1 files changed, 110 insertions, 0 deletions
diff --git a/src/de/fhswf/in/inf/upnfx/util/UPN.java b/src/de/fhswf/in/inf/upnfx/util/UPN.java
new file mode 100644
index 0000000..bc773d5
--- /dev/null
+++ b/src/de/fhswf/in/inf/upnfx/util/UPN.java
@@ -0,0 +1,110 @@
+/**
+ *
+ */
+package de.fhswf.in.inf.upnfx.util;
+
+
+/**
+ * A class that calculates in UPN.
+ *
+ * @author $Author: $
+ * @version $Revision: $, $Date: $ UTC
+ */
+public class UPN
+{
+
+   private ObservableDoubleStack upnStack = new ObservableDoubleStack();
+
+   private Double lastX;
+
+   /**
+    * Empty constructor.
+    *
+    */
+   public UPN()
+   {
+   }
+
+   /**
+    * Reads a string and puts it on the UPN upnStack.
+    *
+    * @param upnString
+    *           A space delimited string in UPN notation.
+    */
+   public final void calculate(Operator operator)
+   {
+      if (operator == null)
+      {
+         throw new IllegalArgumentException("Operator can't be null.");
+      }
+      
+      System.out.println(operator);
+      
+      lastX = upnStack.peek();
+
+      operator.eval(upnStack);
+
+   }
+   
+   public final void addDouble(Double newVal)
+   {
+      if (newVal == null)
+      {
+         throw new IllegalArgumentException("newVal can't be null.");
+      }
+      upnStack.push(newVal);
+   }
+
+   /**
+    * Get the result of a calculation done before.
+    *
+    * @return The top most value on the UPN stack.
+    */
+   public final double getResult()
+   {
+      if (upnStack.isEmpty())
+      {
+         throw new IllegalArgumentException("UPN stack is empty.");
+      }
+      return upnStack.peek();
+   }
+
+   /**
+    * Return the ObservableDoubleStack to tie it to the view.
+    *
+    * @return The ObservableDoubleStack with the operands.
+    */
+   public final ObservableDoubleStack getStack()
+   {
+      return upnStack;
+   }
+
+   /**
+    * Pushes the previous x onto the stack.
+    *
+    */
+   public final void setLastX()
+   {
+      if(lastX != null)
+      {
+         upnStack.push(lastX);
+      }
+   }
+
+   /**
+    * Swap x and y on the stack.
+    *
+    */
+   public final void swapXY()
+   {
+      if(upnStack.size() > 1)
+      {
+         double f1 = upnStack.pop();
+         double f2 = upnStack.pop();
+
+         upnStack.push(f1);
+         upnStack.push(f2);
+      }
+   }
+
+}