Add AREAS function

src/java/org/apache/poi/ss/formula/eval/FunctionEval.java

@@ -139,6 +139,7 @@ private static Function[] produceFunctions() {
         retval[73] = CalendarFieldFunction.SECOND;
         retval[74] = new Now();
         // 75: AREAS
+        retval[75] = new Areas();
         retval[76] = new Rows();
         retval[77] = new Columns();
         retval[FunctionID.OFFSET] = new Offset(); //nominally 78

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

@@ -0,0 +1,35 @@
+package org.apache.poi.ss.formula.functions;
+
+import org.apache.poi.ss.formula.eval.ErrorEval;
+import org.apache.poi.ss.formula.eval.NumberEval;
+import org.apache.poi.ss.formula.eval.RefListEval;
+import org.apache.poi.ss.formula.eval.ValueEval;
+import org.apache.poi.ss.formula.ptg.NumberPtg;
+
+/**
+ * Returns the number of areas in a reference. An area is a range of contiguous cells or a single cell.
+ *
+ * @author Loopbing (loopbing@gmail.com)
+ */
+public final class Areas implements Function {
+
+    @Override
+    public ValueEval evaluate(ValueEval[] args, int srcRowIndex, int srcColumnIndex) {
+        if (args.length == 0) {
+            return ErrorEval.VALUE_INVALID;
+        }
+        try {
+            ValueEval valueEval = args[0];
+            int result = 1;
+            if (valueEval instanceof RefListEval) {
+                RefListEval refListEval = (RefListEval) valueEval;
+                result = refListEval.getList().size();
+            }
+            NumberEval numberEval = new NumberEval(new NumberPtg(result));
+            return numberEval;
+        } catch (Exception e) {
+            return ErrorEval.VALUE_INVALID;
+        }
+
+    }
+}

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

@@ -57,6 +57,7 @@ Licensed to the Apache Software Foundation (ASF) under one or more
     TestValue.class,
     TestXYNumericFunction.class,
     TestAddress.class,
+    TestAreas.class,
     TestClean.class
 })
 public class AllIndividualFunctionEvaluationTests {

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

@@ -0,0 +1,42 @@
+package org.apache.poi.ss.formula.functions;
+
+import junit.framework.TestCase;
+import org.apache.poi.hssf.usermodel.HSSFCell;
+import org.apache.poi.hssf.usermodel.HSSFFormulaEvaluator;
+import org.apache.poi.hssf.usermodel.HSSFWorkbook;
+import org.apache.poi.ss.formula.eval.ErrorEval;
+import org.apache.poi.ss.formula.eval.NumberEval;
+import org.apache.poi.ss.usermodel.CellType;
+import org.apache.poi.ss.usermodel.CellValue;
+
+public final class TestAreas extends TestCase {
+
+    public void testAreas() {
+        HSSFWorkbook wb = new HSSFWorkbook();
+        HSSFCell cell = wb.createSheet().createRow(0).createCell(0);
+        HSSFFormulaEvaluator fe = new HSSFFormulaEvaluator(wb);
+
+        String formulaText = "AREAS(B1)";
+        confirmResult(fe, cell, formulaText,1.0);
+
+        formulaText = "AREAS(B2:D4)";
+        confirmResult(fe, cell, formulaText,1.0);
+
+        formulaText = "AREAS((B2:D4,E5,F6:I9))";
+        confirmResult(fe, cell, formulaText,3.0);
+
+        formulaText = "AREAS((B2:D4,E5,C3,E4))";
+        confirmResult(fe, cell, formulaText,4.0);
+
+        formulaText = "AREAS((I9))";
+        confirmResult(fe, cell, formulaText,1.0);
+    }
+
+    private static void confirmResult(HSSFFormulaEvaluator fe, HSSFCell cell, String formulaText,Double expectedResult) {
+        cell.setCellFormula(formulaText);
+        fe.notifyUpdateCell(cell);
+        CellValue result = fe.evaluate(cell);
+        assertEquals(result.getCellTypeEnum(), CellType.NUMERIC);
+        assertEquals(expectedResult, result.getNumberValue());
+    }
+}