implement toFields and make strings 31 chars (#18)

.eslintrc.cjs

@@ -16,7 +16,7 @@ module.exports = {
     ecmaVersion: 'latest',
   },
   plugins: ['@typescript-eslint', 'o1js'],
-  ignorePatterns: ['README.md'],
+  ignorePatterns: ['*.md'],
   rules: {
     'no-constant-condition': 'off',
     'prefer-const': 'off',

CHANGELOG.md

@@ -0,0 +1,5 @@
+## v0.5
+
+- Making PackedString class 31 characters instead of 15
+  - This has implications in any source code using the default packed string implementation
+  - Unpacked character arrays will now be 31 characters long, so code expecting a 15-character array may break!

package.json

@@ -1,6 +1,6 @@
 {
   "name": "o1js-pack",
-  "version": "0.4.4",
+  "version": "0.5.0",
   "description": "",
   "author": "45930",
   "license": "Apache-2.0",

src/lib/PackingPlant.ts

@@ -92,6 +92,14 @@ export function PackingPlant<A, T extends InferProvable<A> = InferProvable<A>>(
       return unpacked;
     }
 
+    // NOTE: adding to fields here breaks the proof generation.  Probably not overriding it correctly
+    /**
+     * @returns array of single Field element which constitute the packed object
+     */
+    toFields(): Array<Field> {
+      return [this.packed];
+    }
+
     assertEquals(other: Packed_) {
       this.packed.assertEquals(other.packed);
     }
@@ -216,6 +224,14 @@ export function MultiPackingPlant<
       return uints_;
     }
 
+    // NOTE: adding to fields here breaks the proof generation.  Probably not overriding it correctly
+    /**
+     * @returns array of Field elements which constitute the multi-packed object
+     */
+    toFields(): Array<Field> {
+      return this.packed;
+    }
+
     assertEquals(other: Packed_) {
       for (let x = 0; x < n; x++) {
         this.packed[x].assertEquals(other.packed[x]);

src/lib/packed-types/PackedString.test.ts

@@ -4,7 +4,7 @@ import { PackedStringFactory, MultiPackedStringFactory } from './PackedString';
 describe('PackedString', () => {
   describe('Outside of the Circuit', () => {
     const vitalik_dot_eth = '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045';
-    class EthAddressString extends MultiPackedStringFactory(3) {}
+    class EthAddressString extends MultiPackedStringFactory(2) {}
     let characters: Array<Character> = [];
 
     beforeEach(() => {
@@ -30,17 +30,48 @@ describe('PackedString', () => {
       );
       const packed = EthAddressString.pack(unpacked);
 
-      expect(packed.length).toBe(Math.ceil(vitalik_dot_eth.length / 15));
+      expect(packed.length).toBe(Math.ceil(vitalik_dot_eth.length / 31));
       expect(unpacked.length).toBe(EthAddressString.l);
-      expect(unpacked.length).toBe(45);
+      expect(unpacked.length).toBe(62);
       expect(unpacked.slice(0, characters.length).toString()).toBe(
         characters.toString()
       );
     });
+
+    it('#toFields', () => {
+      class Single extends PackedStringFactory() {}
+      class Double extends MultiPackedStringFactory(2) {}
+      const abbaPacked = '1633837665';
+
+      expect(Single.fromString('abba').toFields().toString()).toBe(
+        [Single.fromString('abba').packed].toString()
+      );
+      expect(Single.fromString('abba').toFields().toString()).toBe(abbaPacked);
+      expect(
+        Single.unpack(Field(abbaPacked)).slice(0, 4).join('').toString()
+      ).toBe('abba');
+
+      const abbaAlot = 'abba'.repeat(10);
+      const abbaAlotPacked1 =
+        '173830008860859097861870638220020642754739197069143560335286125952244015713';
+      const abbaAlotPacked2 = '1796423510984151425377';
+      expect(Double.fromString(abbaAlot).toFields().toString()).toBe(
+        [Double.fromString(abbaAlot).packed].toString()
+      );
+      expect(Double.fromString(abbaAlot).toFields().toString()).toBe(
+        abbaAlotPacked1 + ',' + abbaAlotPacked2
+      );
+      expect(
+        Double.unpack([Field(abbaAlotPacked1), Field(abbaAlotPacked2)])
+          .slice(0, 40)
+          .join('')
+          .toString()
+      ).toBe(abbaAlot);
+    });
   });
   describe('Provable Properties', () => {
     it('#sizeInFields', () => {
-      class one extends PackedStringFactory(15) {}
+      class one extends PackedStringFactory(31) {}
       class two extends MultiPackedStringFactory(2) {}
       class three extends MultiPackedStringFactory(3) {}
 
@@ -67,7 +98,7 @@ describe('PackedString', () => {
       }).toThrow();
     });
     it('Exceeds maximum size string', () => {
-      const tooLong = 'too long!'.repeat(20);
+      const tooLong = 'too long!'.repeat(50);
       class MaxString extends MultiPackedStringFactory(8) {}
       expect(() => {
         MaxString.fromString(tooLong);

src/lib/packed-types/PackedString.ts

@@ -1,9 +1,9 @@
 import { Field, Provable, Character, Poseidon } from 'o1js';
 import { PackingPlant, MultiPackingPlant } from '../PackingPlant.js';
 
-const SIZE_IN_BITS = 16n;
-const L = 15; // Default to one-field worth of characters
-const CHARS_PER_FIELD = 15;
+const SIZE_IN_BITS = 8n;
+const L = 31; // Default to one-field worth of characters
+const CHARS_PER_FIELD = 31;
 
 export function PackedStringFactory(l: number = L) {
   class PackedString_ extends PackingPlant(Character, l, SIZE_IN_BITS) {

tests/provable/example_packed_string_circuit.ts

@@ -6,9 +6,9 @@ import {
   Provable,
   Field,
 } from 'o1js';
-import { MultiPackedStringFactory } from '../../src/lib/packed-types/PackedString';
+import { PackedStringFactory } from '../../src/lib/packed-types/PackedString';
 
-export class TextInput extends MultiPackedStringFactory(3) {}
+export class TextInput extends PackedStringFactory() {}
 
 export const TextInputProgram = ZkProgram({
   name: 'TextInputProgram',
@@ -23,7 +23,7 @@ export const TextInputProgram = ZkProgram({
       },
     },
     changeFirstLetter: {
-      privateInputs: [SelfProof, Provable.Array(Character, 45), Character],
+      privateInputs: [SelfProof, Provable.Array(Character, 31), Character],
       method(
         newState: TextInput,
         oldProof: SelfProof<TextInput, TextInput>,