public static function difference($from, $to, $contextLines = 3)
{
if (is_string($from)) {
$from = preg_split('(\\r\\n|\\r|\\n)', $from);
}
if (is_string($to)) {
$to = preg_split('(\\r\\n|\\r|\\n)', $to);
}
$buffer = "";
$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;
}
}
$common = self::longestCommonSubsequence(array_values($from), array_values($to));
$diff = array();
$line = 0;
foreach ($start as $token) {
$diff[] = array($token, 0);
}
reset($from);
reset($to);
foreach ($common as $token) {
while (($fromToken = reset($from)) !== $token) {
$diff[] = array(array_shift($from), 2);
}
while (($toToken = reset($to)) !== $token) {
$diff[] = array(array_shift($to), 1);
}
$diff[] = array($token, 0);
array_shift($from);
array_shift($to);
}
while (($token = array_shift($from)) !== NULL) {
$diff[] = array($token, 2);
}
while (($token = array_shift($to)) !== NULL) {
$diff[] = array($token, 1);
}
foreach ($end as $token) {
$diff[] = array($token, 0);
}
$inOld = FALSE;
$i = 0;
$old = array();
foreach ($diff as $line) {
if ($line[1] === 0) {
if ($inOld === FALSE) {
$inOld = $i;
}
} else {
if ($inOld !== FALSE) {
if ($i - $inOld > 5) {
$old[$inOld] = $i - 1;
}
$inOld = FALSE;
}
}
++$i;
}
$start = isset($old[0]) ? $old[0] : 0;
$end = count($diff);
$i = 0;
if ($tmp = array_search($end, $old)) {
$end = $tmp;
}
$newChunk = TRUE;
$context = array();
$contextPre = array();
$contextPost = array();
$contextPreSet = false;
for ($i = $start; $i < $end; $i++) {
if (isset($old[$i])) {
$buffer .= "\n";
$newChunk = TRUE;
$i = $old[$i];
}
if ($newChunk) {
// TODO: Implement chunk range information.
$buffer .= "@@ @@\n";
$newChunk = FALSE;
}
if ($diff[$i][1] === 1) {
$buffer .= '+' . $diff[$i][0] . "\n";
} else {
if ($diff[$i][1] === 2) {
$popc = $contextLines;
if (count($context) < $contextLines) {
$popc = count($context);
}
if ($popc > 0) {
while ($popc > 0) {
$buffer .= array_pop($context);
$popc--;
}
}
$context = array();
$contextPreSet = true;
$buffer .= '-' . $diff[$i][0] . "\n";
} else {
$context[] = ' ' . $diff[$i][0] . "\n";
if ($contextPreSet && count($context) == $contextLines) {
$buffer .= implode('', $context);
$context = array();
break;
}
}
}
}
if (count($context) > 0) {
$buffer .= implode('', $context);
}
return $buffer;
}