reformated.

R/check_installed.R

@@ -1,44 +1,55 @@
-## this is a modified version from package rlang that only uses base R functionality.
+## This is a modified version from package rlang that only uses base R functionality.
 
-check_installed <- function (pkg, reason = NULL)
-{
-  if (!is.character(pkg)) {
-    stop("`pkg` must be a package name or a vector of package names.")
-  }
-
-  needs_install <-
-    sapply(pkg, function(x)
-      !requireNamespace(x,
-        quietly = TRUE))
-
-  if (any(needs_install)) {
-    missing_pkgs <- pkg[needs_install]
-    missing_pkgs_enum <- paste(missing_pkgs, collapse = ", ")
-    n <- length(missing_pkgs)
-
-    info <-
-      paste0("The ", missing_pkgs_enum,
-        " package(s) is/are required")
-    if (is.null(reason)) {
-      info <- paste0(info, ".")
-    }
-    else {
-      info <- paste(info, reason)
-    }
-
-    if (!interactive()) {
-      stop(info)
-    }
-
-    question <-
-      "Would you like to install the package(s)?"
-    cat(info, "\n", question)
-    if (utils::menu(c("Yes", "No")) != 1) {
-      invokeRestart("abort")
+## action can be "install" (from CRAN), "stop" (with message), "check" (returns TRUE/FALSE)
+## manual can be either TRUE or a string with installation instructions.
+check_installed <-
+  function (pkg,
+    action = "install",
+    message = NULL)
+  {
+    action <- match.arg(action, choices = c("install", "stop", "check"))
+
+    if (!is.character(pkg))
+      stop("`pkg` must be a package name or a vector of package names.")
+
+    needs_install <-
+      sapply(pkg, function(x)
+        ! requireNamespace(x,
+          quietly = TRUE))
+
+    if (action == "check")
+      return(!any(needs_install))
+
+    if (any(needs_install)) {
+      if (!interactive())
+        stop(info)
+
+      missing_pkgs <- pkg[needs_install]
+      missing_pkgs_enum <- paste(missing_pkgs, collapse = ", ")
+
+      info <-
+        paste("The", missing_pkgs_enum,
+          "package(s) is/are required.")
+
+      if (action == "install") {
+        question <-
+          "Would you like to install the package(s)?"
+        cat(info, "\n", question, sep = '')
+        if (utils::menu(c("Yes", "No")) != 1) {
+          invokeRestart("abort")
+        }
+
+        utils::install.packages(missing_pkgs)
+      } else {
+        ### this is stop
+        cat(info,
+          "\n",
+          message,
+          sep = '')
+
+        invokeRestart("abort")
+      }
     }
-
-    utils::install.packages(missing_pkgs)
-
+
+    invisible(TRUE)
   }
-  invisible(TRUE)
-}