another big refactor

src/lib/Extender.hx

@@ -0,0 +1,69 @@
+package lib;
+
+import haxe.Exception;
+
+class LambdaExtender {
+	/**
+		Returns the first element if there are exectly one element present.
+		Throws exception if not.
+	**/
+	static public function single<T>(it:Iterable<T>):T {
+		var elem:T = null;
+		for (t in it) {
+			if (elem != null) {
+				throw new Exception("Multiple elements found");
+			}
+			elem = t;
+		}
+
+		if (elem == null) {
+			throw new Exception("No element found");
+		}
+
+		return elem;
+	}
+
+	/**
+		Like `single` but when no element was found return the default value.
+	**/
+	static public function singleOrDefault<T>(it:Iterable<T>, defaultValue:T):T {
+		var elem:T = null;
+		for (t in it) {
+			if (elem != null) {
+				throw new Exception("Multiple elements found");
+			}
+			elem = t;
+		}
+
+		if (elem == null) {
+			return defaultValue;
+		}
+
+		return elem;
+	}
+
+	/**
+		Returns the first element.
+		Throws execption if no first element found.
+	**/
+	static public function first<T>(it:Iterable<T>):T {
+		for (t in it) {
+			return t;
+		}
+
+		throw new Exception("No element found");
+	}
+
+	/**
+		Like `first` only if no first element was found it returns the defalt value.
+	**/
+	static public function firstOrDefault<T>(it:Iterable<T>, defaultValue:T):T {
+		var iter = it.iterator();
+
+		if (iter.hasNext()) {
+			return iter.next();
+		}
+
+		return defaultValue;
+	}
+}