Add support for empty sheets

src/Spout/Reader/XLSX.php

@@ -190,9 +190,11 @@ protected function read()
         while ($this->xmlReader->read()) {
             if ($this->xmlReader->nodeType == \XMLReader::ELEMENT && $this->xmlReader->name === 'dimension') {
                 // Read dimensions of the worksheet
-                $dimensionRef = $this->xmlReader->getAttribute('ref'); // returns 'A1:M13' for instance
-                list(, $lastCellIndex) = explode(':', $dimensionRef);
-                $this->numberOfColumns = CellHelper::getColumnIndexFromCellIndex($lastCellIndex) + 1;
+                $dimensionRef = $this->xmlReader->getAttribute('ref'); // returns 'A1:M13' for instance (or 'A1' for empty sheet)
+                if (preg_match('/[A-Z\d]+:([A-Z\d]+)/', $dimensionRef, $matches)) {
+                    $lastCellIndex = $matches[1];
+                    $this->numberOfColumns = CellHelper::getColumnIndexFromCellIndex($lastCellIndex) + 1;
+                }
             } else if ($this->xmlReader->nodeType == \XMLReader::ELEMENT && $this->xmlReader->name === 'row') {
                 // Start of the row description
                 $isInsideRowTag = true;

tests/Spout/Reader/XLSXTest.php

@@ -165,6 +165,15 @@ public function testReadShouldBeProtectedAgainstBillionLaughsAttack()
         $this->assertEquals($expectedFirstRow, $allRows[0], 'Entities should be ignored when reading XML files.');
     }
 
+    /**
+     * @return void
+     */
+    public function testReadShouldBeAbleToProcessEmptySheets()
+    {
+        $allRows = $this->getAllRowsForFile('sheet_with_no_cells.xlsx');
+        $this->assertEquals([], $allRows, 'Sheet with no cells should be correctly processed.');
+    }
+
     /**
      * @param string $fileName
      * @return array All the read rows the given file