Chris@0: <?php
Chris@0: /*
Chris@0:  * This file is part of the Diff package.
Chris@0:  *
Chris@0:  * (c) Sebastian Bergmann <sebastian@phpunit.de>
Chris@0:  *
Chris@0:  * For the full copyright and license information, please view the LICENSE
Chris@0:  * file that was distributed with this source code.
Chris@0:  */
Chris@0: 
Chris@0: namespace SebastianBergmann\Diff;
Chris@0: 
Chris@0: use SebastianBergmann\Diff\LCS\LongestCommonSubsequence;
Chris@0: use SebastianBergmann\Diff\LCS\TimeEfficientImplementation;
Chris@0: use SebastianBergmann\Diff\LCS\MemoryEfficientImplementation;
Chris@0: 
Chris@0: /**
Chris@0:  * Diff implementation.
Chris@0:  */
Chris@0: class Differ
Chris@0: {
Chris@0:     /**
Chris@0:      * @var string
Chris@0:      */
Chris@0:     private $header;
Chris@0: 
Chris@0:     /**
Chris@0:      * @var bool
Chris@0:      */
Chris@0:     private $showNonDiffLines;
Chris@0: 
Chris@0:     /**
Chris@0:      * @param string $header
Chris@0:      */
Chris@0:     public function __construct($header = "--- Original\n+++ New\n", $showNonDiffLines = true)
Chris@0:     {
Chris@0:         $this->header           = $header;
Chris@0:         $this->showNonDiffLines = $showNonDiffLines;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Returns the diff between two arrays or strings as string.
Chris@0:      *
Chris@0:      * @param array|string             $from
Chris@0:      * @param array|string             $to
Chris@0:      * @param LongestCommonSubsequence $lcs
Chris@0:      *
Chris@0:      * @return string
Chris@0:      */
Chris@0:     public function diff($from, $to, LongestCommonSubsequence $lcs = null)
Chris@0:     {
Chris@0:         if (!is_array($from) && !is_string($from)) {
Chris@0:             $from = (string) $from;
Chris@0:         }
Chris@0: 
Chris@0:         if (!is_array($to) && !is_string($to)) {
Chris@0:             $to = (string) $to;
Chris@0:         }
Chris@0: 
Chris@0:         $buffer = $this->header;
Chris@0:         $diff   = $this->diffToArray($from, $to, $lcs);
Chris@0: 
Chris@0:         $inOld = false;
Chris@0:         $i     = 0;
Chris@0:         $old   = array();
Chris@0: 
Chris@0:         foreach ($diff as $line) {
Chris@0:             if ($line[1] ===  0 /* OLD */) {
Chris@0:                 if ($inOld === false) {
Chris@0:                     $inOld = $i;
Chris@0:                 }
Chris@0:             } elseif ($inOld !== false) {
Chris@0:                 if (($i - $inOld) > 5) {
Chris@0:                     $old[$inOld] = $i - 1;
Chris@0:                 }
Chris@0: 
Chris@0:                 $inOld = false;
Chris@0:             }
Chris@0: 
Chris@0:             ++$i;
Chris@0:         }
Chris@0: 
Chris@0:         $start = isset($old[0]) ? $old[0] : 0;
Chris@0:         $end   = count($diff);
Chris@0: 
Chris@0:         if ($tmp = array_search($end, $old)) {
Chris@0:             $end = $tmp;
Chris@0:         }
Chris@0: 
Chris@0:         $newChunk = true;
Chris@0: 
Chris@0:         for ($i = $start; $i < $end; $i++) {
Chris@0:             if (isset($old[$i])) {
Chris@0:                 $buffer  .= "\n";
Chris@0:                 $newChunk = true;
Chris@0:                 $i        = $old[$i];
Chris@0:             }
Chris@0: 
Chris@0:             if ($newChunk) {
Chris@0:                 if ($this->showNonDiffLines === true) {
Chris@0:                     $buffer .= "@@ @@\n";
Chris@0:                 }
Chris@0:                 $newChunk = false;
Chris@0:             }
Chris@0: 
Chris@0:             if ($diff[$i][1] === 1 /* ADDED */) {
Chris@0:                 $buffer .= '+' . $diff[$i][0] . "\n";
Chris@0:             } elseif ($diff[$i][1] === 2 /* REMOVED */) {
Chris@0:                 $buffer .= '-' . $diff[$i][0] . "\n";
Chris@0:             } elseif ($this->showNonDiffLines === true) {
Chris@0:                 $buffer .= ' ' . $diff[$i][0] . "\n";
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         return $buffer;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Returns the diff between two arrays or strings as array.
