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39 lines
1.1 KiB
39 lines
1.1 KiB
<?php
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namespace App\Tables;
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use App\Models\Row;
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use MightyPork\Utils\Utils;
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/**
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* Generates a sequence of string codes for internal naming of columns
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*
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* Produces database-unique lowercase identifiers for created or proposed columns.
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* Column identifiers are used in row objects to uniquely identify data even if the
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* revision header (columns object) is modified, such as reordering, changing name,
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* adding new column in concurrent proposals, etc.
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*
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* Thanks to this uniqueness, it could even be possible to compare or merge forks
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* of the same table.
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*/
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class ColumnNumerator extends BaseNumerator
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{
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const ALPHABET = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
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'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'];
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/**
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* Create numerator for the given number of columns
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*
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* @param int $capacity - how many
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*/
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public function __construct($capacity)
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{
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parent::__construct(Row::allocateColIDs($capacity));
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}
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protected function getKey($index)
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{
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return Utils::alphabetEncode($index, self::ALPHABET);
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}
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}
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