R/check-scalar-isString.R

In acidgenomics/goalie: Assertive Check Functions

#' Does the input contain a (non-empty) character string?
#'
#' @name check-scalar-isString
#' @note Updated 2022-12-14.
#'
#' @inherit check
#' @inheritParams AcidRoxygen::params
#'
#' @examples
#' ## TRUE ====
#' isString("hello")
#'
#' ## FALSE ====
#' isString(1)
#' isString("")
#' isString(NA_character_)
NULL



#' @rdname check-scalar-isString
#' @export
isString <-
    function(x,
             nullOk = FALSE) {
        if (isTRUE(nullOk) && is.null(x)) {
            return(TRUE)
        }
        ok <- isScalar(x)
        if (!isTRUE(ok)) {
            return(ok)
        }
        ok <- is.character(x)
        if (!isTRUE(ok)) {
            return(false("{.var %s} is not character.", .toName(x)))
        }
        ok <- !is.na(x)
        if (!isTRUE(ok)) {
            return(false("{.var %s} is {.val %s}.", .toName(x), "NA"))
        }
        ok <- !identical(x, "")
        if (!isTRUE(ok)) {
            return(false("{.var %s} contains empty string.", .toName(x)))
        }
        TRUE
    }