Function to grab the available packages listed on CRAN

NAMESPACE

@@ -1,3 +1,4 @@
 # Generated by roxygen2: do not edit by hand
 
+export(fetch_available_packages)
 export(list_depends)

R/fetch_available_packages.R

@@ -0,0 +1,41 @@
+# Requires utils.R
+
+.fetch_available_packages <- function(refetch) {
+  check_pacman_dir()
+  fn <- ".pacman/packages.rds"
+  if (file.exists(fn)) {
+    ts <- as.POSIXct("1970-01-01 00:00:00", tz = "GMT") + as.numeric(Sys.Date() + 1) * 86400
+    if (refetch || (ts < file.mtime(fn))) {
+      unlink(fn)
+    }
+  }
+  if (!file.exists(fn)) {
+    download.file(sprintf("%s/src/contrib/PACKAGES.rds", get_cran_repo()), fn)
+  }
+  con <- gzfile(fn, "rb")
+  on.exit(close(con), add = TRUE)
+  packages <- readRDS(con)
+  packages <- as.data.frame(packages)
+  packages <- packages[is.na(packages$Path),]
+  packages <- packages[,c("Package", "Version")]
+  colnames(packages) <- c("package", "version")
+  rownames(packages) <- 1:nrow(packages)
+  return(packages[,c("package", "version")])
+}
+
+#' Fetch the current (or check the cache) list of packages available for install
+#' from the CRAN repositories.
+#'
+#' @param refetch Boolean indicating if the local cache should be invalidated.
+#'
+#' @return A data frame of available packages and their versions
+#' @export
+fetch_available_packages <- function(refetch = FALSE) {
+  tryCatch(
+    {
+      .fetch_available_packages(refetch)
+    },
+    warning = function(e) list(),
+    error = function(e) list()
+  )
+}

R/utils.R

@@ -0,0 +1,24 @@
+
+#' Checks the current project has a valid pacman directory structure
+#'
+#' @return invisible boolean TRUE if the structure is valid, FALSE otherwise
+check_pacman_dir <- function() {
+  if (!dir.exists("./.pacman")) {
+    if (!dir.create("./.pacman")) {
+      return(invisible(FALSE))
+    }
+  }
+  invisible(TRUE)
+}
+
+#' Returns the CRAN repository source or requests the user select one
+#'
+#' @return string CRAN repository URL
+get_cran_repo <- function() {
+  repo <- getOption("repos")[[1]]
+  if (repo == "@CRAN@") {
+    chooseCRANmirror()
+    repo <- getOption("repos")[[1]]
+  }
+  repo
+}

man/check_pacman_dir.Rd

@@ -0,0 +1,14 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/utils.R
+\name{check_pacman_dir}
+\alias{check_pacman_dir}
+\title{Checks the current project has a valid pacman directory structure}
+\usage{
+check_pacman_dir()
+}
+\value{
+invisible boolean TRUE if the structure is valid, FALSE otherwise
+}
+\description{
+Checks the current project has a valid pacman directory structure
+}

man/fetch_available_packages.Rd

@@ -0,0 +1,19 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/fetch_available_packages.R
+\name{fetch_available_packages}
+\alias{fetch_available_packages}
+\title{Fetch the current (or check the cache) list of packages available for install
+from the CRAN repositories.}
+\usage{
+fetch_available_packages(refetch = FALSE)
+}
+\arguments{
+\item{refetch}{Boolean indicating if the local cache should be invalidated.}
+}
+\value{
+A data frame of available packages and their versions
+}
+\description{
+Fetch the current (or check the cache) list of packages available for install
+from the CRAN repositories.
+}

man/get_cran_repo.Rd

@@ -0,0 +1,14 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/utils.R
+\name{get_cran_repo}
+\alias{get_cran_repo}
+\title{Returns the CRAN repository source or requests the user select one}
+\usage{
+get_cran_repo()
+}
+\value{
+string CRAN repository URL
+}
+\description{
+Returns the CRAN repository source or requests the user select one
+}

man/list_depends.Rd

@@ -2,7 +2,8 @@
 % Please edit documentation in R/list_depends.R
 \name{list_depends}
 \alias{list_depends}
-\title{Recursively find all the installed dependencies of one or more packages.}
+\title{Recursively find all the installed dependencies of one or more installed
+packages.}
 \usage{
 list_depends(depends)
 }
@@ -13,5 +14,6 @@ list_depends(depends)
 A data frame with the dependency tree
 }
 \description{
-Recursively find all the installed dependencies of one or more packages.
+Recursively find all the installed dependencies of one or more installed
+packages.
 }