R/print.R

In yamlme: Writing 'YAML' Headers for 'R-Markdown' Documents

#' @name print2text
#' @title Print content of rmd_doc into a text string
#'
#' @description
#' Content of [rmd_doc-class] objects will be converted into a string that will
#' be passed either to [print()] or to [write_rmd()].
#'
#' @param x Input [rmd_doc-class] object.
#'
#' @keywords internal
print2text <- function(x) {
  if ("header" %in% names(x)) {
    x$header <- paste0(c("---\n", as.yaml(x$header), "---\n\n"),
      collapse = ""
    )
  } else {
    x$header <- paste0(c(
      "---\n", "# No header in this document!\n", "---\n\n"
    ),
    collapse = ""
    )
  }
  if ("body" %in% names(x)) {
    x <- x[c("header", "body")]
    x$body <- paste0(x$body, collapse = "")
  }
  return(do.call(paste0, list(x, collapse = "")))
}

#' @name print
#'
#' @title Print Method for rmd_doc
#'
#' @description
#' Quick display for `rmd_doc` objects. This method also defines the way how
#' objects are displayed in the console.
#'
#' @param x An object of class `rmd_doc`.
#' @param maxlines An integer value indicating the number of lines used for the
#'     display. Longer documents will be truncated.
#' @param ... Further arguments passed among methods (not yet in use).
#'
#' @return
#' A display of the resulting R-Markdown document in the console.
#'
#' @example examples/print.R
#'
#' @method print rmd_doc
#' @aliases print,rmd_doc-method
#' @export
print.rmd_doc <- function(x, maxlines = 10, ...) {
  if ("body" %in% names(x) & length(x$body) > maxlines) {
    x$body <- c(x$body[1:maxlines], "\n[...truncated]\n")
  }
  x <- print2text(x)
  cat(x)
}