From c1fa68fa092201353d3666040c1e89bd31720227 Mon Sep 17 00:00:00 2001
From: Wilfred Hughes <me@wilfred.me.uk>
Date: Sun, 31 Dec 2017 00:33:24 +0000
Subject: Highlight keywords in docstrings

See defface for an example.
---
 CHANGELOG.md |  2 ++
 helpful.el   | 14 ++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5d0c04e..4537037 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ Added disassemble buttons to byte-code functions in symbol properties.
 Fixed an issue with the prompt when setting variables to symbol
 values.
 
+Quoted keywords in docstrings are now highlighted.
+
 # v0.5
 
 Allow function tracing to be enabled/disabled from Helpful buffers.
diff --git a/helpful.el b/helpful.el
index b27e75c..c3f46a9 100644
--- a/helpful.el
+++ b/helpful.el
@@ -542,6 +542,19 @@ blank line afterwards."
                 (-cons* first-line "" (cdr lines)))
       docstring)))
 
+(defun helpful--propertize-keywords (docstring)
+  "Propertize quoted keywords in docstrings."
+  (replace-regexp-in-string
+   ;; Replace all text of the form `foo'.
+   (rx "`"
+       (group ":" symbol-start (+? anything) symbol-end)
+       "'")
+   (lambda (it)
+     (propertize (match-string 1 it)
+                 'face 'font-lock-builtin-face))
+   docstring
+   t t))
+
 (defun helpful--propertize-symbols (docstring)
   "Convert symbol references in docstrings to buttons."
   (replace-regexp-in-string
@@ -640,6 +653,7 @@ unescaping too."
       (helpful--split-first-line)
       (helpful--propertize-info)
       (helpful--propertize-symbols)
+      (helpful--propertize-keywords)
       (s-trim)))
 
 (helpful--format-docstring "(apply '+ 1 '(1 2))")
-- 
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