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CharacterDiff.php
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CharacterDiff.php
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<?php
/**
* Bit&Black TypoRules.
*
* @author Tobias Köngeter
* @copyright Copyright © Bit&Black
* @link https://www.bitandblack.com
* @license MIT
*/
namespace BitAndBlack\TypoRules\Diff;
use BitAndBlack\TypoRules\Diff\Output\CliOutput;
use BitAndBlack\TypoRules\Diff\Output\HtmlOutput;
use BitAndBlack\TypoRules\Diff\Output\OutputInterface;
/**
* This class is based on the work of {@see https://stackoverflow.com/users/58805/calmarius}
* in {@see https://stackoverflow.com/a/22021254/8252855}. Thank you!
*/
class CharacterDiff
{
private readonly OutputInterface $output;
public function __construct(OutputInterface $output = null)
{
$autoDecidedOutput = 'cli' === PHP_SAPI
? new CliOutput()
: new HtmlOutput()
;
$this->output = $output ?? $autoDecidedOutput;
}
public static function create(OutputInterface $output = null): self
{
return new self($output);
}
/**
* @param array<int, string> $from
* @param array<int, string> $to
* @return array{
* values: array<int, string>,
* mask: array<int, int>,
* }
*/
private function computeDiff(array $from, array $to): array
{
$diffValues = [];
$diffMask = [];
$dm = [];
$fromCount = count($from);
$toCount = count($to);
for ($counter = -1; $counter < $toCount; $counter++) {
$dm[-1][$counter] = 0;
}
for ($counter = -1; $counter < $fromCount; $counter++) {
$dm[$counter][-1] = 0;
}
for ($counterA = 0; $counterA < $fromCount; $counterA++) {
for ($counterB = 0; $counterB < $toCount; $counterB++) {
if ($from[$counterA] === $to[$counterB]) {
$ad = $dm[$counterA - 1][$counterB - 1];
$dm[$counterA][$counterB] = $ad + 1;
} else {
$a1 = $dm[$counterA - 1][$counterB];
$a2 = $dm[$counterA][$counterB - 1];
$dm[$counterA][$counterB] = max($a1, $a2);
}
}
}
$i = $fromCount - 1;
$j = $toCount - 1;
while (($i > -1) || ($j > -1)) {
if (($j > -1) && $dm[$i][$j - 1] === $dm[$i][$j]) {
$diffValues[] = $to[$j];
$diffMask[] = 1;
$j--;
continue;
}
$diffValues[] = $from[$i];
if (($i > -1) && $dm[$i - 1][$j] === $dm[$i][$j]) {
$diffMask[] = -1;
$i--;
continue;
}
$diffMask[] = 0;
$i--;
$j--;
}
$diffValues = array_reverse($diffValues);
$diffMask = array_reverse($diffMask);
return [
'values' => $diffValues,
'mask' => $diffMask,
];
}
public function getDiff(string $before, string $after): string
{
$diff = $this->computeDiff(
str_split($before),
str_split($after)
);
$diffValue = $diff['values'];
$diffMask = $diff['mask'];
$diffValueCount = count($diffValue);
$pmc = 0;
$result = '';
for ($counter = 0; $counter < $diffValueCount; $counter++) {
$mc = $diffMask[$counter];
if ($mc !== $pmc) {
switch ($pmc) {
case -1: $result .= $this->output->getDeleteEnd();
break;
case 1: $result .= $this->output->getInsertEnd();
break;
}
switch ($mc) {
case -1: $result .= $this->output->getDeleteStart();
break;
case 1: $result .= $this->output->getInsertStart();
break;
}
}
$result .= $diffValue[$counter];
$pmc = $mc;
}
match ($pmc) {
-1 => $result .= $this->output->getDeleteEnd(),
1 => $result .= $this->output->getInsertEnd(),
default => $result,
};
return $result;
}
}