##' @rdname nanoduration
setClass("nanoduration", contains = "integer64")

##' Duration type with nanosecond precision
##'
##' The type \code{nanoduration} is a length of time (implemented as
##' an S4 class) with nanosecond precision. It is a count of
##' nanoseconds and may be negative. The expected arithmetic
##' operations are provided, including sequence generation.
##'
##' A \code{nanoduration} can be constructed with the function
##' \code{as.nanoduration} which can take the types \code{integer64},
##' \code{integer} and \code{numeric} (all indicating the count in
##' nanosecond units) or the type \code{character}.
##'
##' It can also be constructed by specifying with individual arguments
##' the hours, minutes, seconds and nanoseconds with a call to
##' \code{nanoduration}.
##'
##' A \code{nanoduration} is displayed as hours, minutes, seconds and
##' nanoseconds like this: \code{110:12:34.123_453_001}. The nanosecond
##' precision displayed is adjusted as necessary, so e.g. 1 second is
##' displayed as \code{00:00:01}.
##'
##' @param hours number of hours
##' @param minutes number of minutes
##' @param seconds number of seconds
##' @param nanoseconds number of nanoseconds
##' @param x a \code{nanoduration} object
##' @param ... further arguments passed to or from methods.
##' @param e1 Operand of class \code{nanoival}
##' @param e2 Operand of class \code{nanoival}
##' @param object argument for method \code{show}
##' @param i index specifying elements to extract or replace.
##' @param j Required for \code{[} signature but ignored here
##' @param drop Required for \code{[} signature but ignored here
##' @param value argument for \code{nanoduration-class}
##' @param na.rm if \code{TRUE} NA values are removed for the
##'     computation
##' @param quote indicates if the output of \code{print} should be
##'     quoted
##' @return A nanoduration object
##' @author Dirk Eddelbuettel
##' @author Leonardo Silvestri
##' @examples
##' ## constructors:
##' nanoduration(hours=10, minutes=3, seconds=2, nanoseconds=999999999)
##' as.nanoduration("10:03:02.999_999_999")
##' as.nanoduration(36182999999999)
##'
##' ## arithmetic:
##' as.nanoduration(10e9) - as.nanoduration(9e9)
##' as.nanoduration(10e9) + as.nanoduration(-9e9)
##' as.nanoduration("24:00:00") / 2
##' as.nanoduration("24:00:00") / as.nanoduration("12:00:00")
##'
##' ## comparison:
##' as.nanoduration("10:03:02.999_999_999") == 36182999999999
##' as.nanoduration("10:03:02.999_999_999") > as.nanoduration("10:03:02.999_999_998")
##' as.nanoduration("10:03:02.999_999_998") < "10:03:02.999_999_999"
##'
##' @seealso
##' \code{\link{nanotime}}
##'
##' @aliases  *,ANY,nanoduration-method
##' @aliases  *,nanoduration,ANY-method
##' @aliases  *,nanoduration,nanoduration-method
##' @aliases  +,ANY,nanoduration-method
##' @aliases  /,ANY,nanoduration-method
##' @aliases  /,nanoduration,ANY-method
##' @aliases  Complex,nanoduration-method
##' @aliases  Logic,ANY,nanoduration-method
##' @aliases  Logic,nanoduration,ANY-method
##' @aliases  Logic,nanoduration,nanoduration-method
##' @aliases  Math2,nanoduration-method
##' @aliases  Math,nanoduration-method
##' @aliases  Summary,nanoduration-method
##'
##' @rdname nanoduration
nanoduration <- function(hours = 0L, minutes = 0L, seconds = 0L, nanoseconds = 0L) {
    if (nargs()==0) {
        as.nanoduration(NULL)
    } else {
        make_duration_impl(as.integer64(hours),
                           as.integer64(minutes),
                           as.integer64(seconds),
                           as.integer64(nanoseconds))
    }
}

setOldClass("difftime")

##' @noRd
setGeneric("as.nanoduration", function(x) standardGeneric("as.nanoduration"))

##' @rdname nanoduration
##' @aliases as.nanoduration
setMethod("as.nanoduration",
          "character",
          function(x) {
              duration_from_string_impl(x)
          })

setAs("character", "nanoduration", function(from) as.nanoduration(from))

##' @rdname nanoduration
setMethod("as.nanoduration",
          "integer64",
          function(x) {
              new("nanoduration", x)
          })

setAs("integer64", "nanoduration", function(from) as.nanoduration(from))


