feat: Add c.stream()

deno_dist/context.ts

@@ -4,6 +4,7 @@ import type { Env, NotFoundHandler, Input, TypedResponse } from './types.ts'
 import type { CookieOptions } from './utils/cookie.ts'
 import { serialize } from './utils/cookie.ts'
 import type { StatusCode } from './utils/http-status.ts'
+import { StreamingApi } from './utils/stream.ts'
 import type { JSONValue, InterfaceToType } from './utils/types.ts'
 
 type Runtime = 'node' | 'deno' | 'bun' | 'workerd' | 'fastly' | 'edge-light' | 'lagon' | 'other'
@@ -335,6 +336,33 @@ export class Context<
     return this.newResponse(null, status)
   }
 
+  streamText = (
+    cb: (stream: StreamingApi) => Promise<void>,
+    arg?: StatusCode | ResponseInit,
+    headers?: HeaderRecord
+  ): Response => {
+    headers ??= {}
+    headers['content-type'] = 'text/plain; charset=UTF-8'
+    headers['x-content-type-options'] = 'nosniff'
+    headers['transfer-encoding'] = 'chunked'
+
+    return this.stream(cb, arg, headers)
+  }
+
+  stream = (
+    cb: (stream: StreamingApi) => Promise<void>,
+    arg?: StatusCode | ResponseInit,
+    headers?: HeaderRecord
+  ): Response => {
+    const { readable, writable } = new TransformStream()
+    const stream = new StreamingApi(writable)
+    cb(stream).finally(() => stream.close())
+
+    return typeof arg === 'number'
+      ? this.newResponse(readable, arg, headers)
+      : this.newResponse(readable, arg)
+  }
+
   /** @deprecated
    * Use Cookie Middleware instead of `c.cookie()`. The `c.cookie()` will be removed in v4.
    *

deno_dist/utils/stream.ts

@@ -0,0 +1,38 @@
+export class StreamingApi {
+  private writer: WritableStreamDefaultWriter<Uint8Array>
+  private encoder: TextEncoder
+  private writable: WritableStream
+
+  constructor(writable: WritableStream) {
+    this.writable = writable
+    this.writer = writable.getWriter()
+    this.encoder = new TextEncoder()
+  }
+
+  async write(input: Uint8Array | string) {
+    if (typeof input === 'string') {
+      input = this.encoder.encode(input)
+    }
+    await this.writer.write(input)
+    return this
+  }
+
+  async writeln(input: string) {
+    await this.write(input + '\n')
+    return this
+  }
+
+  sleep(ms: number) {
+    return new Promise((res) => setTimeout(res, ms))
+  }
+
+  async close() {
+    await this.writer.close()
+  }
+
+  async pipe(body: ReadableStream) {
+    this.writer.releaseLock()
+    await body.pipeTo(this.writable, { preventClose: true })
+    this.writer = this.writable.getWriter()
+  }
+}

src/context.test.ts

@@ -259,4 +259,39 @@ describe('Pass a ResponseInit to respond methods', () => {
     expect(res.headers.get('content-type')).toMatch(/^text\/html/)
     expect(await res.text()).toBe('<h1>foo</h1>')
   })
+
+  it('c.streamText()', async () => {
+    const res = c.streamText(async (stream) => {
+      for (let i = 0; i < 3; i++) {
+        await stream.write(`${i}`)
+        await stream.sleep(1)
+      }
+    })
+    if (!res.body) {
+      throw new Error('Body is null')
+    }
+    const reader = res.body.getReader()
+    const decoder = new TextDecoder()
+    for (let i = 0; i < 3; i++) {
+      const { value } = await reader.read()
+      expect(decoder.decode(value)).toEqual(`${i}`)
+    }
+  })
+
+  it('c.stream()', async () => {
+    const res = c.stream(async (stream) => {
+      for (let i = 0; i < 3; i++) {
+        await stream.write(new Uint8Array([i]))
+        await stream.sleep(1)
+      }
+    })
+    if (!res.body) {
+      throw new Error('Body is null')
+    }
+    const reader = res.body.getReader()
+    for (let i = 0; i < 3; i++) {
+      const { value } = await reader.read()
+      expect(value).toEqual(new Uint8Array([i]))
+    }
+  })
 })

src/context.ts

@@ -4,6 +4,7 @@ import type { Env, NotFoundHandler, Input, TypedResponse } from './types'
 import type { CookieOptions } from './utils/cookie'
 import { serialize } from './utils/cookie'
 import type { StatusCode } from './utils/http-status'
+import { StreamingApi } from './utils/stream'
 import type { JSONValue, InterfaceToType } from './utils/types'
 
 type Runtime = 'node' | 'deno' | 'bun' | 'workerd' | 'fastly' | 'edge-light' | 'lagon' | 'other'
@@ -335,6 +336,33 @@ export class Context<
     return this.newResponse(null, status)
   }
 
