chore(internal): minor restructuring (#143)

src/internal/decoders/line.ts

@@ -1,6 +1,6 @@
 import { WriterError } from '../../error';
 
-type Bytes = string | ArrayBuffer | Uint8Array | Buffer | null | undefined;
+export type Bytes = string | ArrayBuffer | Uint8Array | Buffer | null | undefined;
 
 /**
  * A re-implementation of httpx's `LineDecoder` in Python that handles incrementally

src/internal/stream-utils.ts

@@ -0,0 +1,32 @@
+/**
+ * Most browsers don't yet have async iterable support for ReadableStream,
+ * and Node has a very different way of reading bytes from its "ReadableStream".
+ *
+ * This polyfill was pulled from https://github.com/MattiasBuelens/web-streams-polyfill/pull/122#issuecomment-1627354490
+ */
+export function ReadableStreamToAsyncIterable<T>(stream: any): AsyncIterableIterator<T> {
+  if (stream[Symbol.asyncIterator]) return stream;
+
+  const reader = stream.getReader();
+  return {
+    async next() {
+      try {
+        const result = await reader.read();
+        if (result?.done) reader.releaseLock(); // release lock when stream becomes closed
+        return result;
+      } catch (e) {
+        reader.releaseLock(); // release lock when stream becomes errored
+        throw e;
+      }
+    },
+    async return() {
+      const cancelPromise = reader.cancel();
+      reader.releaseLock();
+      await cancelPromise;
+      return { done: true, value: undefined };
+    },
+    [Symbol.asyncIterator]() {
+      return this;
+    },
+  };
+}

src/streaming.ts

@@ -1,6 +1,7 @@
 import { ReadableStream, type Response } from './_shims/index';
 import { WriterError } from './error';
 import { LineDecoder } from './internal/decoders/line';
+import { ReadableStreamToAsyncIterable } from './internal/stream-utils';
 
 import { createResponseHeaders } from './core';
 import { APIError } from './error';
@@ -84,7 +85,7 @@ export class Stream<Item> implements AsyncIterable<Item> {
     async function* iterLines(): AsyncGenerator<string, void, unknown> {
       const lineDecoder = new LineDecoder();
 
-      const iter = readableStreamAsyncIterable<Bytes>(readableStream);
+      const iter = ReadableStreamToAsyncIterable<Bytes>(readableStream);
       for await (const chunk of iter) {
         for (const line of lineDecoder.decode(chunk)) {
           yield line;
@@ -198,7 +199,7 @@ export async function* _iterSSEMessages(
   const sseDecoder = new SSEDecoder();
   const lineDecoder = new LineDecoder();
 
-  const iter = readableStreamAsyncIterable<Bytes>(response.body);
+  const iter = ReadableStreamToAsyncIterable<Bytes>(response.body);
   for await (const sseChunk of iterSSEChunks(iter)) {
     for (const line of lineDecoder.decode(sseChunk)) {
       const sse = sseDecoder.decode(line);
@@ -351,36 +352,3 @@ function partition(str: string, delimiter: string): [string, string, string] {
 
   return [str, '', ''];
 }
-
-/**
- * Most browsers don't yet have async iterable support for ReadableStream,
- * and Node has a very different way of reading bytes from its "ReadableStream".
- *
- * This polyfill was pulled from https://github.com/MattiasBuelens/web-streams-polyfill/pull/122#issuecomment-1627354490
- */
-export function readableStreamAsyncIterable<T>(stream: any): AsyncIterableIterator<T> {
-  if (stream[Symbol.asyncIterator]) return stream;
-
-  const reader = stream.getReader();
-  return {
-    async next() {
-      try {
-        const result = await reader.read();
-        if (result?.done) reader.releaseLock(); // release lock when stream becomes closed
-        return result;
-      } catch (e) {
-        reader.releaseLock(); // release lock when stream becomes errored
-        throw e;
-      }
-    },
-    async return() {
-      const cancelPromise = reader.cancel();
-      reader.releaseLock();
-      await cancelPromise;
-      return { done: true, value: undefined };
-    },
-    [Symbol.asyncIterator]() {
-      return this;
-    },
-  };
-}