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<?php
/*
* This file is part of the Diff package.
*
* (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 SebastianBergmann\Diff\LCS\LongestCommonSubsequence;
use SebastianBergmann\Diff\LCS\TimeEfficientImplementation;
use SebastianBergmann\Diff\LCS\MemoryEfficientImplementation;
/**
* Diff implementation.
*/
class Differ
{
/**
* @var string
*/
private $header;
/**
* @var bool
*/
private $showNonDiffLines;
/**
* @param string $header
*/
public function __construct($header = "--- Original\n+++ New\n", $showNonDiffLines = true)
{
$this->header = $header;
$this->showNonDiffLines = $showNonDiffLines;
}
/**
* Returns the diff between two arrays or strings as string.
*
* @param array|string $from
* @param array|string $to
* @param LongestCommonSubsequence $lcs
*
* @return string
*/
public function diff($from, $to, LongestCommonSubsequence $lcs = null)
{
if (!is_array($from) && !is_string($from)) {
$from = (string) $from;
}
if (!is_array($to) && !is_string($to)) {
$to = (string) $to;
}
$buffer = $this->header;
$diff = $this->diffToArray($from, $to, $lcs);
$inOld = false;
$i = 0;
$old = array();
foreach ($diff as $line) {
if ($line[1] === 0 /* OLD */) {
if ($inOld === false) {
$inOld = $i;
}
} elseif ($inOld !== false) {
if (($i - $inOld) > 5) {
$old[$inOld] = $i - 1;
}
$inOld = false;
}
++$i;
}
$start = isset($old[0]) ? $old[0] : 0;
$end = count($diff);
if ($tmp = array_search($end, $old)) {
$end = $tmp;
}
$newChunk = true;
for ($i = $start; $i < $end; $i++) {
if (isset($old[$i])) {
$buffer .= "\n";
$newChunk = true;
$i = $old[$i];
}
if ($newChunk) {
if ($this->showNonDiffLines === true) {
$buffer .= "@@ @@\n";
}
$newChunk = false;
}
if ($diff[$i][1] === 1 /* ADDED */) {
$buffer .= '+' . $diff[$i][0] . "\n";
} elseif ($diff[$i][1] === 2 /* REMOVED */) {
$buffer .= '-' . $diff[$i][0] . "\n";
} elseif ($this->showNonDiffLines === true) {
$buffer .= ' ' . $diff[$i][0] . "\n";
}
}
return $buffer;
}
/**
* Returns the diff between two arrays or strings as array.
*
* Each array element contains two elements:
* - [0] => string $token
* - [1] => 2|1|0
*
* - 2: REMOVED: $token was removed from $from
* - 1: ADDED: $token was added to $from
* - 0: OLD: $token is not changed in $to
*
* @param array|string $from
* @param array|string $to
* @param LongestCommonSubsequence $lcs
*
* @return array
*/
public function diffToArray($from, $to, LongestCommonSubsequence $lcs = null)
{
preg_match_all('(\r\n|\r|\n)', $from, $fromMatches);
preg_match_all('(\r\n|\r|\n)', $to, $toMatches);
if (is_string($from)) {
$from = preg_split('(\r\n|\r|\n)', $from);
}
if (is_string($to)) {
$to = preg_split('(\r\n|\r|\n)', $to);
}
$start = array();
$end = array();
$fromLength = count($from);
$toLength = count($to);
$length = min($fromLength, $toLength);
for ($i = 0; $i < $length; ++$i) {
if ($from[$i] === $to[$i]) {
$start[] = $from[$i];
unset($from[$i], $to[$i]);
} else {
break;
}
}
$length -= $i;
for ($i = 1; $i < $length; ++$i) {
if ($from[$fromLength - $i] === $to[$toLength - $i]) {
array_unshift($end, $from[$fromLength - $i]);
unset($from[$fromLength - $i], $to[$toLength - $i]);
} else {
break;
}
}
if ($lcs === null) {
$lcs = $this->selectLcsImplementation($from, $to);
}
$common = $lcs->calculate(array_values($from), array_values($to));
$diff = array();
if (isset($fromMatches[0]) && $toMatches[0] &&
count($fromMatches[0]) === count($toMatches[0]) &&
$fromMatches[0] !== $toMatches[0]) {
$diff[] = array(
'#Warning: Strings contain different line endings!', 0
);
}
foreach ($start as $token) {
$diff[] = array($token, 0 /* OLD */);
}
reset($from);
reset($to);
foreach ($common as $token) {
while ((($fromToken = reset($from)) !== $token)) {
$diff[] = array(array_shift($from), 2 /* REMOVED */);
}
while ((($toToken = reset($to)) !== $token)) {
$diff[] = array(array_shift($to), 1 /* ADDED */);
}
$diff[] = array($token, 0 /* OLD */);
array_shift($from);
array_shift($to);
}
while (($token = array_shift($from)) !== null) {
$diff[] = array($token, 2 /* REMOVED */);
}
while (($token = array_shift($to)) !== null) {
$diff[] = array($token, 1 /* ADDED */);
}
foreach ($end as $token) {
$diff[] = array($token, 0 /* OLD */);
}
return $diff;
}
/**
* @param array $from
* @param array $to
*
* @return LongestCommonSubsequence
*/
private function selectLcsImplementation(array $from, array $to)
{
// 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 MemoryEfficientImplementation;
}
return new TimeEfficientImplementation;
}
/**
* Calculates the estimated memory footprint for the DP-based method.
*
* @param array $from
* @param array $to
*
* @return int
*/
private function calculateEstimatedFootprint(array $from, array $to)
{
$itemSize = PHP_INT_SIZE == 4 ? 76 : 144;
return $itemSize * pow(min(count($from), count($to)), 2);
}
}
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