Changes to INDEX Function

Fix #64 (really!), closed as stale in December 2017, another in our "better late than never" series. Excel's INDEX function doesn't really behave quite as described. If a single row is used as an argument, either in literal form `{item1, item2, item3}` or expressed as a range `A1:A6`, INDEX is happy to evaluate the array as if each entry were a row rather than a single item. PhpSpreadsheet is changed to do likewise.

INDEX also returned `#REF!` when it would normally return an array (which would often be reduced to its leftmost topmost entry later). This code is deleted, invalidating one existing test, and INDEX will now operate like other functions which can return arrays.

Author: oleibman

src/PhpSpreadsheet/Calculation/LookupRef/Matrix.php

@@ -81,7 +81,6 @@ public static function index(mixed $matrix, mixed $rowNum = 0, mixed $columnNum
         }
 
         $rowNum = $rowNum ?? 0;
-        $originalColumnNum = $columnNum;
         $columnNum = $columnNum ?? 0;
 
         try {
@@ -91,6 +90,17 @@ public static function index(mixed $matrix, mixed $rowNum = 0, mixed $columnNum
             return $e->getMessage();
         }
 
+        if (is_array($matrix) && count($matrix) === 1 && $rowNum > 1) {
+            $matrixKey = array_keys($matrix)[0];
+            if (is_array($matrix[$matrixKey])) {
+                $tempMatrix = [];
+                foreach ($matrix[$matrixKey] as $key => $value) {
+                    $tempMatrix[$key] = [$value];
+                }
+                $matrix = $tempMatrix;
+            }
+        }
+
         if (!is_array($matrix) || ($rowNum > count($matrix))) {
             return ExcelError::REF();
         }
@@ -101,9 +111,6 @@ public static function index(mixed $matrix, mixed $rowNum = 0, mixed $columnNum
         if ($columnNum > count($columnKeys)) {
             return ExcelError::REF();
         }
-        if ($originalColumnNum === null && 1 < count($columnKeys)) {
-            return ExcelError::REF();
-        }
 
         if ($columnNum === 0) {
             return self::extractRowValue($matrix, $rowKeys, $rowNum);

tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/IndexOnSpreadsheetTest.php

@@ -34,4 +34,37 @@ public static function providerINDEXonSpreadsheet(): array
     {
         return require 'tests/data/Calculation/LookupRef/INDEXonSpreadsheet.php';
     }
+
+    /**
+     * @dataProvider providerIndexLiteralArrays
+     */
+    public function testLiteralArrays(mixed $expectedResult, string $indexArgs): void
+    {
+        $sheet = $this->getSheet();
+        $sheet->getCell('A10')->setValue(10);
+        $sheet->getCell('B10')->setValue(11);
+        $sheet->getCell('C10')->setValue(12);
+        $sheet->getCell('D10')->setValue(13);
+        $sheet->getCell('X10')->setValue(10);
+        $sheet->getCell('X11')->setValue(11);
+        $sheet->getCell('X12')->setValue(12);
+        $sheet->getCell('X13')->setValue(13);
+        $sheet->getCell('A1')->setValue("=INDEX($indexArgs)");
+        $result = $sheet->getCell('A1')->getCalculatedValue();
+        self::assertEquals($expectedResult, $result);
+    }
+
+    public static function providerIndexLiteralArrays(): array
+    {
+        return [
+            'issue 64' => ['Fourth', '{"First","Second","Third","Fourth","Fifth","Sixth","Seventh"}, 4'],
+            'issue 64 selecting first "row"' => ['First', '{"First","Second","Third","Fourth","Fifth","Sixth","Seventh"}, 1'],
+            'array result condensed to single value' => [40, '{10,11;20,21;30,31;40,41;50,51;60,61},4'],
+            'both row and column' => [41, '{10,11;20,21;30,31;40,41;50,51;60,61},4,2'],
+            '1*1 array' => ['first', '{"first"},1'],
+            'array expressed in rows' => [20, '{10;20;30;40},2'],
+            'spreadsheet single row' => [11, 'A10:D10,2'],
+            'spreadsheet single column' => [13, 'X10:X13,4'],
+        ];
+    }
 }

tests/data/Calculation/LookupRef/INDEXonSpreadsheet.php

@@ -82,7 +82,7 @@
         2,
     ],
     'Column number omitted from 2-column matrix' => [
-        '#REF!', // Expected
+        'abc', // Expected
         [
             ['abc', 'def'],
             ['xyz', 'tuv'],