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<?php declare(strict_types=1);
/*
* This file is part of sebastian/diff.
*
* (c) Sebastian Bergmann <sebastian@phpunit.de>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace SebastianBergmann\Diff;
use const PHP_INT_SIZE;
use const PREG_SPLIT_DELIM_CAPTURE;
use const PREG_SPLIT_NO_EMPTY;
use function array_shift;
use function array_unshift;
use function array_values;
use function count;
use function current;
use function end;
use function is_string;
use function key;
use function min;
use function preg_split;
use function prev;
use function reset;
use function str_ends_with;
use function substr;
use SebastianBergmann\Diff\Output\DiffOutputBuilderInterface;
final class Differ
{
public const OLD = 0;
public const ADDED = 1;
public const REMOVED = 2;
public const DIFF_LINE_END_WARNING = 3;
public const NO_LINE_END_EOF_WARNING = 4;
private DiffOutputBuilderInterface $outputBuilder;
public function __construct(DiffOutputBuilderInterface $outputBuilder)
{
$this->outputBuilder = $outputBuilder;
}
public function diff(array|string $from, array|string $to, ?LongestCommonSubsequenceCalculator $lcs = null): string
{
$diff = $this->diffToArray($from, $to, $lcs);
return $this->outputBuilder->getDiff($diff);
}
public function diffToArray(array|string $from, array|string $to, ?LongestCommonSubsequenceCalculator $lcs = null): array
{
if (is_string($from)) {
$from = $this->splitStringByLines($from);
}
if (is_string($to)) {
$to = $this->splitStringByLines($to);
}
[$from, $to, $start, $end] = self::getArrayDiffParted($from, $to);
if ($lcs === null) {
$lcs = $this->selectLcsImplementation($from, $to);
}
$common = $lcs->calculate(array_values($from), array_values($to));
$diff = [];
foreach ($start as $token) {
$diff[] = [$token, self::OLD];
}
reset($from);
reset($to);
foreach ($common as $token) {
while (($fromToken = reset($from)) !== $token) {
$diff[] = [array_shift($from), self::REMOVED];
}
while (($toToken = reset($to)) !== $token) {
$diff[] = [array_shift($to), self::ADDED];
}
$diff[] = [$token, self::OLD];
array_shift($from);
array_shift($to);
}
while (($token = array_shift($from)) !== null) {
$diff[] = [$token, self::REMOVED];
}
while (($token = array_shift($to)) !== null) {
$diff[] = [$token, self::ADDED];
}
foreach ($end as $token) {
$diff[] = [$token, self::OLD];
}
if ($this->detectUnmatchedLineEndings($diff)) {
array_unshift($diff, ["#Warning: Strings contain different line endings!\n", self::DIFF_LINE_END_WARNING]);
}
return $diff;
}
private function splitStringByLines(string $input): array
{
return preg_split('/(.*\R)/', $input, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
}
private function selectLcsImplementation(array $from, array $to): LongestCommonSubsequenceCalculator
{
// We do not want to use the time-efficient implementation if its memory
// footprint will probably exceed this value. Note that the footprint
// calculation is only an estimation for the matrix and the LCS method
// will typically allocate a bit more memory than this.
$memoryLimit = 100 * 1024 * 1024;
if ($this->calculateEstimatedFootprint($from, $to) > $memoryLimit) {
return new MemoryEfficientLongestCommonSubsequenceCalculator;
}
return new TimeEfficientLongestCommonSubsequenceCalculator;
}
private function calculateEstimatedFootprint(array $from, array $to): float|int
{
$itemSize = PHP_INT_SIZE === 4 ? 76 : 144;
return $itemSize * min(count($from), count($to)) ** 2;
}
private function detectUnmatchedLineEndings(array $diff): bool
{
$newLineBreaks = ['' => true];
$oldLineBreaks = ['' => true];
foreach ($diff as $entry) {
if (self::OLD === $entry[1]) {
$ln = $this->getLinebreak($entry[0]);
$oldLineBreaks[$ln] = true;
$newLineBreaks[$ln] = true;
} elseif (self::ADDED === $entry[1]) {
$newLineBreaks[$this->getLinebreak($entry[0])] = true;
} elseif (self::REMOVED === $entry[1]) {
$oldLineBreaks[$this->getLinebreak($entry[0])] = true;
}
}
// if either input or output is a single line without breaks than no warning should be raised
if (['' => true] === $newLineBreaks || ['' => true] === $oldLineBreaks) {
return false;
}
// two-way compare
foreach ($newLineBreaks as $break => $set) {
if (!isset($oldLineBreaks[$break])) {
return true;
}
}
foreach ($oldLineBreaks as $break => $set) {
if (!isset($newLineBreaks[$break])) {
return true;
}
}
return false;
}
private function getLinebreak($line): string
{
if (!is_string($line)) {
return '';
}
$lc = substr($line, -1);
if ("\r" === $lc) {
return "\r";
}
if ("\n" !== $lc) {
return '';
}
if (str_ends_with($line, "\r\n")) {
return "\r\n";
}
return "\n";
}
private static function getArrayDiffParted(array &$from, array &$to): array
{
$start = [];
$end = [];
reset($to);
foreach ($from as $k => $v) {
$toK = key($to);
if ($toK === $k && $v === $to[$k]) {
$start[$k] = $v;
unset($from[$k], $to[$k]);
} else {
break;
}
}
end($from);
end($to);
do {
$fromK = key($from);
$toK = key($to);
if (null === $fromK || null === $toK || current($from) !== current($to)) {
break;
}
prev($from);
prev($to);
$end = [$fromK => $from[$fromK]] + $end;
unset($from[$fromK], $to[$toK]);
} while (true);
return [$from, $to, $start, $end];
}
}
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