class Reader

class Reader {
    private int $length;
    private int $position = 0;
    public function __construct(string $source) {
        $this->length = \strlen($source);
    }
    public function isEOF() : bool {
        return $this->position >= $this->length;
    }
    public function getPosition() : int {
        return $this->position;
    }
    public function getRemainingLength() : int {
        return $this->length - $this->position;
    }
    public function getSubstring(int $length, int $offset = 0) : string {
        return substr($this->source, $this->position + $offset, $length);
    }
    public function getOffset(string $string) : int|false {
        $position = strpos($this->source, $string, $this->position);
        return false === $position ? false : $position - $this->position;
    }
    public function findPattern(string $pattern) : array|false {
        $source = substr($this->source, $this->position);
        if (preg_match($pattern, $source, $matches)) {
            return $matches;
        }
        return false;
    }
    public function moveForward(int $length) : void {
        $this->position += $length;
    }
    public function moveToEnd() : void {
        $this->position = $this->length;
    }

}