feat(json-crdt): 🎸 add type which infers schema from JSON CRDT nodes

Author: streamich

src/json-crdt/schema/__tests__/types.spec.ts

@@ -0,0 +1,55 @@
+import {s} from '../../../json-crdt-patch';
+import {Model} from '../../model';
+import {JsonNodeToSchema, SchemaToJsonNode} from '../types';
+
+describe('can infer schema of JSON CRDT nodes', () => {
+  test('con', () => {
+    const schema1 = s.con(123);
+    const schema2: JsonNodeToSchema<SchemaToJsonNode<typeof schema1>> = schema1;
+  });
+
+  test('val', () => {
+    const schema1 = s.val(s.con(true));
+    const schema2: JsonNodeToSchema<SchemaToJsonNode<typeof schema1>> = schema1;
+  });
+
+  test('obj', () => {
+    const schema1 = s.obj({
+      hello: s.con('world'),
+    });
+    const schema2: JsonNodeToSchema<SchemaToJsonNode<typeof schema1>> = schema1;
+  });
+
+  test('vec', () => {
+    const schema1 = s.vec(s.con(1), s.val(s.con(2)));
+    const schema2: JsonNodeToSchema<SchemaToJsonNode<typeof schema1>> = schema1;
+  });
+
+  test('str', () => {
+    const schema1 = s.str('asdf');
+    const schema2: JsonNodeToSchema<SchemaToJsonNode<typeof schema1>> = schema1;
+  });
+
+  test('bin', () => {
+    const schema1 = s.bin(new Uint8Array([1, 2, 3]));
+    const schema2: JsonNodeToSchema<SchemaToJsonNode<typeof schema1>> = schema1;
+  });
+
+  test('arr', () => {
+    const schema1 = s.arr([s.con(1), s.val(s.con(2))]);
+    const schema2: JsonNodeToSchema<SchemaToJsonNode<typeof schema1>> = schema1;
+  });
+
+  test('from typed model', () => {
+    const model = Model.withLogicalClock().setSchema(s.obj({
+      id: s.con('asdf'),
+      age: s.val(s.con(42)),
+    }));
+    type Node = ReturnType<typeof model.root.node>;
+    type Schema = JsonNodeToSchema<Node>;
+    const schema: Schema = s.obj({
+      id: s.con('asdf'),
+      age: s.val(s.con(42)),
+    });
+  });
+});

src/json-crdt/schema/types.ts

@@ -17,3 +17,20 @@ export type SchemaToJsonNode<S> = S extends builder.str<infer T>
             : S extends builder.arr<infer T>
               ? nodes.ArrNode<SchemaToJsonNode<T>>
               : nodes.JsonNode;
+
+// prettier-ignore
+export type JsonNodeToSchema<N> = N extends nodes.StrNode<infer T>
+  ? builder.str<T>
+  : N extends nodes.BinNode
+    ? builder.bin
+    : N extends nodes.ConNode<infer T>
+      ? builder.con<T>
+      : N extends nodes.ValNode<infer T>
+        ? builder.val<JsonNodeToSchema<T>>
+        : N extends nodes.VecNode<infer T>
+          ? builder.vec<{[K in keyof T]: JsonNodeToSchema<T[K]>}>
+          : N extends nodes.ObjNode<infer T>
+            ? builder.obj<{[K in keyof T]: JsonNodeToSchema<T[K]>}>
+            : N extends nodes.ArrNode<infer T>
+              ? builder.arr<JsonNodeToSchema<T>>
+              : builder.con<undefined>;