Add support for Ruby/Rails hashes (class: "...")

See #1.

README.markdown

@@ -1,15 +1,22 @@
 # tcs - Tailwind Class Sorter
 
-A standalone script which sorts the classes in your HTML following Tailwind's [recommended class order](https://tailwindcss.com/blog/automatic-class-sorting-with-prettier#how-classes-are-sorted).  It does not require [Prettier](https://tailwindcss.com/docs/editor-setup#automatic-class-sorting-with-prettier).
+A standalone script which sorts the classes in your markup following Tailwind's [recommended class order](https://tailwindcss.com/blog/automatic-class-sorting-with-prettier#how-classes-are-sorted).  It does not require [Prettier](https://tailwindcss.com/docs/editor-setup#automatic-class-sorting-with-prettier).
 
 You can run it on the command line or integrate it with your text editor.
 
 
 ## Features
 
-- It sorts the classes in your HTML according to Tailwind's recommended order.
-- It leaves the rest of your HTML alone.
+- It sorts the classes in your markup according to Tailwind's recommended order.
+- It leaves the rest of your markup alone.
 - It does not require Prettier.
+- Supports HTML class attributes (`class="..."`) and Ruby/Rails hashes (`class: "..."`).
+
+
+## Constraints
+
+- Your class names have to be enclosed with double- (not single-) quotation marks (`<p class="...">`).
+- [Slim] You have to use `class="foo bar"` rather than the `.foo.bar` class shortcut.
 
 
 ## Installation

tcs

@@ -11,9 +11,12 @@ class Tcs
     [,{]
   /x
 
-  # Class declaration in HTML, i.e. the stuff inside the quotation marks
-  # in `class="..."`.
-  CLASS_LIST = /(?<=class=")([^"]+)(?=")/
+  # Class declaration in markup, i.e. the stuff inside the quotation marks
+  # in `class="..."` or `class: "..."`.
+  #
+  # Note that the lookbehind alternatives have to be fixed-length so we cannot
+  # match a variable number of spaces after `class:`.
+  CLASS_LIST = /(?<=class="|class:\s")([^"]+)(?=")/
 
   # modifier -> css
   PSEUDO_CLASSES = {

test/fixtures/rails.expected.html

@@ -0,0 +1 @@
+= link_to "Home", root_path, class: "bg-sky-700 px-4 py-2 text-white hover:bg-sky-800 sm:px-8 sm:py-3"

test/fixtures/rails.html

@@ -0,0 +1 @@
+= link_to "Home", root_path, class: "text-white px-4 sm:px-8 py-2 sm:py-3 bg-sky-700 hover:bg-sky-800"