feat: encode errors and promise rejections

jacob-ebey · Oct 25, 2023 · fa120e9 · fa120e9
1 parent 315c8b6
commit fa120e9
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Showing 7 changed files with 162 additions and 12 deletions.
diff --git a/README.md b/README.md
@@ -18,10 +18,10 @@ npm install turbo-stream
 ```js
 import { decode, encode } from "turbo-stream";
 
-const encodedStream = encode({ answer: Promise.resolve(42) });
+const encodedStream = encode(Promise.resolve(42));
 const decoded = await decode(encodedStream);
-console.log(decoded.value.answer); // a Promise
-console.log(await decoded.value.answer); // 42
+console.log(decoded.value); // a Promise
+console.log(await decoded.value); // 42
 await decoded.done; // wait for the stream to finish
 ```
 

diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "turbo-stream",
-  "version": "0.0.6",
+  "version": "0.0.7",
   "description": "A streaming data transport format that aims to support built-in features such as Promises, Dates, RegExps, Maps, Sets and more.",
   "type": "module",
   "files": [

diff --git a/src/flatten.ts b/src/flatten.ts
@@ -6,6 +6,7 @@ import {
   POSITIVE_INFINITY,
   TYPE_BIGINT,
   TYPE_DATE,
+  TYPE_ERROR,
   TYPE_MAP,
   TYPE_PROMISE,
   TYPE_REGEXP,
@@ -80,6 +81,12 @@ function stringify(this: ThisEncode, input: unknown, index: number) {
       } else if (input instanceof Promise) {
         str[index] = `["${TYPE_PROMISE}",${index}]`;
         this.deferred[index] = input;
+      } else if (input instanceof Error) {
+        str[index] = `["${TYPE_ERROR}",${JSON.stringify(input.message)}`;
+        if (input.name !== "Error") {
+          str[index] += `,${JSON.stringify(input.name)}`;
+        }
+        str[index] += "]";
       } else if (isPlainObject(input)) {
         const parts = [];
         for (const key in input)

diff --git a/src/turbo-stream.spec.ts b/src/turbo-stream.spec.ts
@@ -43,6 +43,81 @@ test("should encode and decode string", async () => {
   expect(output).toEqual(input);
 });
 
+test("should encode and decode Date", async () => {
+  const input = new Date();
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode NaN", async () => {
+  const input = NaN;
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode Infinity", async () => {
+  const input = Infinity;
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode -Infinity", async () => {
+  const input = -Infinity;
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode -0", async () => {
+  const input = -0;
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode BigInt", async () => {
+  const input = BigInt(42);
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode RegExp", async () => {
+  const input = /foo/g;
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode Symbol", async () => {
+  const input = Symbol.for("foo");
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode Map", async () => {
+  const input = new Map([
+    ["foo", "bar"],
+    ["baz", "qux"],
+  ]);
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode Set", async () => {
+  const input = new Set(["foo", "bar"]);
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode an Error", async () => {
+  const input = new Error("foo");
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
+test("should encode and decode an EvalError", async () => {
+  const input = new EvalError("foo");
+  const output = await quickDecode(encode(input));
+  expect(output).toEqual(input);
+});
+
 test("should encode and decode array", async () => {
   const input = [1, 2, 3];
   const output = await quickDecode(encode(input));
@@ -71,7 +146,18 @@ test("should encode and decode object with undefined", async () => {
 test("should encode and decode promise", async () => {
   const input = Promise.resolve("foo");
   const decoded = await decode(encode(input));
-  expect(decoded.value).toEqual(await input);
+  expect(decoded.value).toBeInstanceOf(Promise);
+  expect(await decoded.value).toEqual(await input);
+  await decoded.done;
+});
+
+test("should encode and decode rejected promise", async () => {
+  const input = Promise.reject(new Error("foo"));
+  const decoded = await decode(encode(input));
+  expect(decoded.value).toBeInstanceOf(Promise);
+  await expect(decoded.value).rejects.toEqual(
+    await input.catch((reason) => reason)
+  );
   await decoded.done;
 });
 

