Performance Experiment for the Xls Writer, to avoid creating empty cells; and should also be slightly faster

Author: MarkBaker

src/PhpSpreadsheet/Writer/Xls.php

@@ -4,6 +4,7 @@
 
 use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
 use PhpOffice\PhpSpreadsheet\Calculation\Functions;
+use PhpOffice\PhpSpreadsheet\Cell\Cell;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\RichText\RichText;
 use PhpOffice\PhpSpreadsheet\RichText\Run;
@@ -161,8 +162,9 @@ public function save($filename, int $flags = 0): void
 
         // add fonts from rich text eleemnts
         for ($i = 0; $i < $countSheets; ++$i) {
-            foreach ($this->writerWorksheets[$i]->phpSheet->getCoordinates() as $coordinate) {
-                $cell = $this->writerWorksheets[$i]->phpSheet->getCell($coordinate);
+            foreach ($this->writerWorksheets[$i]->phpSheet->getCellCollection()->getCoordinates() as $coordinate) {
+                /** @var Cell $cell */
+                $cell = $this->writerWorksheets[$i]->phpSheet->getCellCollection()->get($coordinate);
                 $cVal = $cell->getValue();
                 if ($cVal instanceof RichText) {
                     $elements = $cVal->getRichTextElements();

src/PhpSpreadsheet/Writer/Xls/Worksheet.php

@@ -3,6 +3,7 @@
 namespace PhpOffice\PhpSpreadsheet\Writer\Xls;
 
 use GdImage;
+use PhpOffice\PhpSpreadsheet\Cell\Cell;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Cell\DataType;
 use PhpOffice\PhpSpreadsheet\Exception as PhpSpreadsheetException;
@@ -406,8 +407,9 @@ public function close(): void
         }
 
         // Write Cells
-        foreach ($phpSheet->getCoordinates() as $coordinate) {
-            $cell = $phpSheet->getCell($coordinate);
+        foreach ($phpSheet->getCellCollection()->getSortedCoordinates() as $coordinate) {
+            /** @var Cell $cell */
+            $cell = $phpSheet->getCellCollection()->get($coordinate);
             $row = $cell->getRow() - 1;
             $column = Coordinate::columnIndexFromString($cell->getColumn()) - 1;
 

src/PhpSpreadsheet/Writer/Xlsx/StringTable.php

@@ -2,6 +2,7 @@
 
 namespace PhpOffice\PhpSpreadsheet\Writer\Xlsx;
 
+use PhpOffice\PhpSpreadsheet\Cell\Cell;
 use PhpOffice\PhpSpreadsheet\Cell\DataType;
 use PhpOffice\PhpSpreadsheet\RichText\RichText;
 use PhpOffice\PhpSpreadsheet\RichText\Run;
@@ -36,6 +37,7 @@ public function createStringTable(Worksheet $worksheet, $existingTable = null)
 
         // Loop through cells
         foreach ($worksheet->getCellCollection()->getCoordinates() as $coordinate) {
+            /** @var Cell $cell */
             $cell = $worksheet->getCellCollection()->get($coordinate);
             $cellValue = $cell->getValue();
             if (