R/expand_path.R

In pobsteta/theia2r: An R toolbox to find, download and preprocess Sentinel-2 data

#' @title Expand a path with a parent directory
#' @description Accessory function which checks if a path is absolute or relative;
#'  if relative, use a specified parent directory instead than the working
#'  dorectory to expand it.
#'  Useful for functions which accept more than one path as arguments,
#'  in which one of them contains the absolute position, and the others
#'  do not.
#' @param ... `R` objects which are concatenated.
#' @param path The path name (`character`) to check ad eventually expand.
#' @param parent The parent directory (`character`) to use if `path` is
#'  relative (default value: the working directory).
#' @param silent Logical value: if TRUE (default), no message are shown;
#'  if FALSE, a message inform if `parent` were applied or not;
#'  if NA, a warning is returned if `path` is expanded, nothing if it
#'  is already an absolute path.
#' @param normalize Logical value: if TRUE (default), the path is normalised
#'  (\code{\link[base]{normalizePath}} is applied); if FALSE it is simply
#'  appended.
#' @return The path eventually expanded.
#' @export
#' @importFrom magrittr '%>%'
#' @author Luigi Ranghetti, phD (2017) \email{ranghetti.l@@irea.cnr.it}
#' @note License: GPL 3.0


expand_path <- function(path, parent = getwd(), silent = TRUE, normalize = TRUE) {
    
    # to avoid NOTE on check
    . <- NULL
    
    # chose the function to apply
    expand_fun <- ifelse(normalize == TRUE, "normalizePath", "path.expand")
    
    # check if path is relative
    path_isabsolute <- if (Sys.info()["sysname"] == "Windows") {
        # for windows, the second character is used to discriminate absolute from relative
        substr(path.expand(path), 2, 2) == ":"
    } else {
        # for unix, the first character is used
        substr(path.expand(path), 1, 1) == "/"
    }
    
    # return
    if (path_isabsolute) {
        
        if (!is.na(silent) & silent == FALSE) {
            print_message(type = "message", "Path '", path, "' is already absolute.")
        }
        do.call(expand_fun, list(path)) %>% return()
        
    } else {
        
        if (is.na(silent) | silent == FALSE) {
            print_message(type = ifelse(is.na(silent), "warning", "message"), "Path '", path, "' is not absolute; '", gsub("/$", "", parent), "' is used as prefix.")
        }
        
        gsub("/$", "", parent) %>% file.path(path) %>% list() %>% do.call(expand_fun, .) %>% return()
        
    }
    
}




#' @title Express file paths in canonical Form basing on the operating system
#' @description Accessory function wrapper for `normalizePath()` in Linux
#'  and `shortPathName(normalizePath())` in Windows.
#' @param path character vector of file paths
#' @param ... additional parameters passed to [normalizePath] (i.e. mustWork).
#' @return The paths normalized.
#' @export
#' @author Luigi Ranghetti, phD (2018) \email{ranghetti.l@@irea.cnr.it}
#' @note License: GPL 3.0


normalize_path <- function(path, ...) {
    
    if (Sys.info()["sysname"] == "Windows") {
        utils::shortPathName(normalizePath(gsub("\\\\$", "", path), ...))
        
    } else {
        normalizePath(path, ...)
    }
    
}