<?php
/**
* General API for generating and formatting diffs - the differences between
* two sequences of strings.
*
* The original PHP version of this code was written by Geoffrey T. Dairiki
* <dairiki@dairiki.org>, and is used/adapted with his permission.
*
* Copyright 2004 Geoffrey T. Dairiki <dairiki@dairiki.org>
* Copyright 2004-2010 The Horde Project (http://www.horde.org/)
*
* See the enclosed file COPYING for license information (LGPL). If you did
* not receive this file, see https://opensource.org/license/lgpl-2-1/.
*
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*/
class Text_Diff {

/**
* Array of changes.
*
* @var array
*/
var $_edits;

/**
* Computes diffs between sequences of strings.
*
* @param string $engine Name of the diffing engine to use. 'auto'
* will automatically select the best.
* @param array $params Parameters to pass to the diffing engine.
* Normally an array of two arrays, each
* containing the lines from a file.
*/
function __construct( $engine, $params )
{
// Backward compatibility workaround.
if (!is_string($engine)) {
$params = array($engine, $params);
$engine = 'auto';
}

if ($engine == 'auto') {
$engine = extension_loaded('xdiff') ? 'xdiff' : 'native';
} else {
$engine = basename($engine);
}

// WP #7391
require_once dirname(__FILE__).'/Diff/Engine/' . $engine . '.php';
$class = 'Text_Diff_Engine_' . $engine;
$diff_engine = new $class();

$this->_edits = call_user_func_array(array($diff_engine, 'diff'), $params);
}

/**
* PHP4 constructor.
*/
public function Text_Diff( $engine, $params ) {
self::__construct( $engine, $params );
}

/**
* Returns the array of differences.
*/
function getDiff()
{
return $this->_edits;
}

/**
* returns the number of new (added) lines in a given diff.
*
* @since Text_Diff 1.1.0
*
* @return int The number of new lines
*/
function countAddedLines()
{
$count = 0;
foreach ($this->_edits as $edit) {
if (is_a($edit, 'Text_Diff_Op_add') ||
is_a($edit, 'Text_Diff_Op_change')) {
$count += $edit->nfinal();
}
}
return $count;
}

/**
* Returns the number of deleted (removed) lines in a given diff.
*
* @since Text_Diff 1.1.0
*
* @return int The number of deleted lines
*/
function countDeletedLines()
{
$count = 0;
foreach ($this->_edits as $edit) {
if (is_a($edit, 'Text_Diff_Op_delete') ||
is_a($edit, 'Text_Diff_Op_change')) {
$count += $edit->norig();
}
}
return $count;
}

/**
* Computes a reversed diff.
*
* Example:
* <code>
* $diff = new Text_Diff($lines1, $lines2);
* $rev = $diff->reverse();
* </code>
*
* @return Text_Diff A Diff object representing the inverse of the
* original diff. Note that we purposely don't return a
* reference here, since this essentially is a clone()
* method.
*/
function reverse()
{
if (version_compare(zend_version(), '2', '>')) {
$rev = clone($this);
} else {
$rev = $this;
}
$rev->_edits = array();
foreach ($this->_edits as $edit) {
$rev->_edits[] = $edit->reverse();
}
return $rev;
}

/**
* Checks for an empty diff.
*
* @return bool True if two sequences were identical.
*/
function isEmpty()
{
foreach ($this->_edits as $edit) {
if (!is_a($edit, 'Text_Diff_Op_copy')) {
return false;
}
}
return true;
}

/**
* Computes the length of the Longest Common Subsequence (LCS).
*
* This is mostly for diagnostic purposes.
*
* @return int The length of the LCS.
*/
function lcs()
{
$lcs = 0;
foreach ($this->_edits as $edit) {
if (is_a($edit, 'Text_Diff_Op_copy')) {
$lcs += count($edit->orig);
}
}
return $lcs;
}

/**
* Gets the original set of lines.
*
* This reconstructs the $from_lines parameter passed to the constructor.
*
* @return array The original sequence of strings.
*/
function getOriginal()
{
$lines = array();
foreach ($this->_edits as $edit) {
if ($edit->orig) {
array_splice($lines, count($lines), 0, $edit->orig);
}
}
return $lines;
}

/**
* Gets the final set of lines.
*
* This reconstructs the $to_lines parameter passed to the constructor.
*
* @return array The sequence of strings.
*/
function getFinal()
{
$lines = array();
foreach ($this->_edits as $edit) {
if ($edit->final) {
array_splice($lines, count($lines), 0, $edit->final);
}
}
return $lines;
}

/**
* Removes trailing newlines from a line of text. This is meant to be used
* with array_walk().
*
* @param string $line The line to trim.
* @param int $key The index of the line in the array. Not used.
*/
static function trimNewlines(&$line, $key)
{
$line = str_replace(array("\n", "\r"), '', $line);
}

/**
* Determines the location of the system temporary directory.
*
* @access protected
*
* @return string A directory name which can be used for temp files.
* Returns false if one could not be found.
*/
static function _getTempDir()
{
$tmp_locations = array('/tmp', '/var/tmp', 'c:\WUTemp', 'c:\temp',
'c:\windows\temp', 'c:\winnt\temp');