+  streamText = (
+    cb: (stream: StreamingApi) => Promise<void>,
+    arg?: StatusCode | ResponseInit,
+    headers?: HeaderRecord
+  ): Response => {
+    headers ??= {}
+    headers['content-type'] = 'text/plain; charset=UTF-8'
+    headers['x-content-type-options'] = 'nosniff'
+    headers['transfer-encoding'] = 'chunked'
+
+    return this.stream(cb, arg, headers)
+  }
+
+  stream = (
+    cb: (stream: StreamingApi) => Promise<void>,
+    arg?: StatusCode | ResponseInit,
+    headers?: HeaderRecord
+  ): Response => {
+    const { readable, writable } = new TransformStream()
+    const stream = new StreamingApi(writable)
+    cb(stream).finally(() => stream.close())
+
+    return typeof arg === 'number'
+      ? this.newResponse(readable, arg, headers)
+      : this.newResponse(readable, arg)
+  }
+
   /** @deprecated
    * Use Cookie Middleware instead of `c.cookie()`. The `c.cookie()` will be removed in v4.
    *

src/utils/stream.test.ts

@@ -0,0 +1,68 @@
+import { StreamingApi } from './stream'
+
+describe('StreamingApi', () => {
+  it('write(string)', async () => {
+    const { readable, writable } = new TransformStream()
+    const api = new StreamingApi(writable)
+    const reader = readable.getReader()
+    api.write('foo')
+    expect((await reader.read()).value).toEqual(new TextEncoder().encode('foo'))
+    api.write('bar')
+    expect((await reader.read()).value).toEqual(new TextEncoder().encode('bar'))
+  })
+
+  it('write(Uint8Array)', async () => {
+    const { readable, writable } = new TransformStream()
+    const api = new StreamingApi(writable)
+    const reader = readable.getReader()
+    api.write(new Uint8Array([1, 2, 3]))
+    expect((await reader.read()).value).toEqual(new Uint8Array([1, 2, 3]))
+    api.write(new Uint8Array([4, 5, 6]))
+    expect((await reader.read()).value).toEqual(new Uint8Array([4, 5, 6]))
+  })
+
+  it('writeln(string)', async () => {
+    const { readable, writable } = new TransformStream()
+    const api = new StreamingApi(writable)
+    const reader = readable.getReader()
+    api.writeln('foo')
+    expect((await reader.read()).value).toEqual(new TextEncoder().encode('foo\n'))
+    api.writeln('bar')
+    expect((await reader.read()).value).toEqual(new TextEncoder().encode('bar\n'))
+  })
+
+  it('pipe()', async () => {
+    const { readable: senderReadable, writable: senderWritable } = new TransformStream()
+
+    // send data to readable in other scope
+    ;(async () => {
+      const writer = senderWritable.getWriter()
+      await writer.write(new TextEncoder().encode('foo'))
+      await writer.write(new TextEncoder().encode('bar'))
+      // await writer.close()
+    })()
+
+    const { readable: receiverReadable, writable: receiverWritable } = new TransformStream()
+
+    const api = new StreamingApi(receiverWritable)
+
+    // pipe readable to api in other scope
+    ;(async () => {
+      await api.pipe(senderReadable)
+    })()
+
+    // read data from api
+    const reader = receiverReadable.getReader()
+    expect((await reader.read()).value).toEqual(new TextEncoder().encode('foo'))
+    expect((await reader.read()).value).toEqual(new TextEncoder().encode('bar'))
+  })
+
+  it('close()', async () => {
+    const { readable, writable } = new TransformStream()
+    const api = new StreamingApi(writable)
+    const reader = readable.getReader()
+    await api.close()
+    expect((await reader.read()).done).toBe(true)
+    await expect(api.write('foo')).rejects.toThrow()
+  })
+})

src/utils/stream.ts

@@ -0,0 +1,38 @@
+export class StreamingApi {
+  private writer: WritableStreamDefaultWriter<Uint8Array>
+  private encoder: TextEncoder
+  private writable: WritableStream
+
+  constructor(writable: WritableStream) {
+    this.writable = writable
+    this.writer = writable.getWriter()
+    this.encoder = new TextEncoder()
+  }
+
+  async write(input: Uint8Array | string) {
+    if (typeof input === 'string') {
+      input = this.encoder.encode(input)
+    }
+    await this.writer.write(input)
+    return this
+  }
+
+  async writeln(input: string) {
+    await this.write(input + '\n')
+    return this
+  }
+
+  sleep(ms: number) {
+    return new Promise((res) => setTimeout(res, ms))
+  }
+
+  async close() {
+    await this.writer.close()
+  }
+
+  async pipe(body: ReadableStream) {
+    this.writer.releaseLock()
+    await body.pipeTo(this.writable, { preventClose: true })
+    this.writer = this.writable.getWriter()
+  }
+}