[bug-62254] update offset function to support optional offset values

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1828288 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -163,18 +163,20 @@ public final class Offset implements Function {
 
 	@SuppressWarnings("fallthrough")
 	public ValueEval evaluate(ValueEval[] args, int srcCellRow, int srcCellCol) {
-		if(args.length < 3 || args.length > 5) {
+		if(args.length < 1 || args.length > 5) {
 			return ErrorEval.VALUE_INVALID;
 		}
 
 		try {
 			BaseRef baseRef = evaluateBaseRef(args[0]);
-			int rowOffset = evaluateIntArg(args[1], srcCellRow, srcCellCol);
+			// optional arguments
-			int columnOffset = evaluateIntArg(args[2], srcCellRow, srcCellCol);
+			// If offsets are omitted, it is assumed to be 0.
+			int rowOffset = (args[1] instanceof MissingArgEval) ? 0 : evaluateIntArg(args[1], srcCellRow, srcCellCol);
+			int columnOffset = (args[2] instanceof MissingArgEval) ? 0 : evaluateIntArg(args[2], srcCellRow, srcCellCol);
 			int height = baseRef.getHeight();
 			int width = baseRef.getWidth();
 			// optional arguments
-			// If height or width is omitted, it is assumed to be the same height or width as reference.
+			// If height or width are omitted, it is assumed to be the same height or width as reference.
 			switch(args.length) {
 				case 5:
 					if(!(args[4] instanceof MissingArgEval)) {

src/ooxml/testcases/org/apache/poi/xssf/TestXSSFOffset.java

@@ -0,0 +1,48 @@
+/* ====================================================================
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+==================================================================== */
+
+package org.apache.poi.xssf;
+
+import java.io.IOException;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.CellType;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class TestXSSFOffset {
+
+    @Test
+    public void testOffsetWithEmpty23Arguments() throws IOException {
+        try (Workbook workbook = new XSSFWorkbook()) {
+            Cell cell = workbook.createSheet().createRow(0).createCell(0);
+            cell.setCellFormula("OFFSET(B1,,)");
+
+            String value = "EXPECTED_VALUE";
+            Cell valueCell = cell.getRow().createCell(1);
+            valueCell.setCellValue(value);
+
+            workbook.getCreationHelper().createFormulaEvaluator().evaluateAll();
+
+            assertEquals(CellType.STRING, cell.getCachedFormulaResultType());
+            assertEquals(value, cell.getStringCellValue());
+        }
+    }
+}

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

@@ -17,12 +17,18 @@
 
 package org.apache.poi.ss.formula.functions;
 
+import java.io.IOException;
+
 import junit.framework.AssertionFailedError;
 import junit.framework.TestCase;
 
+import org.apache.poi.hssf.usermodel.HSSFWorkbook;
 import org.apache.poi.ss.formula.eval.EvaluationException;
 import org.apache.poi.ss.formula.eval.NumberEval;
 import org.apache.poi.ss.formula.functions.Offset.LinearOffsetRange;
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.CellType;
+import org.apache.poi.ss.usermodel.Workbook;
 
 /**
  * Tests for OFFSET function implementation
@@ -96,4 +102,20 @@ public final class TestOffset extends TestCase {
 		assertTrue(lor.isOutOfBounds(0, 16383));
 		assertFalse(lor.isOutOfBounds(0, 65535));
 	}
+
+	public void testOffsetWithEmpty23Arguments() throws IOException {
+		try (Workbook workbook = new HSSFWorkbook()) {
+			Cell cell = workbook.createSheet().createRow(0).createCell(0);
+			cell.setCellFormula("OFFSET(B1,,)");
+
+			String value = "EXPECTED_VALUE";
+			Cell valueCell = cell.getRow().createCell(1);
+			valueCell.setCellValue(value);
+
+			workbook.getCreationHelper().createFormulaEvaluator().evaluateAll();
+
+			assertEquals(CellType.STRING, cell.getCachedFormulaResultType());
+			assertEquals(value, cell.getStringCellValue());
+		}
+	}
 }