feat(ext/node): embed std/node into the snapshot (#17724)

This commit moves "deno_std/node" in "ext/node" crate. The code is
transpiled and snapshotted during the build process.

During the first pass a minimal amount of work was done to create the
snapshot, a lot of code in "ext/node" depends on presence of "Deno"
global. This code will be gradually fixed in the follow up PRs to migrate
it to import relevant APIs from "internal:" modules.

Currently the code from snapshot is not used in any way, and all
Node/npm compatibility still uses code from 
"https://deno.land/std/node" (or from the location specified by 
"DENO_NODE_COMPAT_URL"). This will also be handled in a follow 
up PRs.

---------

Co-authored-by: crowlkats <crowlkats@toaxl.com>
Co-authored-by: Divy Srivastava <dj.srivastava23@gmail.com>
Co-authored-by: Yoshiya Hinosawa <stibium121@gmail.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/ext/node/polyfills/_fs/_fs_exists.ts b/ext/node/polyfills/_fs/_fs_exists.ts
new file mode 100644
index 000000000..9b0f18303
--- /dev/null
+++ b/ext/node/polyfills/_fs/_fs_exists.ts
@@ -0,0 +1,40 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+import { fromFileUrl } from "internal:deno_node/polyfills/path.ts";
+
+type ExistsCallback = (exists: boolean) => void;
+
+/**
+ * TODO: Also accept 'path' parameter as a Node polyfill Buffer type once these
+ * are implemented. See https://github.com/denoland/deno/issues/3403
+ * Deprecated in node api
+ */
+export function exists(path: string | URL, callback: ExistsCallback) {
+  path = path instanceof URL ? fromFileUrl(path) : path;
+  Deno.lstat(path).then(() => callback(true), () => callback(false));
+}
+
+// The callback of fs.exists doesn't have standard callback signature.
+// We need to provide special implementation for promisify.
+// See https://github.com/nodejs/node/pull/13316
+const kCustomPromisifiedSymbol = Symbol.for("nodejs.util.promisify.custom");
+Object.defineProperty(exists, kCustomPromisifiedSymbol, {
+  value: (path: string | URL) => {
+    return new Promise((resolve) => {
+      exists(path, (exists) => resolve(exists));
+    });
+  },
+});
+
+/**
+ * TODO: Also accept 'path' parameter as a Node polyfill Buffer or URL type once these
+ * are implemented. See https://github.com/denoland/deno/issues/3403
+ */
+export function existsSync(path: string | URL): boolean {
+  path = path instanceof URL ? fromFileUrl(path) : path;
+  try {
+    Deno.lstatSync(path);
+    return true;
+  } catch (_err) {
+    return false;
+  }
+}