Improve link creation from Info manual references

* helpful.el (helpful--propertize-info): Follow Emacs convention for
function documentation. Consider lowercase "info" and angular
quotation marks in docstrings. Default to the Emacs manual if there's
no manual reference (ie. see the `blink-cursor-mode' variable).
* test/helpful-unit-test.el (helpful--format-docstring--info): Add new
testcases for the now covered cases.

2 files changed, 46 insertions, 12 deletions

diff --git a/helpful.el b/helpful.el
index 7a71f4e..717d6a9 100644
--- a/helpful.el
+++ b/helpful.el
@@ -788,22 +788,35 @@ bound) or else highlight."
                   'face 'font-lock-constant-face)))))
 
 (defun helpful--propertize-info (docstring)
-  "Convert info references in docstrings to buttons."
+  "Convert info references in DOCSTRING to buttons."
   (replace-regexp-in-string
-   ;; Replace all text of the form `foo'.
-   (rx "Info "
-       (group
-        (or "anchor" "node")
-        (+ whitespace))
-       "`"
-       (group (+ (not (in "'"))))
-       "'")
+   ;; Replace all text that looks like a link to an Info page.
+   (rx (seq (group
+             bow
+             (any "Ii")
+             "nfo"
+             (one-or-more whitespace))
+            (group
+             (or "node" "anchor")
+             (one-or-more whitespace))
+            (any "'`‘")
+            (group
+             (one-or-more
+              (not (any "'’"))))
+            (any "'’")))
    (lambda (it)
+     ;; info-name matches "[Ii]nfo ".
+     ;; space matches "node " or "anchor ".
      ;; info-node has the form "(cl)Loop Facility".
-     (let ((space (match-string 1 it))
-           (info-node (match-string 2 it)))
+     (let ((info-name (match-string 1 it))
+           (space (match-string 2 it))
+           (info-node (match-string 3 it)))
+       ;; If the docstring doesn't specify a manual, assume the Emacs manual.
+       (save-match-data
+         (unless (string-match "^([^)]+)" info-node)
+           (setq info-node (concat "(emacs)" info-node))))
        (concat
-        "Info "
+        info-name
         space
         (helpful--button
          info-node
diff --git a/test/helpful-unit-test.el b/test/helpful-unit-test.el
index d296423..0250980 100644
--- a/test/helpful-unit-test.el
+++ b/test/helpful-unit-test.el
@@ -317,6 +317,27 @@ symbol (not a form)."
     (should
      (string-equal formatted "Info node (elisp)foo \nbar"))
     (should
+     (get-text-property paren-position 'button formatted)))
+  ;; Some docstrings use "info" (lowercase).
+  (let* ((formatted (helpful--format-docstring "info node `(elisp)foo'"))
+         (paren-position (s-index-of "(" formatted)))
+    (should
+     (string-equal formatted "info node (elisp)foo"))
+    (should
+     (get-text-property paren-position 'button formatted)))
+  ;; Some docstrings use angular quotation marks.
+  (let* ((formatted (helpful--format-docstring "Info node ‘(elisp)foo’"))
+         (paren-position (s-index-of "(" formatted)))
+    (should
+     (string-equal formatted "Info node (elisp)foo"))
+    (should
+     (get-text-property paren-position 'button formatted)))
+  ;; If there's no manual information, assume it is part of the Emacs manual.
+  (let* ((formatted (helpful--format-docstring "Info node ‘foo’"))
+         (paren-position (s-index-of "(" formatted)))
+    (should
+     (string-equal formatted "Info node (emacs)foo"))
+    (should
      (get-text-property paren-position 'button formatted))))
 
 (ert-deftest helpful--format-docstring--url ()