Add a class toggle binding, data-class-[class].

@@ -17,6 +17,7 @@ class Rivets.Binding
   constructor: (@el, @type, @model, @keypath, @options = {}) ->
   constructor: (@el, @type, @model, @keypath, @options = {}) ->
     @routine = switch @options.special
     @routine = switch @options.special
       when "event"     then eventBinding @type
       when "event"     then eventBinding @type
+      when "class"     then classBinding @type
       when "iteration" then iterationBinding @type
       when "iteration" then iterationBinding @type
       else Rivets.routines[@type] || attributeBinding @type
       else Rivets.routines[@type] || attributeBinding @type
 
 
@@ -118,6 +119,7 @@ class Rivets.View
     iterator = null
     iterator = null
     bindingRegExp = @bindingRegExp()
     bindingRegExp = @bindingRegExp()
     eventRegExp = /^on-/
     eventRegExp = /^on-/
+    classRegExp = /^class-/
     iterationRegExp = /^each-/
     iterationRegExp = /^each-/
 
 
     parseNode = (node) =>
     parseNode = (node) =>
@@ -153,6 +155,10 @@ class Rivets.View
                 type = type.replace eventRegExp, ''
                 type = type.replace eventRegExp, ''
                 options.special = "event"
                 options.special = "event"
 
 
+              if classRegExp.test type
+                type = type.replace classRegExp, ''
+                options.special = "class"
+
               if iterationRegExp.test type
               if iterationRegExp.test type
                 type = type.replace iterationRegExp, ''
                 type = type.replace iterationRegExp, ''
                 options.special = "iteration"
                 options.special = "iteration"
@@ -208,6 +214,17 @@ eventBinding = (event) -> (el, bind, unbind) ->
   bindEvent el, event, bind if bind
   bindEvent el, event, bind if bind
   unbindEvent el, event, unbind if unbind
   unbindEvent el, event, unbind if unbind
 
 
+# Returns a class binding routine for the specified class name.
+classBinding = (name) -> (el, value) ->
+  elClass = " #{el.className} "
+  hasClass = elClass.indexOf(" #{name} ") != -1
+
+  if !value is hasClass
+    el.className = if value
+      "#{el.className} #{name}"
+    else
+      elClass.replace(" #{name} ", " ").trim()
+
 # Returns an iteration binding routine for the specified collection.
 # Returns an iteration binding routine for the specified collection.
 iterationBinding = (name) -> (el, collection, binding) ->
 iterationBinding = (name) -> (el, collection, binding) ->
   if binding.iterated?
   if binding.iterated?