unescape css identifiers to allow use in css queries

lib/nokogiri/css/parser.y

@@ -55,7 +55,7 @@ rule
     | simple_selector
     ;
   class
-    : '.' IDENT { result = Node.new(:CLASS_CONDITION, [val[1]]) }
+    : '.' IDENT { result = Node.new(:CLASS_CONDITION, [unescape_css_identifier(val[1])]) }
     ;
   element_name
     : namespaced_ident
@@ -218,7 +218,7 @@ rule
     | negation
     ;
   attribute_id
-    : HASH { result = Node.new(:ID, val) }
+    : HASH { result = Node.new(:ID, [unescape_css_identifier(val.first)]) }
     ;
   attrib_val_0or1
     : eql_incl_dash IDENT { result = [val.first, val[1]] }
@@ -254,3 +254,8 @@ end
 
 require 'nokogiri/css/parser_extras'
 
+---- inner
+
+def unescape_css_identifier(identifier)
+  identifier.gsub(/\\(?:([^0-9a-fA-F])|([0-9a-fA-F]{1,6})\s?)/){ |m| $1 || [$2.hex].pack('U') }
+end

test/css/test_parser.rb

@@ -160,7 +160,7 @@ def test_standard_nth_selectors
         assert_xpath '//a[position() = 1]',             @parser.parse('a:first-of-type') # no parens
         assert_xpath "//a[contains(concat(' ', normalize-space(@class), ' '), ' b ')][position() = 1]",
                      @parser.parse('a.b:first-of-type') # no parens
-        assert_xpath '//a[position() = 99]',            @parser.parse('a:nth-of-type(99)') 
+        assert_xpath '//a[position() = 99]',            @parser.parse('a:nth-of-type(99)')
         assert_xpath "//a[contains(concat(' ', normalize-space(@class), ' '), ' b ')][position() = 99]",
                      @parser.parse('a.b:nth-of-type(99)')
         assert_xpath '//a[position() = last()]',        @parser.parse('a:last-of-type()')
@@ -259,6 +259,10 @@ def test_attribute
 
       def test_id
         assert_xpath "//*[@id = 'foo']", @parser.parse('#foo')
+        assert_xpath "//*[@id = 'escape:needed,']", @parser.parse('#escape\:needed\,')
+        assert_xpath "//*[@id = 'escape:needed,']", @parser.parse('#escape\3Aneeded\,')
+        assert_xpath "//*[@id = 'escape:needed,']", @parser.parse('#escape\3A needed\2C')
+        assert_xpath "//*[@id = 'escape:needed']", @parser.parse('#escape\00003Aneeded')
       end
 
       def test_pseudo_class_no_ident
@@ -294,6 +298,8 @@ def test_class
                       @parser.parse('foo.awesome')
         assert_xpath  "//foo//*[contains(concat(' ', normalize-space(@class), ' '), ' awesome ')]",
                       @parser.parse('foo .awesome')
+        assert_xpath  "//foo//*[contains(concat(' ', normalize-space(@class), ' '), ' awe.some ')]",
+                      @parser.parse('foo .awe\.some')
       end
 
       def test_bare_not