Added CometObs.scala to the repo

farquet · Jun 6, 2014 · a3d83cd · a3d83cd
1 parent 841d201
commit a3d83cd
Showing 1 changed file with 48 additions and 0 deletions.
diff --git a/CometObs.scala b/CometObs.scala
@@ -0,0 +1,48 @@
+package controllers
+
+import play.api.templates.Html
+import scala.collection.mutable.Map
+import rx.lang.scala.Observable
+import rx.lang.scala._
+
+import ImplicitFunctionConversions._
+import JavaConversions._
+
+object CometObs {
+
+  /**
+   * Transform an Observable into a Comet Observable.
+   *
+   * @tparam E Type of messages handled by this comet stream.
+   * @param callback Javascript function to call on the browser for each message.
+   * @param initialChunk Initial chunk of data to send for browser compatibility (default to send 5Kb of blank data)
+   */
+
+  def apply[E](obs: Observable[E], callback: String, initialChunk: Html = Html(Array.fill[Char](5 * 1024)(' ').mkString + "<html><body>")): Observable[Html] = {
+
+    val obsNext: Observable[Html] = convertToJsFunction(obs, callback)
+
+    if (initialChunk != null) {
+      val obsInit: Observable[Html] = Observable.from(List(initialChunk))
+      obsInit ++ obsNext
+    } else {
+      obsNext
+    }
+  }
+
+  def apply[E](obsMap: Map[String, Observable[E]], initialChunk: Html = Html(Array.fill[Char](5 * 1024)(' ').mkString + "<html><body>")): Observable[Html] = {
+
+    val obsInit: Observable[Html] = Observable.from(List(initialChunk))
+
+    val htmlObsList = obsMap.map(el => convertToJsFunction(el._2, el._1))
+
+    // merging all observables from the list of callback functions with corresponding values to a single observable of everything
+    obsInit ++ htmlObsList.reduceLeft((a, b) => a.mergeDelayError(b))
+  }
+
+  private def convertToJsFunction[E](obs: Observable[E], callback: String): Observable[Html] = {
+    obs.map[Html](data => Html("<script type=\"text/javascript\">" + callback + "(\"" + escapeString(data.toString) + "\");</script>"))
+  }
+
+  private def escapeString(str : String) = str.replace("\\","\\\\").replace("\n","\\n").replace("\b","\\b").replace("\r","\\r").replace("\t","\\t").replace("\'","\\'").replace("\f","\\f").replace("\"","\\\"")
+}