add support for columns AA-ZZ

src/main/java/edu/harvard/iq/dataverse/ingest/tabulardata/impl/plugins/xlsx/XLSXFileReader.java

@@ -359,21 +359,43 @@ public void startElement(String uri, String localName, String name,
             cellContents = "";
         }
 
+        /* Works from 1-702 columns. Could be made recursive to work beyond that*/
         private int getColumnCount(String columnTag) {
             int count = -1;
             if (columnTag.length() == 1 && columnTag.matches("[A-Z]")) {
                 count = columnTag.charAt(0) - 'A';
             } else {
-                dbglog.warning("Unsupported column index tag: "+columnTag);
+                if (columnTag.length() == 2) {
+                    int c1 = columnTag.charAt(0) - 'A';
+                    int c2 = columnTag.charAt(1) - 'A';
+                    if (c1 >= 0 && c1 < 26 && c2 >= 0 && c2 < 26) {
+                        dbglog.fine(columnTag + ": " + ((c1 + 1) * 26 + c2));
+                        return ((c1 + 1) * 26 + c2);
+                    } else {
+                        dbglog.warning("Unsupported column index tag: " + columnTag);
+                    }
+                } else {
+                    dbglog.warning("Unsupported column index tag: " + columnTag);
+                }
             }
 
             return count;
         }
-
+        /* Supports A-Z and AA-ZZ (0-701 column count/position) */
         private String getColumnLetterTag(int columnCount) {
             if (columnCount < 0 || columnCount > 25) {
-                dbglog.warning("Multi-letter column codes not yet supported.");
-                return null; 
+                if(columnCount >25 && columnCount < 702) { //AA-ZZ
+                    int code1 = 'A' + columnCount/26 -1;
+                    int code2 = 'A' + columnCount%26;
+                    char[] letterTag = new char[2]; 
+                    letterTag[0] = (char)code1;
+                    letterTag[1] = (char)code2;
+                    dbglog.fine(columnCount + ": " + new String(letterTag));
+                    return new String(letterTag);
+                } else {
+                    dbglog.warning("3+ letter column codes not yet supported.");
+                    return null;
+                }
             }
             int letterCode = 'A' + columnCount;
             char[] letterTag = new char[1];