Add new sass_html_dependencies() function for more convenient htmlDependency bundling

DESCRIPTION

@@ -1,6 +1,6 @@
 Type: Package
 Package: sass
-Version: 0.2.0.9001
+Version: 0.2.0.9002
 Title: Syntactically Awesome Style Sheets ('Sass')
 Description: An 'SCSS' compiler, powered by the 'LibSass' library. With this,
     R developers can use variables, inheritance, and functions to generate

NAMESPACE

@@ -12,6 +12,7 @@ export(sass_cache_set)
 export(sass_file)
 export(sass_file_cache)
 export(sass_hash)
+export(sass_html_dependencies)
 export(sass_import)
 export(sass_layer)
 export(sass_layer_merge)

R/sass-dependencies.R

@@ -0,0 +1,58 @@
+#' Compile Sass to CSS using LibSass, then return an HTML Dependencies
+#'
+#' Calls `sass(input, ...)` and wraps the output into a [htmltools::htmlDependency()].
+#'
+#' @inheritParams sass
+#' @inheritParams htmltools::htmlDependency
+#' @param cache_key additional information to include in the `sass_hash()` call used to
+#' determine the output directory. This should include any information that could possibly
+#' influence the resulting CSS that isn't already captured by `input`. For example, if
+#' `input` contains something like `"@import sass_file.scss"` you may want to include the
+#' [file.mtime()] of `sass_file.scss` (or, perhaps, a [packageVersion()] if `sass_file.scss`
+#' is bundled with an R package).
+#' @param stylesheet Absolute file path(s) pointing to stylesheet(s) to include with the dependency
+#'
+#' @return returns a list of [htmltools::htmlDependency()] objects. The length
+#' of the list use 1 unless `input` contains [sass_layer()] object(s) that
+#' have `html_deps`.
+#'
+#' @export
+#' @seealso [sass()]
+#' @examples
+#' str(sass_html_dependencies(
+#'   input = list(list(color = "red"), "body {color: $color}"),
+#'   name = "foo", version = "1.0.0",
+#'   stylesheet = "my-style.css"
+#' ))
+sass_html_dependencies <- function(
+  input, name, version, stylesheet, cache_key = NULL,
+  options = sass_options(), write_attachments = TRUE, cache = sass_cache_get(),
+  script = NULL, meta = NULL, head = NULL) {
+
+  key <- sass_hash(list(input, options, cache_key))
+  outDir <- file.path(tempdir(), paste(name, version, key, sep = "-"))
+  if (!dir.exists(outDir)) dir.create(outDir)
+  sass(
+    input, output = file.path(outDir, stylesheet), options = options,
+    write_attachments = write_attachments, cache = cache
+  )
+
+  if (!is.null(script)) {
+    if (!all(fs::is_absolute_path(script))) {
+      stop("script file paths must all be absolute file paths")
+    }
+    fs::file_copy(script, outDir, overwrite = TRUE)
+    script <- basename(script)
+  }
+
+  c(
+    list(htmltools::htmlDependency(
+      name = name, version = version,
+      src = c(file = outDir),
+      stylesheet = stylesheet,
+      script = script,
+      meta = meta, head = head
+    )),
+    extract_layer(input)$html_deps
+  )
+}

R/sass.R

@@ -44,7 +44,7 @@
 #' @return If \code{output = NULL}, the function returns a string value of the
 #'   compiled CSS. If the output path is specified, the compiled CSS is written
 #'   to that file and \code{invisible()} is returned.
-#' @seealso \url{http://sass-lang.com/guide}
+#' @seealso \url{http://sass-lang.com/guide}, [sass_html_dependencies()]
 #' @export
 #' @examples
 #' # raw Sass input