feat(fetch): accept async iterables for body (#26882)

Reland of #24623, but with a fix for `String` objects.

Co-authored-by: crowlkats <[email protected]>

ext/fetch/22_body.js

@@ -15,6 +15,7 @@ import { core, primordials } from "ext:core/mod.js";
 const {
   isAnyArrayBuffer,
   isArrayBuffer,
+  isStringObject,
 } = core;
 const {
   ArrayBufferIsView,
@@ -466,6 +467,8 @@ function extractBody(object) {
     if (object.locked || isReadableStreamDisturbed(object)) {
       throw new TypeError("ReadableStream is locked or disturbed");
     }
+  } else if (object[webidl.AsyncIterable] === webidl.AsyncIterable) {
+    stream = ReadableStream.from(object.open());
   }
   if (typeof source === "string") {
     // WARNING: this deviates from spec (expects length to be set)
@@ -483,6 +486,9 @@ function extractBody(object) {
   return { body, contentType };
 }
 
+webidl.converters["async iterable<Uint8Array>"] = webidl
+  .createAsyncIterableConverter(webidl.converters.Uint8Array);
+
 webidl.converters["BodyInit_DOMString"] = (V, prefix, context, opts) => {
   // Union for (ReadableStream or Blob or ArrayBufferView or ArrayBuffer or FormData or URLSearchParams or USVString)
   if (ObjectPrototypeIsPrototypeOf(ReadableStreamPrototype, V)) {
@@ -501,6 +507,14 @@ webidl.converters["BodyInit_DOMString"] = (V, prefix, context, opts) => {
     if (ArrayBufferIsView(V)) {
       return webidl.converters["ArrayBufferView"](V, prefix, context, opts);
     }
+    if (webidl.isAsyncIterable(V) && !isStringObject(V)) {
+      return webidl.converters["async iterable<Uint8Array>"](
+        V,
+        prefix,
+        context,
+        opts,
+      );
+    }
   }
   // BodyInit conversion is passed to extractBody(), which calls core.encode().
   // core.encode() will UTF-8 encode strings with replacement, being equivalent to the USV normalization.

ext/fetch/lib.deno_fetch.d.ts

@@ -163,6 +163,8 @@ type BodyInit =
   | FormData
   | URLSearchParams
   | ReadableStream<Uint8Array>
+  | Iterable<Uint8Array>
+  | AsyncIterable<Uint8Array>
   | string;
 /** @category Fetch */
 type RequestDestination =

ext/web/06_streams.js

@@ -70,7 +70,6 @@ const {
   String,
   Symbol,
   SymbolAsyncIterator,
-  SymbolIterator,
   SymbolFor,
   TypeError,
   TypedArrayPrototypeGetBuffer,
@@ -5084,34 +5083,6 @@ function initializeCountSizeFunction(globalObject) {
   WeakMapPrototypeSet(countSizeFunctionWeakMap, globalObject, size);
 }
 
-// Ref: https://tc39.es/ecma262/#sec-getiterator
-function getAsyncOrSyncIterator(obj) {
-  let iterator;
-  if (obj[SymbolAsyncIterator] != null) {
-    iterator = obj[SymbolAsyncIterator]();
-    if (!isObject(iterator)) {
-      throw new TypeError(
-        "[Symbol.asyncIterator] returned a non-object value",
-      );
-    }
-  } else if (obj[SymbolIterator] != null) {
-    iterator = obj[SymbolIterator]();
-    if (!isObject(iterator)) {
-      throw new TypeError("[Symbol.iterator] returned a non-object value");
-    }
-  } else {
-    throw new TypeError("No iterator found");
-  }
-  if (typeof iterator.next !== "function") {
-    throw new TypeError("iterator.next is not a function");
-  }
-  return iterator;
-}
-
-function isObject(x) {
-  return (typeof x === "object" && x != null) || typeof x === "function";
-}
-
 const _resourceBacking = Symbol("[[resourceBacking]]");
 // This distinction exists to prevent unrefable streams being used in
 // regular fast streams that are unaware of refability
@@ -5197,21 +5168,22 @@ class ReadableStream {
   }
 