##' @rdname nanoduration
setMethod("as.nanoduration",
          "numeric",
          function(x) {
              nm <- names(x)
              res <- new("nanoduration", as.integer64(x))
              if (!is.null(nm)) {
                  names(res) <- nm
              }
              res
          })

setAs("numeric", "nanoduration", function(from) as.nanoduration(from))


##' @rdname nanoduration
setMethod("as.nanoduration",
          "integer",
          function(x) {
              nm <- names(x)
              res <- new("nanoduration", as.integer64(x))
              if (!is.null(nm)) {
                  names(res) <- nm
              }
              res
          })

setAs("integer", "nanoduration", function(from) as.nanoduration(from))

##' @rdname nanoduration
setMethod("as.nanoduration",
          "difftime",
          function(x) {
              x <- as.numeric(x, units = "secs")
              s <- as.integer(x) # seconds
              n <- as.integer(1e9 * (x - s)) # nanoseconds
              nanoduration(seconds = s, nanoseconds = n)
})

setAs("difftime", "nanoduration", function(from) as.nanoduration(from))


##' @rdname nanoduration
setMethod("as.nanoduration",
          "NULL",
          function(x) {
              new("nanoduration", as.integer64(NULL))
          })

##' @rdname nanoduration
setMethod("as.nanoduration",
          "missing",
          function(x) {
              new("nanoduration", integer64())
          })

##' @rdname nanoduration
setMethod("show",
          signature("nanoduration"),
          function(object) print(object))

##' @rdname nanoduration
setMethod("print",
          "nanoduration",
          function(x, quote=FALSE, ...) {
              if (length(x) == 0) {
                  print("nanoduration(0)", quote=quote)
              } else {
                  print(duration_to_string_impl(x), quote=quote)
              }
          })

##' @rdname nanoduration
format.nanoduration <- function(x, ...) {
    as.character(x)
}


##' @rdname nanoduration
##' @method as.integer64 nanoduration
as.integer64.nanoduration <- function(x, ...) {
    S3Part(x, strictS3=TRUE)
}


##' @rdname nanoduration
setMethod("as.character",
          signature("nanoduration"),
          function(x) {
              duration_to_string_impl(x)
          })


##' @rdname nanoduration
setMethod("is.na",
          "nanoduration",
          function(x) {
              duration_is_na_impl(x)
          })


## ------------ `-`

## nanoduration - other
##' @rdname nanoduration
setMethod("-", c("nanoduration", "nanoduration"),
          function(e1, e2) {
              new("nanoduration", S3Part(e1, strictS3=TRUE) - S3Part(e2, strictS3=TRUE))
          })
##' @rdname nanoduration
setMethod("-", c("nanoduration", "integer64"),
          function(e1, e2) {
              new("nanoduration", S3Part(e1, strictS3=TRUE) - e2)
          })
##' @rdname nanoduration
setMethod("-", c("nanoduration", "integer"),
          function(e1, e2) {
              new("nanoduration", S3Part(e1, strictS3=TRUE) - e2)
          })
##' @rdname nanoduration
setMethod("-", c("nanoduration", "numeric"),
          function(e1, e2) {
              new("nanoduration", S3Part(e1, strictS3=TRUE) - e2)
          })
##' @rdname nanoduration
setMethod("-", c("nanoduration", "difftime"),
          function(e1, e2) {
              e1 - as.nanoduration(e2)
          })
##' @rdname nanoduration
setMethod("-", c("nanoduration", "ANY"),
          function(e1, e2) {
              if (missing(e2)) {
                  new("nanoduration", -S3Part(e1, strictS3=TRUE))
              }
              else {
                  stop("invalid operand types")
              }
          })

## other - nanoduration

##' @rdname nanoduration
setMethod("-", c("nanotime", "nanoduration"),
          function(e1, e2) {
              new("nanotime", S3Part(e1, strictS3=TRUE) - e2)
          })
##' @rdname nanoduration
setMethod("-", c("nanotime", "difftime"),
          function(e1, e2) {
              e1 - as.nanoduration(e2)
          })
##' @rdname nanoduration
setMethod("-", c("integer64", "nanoduration"),
          function(e1, e2) {
              new("nanoduration", e1 - S3Part(e2, strictS3=TRUE))
          })
##' @rdname nanoduration
setMethod("-", c("integer", "nanoduration"),
          function(e1, e2) {
              new("nanoduration", e1 - S3Part(e2, strictS3=TRUE))
          })
##' @rdname nanoduration
setMethod("-", c("numeric", "nanoduration"),
          function(e1, e2) {
              new("nanoduration", e1 - S3Part(e2, strictS3=TRUE))
          })
##' @rdname nanoduration
setMethod("-", c("difftime", "nanoduration"),
          function(e1, e2) {
              as.nanoduration(e1) - e2
          })
##' @rdname nanoduration
setMethod("-", c("ANY", "nanoduration"),
          function(e1, e2) {
              stop("invalid operand types")
          })

