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<?php
class StringInputStream
{
private $stream;
private $index = -1;
private $length;
public function __construct($string)
{
$this->stream = $string;
$this->length = TextHelper::strlen($this->stream);
}
public function has_next()
{
return $this->index < ($this->length - 1);
}
public function next()
{
$this->index++;
return $this->get_current();
}
public function get_current()
{
if ($this->index < 0)
{
throw new OutOfBoundsException('out of stream', 0);
}
return $this->stream[$this->index];
}
public function get_next()
{
if (!$this->has_next())
{
throw new OutOfBoundsException('end of stream', 0);
}
return $this->stream[$this->index + 1];
}
public function get_previous()
{
if ($this->index <= 0)
{
throw new OutOfBoundsException('beginning of stream', 0);
}
return $this->stream[$this->index - 1];
}
public function assert_next($pattern, $options = '', array &$matches = null)
{
$subject = TextHelper::substr($this->stream, $this->index + 1);
return preg_match('`^(?:' . $pattern . ')`u' . $options, $subject, $matches);
}
public function consume_next($pattern, $options = '', array &$matches = null)
{
if ($this->assert_next($pattern, $options, $matches))
{
$this->move(TextHelper::strlen($matches[0]));
return true;
}
return false;
}
public function move($delta)
{
$new_index = $this->index + $delta;
$this->seek($new_index);
}
public function safe_move($delta)
{
$new_index = $this->index + $delta;
$safe_index = max(0, min($new_index, $this->length - 1));
$this->seek($safe_index);
}
public function tell()
{
return $this->index;
}
public function seek($new_index)
{
if (!($new_index >= -1 && $new_index < $this->length))
{
throw new OutOfBoundsException('new index ' . $new_index .
' is out of bounds (size: ' . $this->length . ')', 0);
}
$this->index = $new_index;
}
public function to_string($delta = 0, $max_length = 50)
{
$old_index = $this->index;
$this->safe_move($delta);
$str = TextHelper::substr($this->stream, $this->index);
$this->seek($old_index);
if ($max_length > 0)
{
return TextHelper::substr($str, 0, $max_length);
}
return $str;
}
public function entire_string()
{
return $this->stream;
}
}
?>