helpful

commit 89668dd787248c7f0d35d4ab26f4a61f2efefdcb
parent 50ff4f3aec573602eb7195e393b5acab23185a53
Author: Wilfred Hughes <me@wilfred.me.uk>
Date:   Sun, 22 Jul 2018 23:57:25 +0100

Allow users to view all the buffer-local values

Fixes #49

Diffstat:
M
CHANGELOG.md
 | 
3
++-
M
helpful.el
 | 
95
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------

2 files changed, 87 insertions(+), 11 deletions(-)
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # v0.13
 
-Buffer-local variables are now highlighted.
+Buffer-local variables are now highlighted, and it's possible to see
+all the different values of a buffer-local variable.
 
 Variable values are now shown before docstrings.
 
diff --git a/helpful.el b/helpful.el
@@ -444,9 +444,10 @@ or disable if already enabled."
   (let ((buf (button-get button 'buffer))
         (pos (button-get button 'position)))
     (switch-to-buffer buf)
-    (goto-char pos)))
+    (when pos
+      (goto-char pos))))
 
-(defun helpful--buffer-button (buffer pos)
+(defun helpful--buffer-button (buffer &optional pos)
   "Return a button that switches to BUFFER and puts point at POS."
   (helpful--button
    (buffer-name buffer)
@@ -464,6 +465,38 @@ or disable if already enabled."
   "Open Customize for this symbol."
   (customize-variable (button-get button 'symbol)))
 
+(define-button-type 'helpful-associated-buffer-button
+  'action #'helpful--associated-buffer
+  'symbol nil
+  'prompt-p nil
+  'follow-link t
+  'help-echo "Change associated buffer")
+
+(defun helpful--read-live-buffer (prompt predicate)
+  "Read a live buffer name, and return the buffer object.
+
+This is largely equivalent to `read-buffer', but counsel.el
+overrides that to include previously opened buffers."
+  (get-buffer
+   (completing-read
+    prompt
+    (-map #'buffer-name (buffer-list))
+    predicate
+    t)))
+
+(defun helpful--associated-buffer (button)
+  "Change the associated buffer, so we can see buffer-local values."
+  (let ((sym (button-get button 'symbol))
+        (prompt-p (button-get button 'prompt-p)))
+    (if prompt-p
+        (setq helpful--associated-buffer
+              (helpful--read-live-buffer
+               "View variable in: "
+               (lambda (buf-name)
+                 (local-variable-p sym (get-buffer buf-name)))))
+      (setq helpful--associated-buffer nil)))
+  (helpful-update))
+
 (define-button-type 'helpful-toggle-button
   'action #'helpful--toggle
   'symbol nil
@@ -1378,8 +1411,19 @@ POSITION-HEADS takes the form ((123 (defun foo)) (456 (defun bar)))."
 
 (defun helpful--sym-value (sym buf)
   "Return the value of SYM in BUF."
-  (with-current-buffer buf
-    (symbol-value sym)))
+  (cond
+   ;; If we're given a buffer, look up the variable in that buffer.
+   (buf
+    (with-current-buffer buf
+      (symbol-value sym)))
+   ;; If we don't have a buffer, and this is a buffer-local variable,
+   ;; ensure we return the default value.
+   ((local-variable-if-set-p sym)
+    (default-value sym))
+   ;; Otherwise, just return the value in the current buffer, which is
+   ;; the global value.
+   (t
+    (symbol-value sym))))
 
 (defun helpful--insert-section-break ()
   "Insert section break into helpful buffer."
@@ -1720,15 +1764,31 @@ state of the current symbol."
     (when (not helpful--callable-p)
       (helpful--insert-section-break)
       (let* ((sym helpful--sym)
-             (val-buf (or helpful--associated-buffer (current-buffer)))
-             (val (helpful--sym-value sym val-buf))
+             (val (helpful--sym-value sym helpful--associated-buffer))
              (multiple-views-p
               (or (stringp val)
                   (keymapp val)
                   (and (s-ends-with-p "-hook" (symbol-name sym))
                        (consp val)))))
         (insert
-         (helpful--heading "Value")
+         (helpful--heading
+          (cond
+           ;; Buffer-local variable and we're looking at the value in
+           ;; a specific buffer.
+           ((and
+             helpful--associated-buffer
+             (local-variable-p sym helpful--associated-buffer))
+            (format "Value in %s"
+                    (helpful--button
+                     (format "#<buffer %s>" (buffer-name helpful--associated-buffer))
+                     'helpful-buffer-button
+                     'buffer helpful--associated-buffer
+                     'position pos)))
+           ;; Buffer-local variable but default value.
+           ((local-variable-if-set-p sym)
+            "Default Value")
+           ;; This variable is not buffer-local.
+           (t "Value")))
          (cond
           (helpful--view-literal
            (helpful--pretty-print val))
@@ -1749,9 +1809,24 @@ state of the current symbol."
          "\n\n")
         (when multiple-views-p
           (insert (helpful--make-toggle-literal-button) " "))
-        (when (memq (helpful--sym-value helpful--sym val-buf) '(nil t))
-          (insert (helpful--make-toggle-button helpful--sym val-buf) " "))
-        (insert (helpful--make-set-button helpful--sym val-buf))
+
+        (when (local-variable-if-set-p sym)
+          (insert
+           (helpful--button
+            "Buffer values"
+            'helpful-associated-buffer-button
+            'symbol sym
+            'prompt-p t)
+           " "
+           (helpful--button
+            "Default value"
+            'helpful-associated-buffer-button
+            'symbol sym
+            'prompt-p nil)
+           " "))
+        (when (memq (helpful--sym-value helpful--sym helpful--associated-buffer) '(nil t))
+          (insert (helpful--make-toggle-button helpful--sym helpful--associated-buffer) " "))
+        (insert (helpful--make-set-button helpful--sym helpful--associated-buffer))
         (when (custom-variable-p helpful--sym)
           (insert " " (helpful--make-customize-button helpful--sym)))))