refactor: move existing fs implementation to internal _fs directory (#4381)

1 files changed, 80 insertions, 0 deletions

diff --git a/std/node/_fs/_fs_readFile.ts b/std/node/_fs/_fs_readFile.ts
new file mode 100644
index 000000000..05bad6f3d
--- /dev/null
+++ b/std/node/_fs/_fs_readFile.ts
@@ -0,0 +1,80 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import {
+  notImplemented,
+  intoCallbackAPIWithIntercept,
+  MaybeEmpty
+} from "../_utils.ts";
+
+const { readFile: denoReadFile, readFileSync: denoReadFileSync } = Deno;
+
+type ReadFileCallback = (
+  err: MaybeEmpty<Error>,
+  data: MaybeEmpty<string | Uint8Array>
+) => void;
+
+interface ReadFileOptions {
+  encoding?: string | null;
+  flag?: string;
+}
+
+function getEncoding(
+  optOrCallback?: ReadFileOptions | ReadFileCallback
+): string | null {
+  if (!optOrCallback || typeof optOrCallback === "function") {
+    return null;
+  } else {
+    if (optOrCallback.encoding) {
+      if (
+        optOrCallback.encoding === "utf8" ||
+        optOrCallback.encoding === "utf-8"
+      ) {
+        return "utf8";
+      } else if (optOrCallback.encoding === "buffer") {
+        return "buffer";
+      } else {
+        notImplemented();
+      }
+    }
+    return null;
+  }
+}
+
+function maybeDecode(
+  data: Uint8Array,
+  encoding: string | null
+): string | Uint8Array {
+  if (encoding === "utf8") {
+    return new TextDecoder().decode(data);
+  }
+  return data;
+}
+
+export function readFile(
+  path: string,
+  optOrCallback: ReadFileCallback | ReadFileOptions,
+  callback?: ReadFileCallback
+): void {
+  let cb: ReadFileCallback | undefined;
+  if (typeof optOrCallback === "function") {
+    cb = optOrCallback;
+  } else {
+    cb = callback;
+  }
+
+  const encoding = getEncoding(optOrCallback);
+
+  intoCallbackAPIWithIntercept<Uint8Array, string | Uint8Array>(
+    denoReadFile,
+    (data: Uint8Array): string | Uint8Array => maybeDecode(data, encoding),
+    cb,
+    path
+  );
+}
+
+export function readFileSync(
+  path: string,
+  opt?: ReadFileOptions
+): string | Uint8Array {
+  return maybeDecode(denoReadFileSync(path), getEncoding(opt));
+}