   static from(asyncIterable) {
+    const prefix = "Failed to execute 'ReadableStream.from'";
     webidl.requiredArguments(
       arguments.length,
       1,
-      "Failed to execute 'ReadableStream.from'",
+      prefix,
     );
-    asyncIterable = webidl.converters.any(asyncIterable);
-
-    const iterator = getAsyncOrSyncIterator(asyncIterable);
+    asyncIterable = webidl.converters["async iterable<any>"](
+      asyncIterable,
+      prefix,
+      "Argument 1",
+    );
+    const iter = asyncIterable.open();
 
     const stream = createReadableStream(noop, async () => {
       // deno-lint-ignore prefer-primordials
-      const res = await iterator.next();
-      if (!isObject(res)) {
-        throw new TypeError("iterator.next value is not an object");
-      }
+      const res = await iter.next();
       if (res.done) {
         readableStreamDefaultControllerClose(stream[_controller]);
       } else {
@@ -5221,17 +5193,8 @@ class ReadableStream {
         );
       }
     }, async (reason) => {
-      if (iterator.return == null) {
-        return undefined;
-      } else {
-        // deno-lint-ignore prefer-primordials
-        const res = await iterator.return(reason);
-        if (!isObject(res)) {
-          throw new TypeError("iterator.return value is not an object");
-        } else {
-          return undefined;
-        }
-      }
+      // deno-lint-ignore prefer-primordials
+      await iter.return(reason);
     }, 0);
     return stream;
   }
@@ -6892,6 +6855,10 @@ webidl.converters.StreamPipeOptions = webidl
     { key: "signal", converter: webidl.converters.AbortSignal },
   ]);
 
+webidl.converters["async iterable<any>"] = webidl.createAsyncIterableConverter(
+  webidl.converters.any,
+);
+
 internals.resourceForReadableStream = resourceForReadableStream;
 
 export {

ext/webidl/00_webidl.js

@@ -26,6 +26,7 @@ const {
   Float32Array,
   Float64Array,
   FunctionPrototypeBind,
+  FunctionPrototypeCall,
   Int16Array,
   Int32Array,
   Int8Array,
@@ -77,6 +78,7 @@ const {
   StringPrototypeToWellFormed,
   Symbol,
   SymbolIterator,
+  SymbolAsyncIterator,
   SymbolToStringTag,
   TypedArrayPrototypeGetBuffer,
   TypedArrayPrototypeGetSymbolToStringTag,
@@ -920,6 +922,127 @@ function createSequenceConverter(converter) {
   };
 }
 
+function isAsyncIterable(obj) {
+  if (obj[SymbolAsyncIterator] === undefined) {
+    if (obj[SymbolIterator] === undefined) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+const AsyncIterable = Symbol("[[asyncIterable]]");
+
+function createAsyncIterableConverter(converter) {
+  return function (
+    V,
+    prefix = undefined,
+    context = undefined,
+    opts = { __proto__: null },
+  ) {
+    if (type(V) !== "Object") {
+      throw makeException(
+        TypeError,
+        "can not be converted to async iterable.",
+        prefix,
+        context,
+      );
+    }
+
+    let isAsync = true;
+    let method = V[SymbolAsyncIterator];
+    if (method === undefined) {
+      method = V[SymbolIterator];
+
+      if (method === undefined) {
+        throw makeException(
+          TypeError,
+          "is not iterable.",
+          prefix,
+          context,
+        );
+      }
+
+      isAsync = false;
+    }
+
+    return {
+      value: V,
+      [AsyncIterable]: AsyncIterable,
+      open(context) {
+        const iter = FunctionPrototypeCall(method, V);
+        if (type(iter) !== "Object") {
+          throw new TypeError(
+            `${context} could not be iterated because iterator method did not return object, but ${
+              type(iter)
+            }.`,
+          );
+        }
+
+        let asyncIterator = iter;
+
+        if (!isAsync) {
+          asyncIterator = {
+            // deno-lint-ignore require-await
+            async next() {
+              // deno-lint-ignore prefer-primordials
+              return iter.next();
+            },
+          };
+        }
+
+        return {
+          async next() {
+            // deno-lint-ignore prefer-primordials
+            const iterResult = await asyncIterator.next();
+            if (type(iterResult) !== "Object") {
+              throw TypeError(
+                `${context} failed to iterate next value because the next() method did not return an object, but ${
+                  type(iterResult)
+                }.`,
+              );
+            }
+
+            if (iterResult.done) {
+              return { done: true };
+            }
+
+            const iterValue = converter(
+              iterResult.value,
+              `${context} failed to iterate next value`,
+              `The value returned from the next() method`,
+              opts,
+            );
+
+            return { done: false, value: iterValue };
+          },
+          async return(reason) {
+            if (asyncIterator.return === undefined) {
+              return undefined;
+            }
+
+            // deno-lint-ignore prefer-primordials
+            const returnPromiseResult = await asyncIterator.return(reason);
+            if (type(returnPromiseResult) !== "Object") {
+              throw TypeError(
+                `${context} failed to close iterator because the return() method did not return an object, but ${
+                  type(returnPromiseResult)
+                }.`,
+              );
+            }
+
+            return undefined;
+          },
+          [SymbolAsyncIterator]() {
+            return this;
+          },
+        };
+      },
+    };
+  };
+}
+
 function createRecordConverter(keyConverter, valueConverter) {
   return (V, prefix, context, opts) => {
     if (type(V) !== "Object") {
@@ -1302,9 +1425,11 @@ function setlike(obj, objPrototype, readonly) {
 
