public function next($length = INF)
{
if ($this->operations->has($this->index)) {
$nextOperation = $this->operations[$this->index];
$offset = $this->offset;
$operationLength = $this->calculateLength($nextOperation);
if ($length >= $operationLength - $offset) {
$length = $operationLength - $offset;
$this->index += 1;
$this->offset = 0;
} else {
$this->offset += $length;
}
if ($nextOperation->getType() === OperationInterface::TYPE_DELETE) {
return new DeleteOperation($length);
} else {
if ($nextOperation->getType() === OperationInterface::TYPE_RETAIN) {
return new RetainOperation($length, $nextOperation->getAttributes());
} elseif (is_string($nextOperation->getValue())) {
return new InsertOperation(mb_substr($nextOperation->getValue(), $offset, $length), $nextOperation->getAttributes());
}
return new InsertOperation($nextOperation->getValue(), $nextOperation->getAttributes());
}
}
return new RetainOperation(INF);
}
public function chop()
{
$lastOperation = ($index = count($this->operations)) > 0 ? $this->operations[$index - 1] : null;
if ($lastOperation instanceof OperationInterface && $lastOperation->getType() === OperationInterface::TYPE_RETAIN && !$lastOperation->hasAttributes()) {
$this->operations->pop();
}
return $this;
}
