Match class by name

Author: spalladino

yarn-project/foundation/src/json-rpc/class_converter.ts

@@ -103,7 +103,6 @@ export type ClassEncoding = 'string' | 'object';
  */
 export class ClassConverter {
   private toClass = new Map<string, [IOClass, ClassEncoding]>();
-  private toName = new Map<IOClass, [string, ClassEncoding]>();
 
   /**
    * Create a class converter from a table of classes.
@@ -140,7 +139,6 @@ export class ClassConverter {
       (class_ as StringIOClass)['fromString'] || (class_ as ObjIOClass)['fromJSON'],
       `Class ${type} must define a fromString() OR fromJSON() static method.`,
     );
-    this.toName.set(class_, [type, encoding]);
     this.toClass.set(type, [class_, encoding]);
   }
 
@@ -153,12 +151,13 @@ export class ClassConverter {
     return this.toClass.has(type);
   }
   /**
-   * Is this class object registered?
+   * Is this class object registered under its constructor name?
    * @param obj - The class object.
    * @returns If it is a registered class.
    */
   isRegisteredClass(obj: any) {
-    return this.toName.has(obj);
+    const name = obj.prototype.constructor.name;
+    return this.isRegisteredClassName(name);
   }
   /**
    * Convert a JSON-like object to a class object.
@@ -182,10 +181,11 @@ export class ClassConverter {
    * @returns The class object.
    */
   toJsonObj(classObj: any): JsonEncodedClass | StringEncodedClass {
-    const result = this.toName.get(classObj.constructor);
+    const type = classObj.constructor.name;
+    const result = this.toClass.get(type);
     assert(result, `Could not find class in lookup.`);
-    const [type, encoding] = result;
+    const [_class, encoding] = result;
     const data = encoding === 'string' ? classObj.toString() : classObj.toJSON();
-    return { type: type!, data };
+    return { type, data };
   }
 }

yarn-project/foundation/src/json-rpc/convert.test.ts

@@ -2,6 +2,8 @@ import { Buffer } from 'buffer';
 
 import { ClassConverter } from './class_converter.js';
 import { convertBigintsInObj, convertFromJsonObj, convertToJsonObj } from './convert.js';
+import { ToStringClass as ToStringClassA } from './fixtures/class_a.js';
+import { ToStringClass as ToStringClassB } from './fixtures/class_b.js';
 import { TestNote } from './fixtures/test_state.js';
 
 const TEST_BASE64 = 'YmFzZTY0IGRlY29kZXI=';
@@ -24,3 +26,23 @@ test('does not convert a string', () => {
   expect(convertBigintsInObj('hello')).toEqual('hello');
   expect(convertBigintsInObj({ msg: 'hello' })).toEqual({ msg: 'hello' });
 });
+
+test('converts a registered class', () => {
+  const cc = new ClassConverter({ ToStringClass: ToStringClassA });
+  const obj = { content: new ToStringClassA('a', 'b') };
+  const serialised = convertToJsonObj(cc, obj);
+  const deserialised = convertFromJsonObj(cc, serialised) as { content: ToStringClassA };
+  expect(deserialised.content).toBeInstanceOf(ToStringClassA);
+  expect(deserialised.content.x).toEqual('a');
+  expect(deserialised.content.y).toEqual('b');
+});
+
+test('converts a class by name', () => {
+  const cc = new ClassConverter({ ToStringClass: ToStringClassA });
+  const obj = { content: new ToStringClassB('a', 'b') };
+  const serialised = convertToJsonObj(cc, obj);
+  const deserialised = convertFromJsonObj(cc, serialised) as { content: ToStringClassA };
+  expect(deserialised.content).toBeInstanceOf(ToStringClassA);
+  expect(deserialised.content.x).toEqual('a');
+  expect(deserialised.content.y).toEqual('b');
+});

yarn-project/foundation/src/json-rpc/convert.ts

@@ -76,8 +76,8 @@ export function convertFromJsonObj(cc: ClassConverter, obj: any): any {
     return newObj;
   }
   // Throw if this is a non-primitive class that was not registered
-  if (typeof obj === 'object' && obj.constructor !== Object) {
-    throw new Error(`Object ${obj.constructor.name} not registered for deserialisation`);
+  if (typeof obj === 'object' && Object.getPrototypeOf(obj) === Object.getPrototypeOf({})) {
+    throw new Error(`Class ${obj.constructor.name} not registered for deserialisation`);
   }
   // Leave alone, assume JSON primitive
   return obj;
@@ -122,7 +122,7 @@ export function convertToJsonObj(cc: ClassConverter, obj: any): any {
     return newObj;
   }
   // Throw if this is a non-primitive class that was not registered
-  if (typeof obj === 'object' && obj.constructor !== Object) {
+  if (typeof obj === 'object' && Object.getPrototypeOf(obj) === Object.getPrototypeOf({})) {
     throw new Error(`Object ${obj.constructor.name} not registered for serialisation`);
   }
   // Leave alone, assume JSON primitive

yarn-project/foundation/src/json-rpc/fixtures/class_a.ts

@@ -0,0 +1,15 @@
+/**
+ * Test class for testing string converter.
+ */
+export class ToStringClass {
+  constructor(/** A value */ public readonly x: string, /** Another value */ public readonly y: string) {}
+
+  toString(): string {
+    return [this.x, this.y].join('-');
+  }
+
+  static fromString(value: string) {
+    const [x, y] = value.split('-');
+    return new ToStringClass(x, y);
+  }
+}

yarn-project/foundation/src/json-rpc/fixtures/class_b.ts

@@ -0,0 +1,15 @@
+/**
+ * Test class for testing string converter.
+ */
+export class ToStringClass {
+  constructor(/** A value */ public readonly x: string, /** Another value */ public readonly y: string) {}
+
+  toString(): string {
+    return [this.x, this.y].join('-');
+  }
+
+  static fromString(value: string) {
+    const [x, y] = value.split('-');
+    return new ToStringClass(x, y);
+  }
+}