FormulaRecord patch (and testcase) to preserve Excel's NaN representation when dealing with NaN formula value. We currently have NaN support in LittleEndian but the constant for NaN seems to change so we need to preserve the original bits on fill fields. Thanks Glen for your input!

PR: 18114, 18155
Submitted by:	Additional bug report submitted by jsun@teloptica.com (Jerry Sun)


git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@353037 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/hssf/record/FormulaRecord.java

@@ -2,7 +2,7 @@
 /* ====================================================================
  * The Apache Software License, Version 1.1
  *
- * Copyright (c) 2002 The Apache Software Foundation.  All rights
+ * Copyright (c) 2002, 2003 The Apache Software Foundation.  All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -60,11 +60,11 @@
  */
 package org.apache.poi.hssf.record;
 
-import java.util.Stack;
 import java.util.List;
+import java.util.Stack;
 
+import org.apache.poi.hssf.record.formula.Ptg;
 import org.apache.poi.util.LittleEndian;
-import org.apache.poi.hssf.record.formula.*;
 
 /**
  * Formula Record.
@@ -94,6 +94,10 @@ public class FormulaRecord
     private short             field_7_expression_len;
     private Stack             field_8_parsed_expr;
     
+    /**
+     * Since the NaN support seems sketchy (different constants) we'll store and spit it out directly
+     */
+    private byte[]			value_data;
     private byte[]            all_data; //if formula support is not enabled then
                                         //we'll just store/reserialize
 
@@ -141,7 +145,13 @@ public class FormulaRecord
         field_2_column         = LittleEndian.getShort(data, 2 + offset);
         field_3_xf             = LittleEndian.getShort(data, 4 + offset);
         field_4_value          = LittleEndian.getDouble(data, 6 + offset);
-        field_5_options        = LittleEndian.getShort(data, 14 + offset);
+		field_5_options        = LittleEndian.getShort(data, 14 + offset);
+		        
+        if (Double.isNaN(field_4_value)) {
+        	value_data = new byte[8];
+        	System.arraycopy(data, offset+6, value_data, 0, 8);
+        }
+        
         field_6_zero           = LittleEndian.getInt(data, 16 + offset);
         field_7_expression_len = LittleEndian.getShort(data, 20 + offset);
         field_8_parsed_expr    = getParsedExpressionTokens(data, size,
@@ -371,9 +381,19 @@ public class FormulaRecord
         LittleEndian.putShort(data, 4 + offset, ( short ) getRow());
         LittleEndian.putShort(data, 6 + offset, getColumn());
         LittleEndian.putShort(data, 8 + offset, getXFIndex());
-        LittleEndian.putDouble(data, 10 + offset, field_4_value);
+        
+        //only reserialize if the value is still NaN and we have old nan data
+        if (Double.isNaN(this.getValue()) && value_data != null) {        	
+			System.arraycopy(value_data,0,data,10 + offset,value_data.length);
+        } else {
+			LittleEndian.putDouble(data, 10 + offset, field_4_value);
+        }
+        	
         LittleEndian.putShort(data, 18 + offset, getOptions());
-        LittleEndian.putInt(data, 20 + offset, field_6_zero);
+        
+        //when writing the chn field (offset 20), it's supposed to be 0 but ignored on read
+        //Microsoft Excel Developer's Kit Page 318
+        LittleEndian.putInt(data, 20 + offset, 0);
         LittleEndian.putShort(data, 24 + offset, getExpressionLength());
         serializePtgs(data, 26+offset);
         } else {

src/testcases/org/apache/poi/hssf/record/TestFormulaRecord.java

@@ -2,7 +2,7 @@
 /* ====================================================================
  * The Apache Software License, Version 1.1
  *
- * Copyright (c) 2002 The Apache Software Foundation.  All rights
+ * Copyright (c) 2002, 2003 The Apache Software Foundation.  All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -87,6 +87,40 @@ public class TestFormulaRecord
         assertEquals(record.getXFIndex(),(short)4);
     }
     
+    /**
+     * Make sure a NAN value is preserved
+     * This formula record is a representation of =1/0 at row 0, column 0 
+     */
+    public void testCheckNanPreserve() {
+    	byte[] formulaByte = new byte[29];
+    	for (int i = 0; i < formulaByte.length; i++) formulaByte[i] = (byte)0;
+    	formulaByte[4] = (byte)0x0F;
+		formulaByte[6] = (byte)0x02;
+		formulaByte[8] = (byte)0x07;
+		formulaByte[12] = (byte)0xFF;
+		formulaByte[13] = (byte)0xFF;
+		formulaByte[18] = (byte)0xE0;
+		formulaByte[19] = (byte)0xFC;
+		formulaByte[20] = (byte)0x07;
+		formulaByte[22] = (byte)0x1E;
+		formulaByte[23] = (byte)0x01;
+		formulaByte[25] = (byte)0x1E;
+		formulaByte[28] = (byte)0x06;
+    	
+		FormulaRecord record = new FormulaRecord(FormulaRecord.sid, (short)29, formulaByte);
+		assertEquals("Row", 0, record.getRow());
+		assertEquals("Column", 0, record.getColumn());		
+		assertTrue("Value is not NaN", Double.isNaN(record.getValue()));
+		
+		byte[] output = record.serialize();
+		assertEquals("Output size", 33, output.length); //includes sid+recordlength
+		
+		for (int i = 5; i < 13;i++) {
+			assertEquals("FormulaByte NaN doesn't match", formulaByte[i], output[i+4]);
+		}
+		
+    }
+    
     public static void main(String [] ignored_args)
     {
         String filename = System.getProperty("HSSF.testdata.path");