From 26079174a05b8b61358698116ff1fca1f86a9950 Mon Sep 17 00:00:00 2001
From: Mark Baker <mark@lange.demon.co.uk>
Date: Sat, 29 Jan 2022 14:32:40 +0100
Subject: [PATCH] Implementation of the SEQUENCE() Excel365 function (#2536)

* Implementation of the SEQUENCE() Excel365 function

Note that the Calculation Engine does not yet support the Spill operator, or spilling functions

* Handle the use-case of step = 0; and tests for exception handling for invalid arguments

* Update Change Log
---
 CHANGELOG.md                                  |  3 +
 .../Calculation/Calculation.php               |  4 +-
 .../Calculation/MathTrig/MatrixFunctions.php  | 41 ++++++++
 .../Functions/MathTrig/SequenceTest.php       | 25 +++++
 tests/data/Calculation/MathTrig/SEQUENCE.php  | 95 +++++++++++++++++++
 5 files changed, 166 insertions(+), 2 deletions(-)
 create mode 100644 tests/PhpSpreadsheetTests/Calculation/Functions/MathTrig/SequenceTest.php
 create mode 100644 tests/data/Calculation/MathTrig/SEQUENCE.php

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 58bb9a3a..433dfb6c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,9 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 
 ### Added
 
+- Support for the Excel365 Math/Trig SEQUENCE() function [PR #2536](https://github.com/PHPOffice/PhpSpreadsheet/pull/2536) 
+
+  Note that the Spill Operator is not yet supported in the Calculation Engine; but this can still be useful for defining array constants.
 - Improved support for Conditional Formatting Rules [PR #2491](https://github.com/PHPOffice/PhpSpreadsheet/pull/2491)
   - Provide support for a wider range of Conditional Formatting Rules for Xlsx Reader/Writer:
     - Cells Containing (cellIs)
diff --git a/src/PhpSpreadsheet/Calculation/Calculation.php b/src/PhpSpreadsheet/Calculation/Calculation.php
index 4f4b0607..41320a7c 100644
--- a/src/PhpSpreadsheet/Calculation/Calculation.php
+++ b/src/PhpSpreadsheet/Calculation/Calculation.php
@@ -2220,8 +2220,8 @@ class Calculation
         ],
         'SEQUENCE' => [
             'category' => Category::CATEGORY_MATH_AND_TRIG,
-            'functionCall' => [Functions::class, 'DUMMY'],
-            'argumentCount' => '2',
+            'functionCall' => [MathTrig\MatrixFunctions::class, 'sequence'],
+            'argumentCount' => '1-4',
         ],
         'SERIESSUM' => [
             'category' => Category::CATEGORY_MATH_AND_TRIG,
diff --git a/src/PhpSpreadsheet/Calculation/MathTrig/MatrixFunctions.php b/src/PhpSpreadsheet/Calculation/MathTrig/MatrixFunctions.php
index 92e1ff8e..4cef4625 100644
--- a/src/PhpSpreadsheet/Calculation/MathTrig/MatrixFunctions.php
+++ b/src/PhpSpreadsheet/Calculation/MathTrig/MatrixFunctions.php
@@ -42,6 +42,47 @@ class MatrixFunctions
         return new Matrix($matrixData);
     }
 