/* Try PHP's upload_tmp_dir directive. */
$tmp = ini_get('upload_tmp_dir');

/* Otherwise, try to determine the TMPDIR environment variable. */
if (!strlen($tmp)) {
$tmp = getenv('TMPDIR');
}

/* If we still cannot determine a value, then cycle through a list of
* preset possibilities. */
while (!strlen($tmp) && count($tmp_locations)) {
$tmp_check = array_shift($tmp_locations);
if (@is_dir($tmp_check)) {
$tmp = $tmp_check;
}
}

/* If it is still empty, we have failed, so return false; otherwise
* return the directory determined. */
return strlen($tmp) ? $tmp : false;
}

/**
* Checks a diff for validity.
*
* This is here only for debugging purposes.
*/
function _check($from_lines, $to_lines)
{
if (serialize($from_lines) != serialize($this->getOriginal())) {
throw new Text_Exception("Reconstructed original does not match");
}
if (serialize($to_lines) != serialize($this->getFinal())) {
throw new Text_Exception("Reconstructed final does not match");
}

$rev = $this->reverse();
if (serialize($to_lines) != serialize($rev->getOriginal())) {
throw new Text_Exception("Reversed original does not match");
}
if (serialize($from_lines) != serialize($rev->getFinal())) {
throw new Text_Exception("Reversed final does not match");
}

$prevtype = null;
foreach ($this->_edits as $edit) {
if ($prevtype !== null && $edit instanceof $prevtype) {
throw new Text_Exception("Edit sequence is non-optimal");
}
$prevtype = get_class($edit);
}

return true;
}

}

/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*/
class Text_MappedDiff extends Text_Diff {

/**
* Computes a diff between sequences of strings.
*
* This can be used to compute things like case-insensitive diffs, or diffs
* which ignore changes in white-space.
*
* @param array $from_lines An array of strings.
* @param array $to_lines An array of strings.
* @param array $mapped_from_lines This array should have the same size
* number of elements as $from_lines. The
* elements in $mapped_from_lines and
* $mapped_to_lines are what is actually
* compared when computing the diff.
* @param array $mapped_to_lines This array should have the same number
* of elements as $to_lines.
*/
function __construct($from_lines, $to_lines,
$mapped_from_lines, $mapped_to_lines)
{
assert(count($from_lines) == count($mapped_from_lines));
assert(count($to_lines) == count($mapped_to_lines));

parent::Text_Diff($mapped_from_lines, $mapped_to_lines);

$xi = $yi = 0;
for ($i = 0; $i < count($this->_edits); $i++) {
$orig = &$this->_edits[$i]->orig;
if (is_array($orig)) {
$orig = array_slice($from_lines, $xi, count($orig));
$xi += count($orig);
}

$final = &$this->_edits[$i]->final;
if (is_array($final)) {
$final = array_slice($to_lines, $yi, count($final));
$yi += count($final);
}
}
}

/**
* PHP4 constructor.
*/
public function Text_MappedDiff( $from_lines, $to_lines,
$mapped_from_lines, $mapped_to_lines ) {
self::__construct( $from_lines, $to_lines,
$mapped_from_lines, $mapped_to_lines );
}

}

/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
abstract class Text_Diff_Op {

var $orig;
var $final;

abstract function &reverse();

function norig()
{
return $this->orig ? count($this->orig) : 0;
}

function nfinal()
{
return $this->final ? count($this->final) : 0;
}

}

/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
class Text_Diff_Op_copy extends Text_Diff_Op {

/**
* PHP5 constructor.
*/
function __construct( $orig, $final = false )
{
if (!is_array($final)) {
$final = $orig;
}
$this->orig = $orig;
$this->final = $final;
}

/**
* PHP4 constructor.
*/
public function Text_Diff_Op_copy( $orig, $final = false ) {
self::__construct( $orig, $final );
}

function &reverse()
{
$reverse = new Text_Diff_Op_copy($this->final, $this->orig);
return $reverse;
}

}

/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
class Text_Diff_Op_delete extends Text_Diff_Op {

/**
* PHP5 constructor.
*/
function __construct( $lines )
{
$this->orig = $lines;
$this->final = false;
}

/**
* PHP4 constructor.
*/
public function Text_Diff_Op_delete( $lines ) {
self::__construct( $lines );
}

function &reverse()
{
$reverse = new Text_Diff_Op_add($this->orig);
return $reverse;
}

}

/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
class Text_Diff_Op_add extends Text_Diff_Op {

/**
* PHP5 constructor.
*/
function __construct( $lines )
{
$this->final = $lines;
$this->orig = false;
}

/**
* PHP4 constructor.
*/
public function Text_Diff_Op_add( $lines ) {
self::__construct( $lines );
}

function &reverse()
{
$reverse = new Text_Diff_Op_delete($this->final);
return $reverse;
}

}

/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
class Text_Diff_Op_change extends Text_Diff_Op {

/**
* PHP5 constructor.
*/
function __construct( $orig, $final )
{
$this->orig = $orig;
$this->final = $final;
}

/**
* PHP4 constructor.
*/
public function Text_Diff_Op_change( $orig, $final ) {
self::__construct( $orig, $final );
}

function &reverse()
{
$reverse = new Text_Diff_Op_change($this->final, $this->orig);
return $reverse;
}

}