From 673864cdc5264e90837afbb92aaa1c96fb2ec567 Mon Sep 17 00:00:00 2001
From: Nick Burch <nick@apache.org>
Date: Fri, 23 Aug 2013 19:00:01 +0000
Subject: [PATCH] More unit tests for column conversion, and avoid the use of
 Math.pow based on the suggestion from github-6

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1516983 13f79535-47bb-0310-9956-ffa450edef68
---
 .../org/apache/poi/ss/util/CellReference.java   | 17 +++++++----------
 .../apache/poi/hssf/util/TestCellReference.java | 11 +++++++++++
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/java/org/apache/poi/ss/util/CellReference.java b/src/java/org/apache/poi/ss/util/CellReference.java
index c9bea9fd1..3bd7ba908 100644
--- a/src/java/org/apache/poi/ss/util/CellReference.java
+++ b/src/java/org/apache/poi/ss/util/CellReference.java
@@ -170,22 +170,19 @@ public class CellReference {
 	 * @return zero based column index
 	 */
 	public static int convertColStringToIndex(String ref) {
-
-		int pos = 0;
 		int retval=0;
-		for (int k = ref.length()-1; k >= 0; k--) {
-			char thechar = ref.charAt(k);
+		char[] refs = ref.toUpperCase().toCharArray();
+		for (int k=0; k<refs.length; k++) {
+			char thechar = refs[k];
 			if (thechar == ABSOLUTE_REFERENCE_MARKER) {
 				if (k != 0) {
 					throw new IllegalArgumentException("Bad col ref format '" + ref + "'");
 				}
-				break;
+				continue;
 			}
-			// Character.getNumericValue() returns the values
-			//  10-35 for the letter A-Z
-			int shift = (int)Math.pow(26, pos);
-			retval += (Character.getNumericValue(thechar)-9) * shift;
-			pos++;
+			
+			// Character is uppercase letter, find relative value to A
+			retval = (retval * 26) + (thechar - 'A' + 1);
 		}
 		return retval-1;
 	}
diff --git a/src/testcases/org/apache/poi/hssf/util/TestCellReference.java b/src/testcases/org/apache/poi/hssf/util/TestCellReference.java
index 2e1a775a0..79fc876e9 100644
--- a/src/testcases/org/apache/poi/hssf/util/TestCellReference.java
+++ b/src/testcases/org/apache/poi/hssf/util/TestCellReference.java
@@ -44,6 +44,17 @@ public final class TestCellReference extends TestCase {
         assertEquals("ZZ", CellReference.convertNumToColString(701));
         assertEquals("AAA", CellReference.convertNumToColString(702));
         assertEquals("ZZZ", CellReference.convertNumToColString(18277));
+        
+        // Absolute references are allowed for the string ones
+        assertEquals(0, CellReference.convertColStringToIndex("$A"));
+        assertEquals(25, CellReference.convertColStringToIndex("$Z"));
+        assertEquals(26, CellReference.convertColStringToIndex("$AA"));
+        
+        // $ sign isn't allowed elsewhere though
+        try {
+            CellReference.convertColStringToIndex("A$B$");
+            fail("Column reference is invalid and shouldn't be accepted");
+        } catch (IllegalArgumentException e) {}
     }
 
     public void testAbsRef1(){