+    /**
+     * SEQUENCE.
+     *
+     * Generates a list of sequential numbers in an array.
+     *
+     * Excel Function:
+     *      SEQUENCE(rows,[columns],[start],[step])
+     *
+     * @param mixed $rows the number of rows to return, defaults to 1
+     * @param mixed $columns the number of columns to return, defaults to 1
+     * @param mixed $start the first number in the sequence, defaults to 1
+     * @param mixed $step the amount to increment each subsequent value in the array, defaults to 1
+     *
+     * @return array|string The resulting array, or a string containing an error
+     */
+    public static function sequence($rows = 1, $columns = 1, $start = 1, $step = 1)
+    {
+        try {
+            $rows = (int) Helpers::validateNumericNullSubstitution($rows, 1);
+            Helpers::validatePositive($rows);
+            $columns = (int) Helpers::validateNumericNullSubstitution($columns, 1);
+            Helpers::validatePositive($columns);
+            $start = Helpers::validateNumericNullSubstitution($start, 1);
+            $step = Helpers::validateNumericNullSubstitution($step, 1);
+        } catch (Exception $e) {
+            return $e->getMessage();
+        }
+
+        if ($step === 0) {
+            return array_chunk(
+                array_fill(0, $rows * $columns, $start),
+                $columns
+            );
+        }
+
+        return array_chunk(
+            range($start, $start + (($rows * $columns - 1) * $step), $step),
+            $columns
+        );
+    }
+
     /**
      * MDETERM.
      *
diff --git a/tests/PhpSpreadsheetTests/Calculation/Functions/MathTrig/SequenceTest.php b/tests/PhpSpreadsheetTests/Calculation/Functions/MathTrig/SequenceTest.php
new file mode 100644
index 00000000..d2ba3345
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Calculation/Functions/MathTrig/SequenceTest.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Calculation\Functions\MathTrig;
+
+use PhpOffice\PhpSpreadsheet\Calculation\MathTrig;
+
+class SequenceTest extends AllSetupTeardown
+{
+    /**
+     * @dataProvider providerSEQUENCE
+     *
+     * @param mixed[] $arguments
+     * @param mixed[]|string $expectedResult
+     */
+    public function testSEQUENCE(array $arguments, $expectedResult): void
+    {
+        $result = MathTrig\MatrixFunctions::sequence(...$arguments);
+        self::assertEquals($expectedResult, $result);
+    }
+
+    public function providerSEQUENCE(): array
+    {
+        return require 'tests/data/Calculation/MathTrig/SEQUENCE.php';
+    }
+}
diff --git a/tests/data/Calculation/MathTrig/SEQUENCE.php b/tests/data/Calculation/MathTrig/SEQUENCE.php
new file mode 100644
index 00000000..49c90102
--- /dev/null
+++ b/tests/data/Calculation/MathTrig/SEQUENCE.php
@@ -0,0 +1,95 @@
+<?php
+
+return [
+    [
+        [2, 2],
+        [
+            [1, 2],
+            [3, 4],
+        ],
+    ],
+    [
+        [2, 3],
+        [
+            [1, 2, 3],
+            [4, 5, 6],
+        ],
+    ],
+    [
+        [3, 2],
+        [
+            [1, 2],
+            [3, 4],
+            [5, 6],
+        ],
+    ],
+    [
+        [3],
+        [
+            [1],
+            [2],
+            [3],
+        ],
+    ],
+    [
+        [null, 3],
+        [
+            [1, 2, 3],
+        ],
+    ],
+    [
+        [3, 1, 10, 5],
+        [
+            [10],
+            [15],
+            [20],
+        ],
+    ],
+    [
+        [3, 2, 10, 5],
+        [
+            [10, 15],
+            [20, 25],
+            [30, 35],
+        ],
+    ],
+    [
+        [1, 3, 10, -5],
+        [
+            [10, 5, 0],
+        ],
+    ],
+    [
+        [1, 6, -10, 2],
+        [
+            [-10, -8, -6, -4, -2, 0],
+        ],
+    ],
+    [
+        [3, 3, -10, 2.5],
+        [
+            [-10, -7.5, -5],
+            [-2.5, 0, 2.5],
+            [5, 7.5, 10],
+        ],
+    ],
+    [
+        [3, 3, 10, -2.5],
+        [
+            [10, 7.5, 5],
+            [2.5, 0, -2.5],
+            [-5, -7.5, -10],
+        ],
+    ],
+    [
+        [2, 2, 1, 0],
+        [
+            [1, 1],
+            [1, 1],
+        ],
+    ],
+    [
+        [2, 2, 'A', 0],
+        '#VALUE!',
+    ],
+];