Merge pull request #626 from semaphore-protocol/feat/export-group

New Group `export`/`import` methods

Former-commit-id: f44b0b1

Author: cedoor

packages/group/README.md

@@ -169,3 +169,32 @@ console.log(proof)
 }
 */
 ```
+
+\# **export**(): _string_
+
+```typescript
+import { Group } from "@semaphore-protocol/group"
+
+const group = new Group([1, 2, 3])
+
+const exportedGroup = group.export()
+
+console.log(exportedGroup)
+/*
+[["1","2","3"],["7853200120776062878684798364095072458815029376092732009249414926327459813530","3"],["13816780880028945690020260331303642730075999758909899334839547418969502592169"]]
+*/
+```
+
+\# **import**(exportedGroup: _string_): _Group_
+
+```typescript
+import { Group } from "@semaphore-protocol/group"
+
+const group1 = new Group([1, 2, 3])
+
+const exportedGroup = group.export()
+
+const group2 = Group.import(exportedGroup)
+
+assert(group1.root === group2.root)
+```

packages/group/package.json

@@ -37,6 +37,6 @@
         "rollup-plugin-typescript2": "^0.36.0"
     },
     "dependencies": {
-        "@zk-kit/imt": "^2.0.0-beta"
+        "@zk-kit/imt": "^2.0.0-beta.1"
     }
 }

packages/group/src/group.ts

@@ -102,4 +102,29 @@ export default class Group {
             siblings: siblings.map(String)
         }
     }
+
+    /**
+     * It enables the conversion of the group into a JSON string that
+     * can be re-used for future imports. This approach is beneficial for
+     * large groups, as it avoids re-calculating the tree hashes.
+     * @returns The stringified JSON of the group.
+     */
+    export(): string {
+        return this.leanIMT.export()
+    }
+
+    /**
+     * It imports an entire group by initializing the tree without calculating
+     * any hashes. Note that it is crucial to ensure the integrity of the
+     * exported group.
+     * @param nodes The stringified JSON of the group.
+     * @returns The group instance.
+     */
+    static import(exportedGroup: string): Group {
+        const group = new Group()
+
+        group.leanIMT.import(exportedGroup)
+
+        return group
+    }
 }

packages/group/tests/index.test.ts

@@ -91,4 +91,34 @@ describe("Group", () => {
             expect(proof.leaf).toBe("1")
         })
     })
+
+    describe("# export", () => {
+        it("Should export a group", () => {
+            const group = new Group([1, 2, 3])
+
+            const exportedGroup = group.export()
+
+            console.log(exportedGroup)
+
+            expect(typeof exportedGroup).toBe("string")
+            expect(JSON.parse(exportedGroup)).toHaveLength(3)
+            expect(JSON.parse(exportedGroup)[0]).toHaveLength(3)
+        })
+    })
+
+    describe("# import", () => {
+        it("Should import a group", () => {
+            const group1 = new Group([1, 2, 3])
+            const exportedGroup = group1.export()
+
+            const group2 = Group.import(exportedGroup)
+
+            group1.addMember(4)
+            group2.addMember(4)
+
+            expect(group2.depth).toBe(group1.depth)
+            expect(group2.size).toBe(group1.size)
+            expect(group2.root).toBe(group1.root)
+        })
+    })
 })

yarn.lock.REMOVED.git-id

@@ -1 +1 @@
-41216b543a37ea32df4cb98d913cca8daee1ca63
+905709848cfc19dff98c61c4b975512626b90b89