Method Fill

util/stream/tokenizer.h:174–181

private:
    inline size_t Fill() {
        const size_t avail = BufEnd() - End_;
        const size_t bytesRead = Input_->Read(End_, avail);

        End_ += bytesRead;

        return bytesRead;
    }

    inline char* BufBegin() noexcept {
        return Buf_.Data();