Merge pull request #78 from seanjameshan/feature/utils-shortstring-and-uint256

feat(utils): support shortstring and uint256

Author: janek26

__tests__/utils/shortString.test.ts

@@ -0,0 +1,22 @@
+import { decodeShortString, encodeShortString } from '../../src/utils/shortString';
+
+describe('shortString', () => {
+  test('should convert string to number', () => {
+    expect(encodeShortString('hello')).toMatchInlineSnapshot(`"0x68656c6c6f"`);
+  });
+  test('should convert number to string', () => {
+    expect(decodeShortString('0x68656c6c6f')).toMatchInlineSnapshot(`"hello"`);
+  });
+  test('should throw if string is too long', () => {
+    expect(() =>
+      encodeShortString('hello world hello world hello world hello world hello world hello world')
+    ).toThrowErrorMatchingInlineSnapshot(
+      `"hello world hello world hello world hello world hello world hello world is too long"`
+    );
+  });
+  test('should throw if string contains non ascii chars', () => {
+    expect(() => encodeShortString('hello\uD83D\uDE00')).toThrowErrorMatchingInlineSnapshot(
+      `"hello😀 is not an ASCII string"`
+    );
+  });
+});

__tests__/utils/uint256.test.ts

@@ -0,0 +1,32 @@
+import { ONE } from '../../src/constants';
+import { toBN } from '../../src/utils/number';
+import { UINT_128_MAX, UINT_256_MAX, bnToUint256, uint256ToBN } from '../../src/utils/uint256';
+
+describe('cairo uint256', () => {
+  test('should convert 0 from BN to uint256 struct', () => {
+    const uint256 = bnToUint256('0');
+    expect(uint256).toMatchInlineSnapshot(`
+      Object {
+        "high": "0x0",
+        "low": "0x0",
+      }
+    `);
+  });
+  test('should convert 0 from uint256 to BN', () => {
+    expect(uint256ToBN({ low: '0x0', high: '0x0' }).toString()).toMatchInlineSnapshot(`"0"`);
+  });
+  test('should convert BN over 2^128 to uint256 struct', () => {
+    const uint256 = bnToUint256(UINT_128_MAX.add(ONE));
+    expect(uint256).toMatchInlineSnapshot(`
+      Object {
+        "high": "0x1",
+        "low": "0x0",
+      }
+    `);
+  });
+  test('should throw if BN over uint256 range', () => {
+    expect(() => bnToUint256(UINT_256_MAX.add(toBN(1)))).toThrowErrorMatchingInlineSnapshot(
+      `"Number is too large"`
+    );
+  });
+});

src/constants.ts

@@ -1,13 +1,11 @@
-import BN from 'bn.js';
-
 import { toBN } from './utils/number';
 
 export { IS_BROWSER } from './utils/encode';
 
-export const ZERO: BN = toBN(0);
-export const ONE: BN = toBN(1);
-export const TWO: BN = toBN(2);
-export const MASK_250: BN = TWO.pow(toBN(250)).sub(ONE); // 2 ** 250 - 1
+export const ZERO = toBN(0);
+export const ONE = toBN(1);
+export const TWO = toBN(2);
+export const MASK_250 = TWO.pow(toBN(250)).sub(ONE); // 2 ** 250 - 1
 
 /**
  * The following is taken from https://github.com/starkware-libs/starkex-resources/blob/master/crypto/starkware/crypto/signature/pedersen_params.json but converted to hex, because JS is very bad handling big integers by default

src/index.ts

@@ -16,3 +16,5 @@ export * as json from './utils/json';
 export * as number from './utils/number';
 export * as stark from './utils/stark';
 export * as ec from './utils/ellipticCurve';
+export * as uint256 from './utils/uint256';
+export * as shortString from './utils/shortString';

src/utils/shortString.ts

@@ -0,0 +1,21 @@
+import { addHexPrefix, removeHexPrefix } from './encode';
+
+export function isASCII(str: string) {
+  // eslint-disable-next-line no-control-regex
+  return /^[\x00-\x7F]*$/.test(str);
+}
+
+// function to check if string has less or equal 31 characters
+export function isShortString(str: string) {
+  return str.length <= 31;
+}
+
+export function encodeShortString(str: string) {
+  if (!isASCII(str)) throw new Error(`${str} is not an ASCII string`);
+  if (!isShortString(str)) throw new Error(`${str} is too long`);
+  return addHexPrefix(str.replace(/./g, (char) => char.charCodeAt(0).toString(16)));
+}
+
+export function decodeShortString(str: string) {
+  return removeHexPrefix(str).replace(/.{2}/g, (hex) => String.fromCharCode(parseInt(hex, 16)));
+}

src/utils/stark.ts

@@ -49,3 +49,7 @@ export function formatSignature(sig?: [BigNumberish, BigNumberish]): [string, st
     return [];
   }
 }
+
+export function compileStructToCalldata<S extends { [k: string]: string }>(struct: S): string[] {
+  return Object.values(struct);
+}

src/utils/uint256.ts

@@ -0,0 +1,32 @@
+import { addHexPrefix } from './encode';
+import { BigNumberish, toBN } from './number';
+
+// Represents an integer in the range [0, 2^256).
+export interface Uint256 {
+  // The low 128 bits of the value.
+  low: BigNumberish;
+  // The high 128 bits of the value.
+  high: BigNumberish;
+}
+
+// function to convert Uint256 to BN
+export function uint256ToBN(uint256: Uint256) {
+  return toBN(uint256.high).shln(128).add(toBN(uint256.low));
+}
+
+export const UINT_128_MAX = toBN(1).shln(128).sub(toBN(1));
+export const UINT_256_MAX = toBN(1).shln(256).sub(toBN(1));
+// function to check if BN is smaller or equal 2**256-1
+export function isUint256(bn: BigNumberish): boolean {
+  return toBN(bn).lte(UINT_256_MAX);
+}
+
+// function to convert BN to Uint256
+export function bnToUint256(bignumber: BigNumberish): Uint256 {
+  const bn = toBN(bignumber);
+  if (!isUint256(bn)) throw new Error('Number is too large');
+  return {
+    low: addHexPrefix(bn.maskn(128).toString(16)),
+    high: addHexPrefix(bn.shrn(128).toString(16)),
+  };
+}