Started to implement server

vendor/deno.land/std@0.178.0/streams/readable_stream_from_iterable.ts

@@ -0,0 +1,62 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+/** Create a `ReadableStream` from any kind of iterable.
+ *
+ * ```ts
+ *      import { readableStreamFromIterable } from "https://deno.land/std@$STD_VERSION/streams/readable_stream_from_iterable.ts";
+ *
+ *      const r1 = readableStreamFromIterable(["foo, bar, baz"]);
+ *      const r2 = readableStreamFromIterable(async function* () {
+ *        await new Promise(((r) => setTimeout(r, 1000)));
+ *        yield "foo";
+ *        await new Promise(((r) => setTimeout(r, 1000)));
+ *        yield "bar";
+ *        await new Promise(((r) => setTimeout(r, 1000)));
+ *        yield "baz";
+ *      }());
+ * ```
+ *
+ * If the produced iterator (`iterable[Symbol.asyncIterator]()` or
+ * `iterable[Symbol.iterator]()`) is a generator, or more specifically is found
+ * to have a `.throw()` method on it, that will be called upon
+ * `readableStream.cancel()`. This is the case for the second input type above:
+ *
+ * ```ts
+ * import { readableStreamFromIterable } from "https://deno.land/std@$STD_VERSION/streams/readable_stream_from_iterable.ts";
+ *
+ * const r3 = readableStreamFromIterable(async function* () {
+ *   try {
+ *     yield "foo";
+ *   } catch (error) {
+ *     console.log(error); // Error: Cancelled by consumer.
+ *   }
+ * }());
+ * const reader = r3.getReader();
+ * console.log(await reader.read()); // { value: "foo", done: false }
+ * await reader.cancel(new Error("Cancelled by consumer."));
+ * ```
+ */
+export function readableStreamFromIterable<T>(
+  iterable: Iterable<T> | AsyncIterable<T>,
+): ReadableStream<T> {
+  const iterator: Iterator<T> | AsyncIterator<T> =
+    (iterable as AsyncIterable<T>)[Symbol.asyncIterator]?.() ??
+      (iterable as Iterable<T>)[Symbol.iterator]?.();
+  return new ReadableStream({
+    async pull(controller) {
+      const { value, done } = await iterator.next();
+      if (done) {
+        controller.close();
+      } else {
+        controller.enqueue(value);
+      }
+    },
+    async cancel(reason) {
+      if (typeof iterator.throw == "function") {
+        try {
+          await iterator.throw(reason);
+        } catch { /* `iterator.throw()` always throws on site. We catch it. */ }
+      }
+    },
+  });
+}