 export {
   assertBranded,
+  AsyncIterable,
   brand,
   configureInterface,
   converters,
+  createAsyncIterableConverter,
   createBranded,
   createDictionaryConverter,
   createEnumConverter,
@@ -1315,6 +1440,7 @@ export {
   createSequenceConverter,
   illegalConstructor,
   invokeCallbackFunction,
+  isAsyncIterable,
   makeException,
   mixinPairIterable,
   requiredArguments,

ext/webidl/internal.d.ts

@@ -438,6 +438,27 @@ declare module "ext:deno_webidl/00_webidl.js" {
     opts?: any,
   ) => T[];
 
+  /**
+   * Create a converter that converts an async iterable of the inner type.
+   */
+  function createAsyncIterableConverter<V, T>(
+    converter: (
+      v: V,
+      prefix?: string,
+      context?: string,
+      opts?: any,
+    ) => T,
+  ): (
+    v: any,
+    prefix?: string,
+    context?: string,
+    opts?: any,
+  ) => ConvertedAsyncIterable<V, T>;
+
+  interface ConvertedAsyncIterable<V, T> extends AsyncIterableIterator<T> {
+    value: V;
+  }
+
   /**
    * Create a converter that converts a Promise of the inner type.
    */
@@ -559,4 +580,9 @@ declare module "ext:deno_webidl/00_webidl.js" {
     | "Symbol"
     | "BigInt"
     | "Object";
+
+  /**
+   * Check whether a value is an async iterable.
+   */
+  function isAsyncIterable(v: any): boolean;
 }

tests/integration/node_unit_tests.rs

@@ -72,6 +72,7 @@ util::unit_test_factory!(
     dgram_test,
     domain_test,
     fs_test,
+    fetch_test,
     http_test,
     http2_test,
     inspector_test,

tests/unit/fetch_test.ts

@@ -2119,3 +2119,30 @@ Deno.test(
     await server;
   },
 );
+
+Deno.test("fetch async iterable", async () => {
+  const iterable = (async function* () {
+    yield new Uint8Array([1, 2, 3, 4, 5]);
+    yield new Uint8Array([6, 7, 8, 9, 10]);
+  })();
+  const res = new Response(iterable);
+  const actual = await res.bytes();
+  const expected = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+  assertEquals(actual, expected);
+});
+
+Deno.test("fetch iterable", async () => {
+  const iterable = (function* () {
+    yield new Uint8Array([1, 2, 3, 4, 5]);
+    yield new Uint8Array([6, 7, 8, 9, 10]);
+  })();
+  const res = new Response(iterable);
+  const actual = await res.bytes();
+  const expected = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+  assertEquals(actual, expected);
+});
+
+Deno.test("fetch string object", async () => {
+  const res = new Response(Object("hello"));
+  assertEquals(await res.text(), "hello");
+});