helpful

commit 28bae3e2bd64c6b89c1607c7b1235b306fa7220b
parent 309dba6bb8b199c4ae0f6202f76cd7fa2d42081c
Author: Nick Drozd <nicholasdrozd@gmail.com>
Date:   Sat, 16 Feb 2019 15:01:37 -0600

Handle C-style names in helpful-symbol

In Emacs's C core, Lisp functions and variables take on slightly
different names: dashes are replaced with underscores, and functions
and variables are prefixed with "F" and "V" respectively. This change
allows for looking up those symbols. For example, if I am looking at
the source for `purecopy':

  DEFUN ("purecopy", Fpurecopy, Spurecopy, 1, 1, 0,
         doc: /* Make a copy of object OBJ in pure storage.
  Recursively copies contents of vectors and cons cells.
  Does not copy symbols.  Copies strings without text properties.  */)
    (register Lisp_Object obj)
  {
    if (NILP (Vpurify_flag))
      return obj;
    else if (MARKERP (obj) || OVERLAYP (obj) || SYMBOLP (obj))
      /* Can't purify those.  */
      return obj;
    else
      return purecopy (obj);
  }

I can run `helpful-at-point' on `Vpurify_flag'.

This doesn't support running C-style names through `helpful-callable'
etc, but that doesn't seem like a useful feature.

Diffstat:
M
CHANGELOG.md
 | 
2
++
M
helpful.el
 | 
22
++++++++++++++++++++++
M
test/helpful-unit-test.el
 | 
14
++++++++++++++

3 files changed, 38 insertions(+), 0 deletions(-)
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -14,6 +14,8 @@ macros.
 
 Fixed issues with functions that had more than one advice active.
 
+Added looking up C-style Lisp names.
+
 # v0.15
 
 Fixed a crash on formatting values.
diff --git a/helpful.el b/helpful.el
@@ -2392,6 +2392,20 @@ or :foo."
   (or (fboundp symbol)
       (helpful--variable-p symbol)))
 
+(defun helpful--convert-c-name (symbol var)
+  "Convert SYMBOL from a C name to an Elisp name.
+E.g. convert `Fmake_string' to `make-string' or
+`Vgc_cons_percentage' to `gc-cons-percentage'. Interpret
+SYMBOL as variable name if VAR, else a function name. Return
+nil if SYMBOL doesn't begin with \"F\" or \"V\"."
+  (let ((string (symbol-name symbol))
+        (prefix (if var "V" "F")))
+    (when (s-starts-with-p prefix string)
+      (intern
+       (s-chop-prefix
+        prefix
+        (s-replace "_" "-" string))))))
+
 ;;;###autoload
 (defun helpful-symbol (symbol)
   "Show help for SYMBOL, a variable, function or macro.
@@ -2410,6 +2424,14 @@ See also `helpful-callable' and `helpful-variable'."
     (helpful-callable symbol))
    ((boundp symbol)
     (helpful-variable symbol))
+   ((let ((fsym (helpful--convert-c-name symbol nil)))
+      (when (fboundp fsym)
+        (helpful-callable fsym)
+        fsym)))
+   ((let ((vsym (helpful--convert-c-name symbol t)))
+      (when (boundp vsym)
+        (helpful-variable vsym)
+        vsym)))
    (t
     (user-error "Not bound: %S" symbol))))
 
diff --git a/test/helpful-unit-test.el b/test/helpful-unit-test.el
@@ -866,3 +866,17 @@ find the source code."
   (helpful-variable 'inhibit-read-only)
   (should
    (s-contains-p "Value\nnil" (buffer-string))))
+
+(ert-deftest helpful--convert-c-name ()
+  (should
+   (equal
+    'make-string
+    (helpful--convert-c-name 'Fmake_string nil)))
+  (should
+   (equal
+    'gc-cons-percentage
+    (helpful--convert-c-name 'Vgc_cons_percentage t)))
+  (should-not
+   (helpful--convert-c-name 'Fmake_string t))
+  (should-not
+   (helpful--convert-c-name 'Vgc_cons_percentage nil)))