--extract-titles-alias
                     "titles/aliases.org")
               :to-equal
-              '("roam" "alias"))
+              '("roam" "alias" "second" "line"))
       (expect (test #'org-roam--extract-titles-alias
                     "titles/headline.org")
               :to-equal
@@ -192,7 +192,7 @@
       (expect (test #'org-roam--extract-tags-prop
                     "tags/tag.org")
               :to-equal
-              '("t1" "t2 with space" "t3"))
+              '("t1" "t2 with space" "t3" "t4 second-line"))
       (expect (test #'org-roam--extract-tags-prop
                     "tags/no_tag.org")
               :to-equal
@@ -246,13 +246,13 @@
                   (test #'org-roam--extract-tags
                         "tags/tag.org"))
                 :to-equal
-                '("t1" "t2 with space" "t3")))
+                '("t1" "t2 with space" "t3" "t4 second-line")))
       (it "'(prop all-directories)"
         (expect (let ((org-roam-tag-sources '(prop all-directories)))
                   (test #'org-roam--extract-tags
                         "tags/tag.org"))
                 :to-equal
-                '("t1" "t2 with space" "t3" "tags"))))))
+                '("t1" "t2 with space" "t3" "t4 second-line" "tags"))))))
 
 (describe "ID extraction"
   (before-all