From d0a8a3b18ce00e20621d744e04d842b5cd1780fa Mon Sep 17 00:00:00 2001
From: Yorick Peterse <yorickpeterse@gmail.com>
Date: Sun, 5 Oct 2014 23:46:41 +0200
Subject: [PATCH] Basic support for parsing CSS pseudo classes.

This currently does not yet allow chained pseudo classes, nor does it allow for
pseudos such as nth-child(2n).
---
 lib/oga/css/parser.y                       | 31 +++++++++++++++++++---
 spec/oga/css/parser/pseudo_classes_spec.rb | 18 +++++++++++++
 2 files changed, 46 insertions(+), 3 deletions(-)
 create mode 100644 spec/oga/css/parser/pseudo_classes_spec.rb

diff --git a/lib/oga/css/parser.y b/lib/oga/css/parser.y
index f42dc59..0e76563 100644
--- a/lib/oga/css/parser.y
+++ b/lib/oga/css/parser.y
@@ -14,6 +14,7 @@ rule
   path_member
     : node_test
     | axis
+    | pseudo_class
     ;
 
   path_members
@@ -60,6 +61,11 @@ rule
     | op_members T_HYPHEN_IN   op_members { s(:hyphen_in, val[0],val[2]) }
     ;
 
+  op_members
+    : node_test
+    | string
+    ;
+
   axis
     # x > y
     : node_test T_CHILD node_test
@@ -80,14 +86,33 @@ rule
       }
     ;
 
-  op_members
-    : node_test
-    | string
+  pseudo_class
+    # x:root
+    : node_test T_COLON T_IDENT { s(:pseudo, val[2], val[0]) }
+
+    # x:nth-child(2)
+    | node_test T_COLON T_IDENT T_LPAREN pseudo_args T_RPAREN
+      {
+        s(:pseudo, val[2], val[0], *val[4])
+      }
+    ;
+
+  pseudo_args
+    : pseudo_args pseudo_arg { val[0] << val[1] }
+    | pseudo_arg             { val }
+    ;
+
+  pseudo_arg
+    : integer
     ;
 
   string
     : T_STRING { s(:string, val[0]) }
     ;
+
+  integer
+    : T_INT { s(:int, val[0].to_i) }
+    ;
 end
 
 ---- inner
diff --git a/spec/oga/css/parser/pseudo_classes_spec.rb b/spec/oga/css/parser/pseudo_classes_spec.rb
new file mode 100644
index 0000000..386b8ae
--- /dev/null
+++ b/spec/oga/css/parser/pseudo_classes_spec.rb
@@ -0,0 +1,18 @@
+require 'spec_helper'
+
+describe Oga::CSS::Parser do
+  context 'pseudo classes' do
+    example 'parse the :root pseudo class' do
+      parse_css('x:root').should == s(:pseudo, 'root', s(:test, nil, 'x'))
+    end
+
+    example 'parse the :nth-child pseudo class' do
+      parse_css('x:nth-child(2)').should == s(
+        :pseudo,
+        'nth-child',
+        s(:test, nil, 'x'),
+        s(:int, 2)
+      )
+    end
+  end
+end