1 files changed, 47 insertions, 0 deletions
diff --git a/src/de/fhswf/in/inf/upnfx/util/UnaryOperator.java b/src/de/fhswf/in/inf/upnfx/util/UnaryOperator.java
new file mode 100644
index 0000000..be44b16
--- /dev/null
+++ b/src/de/fhswf/in/inf/upnfx/util/UnaryOperator.java
@@ -0,0 +1,47 @@
+/**
+ *
+ */
+package de.fhswf.in.inf.upnfx.util;
+
+
+/**
+ * An abstract class for calculations with unary operators.
+ *
+ * @author $Author: $
+ * @version $Revision: $, $Date: $ UTC
+ */
+public abstract class UnaryOperator implements Operator
+{
+   /*
+    * (non-Javadoc)
+    *
+    * @see de.fhswf.in.inf.java1.aufgabe12.Operator#eval(java.util.Stack)
+    */
+   @Override
+   public final void eval(ObservableDoubleStack stack)
+   {
+      if (stack == null)
+      {
+         throw new IllegalArgumentException("Stack must not be null.");
+      }
+
+      if (stack.size() < 1)
+      {
+         throw new IllegalArgumentException(
+               "Unary operation requires one operand.");
+      }
+
+      double d = stack.pop();
+
+      stack.push(eval(d));
+   }
+
+   /**
+    * This class implements the calculation.
+    *
+    * @param d
+    *           The unary operator.
+    * @return The result of the calculation.
+    */
+   abstract double eval(double d);
+}