From d47030fdf3eb4d295f139b3b161a82370b25f721 Mon Sep 17 00:00:00 2001
From: Adrian Cochrane <adrian@openwork.nz>
Date: Mon, 17 Jun 2019 17:04:41 +1200
Subject: [PATCH] Handle !important CSS declarations.

---
 src/Stylish/Style/Selector.hs             |  9 +++----
 src/Stylish/Style/Selector/Importance.hs  | 29 +++++++++++++++++++++++
 src/Stylish/Style/Selector/Specificity.hs |  2 +-
 test/Test.hs                              |  2 +-
 4 files changed, 36 insertions(+), 6 deletions(-)
 create mode 100644 src/Stylish/Style/Selector/Importance.hs

diff --git a/src/Stylish/Style/Selector.hs b/src/Stylish/Style/Selector.hs
index 308df4c..98b9701 100644
--- a/src/Stylish/Style/Selector.hs
+++ b/src/Stylish/Style/Selector.hs
@@ -5,13 +5,14 @@ module Stylish.Style.Selector(
 import Stylish.Style.Selector.Index
 import Stylish.Style.Selector.Interpret
 import Stylish.Style.Selector.Specificity
+import Stylish.Style.Selector.Importance
 import Stylish.Style.Selector.Common
 
-ruleStore = OrderedRuleStore (InterpretedRuleStore styleIndex) 0
+ruleStore = ImportanceSplitter $ OrderedRuleStore (InterpretedRuleStore styleIndex) 0
 
-data QueryableStyleSheet = QueryableStyleSheet {
-    store :: RuleStore,
+data QueryableStyleSheet store = QueryableStyleSheet {
+    store :: store,
     priority :: Int -- author vs user agent vs user styles
 }
 
-queryableStyleSheet = QueryableStyleSheet {store = ruleStore, proirity = 0}
+queryableStyleSheet = QueryableStyleSheet {store = ruleStore, priority = 0}
diff --git a/src/Stylish/Style/Selector/Importance.hs b/src/Stylish/Style/Selector/Importance.hs
new file mode 100644
index 0000000..35c88e2
--- /dev/null
+++ b/src/Stylish/Style/Selector/Importance.hs
@@ -0,0 +1,29 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Stylish.Style.Selector.Importance (
+        splitProperties, ImportanceSplitter(..)
+    ) where
+
+import Data.CSS.Syntax.Tokens
+import Data.Text.Internal (Text(..))
+import Stylish.Parse (StyleRule(..))
+import Stylish.Style.Selector.Common
+
+type Property = (Text, [Token])
+splitProperties :: [Property] -> ([Property], [Property])
+splitProperties (prop@(name, value):rest)
+        | (Ident "important":Delim '!':value') <- reverse value =
+            (unimportant, (name, reverse value'):important)
+        | otherwise = (prop:unimportant, important)
+    where (unimportant, important) = splitProperties rest
+
+data ImportanceSplitter a = ImportanceSplitter a
+instance RuleStore inner => RuleStore (ImportanceSplitter inner) where
+    addStyleRule (ImportanceSplitter self) priority rule =
+            ImportanceSplitter $ addStyleRule (
+                addStyleRule self (negate priority) $ buildRule important
+            ) priority $ buildRule unimportant
+        where
+            (important, unimportant) = splitProperties properties
+            (StyleRule selector properties) = inner rule
+            buildRule properties = rule {inner = StyleRule selector properties}
+    lookupRules (ImportanceSplitter self) el = lookupRules self el
diff --git a/src/Stylish/Style/Selector/Specificity.hs b/src/Stylish/Style/Selector/Specificity.hs
index 0b9d6f0..6b809d8 100644
--- a/src/Stylish/Style/Selector/Specificity.hs
+++ b/src/Stylish/Style/Selector/Specificity.hs
@@ -1,5 +1,5 @@
 module Stylish.Style.Selector.Specificity(
-        OrderedRuleStore
+        OrderedRuleStore(..)
     ) where
 
 import Stylish.Parse.Selector
diff --git a/test/Test.hs b/test/Test.hs
index acc47d4..d60ddbd 100644
--- a/test/Test.hs
+++ b/test/Test.hs
@@ -9,8 +9,8 @@ import Stylish.Parse
 import Stylish.Style.Selector.Index
 import Stylish.Element
 import Stylish.Style.Selector.Interpret
-import Stylish.Style.Selector.Specificity
 import Stylish.Style.Selector.Common
+import Stylish.Style.Selector
 
 main = hspec spec
 
-- 
2.30.2