feat(io): un-deprecate readerFromStreamReader()

io/mod.ts

@@ -24,6 +24,7 @@ export * from "./read_long.ts";
 export * from "./read_range.ts";
 export * from "./read_short.ts";
 export * from "./read_string_delim.ts";
+export * from "./reader_from_stream_reader.ts";
 export * from "./slice_long_to_bytes.ts";
 export * from "./string_reader.ts";
 export * from "./string_writer.ts";

io/reader_from_stream_reader.ts

@@ -0,0 +1,42 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { Buffer } from "./buffer.ts";
+import { writeAll } from "./write_all.ts";
+import type { Reader } from "./types.ts";
+
+/**
+ * Create a {@linkcode Reader} from a {@linkcode ReadableStreamDefaultReader}.
+ *
+ * @example
+ * ```ts
+ * import { copy } from "https://deno.land/std@$STD_VERSION/io/copy.ts";
+ * import { readerFromStreamReader } from "https://deno.land/std@$STD_VERSION/io/reader_from_stream_reader.ts";
+ *
+ * const res = await fetch("https://deno.land");
+ * using file = await Deno.open("./deno.land.html", { create: true, write: true });
+ *
+ * const reader = readerFromStreamReader(res.body!.getReader());
+ * await copy(reader, file);
+ * ```
+ */
+export function readerFromStreamReader(
+  streamReader: ReadableStreamDefaultReader<Uint8Array>,
+): Reader {
+  const buffer = new Buffer();
+
+  return {
+    async read(p: Uint8Array): Promise<number | null> {
+      if (buffer.empty()) {
+        const res = await streamReader.read();
+        if (res.done) {
+          return null; // EOF
+        }
+
+        await writeAll(buffer, res.value);
+      }
+
+      return buffer.read(p);
+    },
+  };
+}

io/reader_from_stream_reader_test.ts

@@ -0,0 +1,94 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { assert, assertEquals } from "../assert/mod.ts";
+import { copy } from "./copy.ts";
+import { readerFromStreamReader } from "./reader_from_stream_reader.ts";
+import { Buffer } from "./buffer.ts";
+
+function repeat(c: string, bytes: number): Uint8Array {
+  assertEquals(c.length, 1);
+  const ui8 = new Uint8Array(bytes);
+  ui8.fill(c.charCodeAt(0));
+  return ui8;
+}
+
+Deno.test("[streams] readerFromStreamReader()", async function () {
+  const chunks: string[] = ["hello", "deno", "land"];
+  const expected = chunks.slice();
+  const readChunks: Uint8Array[] = [];
+  const readableStream = ReadableStream.from(chunks)
+    .pipeThrough(new TextEncoderStream());
+
+  const decoder = new TextDecoder();
+  const reader = readerFromStreamReader(readableStream.getReader());
+
+  let i = 0;
+
+  while (true) {
+    const b = new Uint8Array(1024);
+    const n = await reader.read(b);
+
+    if (n === null) break;
+
+    readChunks.push(b.subarray(0, n));
+    assert(i < expected.length);
+
+    i++;
+  }
+
+  assertEquals(
+    expected,
+    readChunks.map((chunk) => decoder.decode(chunk)),
+  );
+});
+
+Deno.test("[streams] readerFromStreamReader() big chunks", async function () {
+  const bufSize = 1024;
+  const chunkSize = 3 * bufSize;
+  const writer = new Buffer();
+
+  // A readable stream can enqueue chunks bigger than Copy bufSize
+  // Reader returned by toReader should enqueue exceeding bytes
+  const chunks: string[] = [
+    "a".repeat(chunkSize),
+    "b".repeat(chunkSize),
+    "c".repeat(chunkSize),
+  ];
+  const expected = chunks.slice();
+  const readableStream = ReadableStream.from(chunks)
+    .pipeThrough(new TextEncoderStream());
+
+  const reader = readerFromStreamReader(readableStream.getReader());
+  const n = await copy(reader, writer, { bufSize });
+
+  const expectedWritten = chunkSize * expected.length;
+  assertEquals(n, chunkSize * expected.length);
+  assertEquals(writer.length, expectedWritten);
+});
+
+Deno.test("[streams] readerFromStreamReader() irregular chunks", async function () {
+  const bufSize = 1024;
+  const chunkSize = 3 * bufSize;
+  const writer = new Buffer();
+
+  // A readable stream can enqueue chunks bigger than Copy bufSize
+  // Reader returned by toReader should enqueue exceeding bytes
+  const chunks: Uint8Array[] = [
+    repeat("a", chunkSize),
+    repeat("b", chunkSize + 253),
+    repeat("c", chunkSize + 8),
+  ];
+  const expected = new Uint8Array(
+    chunks
+      .slice()
+      .map((chunk) => [...chunk])
+      .flat(),
+  );
+  const readableStream = ReadableStream.from(chunks);
+
+  const reader = readerFromStreamReader(readableStream.getReader());
+
+  const n = await copy(reader, writer, { bufSize });
+  assertEquals(n, expected.length);
+  assertEquals(expected, writer.bytes());
+});

streams/reader_from_stream_reader.ts

@@ -1,8 +1,7 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 // This module is browser compatible.
 
-import { Buffer } from "../io/buffer.ts";
-import { writeAll } from "../io/write_all.ts";
+import { readerFromStreamReader as _readerFromStreamReader } from "../io/reader_from_stream_reader.ts";
 import type { Reader } from "../io/types.ts";
 
 /**
@@ -20,25 +19,10 @@ import type { Reader } from "../io/types.ts";
  * await copy(reader, file);
  * ```
  *
- * @deprecated (will be removed after 1.0.0) Use {@linkcode ReadableStreamDefaultReader} directly.
+ * @deprecated (will be removed in 1.0.0) Import from {@link https://deno.land/std/io/reader_from_stream_reader.ts} instead.
  */
 export function readerFromStreamReader(
   streamReader: ReadableStreamDefaultReader<Uint8Array>,
 ): Reader {
-  const buffer = new Buffer();
-
-  return {
-    async read(p: Uint8Array): Promise<number | null> {
-      if (buffer.empty()) {
-        const res = await streamReader.read();
-        if (res.done) {
-          return null; // EOF
-        }
-
-        await writeAll(buffer, res.value);
-      }
-
-      return buffer.read(p);
-    },
-  };
+  return _readerFromStreamReader(streamReader);
 }