joethorley · August 29, 2015 13:56 · Feb 24, 2014 · Feb 24, 2014
diff --git a/ext.R b/ext.R
@@ -1,3 +1,6 @@
+library(tools)
+library(assertthat)
+
 #' @title Filename extension utilities
 #' 
 #' @description Replaces, adds or removes (rm) extensions from filenames or test whether

diff --git a/ext.R b/ext.R
@@ -0,0 +1,70 @@
+#' @title Filename extension utilities
+#' 
+#' @description Replaces, adds or removes (rm) extensions from filenames or test whether
+#' filename has an extension or is a filename with a particular extension. 
+#' Functions are primarily wrappers
+#' on the tools package functions \code{file_ext} and \code{file_path_sans_ext}.
+#' 
+#' @usage
+#' get_ext(x)
+#' has_ext(x)
+#' is_ext(x, ext)
+#' rm_ext(x)
+#' replace_ext(x, ext)
+#' add_ext(x, ext)
+#' 
+#' @param x a character vector of the filenames.
+#' @param ext a character scalar of the extension with or without a leading point.
+#' @return A character vector of the extensions or modified filenames or a logical vector
+#' indicating whether a filename has an extension or is a particular extension.
+#' @seealso \code{\link{file_ext}} and \code{\link{file_path_sans_ext}}
+#' @aliases has_ext is_ext rm_ext replace_ext add_ext
+#' @examples
+#' 
+#' x <- c("file", "file.txt", "file.txt.zip")
+#' get_ext(x)
+#' has_ext(x)
+#' is_ext(x, "txt")
+#' is_ext(x, ".txt")
+#' rm_ext(x)
+#' replace_ext(x, "md")
+#' add_ext(x, "md")
+#' @export
+get_ext <- function (x) {
+  file_ext(x)
+}
+
+rm_leading_dot <- function (x) {
+  sub("^[.]", "", x)
+}
+
+#' @export
+has_ext <- function (x) {
+  get_ext(x) != ""
+}
+
+#' @export
+is_ext <- function (x, ext) {
+  assert_that(is.string(ext))
+  ext <- rm_leading_dot (ext)
+  get_ext(x) == ext
+}
+
+#' @export
+rm_ext <- function (x) {
+  file_path_sans_ext(x)
+}
+
+#' @export
+replace_ext <- function (x, ext) {
+  assert_that(is.string(ext))
+  ext <- rm_leading_dot (ext)
+  paste(rm_ext(x), ext, sep = ".")
+}
+
+#' @export
+add_ext <- function (x, ext) {
+  assert_that(is.string(ext))
+  ext <- rm_leading_dot (ext)
+  paste(x, ext, sep = ".")
+}