First external release

src/Spout/Reader/Helper/XLSX/CellHelper.php

@@ -0,0 +1,97 @@
+<?php
+
+namespace Box\Spout\Reader\Helper\XLSX;
+
+use Box\Spout\Common\Exception\InvalidArgumentException;
+
+/**
+ * Class CellHelper
+ * This class provides helper functions when working with cells
+ *
+ * @package Box\Spout\Reader\Helper\XLSX
+ */
+class CellHelper
+{
+    /**
+     * Fills the missing indexes of an array with a given value.
+     * For instance, $dataArray = []; $a[1] = 1; $a[3] = 3;
+     * Calling fillMissingArrayIndexes($dataArray, 'FILL') will return this array: ['FILL', 1, 'FILL', 3]
+     *
+     * @param array $dataArray The array to fill
+     * @param string|void $fillValue optional
+     * @return array
+     */
+    public static function fillMissingArrayIndexes($dataArray, $fillValue = '')
+    {
+        $existingIndexes = array_keys($dataArray);
+
+        $newIndexes = array_fill_keys(range(min($existingIndexes), max($existingIndexes)), $fillValue);
+        $dataArray += $newIndexes;
+
+        ksort($dataArray);
+
+        return $dataArray;
+    }
+
+    /**
+     * Returns the base 10 column index associated to the cell index (base 26).
+     * Excel uses A to Z letters for column indexing, where A is the 1st column,
+     * Z is the 26th and AA is the 27th.
+     * The mapping is zero based, so that A1 maps to 0, B2 maps to 1, Z13 to 25 and AA4 to 26.
+     *
+     * @param string $cellIndex The Excel cell index ('A1', 'BC13', ...)
+     * @return int
+     * @throws \Box\Spout\Common\Exception\InvalidArgumentException When the given cell index is invalid
+     */
+    public static function getColumnIndexFromCellIndex($cellIndex)
+    {
+        if (!self::isValidCellIndex($cellIndex)) {
+            throw new InvalidArgumentException('Cannot get column index from an invalid cell index.');
+        }
+
+        $columnIndex = 0;
+        $capitalAAsciiValue = ord('A');
+        $capitalZAsciiValue = ord('Z');
+        $step = $capitalZAsciiValue - $capitalAAsciiValue + 1;
+
+        // Remove row information
+        $column = preg_replace('/\d/', '', $cellIndex);
+        $columnLength = strlen($column);
+
+        /*
+         * This is how the following loop will process the data:
+         * A   => 0
+         * Z   => 25
+         * AA  => 26   : (26^(2-1) * (0+1)) + 0
+         * AB  => 27   : (26^(2-1) * (0+1)) + 1
+         * BC  => 54   : (26^(2-1) * (1+1)) + 2
+         * BCZ => 1455 : (26^(3-1) * (1+1)) + (26^(2-1) * (2+1)) + 25
+         */
+        foreach (str_split($column) as $single_cell_index)
+        {
+            $currentColumnIndex = ord($single_cell_index) - $capitalAAsciiValue;
+
+            if ($columnLength == 1) {
+                $columnIndex += $currentColumnIndex;
+            } else {
+                $columnIndex += pow($step, ($columnLength - 1)) * ($currentColumnIndex + 1);
+            }
+
+            $columnLength--;
+        }
+
+        return $columnIndex;
+    }
+
+    /**
+     * Returns whether a cell index is valid, in an Excel world.
+     * To be valid, the cell index should start with capital letters and be followed by numbers.
+     *
+     * @param string $cellIndex The Excel cell index ('A1', 'BC13', ...)
+     * @return bool
+     */
+    protected static function isValidCellIndex($cellIndex)
+    {
+        return (preg_match('/^[A-Z]+\d+$/', $cellIndex) === 1);
+    }
+}