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<?php |
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namespace FluentCart\OpenSpout\Reader\XLSX\Helper; |
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use FluentCart\OpenSpout\Common\Exception\InvalidArgumentException; |
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/** |
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* This class provides helper functions when working with cells. |
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*/ |
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class CellHelper |
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{ |
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// Using ord() is super slow... Using a pre-computed hash table instead. |
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private static $columnLetterToIndexMapping = ['A' => 0, 'B' => 1, 'C' => 2, 'D' => 3, 'E' => 4, 'F' => 5, 'G' => 6, 'H' => 7, 'I' => 8, 'J' => 9, 'K' => 10, 'L' => 11, 'M' => 12, 'N' => 13, 'O' => 14, 'P' => 15, 'Q' => 16, 'R' => 17, 'S' => 18, 'T' => 19, 'U' => 20, 'V' => 21, 'W' => 22, 'X' => 23, 'Y' => 24, 'Z' => 25]; |
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/** |
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* Returns the base 10 column index associated to the cell index (base 26). |
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* Excel uses A to Z letters for column indexing, where A is the 1st column, |
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* Z is the 26th and AA is the 27th. |
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* The mapping is zero based, so that A1 maps to 0, B2 maps to 1, Z13 to 25 and AA4 to 26. |
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* |
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* @param string $cellIndex The Excel cell index ('A1', 'BC13', ...) |
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* |
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* @throws \OpenSpout\Common\Exception\InvalidArgumentException When the given cell index is invalid |
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* |
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* @return int |
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*/ |
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public static function getColumnIndexFromCellIndex($cellIndex) |
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{ |
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if (!self::isValidCellIndex($cellIndex)) { |
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throw new InvalidArgumentException('Cannot get column index from an invalid cell index.'); |
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} |
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$columnIndex = 0; |
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// Remove row information |
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$columnLetters = \preg_replace('/\\d/', '', $cellIndex); |
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// strlen() is super slow too... Using isset() is way faster and not too unreadable, |
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// since we checked before that there are between 1 and 3 letters. |
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$columnLength = isset($columnLetters[1]) ? isset($columnLetters[2]) ? 3 : 2 : 1; |
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// Looping over the different letters of the column is slower than this method. |
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// Also, not using the pow() function because it's slooooow... |
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switch ($columnLength) { |
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case 1: |
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$columnIndex = self::$columnLetterToIndexMapping[$columnLetters]; |
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break; |
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case 2: |
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$firstLetterIndex = (self::$columnLetterToIndexMapping[$columnLetters[0]] + 1) * 26; |
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$secondLetterIndex = self::$columnLetterToIndexMapping[$columnLetters[1]]; |
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$columnIndex = $firstLetterIndex + $secondLetterIndex; |
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break; |
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case 3: |
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$firstLetterIndex = (self::$columnLetterToIndexMapping[$columnLetters[0]] + 1) * 676; |
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$secondLetterIndex = (self::$columnLetterToIndexMapping[$columnLetters[1]] + 1) * 26; |
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$thirdLetterIndex = self::$columnLetterToIndexMapping[$columnLetters[2]]; |
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$columnIndex = $firstLetterIndex + $secondLetterIndex + $thirdLetterIndex; |
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break; |
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} |
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return $columnIndex; |
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} |
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/** |
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* Returns whether a cell index is valid, in an Excel world. |
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* To be valid, the cell index should start with capital letters and be followed by numbers. |
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* There can only be 3 letters, as there can only be 16,384 rows, which is equivalent to 'XFE'. |
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* |
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* @param string $cellIndex The Excel cell index ('A1', 'BC13', ...) |
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* |
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* @return bool |
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*/ |
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protected static function isValidCellIndex($cellIndex) |
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{ |
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return 1 === \preg_match('/^[A-Z]{1,3}\\d+$/', $cellIndex); |
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} |
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} |
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