Bug 55037: patch for missing function DELTA

Add missing TestDeltaFunctionsFromSpreadsheet and register Delta in AnalysisToolPak

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1529809 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/ss/formula/atp/AnalysisToolPak.java

@@ -91,7 +91,7 @@ public final class AnalysisToolPak implements UDFFinder {
         r(m, "DEC2BIN", null);
         r(m, "DEC2HEX", null);
         r(m, "DEC2OCT", null);
-        r(m, "DELTA", null);
+        r(m, "DELTA", Delta.instance);
         r(m, "DISC", null);
         r(m, "DOLLARDE", null);
         r(m, "DOLLARFR", null);

src/java/org/apache/poi/ss/formula/functions/Delta.java

@@ -17,6 +17,7 @@
 
 package org.apache.poi.ss.formula.functions;
 
+import org.apache.poi.ss.formula.OperationEvaluationContext;
 import org.apache.poi.ss.formula.eval.*;
 
 import java.math.BigDecimal;
@@ -37,7 +38,9 @@ import java.math.BigDecimal;
  *
  * @author cedric dot walter @ gmail dot com
  */
-public final class Delta extends Fixed2ArgFunction {
+public final class Delta extends Fixed2ArgFunction implements FreeRefFunction {
+
+    public static final FreeRefFunction instance = new Delta();
 
     private final static NumberEval ONE = new NumberEval(1);
     private final static NumberEval ZERO = new NumberEval(0);
@@ -72,4 +75,11 @@ public final class Delta extends Fixed2ArgFunction {
         return result == 0 ? ONE : ZERO;
     }
 
+    public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
+         if (args.length == 2) {
+            return evaluate(ec.getRowIndex(), ec.getColumnIndex(), args[0], args[1]);
+        }
+
+        return ErrorEval.VALUE_INVALID;
+    }
 }

src/testcases/org/apache/poi/ss/formula/functions/TestDeltaFunctionsFromSpreadsheet.java

@@ -0,0 +1,13 @@
+package org.apache.poi.ss.formula.functions;
+
+/**
+* Tests DELTA() as loaded from a test data spreadsheet.<p/>
+*
+* @author cedric dot walter @ gmail dot com
+*/
+public class TestDeltaFunctionsFromSpreadsheet extends BaseTestFunctionsFromSpreadsheet {
+
+    protected String getFilename() {
+        return "DeltaFunctionTestCaseData.xls";
+    }
+}