Chris@0:      *
Chris@0:      * Each array element contains two elements:
Chris@0:      *   - [0] => string $token
Chris@0:      *   - [1] => 2|1|0
Chris@0:      *
Chris@0:      * - 2: REMOVED: $token was removed from $from
Chris@0:      * - 1: ADDED: $token was added to $from
Chris@0:      * - 0: OLD: $token is not changed in $to
Chris@0:      *
Chris@0:      * @param array|string             $from
Chris@0:      * @param array|string             $to
Chris@0:      * @param LongestCommonSubsequence $lcs
Chris@0:      *
Chris@0:      * @return array
Chris@0:      */
Chris@0:     public function diffToArray($from, $to, LongestCommonSubsequence $lcs = null)
Chris@0:     {
Chris@0:         preg_match_all('(\r\n|\r|\n)', $from, $fromMatches);
Chris@0:         preg_match_all('(\r\n|\r|\n)', $to, $toMatches);
Chris@0: 
Chris@0:         if (is_string($from)) {
Chris@0:             $from = preg_split('(\r\n|\r|\n)', $from);
Chris@0:         }
Chris@0: 
Chris@0:         if (is_string($to)) {
Chris@0:             $to = preg_split('(\r\n|\r|\n)', $to);
Chris@0:         }
Chris@0: 
Chris@0:         $start      = array();
Chris@0:         $end        = array();
Chris@0:         $fromLength = count($from);
Chris@0:         $toLength   = count($to);
Chris@0:         $length     = min($fromLength, $toLength);
Chris@0: 
Chris@0:         for ($i = 0; $i < $length; ++$i) {
Chris@0:             if ($from[$i] === $to[$i]) {
Chris@0:                 $start[] = $from[$i];
Chris@0:                 unset($from[$i], $to[$i]);
Chris@0:             } else {
Chris@0:                 break;
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         $length -= $i;
Chris@0: 
Chris@0:         for ($i = 1; $i < $length; ++$i) {
Chris@0:             if ($from[$fromLength - $i] === $to[$toLength - $i]) {
Chris@0:                 array_unshift($end, $from[$fromLength - $i]);
Chris@0:                 unset($from[$fromLength - $i], $to[$toLength - $i]);
Chris@0:             } else {
Chris@0:                 break;
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         if ($lcs === null) {
Chris@0:             $lcs = $this->selectLcsImplementation($from, $to);
Chris@0:         }
Chris@0: 
Chris@0:         $common = $lcs->calculate(array_values($from), array_values($to));
Chris@0:         $diff   = array();
Chris@0: 
Chris@0:         if (isset($fromMatches[0]) && $toMatches[0] &&
Chris@0:             count($fromMatches[0]) === count($toMatches[0]) &&
Chris@0:             $fromMatches[0] !== $toMatches[0]) {
Chris@0:             $diff[] = array(
Chris@0:               '#Warning: Strings contain different line endings!', 0
Chris@0:             );
Chris@0:         }
Chris@0: 
Chris@0:         foreach ($start as $token) {
Chris@0:             $diff[] = array($token, 0 /* OLD */);
Chris@0:         }
Chris@0: 
Chris@0:         reset($from);
Chris@0:         reset($to);
Chris@0: 
Chris@0:         foreach ($common as $token) {
Chris@0:             while ((($fromToken = reset($from)) !== $token)) {
Chris@0:                 $diff[] = array(array_shift($from), 2 /* REMOVED */);
Chris@0:             }
Chris@0: 
Chris@0:             while ((($toToken = reset($to)) !== $token)) {
Chris@0:                 $diff[] = array(array_shift($to), 1 /* ADDED */);
Chris@0:             }
Chris@0: 
Chris@0:             $diff[] = array($token, 0 /* OLD */);
Chris@0: 
Chris@0:             array_shift($from);
Chris@0:             array_shift($to);
Chris@0:         }
Chris@0: 
Chris@0:         while (($token = array_shift($from)) !== null) {
Chris@0:             $diff[] = array($token, 2 /* REMOVED */);
Chris@0:         }
Chris@0: 
Chris@0:         while (($token = array_shift($to)) !== null) {
Chris@0:             $diff[] = array($token, 1 /* ADDED */);
Chris@0:         }
Chris@0: 
Chris@0:         foreach ($end as $token) {
Chris@0:             $diff[] = array($token, 0 /* OLD */);
Chris@0:         }
Chris@0: 
Chris@0:         return $diff;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * @param array $from
Chris@0:      * @param array $to
Chris@0:      *
Chris@0:      * @return LongestCommonSubsequence
Chris@0:      */
Chris@0:     private function selectLcsImplementation(array $from, array $to)
Chris@0:     {
Chris@0:         // We do not want to use the time-efficient implementation if its memory
Chris@0:         // footprint will probably exceed this value. Note that the footprint
Chris@0:         // calculation is only an estimation for the matrix and the LCS method
Chris@0:         // will typically allocate a bit more memory than this.
Chris@0:         $memoryLimit = 100 * 1024 * 1024;
Chris@0: 
Chris@0:         if ($this->calculateEstimatedFootprint($from, $to) > $memoryLimit) {
Chris@0:             return new MemoryEfficientImplementation;
Chris@0:         }
Chris@0: 
Chris@0:         return new TimeEfficientImplementation;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Calculates the estimated memory footprint for the DP-based method.
Chris@0:      *
Chris@0:      * @param array $from
Chris@0:      * @param array $to
Chris@0:      *
Chris@0:      * @return int
Chris@0:      */
Chris@0:     private function calculateEstimatedFootprint(array $from, array $to)
Chris@0:     {
Chris@0:         $itemSize = PHP_INT_SIZE == 4 ? 76 : 144;
Chris@0: 
Chris@0:         return $itemSize * pow(min(count($from), count($to)), 2);
Chris@0:     }
Chris@0: }