R/utils.R

In rmdfiltr: 'Lua'-Filters for R Markdown

#' #' Verify minimum pandoc version
#' #'
#' #' Verifies that pandoc version 2.0 or later is available.
#' #'
#' #' @param report Character. In case pandoc version is < 2.0 errors if
#' #'   \code{error}, warns if \code{warn}, or remains silent otherwise.
#' #'
#' #' @return Logical. \code{TRUE} if pandoc version is 2.0 or later, \code{FALSE}
#' #'   otherwise.
#' #' @export
#' #'
#' #' @examples
#' #'
#' #' verify_pandoc_version(report = "silent")
#'
#' verify_pandoc_version <- function(report = "error") {
#'   assertthat::assert_that(length(report) == 1)
#'   assertthat::assert_that(is.character(report))
#'
#'   lua_available <- utils::compareVersion("2.0", as.character(rmarkdown::pandoc_version())) <= 0
#'
#'   report_fun <- switch(
#'     report
#'     , "error" = stop
#'     , "warn" = function(x) { warning(x); return(FALSE) }
#'     , function(x) return(FALSE)
#'   )
#'
#'   if(!lua_available) {
#'     report_fun("Lua filters require pandoc 2.0 or later (https://pandoc.org/).")
#'   }
#'
#'   lua_available
#' }