<?php
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namespace PhpOffice\PhpSpreadsheet\Reader\Csv;
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class Delimiter
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{
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protected const POTENTIAL_DELIMETERS = [',', ';', "\t", '|', ':', ' ', '~'];
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/** @var resource */
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protected $fileHandle;
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protected string $escapeCharacter;
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protected string $enclosure;
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protected array $counts = [];
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protected int $numberLines = 0;
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/** @var ?string */
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protected ?string $delimiter = null;
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/**
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* @param resource $fileHandle
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*/
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public function __construct($fileHandle, string $escapeCharacter, string $enclosure)
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{
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$this->fileHandle = $fileHandle;
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$this->escapeCharacter = $escapeCharacter;
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$this->enclosure = $enclosure;
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$this->countPotentialDelimiters();
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}
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public function getDefaultDelimiter(): string
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{
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return self::POTENTIAL_DELIMETERS[0];
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}
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public function linesCounted(): int
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{
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return $this->numberLines;
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}
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protected function countPotentialDelimiters(): void
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{
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$this->counts = array_fill_keys(self::POTENTIAL_DELIMETERS, []);
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$delimiterKeys = array_flip(self::POTENTIAL_DELIMETERS);
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// Count how many times each of the potential delimiters appears in each line
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$this->numberLines = 0;
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while (($line = $this->getNextLine()) !== false && (++$this->numberLines < 1000)) {
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$this->countDelimiterValues($line, $delimiterKeys);
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}
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}
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protected function countDelimiterValues(string $line, array $delimiterKeys): void
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{
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$splitString = str_split($line, 1);
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if (is_array($splitString)) {
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$distribution = array_count_values($splitString);
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$countLine = array_intersect_key($distribution, $delimiterKeys);
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foreach (self::POTENTIAL_DELIMETERS as $delimiter) {
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$this->counts[$delimiter][] = $countLine[$delimiter] ?? 0;
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}
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}
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}
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public function infer(): ?string
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{
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// Calculate the mean square deviations for each delimiter
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// (ignoring delimiters that haven't been found consistently)
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$meanSquareDeviations = [];
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$middleIdx = floor(($this->numberLines - 1) / 2);
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foreach (self::POTENTIAL_DELIMETERS as $delimiter) {
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$series = $this->counts[$delimiter];
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sort($series);
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$median = ($this->numberLines % 2)
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? $series[$middleIdx]
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: ($series[$middleIdx] + $series[$middleIdx + 1]) / 2;
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if ($median === 0) {
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continue;
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}
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$meanSquareDeviations[$delimiter] = array_reduce(
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$series,
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fn ($sum, $value): int|float => $sum + ($value - $median) ** 2
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) / count($series);
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}
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// ... and pick the delimiter with the smallest mean square deviation
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// (in case of ties, the order in potentialDelimiters is respected)
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$min = INF;
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foreach (self::POTENTIAL_DELIMETERS as $delimiter) {
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if (!isset($meanSquareDeviations[$delimiter])) {
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continue;
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}
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if ($meanSquareDeviations[$delimiter] < $min) {
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$min = $meanSquareDeviations[$delimiter];
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$this->delimiter = $delimiter;
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}
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}
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return $this->delimiter;
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}
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/**
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* Get the next full line from the file.
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*
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* @return false|string
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*/
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public function getNextLine()
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{
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$line = '';
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$enclosure = ($this->escapeCharacter === '' ? ''
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: ('(?<!' . preg_quote($this->escapeCharacter, '/') . ')'))
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. preg_quote($this->enclosure, '/');
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do {
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// Get the next line in the file
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$newLine = fgets($this->fileHandle);
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// Return false if there is no next line
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if ($newLine === false) {
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return false;
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}
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// Add the new line to the line passed in
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$line = $line . $newLine;
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// Drop everything that is enclosed to avoid counting false positives in enclosures
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$line = (string) preg_replace('/(' . $enclosure . '.*' . $enclosure . ')/Us', '', $line);
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// See if we have any enclosures left in the line
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// if we still have an enclosure then we need to read the next line as well
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} while (preg_match('/(' . $enclosure . ')/', $line) > 0);
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return ($line !== '') ? $line : false;
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}
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}
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