## ----------- `+`

##' @rdname nanoduration
setMethod("+", c("nanoduration", "ANY"),
          function(e1, e2) {
              if (missing(e2)) {
                  e1
              }
              else {
                  stop("invalid operand types")
              }
          })
##' @rdname nanoduration
setMethod("+", c("nanoduration", "nanoduration"),
          function(e1, e2) {
              new("nanoduration", S3Part(e1, strictS3=TRUE) + e2)
          })
##' @rdname nanoduration
setMethod("+", c("nanoduration", "integer64"),
          function(e1, e2) {
              new("nanoduration", S3Part(e1, strictS3=TRUE) + e2)
          })
##' @rdname nanoduration
setMethod("+", c("nanoduration", "numeric"),
          function(e1, e2) {
              new("nanoduration", S3Part(e1, strictS3=TRUE) + e2)
          })
##' @rdname nanoduration
setMethod("+", c("nanoduration", "difftime"),
          function(e1, e2) {
              e1 + as.nanoduration(e2)
          })
##' @rdname nanoduration
setMethod("+", c("nanotime", "nanoduration"),
          function(e1, e2) {
              new("nanotime", S3Part(e1, strictS3=TRUE) + S3Part(e2, strictS3=TRUE))
          })
##' @rdname nanoduration
setMethod("+", c("nanotime", "difftime"),
          function(e1, e2) {
              e1 + as.nanoduration(e2)
          })
##' @rdname nanoduration
setMethod("+", c("nanoduration", "nanotime"),
          function(e1, e2) {
              new("nanotime", S3Part(e1, strictS3=TRUE) + S3Part(e2, strictS3=TRUE))
          })
##' @rdname nanoduration
setMethod("+", c("difftime", "nanotime"),
          function(e1, e2) {
              as.nanoduration(e1) + e2
          })

##' @rdname nanoduration
setMethod("+", c("nanoival", "nanoduration"),
          function(e1, e2) {
              new("nanoival", nanoival_plus_impl(e1, e2))
          })
##' @rdname nanoduration
setMethod("-", c("nanoival", "nanoduration"),
          function(e1, e2) {
              new("nanoival", nanoival_plus_impl(e1, -e2))
          })
##' @rdname nanoduration
setMethod("+", c("nanoduration", "nanoival"),
          function(e1, e2) {
              new("nanoival", nanoival_plus_impl(e2, e1))
          })
##' @rdname nanoduration
setMethod("+", c("nanoival", "difftime"),
          function(e1, e2) {
              new("nanoival", nanoival_plus_impl(e1, as.nanoduration(e2)))
          })
##' @rdname nanoduration
setMethod("-", c("nanoival", "difftime"),
          function(e1, e2) {
              new("nanoival", nanoival_plus_impl(e1, -as.nanoduration(e2)))
          })
##' @rdname nanoduration
setMethod("+", c("difftime", "nanoival"),
          function(e1, e2) {
              new("nanoival", nanoival_plus_impl(e2, as.nanoduration(e1)))
          })

##' @noRd
setMethod("+", c("ANY", "nanoduration"),
          function(e1, e2) {
              stop("invalid operand types")
          })
##' @rdname nanoduration
setMethod("+", c("integer64", "nanoduration"),
          function(e1, e2) {
              new("nanoduration", e1 + S3Part(e2, strictS3=TRUE))
          })
##' @rdname nanoduration
setMethod("+", c("numeric", "nanoduration"),
          function(e1, e2) {
              new("nanoduration", e1 + S3Part(e2, strictS3=TRUE))
          })
##' @rdname nanoduration
setMethod("+", c("difftime", "nanoduration"),
          function(e1, e2) {
              as.nanoduration(e1) + e2
          })

