/**
* Replace any return statement contained in brackets with null (but retain
* the statement and move to before the return call).
* This isn't perfect - the statement might evaluate to null anyway.
*
* @param array $tokens
* @param int $index
* @return array
*/
public static function getMutation(array &$tokens, $index)
{
$replace = [];
$last = null;
$tokenCount = count($tokens);
for ($i = $index + 1; $i < $tokenCount; $i++) {
if (is_array($tokens[$i]) && $tokens[$i][0] == T_WHITESPACE) {
continue;
} elseif (!is_array($tokens[$i]) && $tokens[$i] == '(') {
// collect statement tokens (skipping one whitespace after 'return')
for ($j = $index + 2; $j < $tokenCount; $j++) {
if (!is_array($tokens[$j]) && $tokens[$j] == ';') {
$last = $j - 1;
break;
}
$replace[$j] = $tokens[$j];
}
// replace them all with blanks and set last to 'null'
foreach ($replace as $k => $t) {
if ($k == $last) {
$tokens[$k] = [T_STRING, 'null'];
} else {
$tokens[$k] = '';
}
}
// shift the instantiation prior to the return statement to
// preserve instantiation behaviour without overwriting anything
// and without upsetting line count.
$replace[] = ';';
$replace[] = [T_WHITESPACE, ' '];
$string = ['-1' => Tokenizer::reconstructFromTokens($replace)];
array_splice($tokens, $index, 0, $string);
break;
}
}
}
/**
* Perform a mutation against the given original source code tokens for
* a mutable element
*
* @param array $tokens
* @param int $index
* @return string
*/
public static function mutate(array &$tokens, $index)
{
static::getMutation($tokens, $index);
return Tokenizer::reconstructFromTokens($tokens);
}