R/ipad.R

In iterors: Fast, Compact Iterators and Tools

#' Iterator that returns an object followed indefinitely by a fill value
#'
#' Constructs an iterator that returns an iterable \code{object} before padding
#' the iterator with the given \code{fill} value indefinitely.
#'
#' @export
#' @param object an iterable object
#' @param fill the value to pad the indefinite iterator after the initial
#' \code{object} is consumed. Default: \code{NA}
#' @param ... Passed along to [iteror] constructor.
#' @return iterator that returns \code{object} followed indefinitely by the
#' \code{fill} value
#' @examples
#'
#' it <- iteror(1:9)
#' it_i_pad <- i_pad(it)
#' as.list(i_slice(it_i_pad, end=9)) # Same as as.list(1:9)
#'
#' it2 <- iteror(1:9)
#' it2_i_pad <- i_pad(it2)
#' as.list(i_slice(it2_i_pad, end=10)) # Same as as.list(c(1:9, NA))
#'
#' it3 <- iteror(1:9)
#' it3_i_pad <- i_pad(it3, fill=TRUE)
#' as.list(i_slice(it3_i_pad, end=10)) # Same as as.list(c(1:9, TRUE))
#'
i_pad <- function(object, fill=NA, ...) {
  it <- iteror(object, ...)
  i_chain(it, i_repeat(fill))
}