## ----------- `*`

##' @noRd
setMethod("*", c("nanoduration", "nanoduration"),
          function(e1, e2) {
              stop("invalid operand types")
          })
##' @rdname nanoduration
setMethod("*", c("nanoduration", "numeric"),
          function(e1, e2) {
              new("nanoduration", S3Part(e1, strictS3=TRUE) * e2)
          })
##' @rdname nanoduration
setMethod("*", c("nanoduration", "integer64"),
          function(e1, e2) {
              new("nanoduration", S3Part(e1, strictS3=TRUE) * e2)
          })
##' @rdname nanoduration
setMethod("*", c("numeric", "nanoduration"),
          function(e1, e2) {
              new("nanoduration", e1 * S3Part(e2, strictS3=TRUE))
          })
##' @rdname nanoduration
setMethod("*", c("integer64", "nanoduration"),
          function(e1, e2) {
              new("nanoduration", e1 * S3Part(e2, strictS3=TRUE))
          })
##' @noRd
setMethod("*", c("nanoduration", "ANY"),
          function(e1, e2) {
              stop("invalid operand types")
          })
##' @noRd
setMethod("*", c("ANY", "nanoduration"),
          function(e1, e2) {
              stop("invalid operand types")
          })

## ----------- `/`

##' @rdname nanoduration
setMethod("/", c("nanoduration", "nanoduration"),
          function(e1, e2) {
              S3Part(e1, strictS3=TRUE) / S3Part(e2, strictS3=TRUE)
          })
##' @rdname nanoduration
setMethod("/", c("nanoduration", "integer64"),
          function(e1, e2) {
              new("nanoduration", as.integer64(S3Part(e1, strictS3=TRUE) / e2))
          })
##' @rdname nanoduration
setMethod("/", c("nanoduration", "numeric"),
          function(e1, e2) {
              new("nanoduration", as.integer64(S3Part(e1, strictS3=TRUE) / e2))
          })
##' @noRd
setMethod("/", c("nanoduration", "ANY"),
          function(e1, e2) {
              stop("invalid operand types")
          })
##' @noRd
setMethod("/", c("ANY", "nanoduration"),
          function(e1, e2) {
              stop("invalid operand types")
          })

## ---------- other ops

##' @rdname nanoduration
setMethod("Arith", c("nanoduration", "ANY"),
          function(e1, e2) {
              callNextMethod(S3Part(e1, strictS3=TRUE), e2)
          })

##' @rdname nanoduration
setMethod("Compare", c("nanoduration", "character"),
          function(e1, e2) {
              ne2 <- as.nanoduration(e2)
              callNextMethod(e1, ne2)
          })

##' @rdname nanoduration
setMethod("Compare", c("character", "nanoduration"),
          function(e1, e2) {
              ne1 <- as.nanoduration(e1)
              callNextMethod(ne1, e2)
          })

##' @rdname nanoduration
setMethod("Compare", c("nanoduration", "ANY"),
          function(e1, e2) {
              callNextMethod(S3Part(e1, strictS3=TRUE), e2)
          })

##' @noRd
setMethod("Logic", c("nanoduration", "nanoduration"),
          function(e1, e2) {
              ## this is the same error message that R gives for "A" | "A"
              stop("operations are possible only for numeric, logical or complex types")
          })

##' @noRd
setMethod("Logic", c("nanoduration", "ANY"),
          function(e1, e2) {
              ## this is the same error message that R gives for "A" | "A"
              stop("operations are possible only for numeric, logical or complex types")
          })

##' @noRd
setMethod("Logic", c("ANY", "nanoduration"),
          function(e1, e2) {
              ## this is the same error message that R gives for "A" | "A"
              stop("operations are possible only for numeric, logical or complex types")
          })

##' @rdname nanoduration
setMethod("abs", c("nanoduration"),
          function(x) {
              new("nanoduration", callNextMethod(S3Part(x, strictS3=TRUE)))
          })
##' @rdname nanoduration
setMethod("sign", c("nanoduration"),
          function(x) {
              callNextMethod(S3Part(x, strictS3=TRUE))
          })


##' @noRd
setMethod("Math", c("nanoduration"),
          function(x) {
              ## this is the same error message that R gives for abs("A")
              stop("non-numeric argument to mathematical function")
          })

##' @noRd
setMethod("Math2", c("nanoduration"),
          function(x, digits) {
              ## this is the same error message that R gives for round("A")
              stop("non-numeric argument to mathematical function")
          })

