Closes lift#1158. data-lift no longer causes stack overflow. Transien…

…tSnippet trait added

web/webkit/src/main/scala/net/liftweb/http/LiftSession.scala

@@ -1540,8 +1540,9 @@ class LiftSession(private[http] val _contextPath: String, val uniqueId: String,
         first(LiftRules.snippetNamesToSearch.vend(tagName)) {
           nameToTry =>
             val ret = findSnippetInstance(nameToTry)
-            // Update the snippetMap so that we reuse the same instance in this request
-            ret.foreach(s => snippetMap.set(snippetMap.is.updated(tagName, s)))
+            // Update the snippetMap so that we reuse the same instance in this request (unless the snippet is transient)
+            ret.filter(TransientSnippet.notTransient(_)).foreach(s => snippetMap.set(snippetMap.is.updated(tagName, s)))
+
             ret
         }
       }
@@ -2241,7 +2242,7 @@ private object SnippetNode {
           if (p.pre == "l" || p.pre == "lift") && p.key == "parallel"
         => par = true
 
-        case up: UnprefixedAttribute if up.key == "lift" => // ignore
+        case up: UnprefixedAttribute if up.key == "lift" || up.key == "data-lift" => // ignore
 
         case p: PrefixedAttribute
           if p.pre == "lift" && p.key == "snippet"

web/webkit/src/main/scala/net/liftweb/http/StatefulSnippet.scala

@@ -167,6 +167,31 @@ trait DispatchSnippet {
   def dispatch: DispatchIt
 }
 
+/**
+ * This trait indicates if the snippet instance should be kept around for the duration of
+ * the Request.  There are cases when you don't want a snippet to be kept around.
+ */
+trait TransientSnippet {
+
+  /**
+   * Calculate if this snippet should be treated as transiet.
+   */
+  def transient_? = true
+}
+
+/**
+ * The companion object to the TransientSnippet trait
+ */
+object TransientSnippet {
+  /**
+   * Compute if the instance should be treated as transient
+   */
+  def notTransient(obj: Any): Boolean = obj match {
+    case t: TransientSnippet => !t.transient_?
+    case _ => true
+  }
+}
+
 /**
  * Mix this snippet into any snippet.  If the snippet is invoked in response to a
  * stateless request, then the behavior method is called with the method name of