Add support for shinyAppDir with single-file app.R

R/app.R

@@ -91,9 +91,6 @@ shinyApp <- function(ui, server, onStart=NULL, options=list(), uiPattern="/") {
 #'   file and either ui.R or www/index.html)
 #' @export
 shinyAppDir <- function(appDir, options=list()) {
-  # Most of the complexity here comes from needing to hot-reload if the .R files
-  # change on disk, or are created, or are removed.
-
   if (!file.exists(appDir)) {
     stop("No Shiny application exists at the path \"", appDir, "\"")
   }
@@ -102,6 +99,21 @@ shinyAppDir <- function(appDir, options=list()) {
   # affected by future changes to the path)
   appDir <- normalizePath(appDir, mustWork = TRUE)
 
+  if (file.exists.ci(appDir, "app.R")) {
+    shinyAppDir_appR(appDir, options = options)
+  } else if (file.exists.ci(appDir, "server.R")) {
+    shinyAppDir_serverR(appDir, options = options)
+  } else {
+    stop("App dir must contain either app.R or server.R.")
+  }
+}
+
+# This reads in an app dir in the case that there's a server.R (and ui.R/www)
+# present, and returns a shiny.appobj.
+shinyAppDir_serverR <- function(appDir, options=list()) {
+  # Most of the complexity here comes from needing to hot-reload if the .R files
+  # change on disk, or are created, or are removed.
+
   # uiHandlerSource is a function that returns an HTTP handler for serving up
   # ui.R as a webpage. The "cachedFuncWithFile" call makes sure that the closure
   # we're creating here only gets executed when ui.R's contents change.
@@ -180,6 +192,60 @@ shinyAppDir <- function(appDir, options=list()) {
   )
 }
 
+# This reads in an app dir in the case that there's a app.R present, and returns
+# a shiny.appobj.
+shinyAppDir_appR <- function(appDir, options=list()) {
+  fullpath <- file.path.ci(appDir, "app.R")
+
+  # This sources app.R and caches the content. When appObj() is called but
+  # app.R hasn't changed, it won't re-source the file. But if called and
+  # app.R has changed, it'll re-source the file and return the result.
+  appObj <- cachedFuncWithFile(appDir, "app.R", case.sensitive = FALSE,
+    function(appR) {
+      result <- sourceUTF8(fullpath, local = new.env(parent = globalenv()))$value
+
+      if (!is.shiny.appobj(result))
+        stop("app.R did not return a shiny.appobj object.")
+
+      return(result)
+    }
+  )
+
+  # A function that invokes the http handler from the appObj in app.R, but
+  # since this uses appObj(), it only re-sources the file when it changes.
+  dynHttpHandler <- function(...) {
+    appObj()$httpHandler(...)
+  }
+
+  dynServerFuncSource <- function(...) {
+    appObj()$serverFuncSource(...)
+  }
+
+  wwwDir <- file.path.ci(appDir, "www")
+  fallbackWWWDir <- system.file("www-dir", package = "shiny")
+
+  oldwd <- NULL
+  onStart <- function() {
+    oldwd <<- getwd()
+    setwd(appDir)
+  }
+  onEnd <- function() {
+    setwd(oldwd)
+  }
+
+  structure(
+    list(
+      httpHandler = joinHandlers(c(dynHttpHandler, wwwDir, fallbackWWWDir)),
+      serverFuncSource = dynServerFuncSource,
+      onStart = onStart,
+      onEnd = onEnd,
+      options = options
+    ),
+    class = "shiny.appobj"
+  )
+}
+
+
 #' @rdname shinyApp
 #' @param x Object to convert to a Shiny app.
 #' @export
@@ -205,6 +271,12 @@ as.shiny.appobj.character <- function(x) {
   shinyAppDir(x)
 }
 
+#' @rdname shinyApp
+#' @export
+is.shiny.appobj <- function(x) {
+  inherits(x, "shiny.appobj")
+}
+
 #' @rdname shinyApp
 #' @param ... Additional parameters to be passed to print.
 #' @export