diff --git a/src/turbo-stream.ts b/src/turbo-stream.ts
@@ -4,6 +4,7 @@ import {
   createLineSplittingTransform,
   Deferred,
   TYPE_PROMISE,
+  TYPE_ERROR,
   type ThisDecode,
   type ThisEncode,
 } from "./utils.js";
@@ -75,7 +76,7 @@ async function decodeDeferred(
     if (!read.value) continue;
     const line = read.value;
     switch (line[0]) {
-      case TYPE_PROMISE:
+      case TYPE_PROMISE: {
         const colonIndex = line.indexOf(":");
         const deferredId = Number(line.slice(1, colonIndex));
         const deferred = this.deferred[deferredId];
@@ -92,9 +93,25 @@ async function decodeDeferred(
         const value = unflatten.call(this, jsonLine);
         deferred.resolve(value);
         break;
-      // case TYPE_PROMISE_ERROR:
-      //   // TODO: transport promise rejections
-      //   break;
+      }
+      case TYPE_ERROR: {
+        const colonIndex = line.indexOf(":");
+        const deferredId = Number(line.slice(1, colonIndex));
+        const deferred = this.deferred[deferredId];
+        if (!deferred) {
+          throw new Error(`Deferred ID ${deferredId} not found in stream`);
+        }
+        const lineData = line.slice(colonIndex + 1);
+        let jsonLine;
+        try {
+          jsonLine = JSON.parse(lineData);
+        } catch (reason) {
+          throw new SyntaxError();
+        }
+        const value = unflatten.call(this, jsonLine);
+        deferred.reject(value);
+        break;
+      }
       default:
         throw new SyntaxError();
     }
@@ -113,7 +130,7 @@ export function encode(input: unknown) {
   let lastSentIndex = 0;
   const readable = new ReadableStream<Uint8Array>({
     async start(controller) {
-      const id = flatten.call(encoder, await input);
+      const id = flatten.call(encoder, input);
       if (id < 0) {
         controller.enqueue(textEncoder.encode(`${id}\n`));
       } else {
@@ -149,8 +166,30 @@ export function encode(input: unknown) {
                   }
                 },
                 (reason) => {
-                  // TODO: Encode and send errors
-                  throw reason;
+                  if (
+                    !reason ||
+                    typeof reason !== "object" ||
+                    !(reason instanceof Error)
+                  ) {
+                    reason = new Error("An unknown error occurred");
+                  }
+
+                  const id = flatten.call(encoder, reason);
+                  if (id < 0) {
+                    controller.enqueue(
+                      textEncoder.encode(`${TYPE_ERROR}${deferredId}:${id}\n`)
+                    );
+                  } else {
+                    const values = encoder.stringified
+                      .slice(lastSentIndex + 1)
+                      .join(",");
+                    controller.enqueue(
+                      textEncoder.encode(
+                        `${TYPE_ERROR}${deferredId}:[${values}]\n`
+                      )
+                    );
+                    lastSentIndex = encoder.stringified.length - 1;
+                  }
                 }
               )
               .finally(() => {

diff --git a/src/unflatten.ts b/src/unflatten.ts
@@ -14,8 +14,17 @@ import {
   TYPE_SYMBOL,
   UNDEFINED,
   type ThisDecode,
+  TYPE_ERROR,
 } from "./utils.js";
 
+const globalObj = (
+  typeof window !== "undefined"
+    ? window
+    : typeof globalThis !== "undefined"
+    ? globalThis
+    : undefined
+) as Record<string, typeof Error> | undefined;
+
 export function unflatten(this: ThisDecode, parsed: unknown): unknown {
   if (typeof parsed === "number") return hydrate.call(this, parsed);
 
@@ -84,6 +93,14 @@ function hydrate(this: ThisDecode, index: number) {
             deferred[value[1]] = d;
             return (hydrated[index] = d.promise);
           }
+        case TYPE_ERROR:
+          const [, message, errorType] = value;
+          let error =
+            errorType && globalObj && globalObj[errorType]
+              ? new globalObj[errorType](message)
+              : new Error(message);
+          hydrated[index] = error;
+          return error;
         default:
           throw new SyntaxError();
       }

diff --git a/src/utils.ts b/src/utils.ts
@@ -13,6 +13,7 @@ export const TYPE_REGEXP = "R";
 export const TYPE_SYMBOL = "Y";
 export const TYPE_NULL_OBJECT = "N";
 export const TYPE_PROMISE = "P";
+export const TYPE_ERROR = "E";
 
 export interface ThisDecode {
   values: unknown[];