##' @noRd
setMethod("Summary", c("nanoduration"),
          function(x, ..., na.rm = FALSE) {
              ## this is the same error message that R gives for sum("A")
              stop("invalid 'type' (nanoduration) of argument")
          })

##' @rdname nanoduration
setMethod("sum", c("nanoduration"),
          function(x, ..., na.rm = FALSE) {
              new("nanoduration", callNextMethod())
          })

##' @rdname nanoduration
setMethod("min", c("nanoduration"),
          function(x, ..., na.rm = FALSE) {
              new("nanoduration", callNextMethod())
          })

##' @rdname nanoduration
setMethod("max", c("nanoduration"),
          function(x, ..., na.rm = FALSE) {
              new("nanoduration", callNextMethod())
          })

##' @rdname nanoduration
setMethod("range", c("nanoduration"),
          function(x, ..., na.rm = FALSE) {
              new("nanoduration", callNextMethod())
          })


##' @noRd
setMethod("Complex", c("nanoduration"),
          function(z) {
              ## this is the same error message that R gives for Arg("A")
              stop("non-numeric argument to function")
          })


## non-ops:
## -------

## subset/subassign

##' @rdname nanoduration
setMethod("[[",
          signature("nanoduration"),
          function (x, i, j, ..., drop=FALSE) {
              new("nanoduration", callNextMethod())
          })

##' @rdname nanoduration
setMethod("[",
          signature("nanoduration", "numeric"),
          function (x, i, j, ..., drop=FALSE) {
              if (!missing(j) || length(list(...)) > 0) {
                  warning("unused indices or arguments in 'nanoduration' subsetting")
              }
              if (isTRUE(any(i < 0))) {
                  new("nanoduration", S3Part(x, strictS3=TRUE)[i])
              } else {            
                  nanoduration_subset_numeric_impl(x, i)
              }
          })

##' @rdname nanoduration
setMethod("[",
          signature("nanoduration", "logical"),
          function (x, i, j, ..., drop=FALSE) {
              if (!missing(j) || length(list(...)) > 0) {
                  warning("unused indices or arguments in 'nanoduration' subsetting")
              }
              nanoduration_subset_logical_impl(x, i)
          })

##' @rdname nanoduration
setMethod("[",
          signature("nanoduration", "character"),
          function (x, i, j, ..., drop=FALSE) {
              ## we don't implement 'period_subset_character_impl' but
              ## do the gymnastic of finding the NAs here at R level;
              ## it's not as efficient, but using 'character' indexing
              ## is by itself inefficient, so the overhead should have
              ## no practical consequences.
              if (!missing(j) || length(list(...)) > 0) {
                  warning("unused indices or arguments in 'nanoduration' subsetting")
              }
              na_index <- !(i %in% names(x)) | is.na(i)
              res <- new("nanoduration", S3Part(x, strictS3=TRUE)[i])
              res[na_index] <- NA_nanoduration_
              res
          })

##' @rdname nanoduration
setMethod("[",
          signature("nanoduration", "ANY"),
          function (x, i, j, ..., drop=FALSE) {
              stop("']' not defined on 'nanoduration' for index of type 'ANY'")
          })

##' @rdname nanoduration
setMethod("[<-",
          signature("nanoduration"),
          function (x, i, j, ..., value) {
              new("nanoduration", callNextMethod())
          })

##' @rdname nanoduration
c.nanoduration <- function(...) {
    as.nanoduration(c.integer64(...))
}

##' @rdname nanotime
as.data.frame.nanoduration <- function(x, ...) {
    ret <- as.data.frame(S3Part(x, strictS3=TRUE), ...)
    ## this works, but see if there's a more idiomatic and efficient way
    ## of doing this:
    ret[] <- as.nanoduration(S3Part(x, strictS3=TRUE))
    ret
}

##' Sequence Generation
##'
##' Generate a sequence of \code{nanoduration}
##'
##' @param ... arguments passed to or from methods
##' @param from,to the starting and (maximal) end values of the
##'     sequence
##' @param by the increment of the sequence
##' @param length.out integer indicating the desired length of the sequence
##' @param along.with take the length from the length of this argument.
##'
##' @examples
##' seq(from=as.nanoduration(0), by=as.nanoduration("01:00:00"), length.out=10)
##' @method seq nanoduration
seq.nanoduration <- function(from, to=NULL, by=NULL, length.out=NULL, along.with=NULL, ...) {
    return(as.nanoduration(seq(as.integer64(from), to, by, length.out, along.with, ...)))
}


