Method setBuffer

inst/include/Rcpp/String.h:656–661

        inline bool is_na() const { return data == NA_STRING; }
        inline void setBuffer() {
            if (!buffer_ready) {
                buffer = char_nocheck(data);
                buffer_ready  = true;
            }
        }
        inline void setData() {
            RCPP_STRING_DEBUG("setData");
            if (!valid) {