R/paths.R

In PredictiveEcology/lazyR: Create Lazy Load Databases for R Objects

################################################################################
#' Check filepath.
#'
#' Checks the specified filepath for formatting consistencies,
#' such as trailing slashes, etc.
#'
#' @param path A character string corresponding to a filepath.
#'
#' @param create A logical indicating whether the path should
#' be created if it doesn't exist. Default is \code{FALSE}.
#'
#' @return Character string denoting the cleaned up filepath.
#'
#' @seealso \code{\link{file.exists}}, \code{\link{dir.create}}.
#'
#' @docType methods
#' @rdname checkPath
#'
setGeneric("checkPath", function(path, create) {
  standardGeneric("checkPath")
})

#' @rdname checkPath
setMethod("checkPath",
          signature(path="character", create="logical"),
          definition=function(path, create) {
            if (length(path)!=1) {
              stop("path must be a character vector of length 1.")
            } else {
              if (is.na(path)) {
                stop("Invalid path: cannot be NA.")
              } else {
                path = normPath(path)
                
                if (!file.exists(path)) {
                  if (create==TRUE) {
                    dir.create(file.path(path), recursive=TRUE, showWarnings=FALSE)
                  } else {
                    stop(paste("Specified path", path, "doesn't exist.",
                               "Create it and try again."))
                  }
                }
                return(path)
              }
            }
          })

#' @rdname checkPath
setMethod("checkPath",
          signature(path="character", create="missing"),
          definition=function(path) {
            return(checkPath(path, create=FALSE))
          })

#' @rdname checkPath
setMethod("checkPath",
          signature(path="NULL", create="ANY"),
          definition=function(path) {
            stop("Invalid path: cannot be NULL.")
          })

#' @rdname checkPath
setMethod("checkPath",
          signature(path="missing", create="ANY"),
          definition=function() {
            stop("Invalid path: no path specified.")
          })

################################################################################
#' Normalize filepath.
#'
#' Checks the specified filepath for formatting consistencies:
#'  1) use slash instead of backslash;
#'  2) do tilde etc. expansion;
#'  3) remove trailing slash.
#'
#' @param path A character vector of filepaths.
#'
#' @return Character vector of cleaned up filepaths.
#'
#' @docType methods
#' @rdname normPath
#' @importFrom magrittr %>%
#'
setGeneric("normPath", function(path) {
  standardGeneric("normPath")
})

#' @rdname normPath
setMethod("normPath",
          signature(path="character"),
          definition=function(path) {
            lapply(path, function(x) {
              if (is.na(x)) {
                NA_character_
              } else {
                normalizePath(x, winslash="/", mustWork=FALSE)
              }
            }) %>%
              unlist %>%
              gsub("^[.]", paste0(getwd()), .) %>%
              gsub("\\\\", "//", .) %>%
              gsub("//", "/", .) %>%
              gsub("/$", "", .)
          })

#' @rdname normPath
setMethod("normPath",
          signature(path="list"),
          definition=function(path) {
            return(normPath(unlist(path)))
          })

#' @rdname normPath
setMethod("normPath",
          signature(path="NULL"),
          definition=function(path) {
            return(character())
          })

#' @rdname normPath
setMethod("normPath",
          signature(path="missing"),
          definition=function() {
            return(character())
          })