##' Test if Two Objects are (Nearly) Equal
##'
##' Compare \code{target} and \code{current} testing \sQuote{near
##' equality}.  If they are different, comparison is still made to
##' some extent, and a report of the differences is returned.  Do not
##' use \code{all.equal} directly in \code{if} expressions---either
##' use \code{isTRUE(all.equal(....))} or \code{\link{identical}} if
##' appropriate.
##'
##' @param target,current \code{nanoduration} arguments to be compared
##' @param ... further arguments for different methods
##' @param tolerance numeric >= 0. Differences smaller than
##'     \code{tolerance} are not reported.  The default value is close
##'     to \code{1.5e-8}.
##' @param  scale \code{NULL} or numeric > 0, typically of length 1 or
##'          \code{length(target)}.  See \sQuote{Details}.
##' @param  countEQ logical indicating if the \code{target == current} cases should be
##'          counted when computing the mean (absolute or relative)
##'          differences.  The default, \code{FALSE} may seem misleading in
##'          cases where \code{target} and \code{current} only differ in a few
##'          places; see the extensive example.
##' @param formatFUN a \code{function} of two arguments, \code{err}, the relative, absolute
##'          or scaled error, and \code{what}, a character string indicating
##'          the _kind_ of error; maybe used, e.g., to format relative and
##'          absolute errors differently.
##' @param check.attributes logical indicating if the \code{attributes} of \code{target}
##'          and \code{current} (other than the names) should be compared.
##'
##' @seealso \code{\link{identical}}, \code{\link{isTRUE}},
##'     \code{\link{==}}, and \code{\link{all}} for exact equality
##'     testing.
##'
##' @method all.equal nanoduration
##'
all.equal.nanoduration <- function(target, current, tolerance = sqrt(.Machine$double.eps), 
                                   scale = NULL, countEQ = FALSE,
                                   formatFUN = function(err, what) format(err), ..., check.attributes = TRUE) {
    ## a bit of a kludge, but both 'nanoduration' and 'nanotime' are
    ## based on 'integer64'; because of a bug in 'all.equal.integer64'
    ## we have to redefine 'all.equal.nanotime' and it is correct for
    ## all 'integer64'-based S4 classes; in theory they would all
    ## three be the same function:
    if (inherits(target, "nanoduration")) target  <- as.nanotime(target)
    if (inherits(current, "nanoduration")) current <- as.nanotime(current)
    all.equal.nanotime(target, current, tolerance, scale, countEQ, formatFUN, ..., check.attributes=check.attributes)
}

##' @rdname all.equal.nanoduration
setMethod("all.equal", c(target = "nanoduration", current="ANY"), all.equal.nanoduration)

##' @rdname nanoduration
NA_nanoduration_  <- as.nanoduration(NA_integer_)


## rounding ops:

##' @rdname rounding
setMethod("nano_ceiling", c(x="nanotime", precision="nanoduration"),
          function(x, precision, origin=nanotime()) {
              if (!inherits(origin, "nanotime")) {
                  stop("'origin' must be of class 'nanotime'")
              }
              ceiling_impl(x, precision, origin)
          })

##' @rdname rounding
setMethod("nano_floor",   c(x="nanotime", precision="nanoduration"),
          function(x, precision, origin=nanotime()) {
              if (!inherits(origin, "nanotime")) {
                  stop("'origin' must be of class 'nanotime'")
              }
              floor_impl(x, precision, origin)
          })


##' Replicate Elements
##'
##' Replicates the values in 'x' similarly to the default method.
##'
##' @param x a vector of \code{nanoduration}
##' @param ... further arguments:
##' 
##'        'times' an integer-valued vector giving the (non-negative)
##'            number of times to repeat each element if of length
##'            'length(x)', or to repeat the whole vector if of length
##'            1. Negative or 'NA' values are an error. A 'double'
##'            vector is accepted, other inputs being coerced to an
##'            integer or double vector.
##' 
##'        'length.out' non-negative integer. The desired length of the
##'            output vector. Other inputs will be coerced to a double
##'            vector and the first element taken. Ignored if 'NA' or
##'            invalid.
##' 
##'        'each' non-negative integer. Each element of 'x' is repeated
##'            'each' times.  Other inputs will be coerced to an integer
##'            or double vector and the first element taken. Treated as
##'            '1' if 'NA' or invalid.
setMethod("rep", c(x = "nanoduration"), function(x, ...) {
    new("nanoduration", callNextMethod())
})

