R/fseq_methods.R

In MyKo101/mpipe: Adds extra functionality to pipelines

#' @name fseq_methods
#'
#' @title
#' Generic methods for fseq manipulations
#'
#' @description
#' When pipelines are created without an initial term, the
#' `magrittr` package (where the pipes originate)
#' creates a specialised type of function called a `fseq`.
#' However, `magrittr` doesn't do much with these
#' `fseq` objects.
#'
#' @param lhs
#' `fseq` to be performed first
#'
#' @param rhs
#' `fseq` to be performed second
#'
#' @examples
#' a <- . %>%
#'   magrittr::add(2) %>%
#'   magrittr::divide_by(3)
#' b <- . %>%
#'   rep(3) %>%
#'   sum()
#'
#' (a + b)(2)
#' (b + a)(2)
#' @export

`+.fseq` <- function(lhs, rhs) {
  new_lhs <- copy_fun(lhs)

  new_function_list <- c(
    functions(new_lhs),
    vector("list", length = length(rhs))
  )

  rhs_fl <- functions(rhs)

  for (i in 1:length(rhs))
  {
    new_function_list[[length(lhs) + i]] <- copy_fun(rhs_fl[[i]])
  }

  environment(new_lhs)[["_function_list"]] <- new_function_list

  new_lhs
}

#' @rdname fseq_methods
#' @export
#'
#' @examples
#' length(a)
#' @param x
#' an `fseq` object.

length.fseq <- function(x) {
  length(magrittr::functions(x))
}

#' @rdname fseq_methods
#' @export
#'
#' @examples
#' is.fseq(a)
#' is.fseq(mean)
#' @param object
#' object to be tested.
#'
#'
#'

is.fseq <- function(object) {
  "fseq" %in% class(object)
}


#' @rdname fseq_methods
#' @export
#'
#' @examples
#' is_fseq(a)
#' is_fseq(mean)
is_fseq <- function(object) {
  "fseq" %in% class(object)
}