4 files changed, 71 insertions, 1 deletions

diff --git a/src/ts/0x.js.ts b/src/ts/0x.js.ts
index cc3c43e79..7c6557b5b 100644
--- a/src/ts/0x.js.ts
+++ b/src/ts/0x.js.ts
@@ -1,12 +1,16 @@
 import * as BigNumber from 'bignumber.js';
+import * as BN from 'bn.js';
 import * as ethUtil from 'ethereumjs-util';
 import * as Web3 from 'web3';
+import * as ethABI from 'ethereumjs-abi';
+import * as _ from 'lodash';
+import {constants} from './utils/constants';
 import {assert} from './utils/assert';
 import {Web3Wrapper} from './web3_wrapper';
 import {ExchangeWrapper} from './contract_wrappers/exchange_wrapper';
 import contract = require('truffle-contract');
 import {ECSignatureSchema} from './schemas/ec_signature_schema';
-import {ECSignature} from './types';
+import {SolidityTypes, ECSignature} from './types';
 
 const MAX_DIGITS_IN_UNSIGNED_256_INT = 78;
 
@@ -14,6 +18,48 @@ export class ZeroEx {
     public web3Wrapper: Web3Wrapper;
     public exchange: ExchangeWrapper;
     /**
+     * Computes the orderHash given the order parameters and returns it as a hex encoded string.
+     */
+    public static getOrderHashHex(exchangeContractAddr: string, makerAddr: string, takerAddr: string,
+                                  tokenMAddress: string, tokenTAddress: string, feeRecipient: string,
+                                  valueM: BigNumber.BigNumber, valueT: BigNumber.BigNumber,
+                                  makerFee: BigNumber.BigNumber, takerFee: BigNumber.BigNumber,
+                                  expiration: BigNumber.BigNumber, salt: BigNumber.BigNumber): string {
+        takerAddr = _.isEmpty(takerAddr) ? constants.NULL_ADDRESS : takerAddr ;
+        assert.isETHAddressHex('exchangeContractAddr', exchangeContractAddr);
+        assert.isETHAddressHex('makerAddr', makerAddr);
+        assert.isETHAddressHex('takerAddr', takerAddr);
+        assert.isETHAddressHex('tokenMAddress', tokenMAddress);
+        assert.isETHAddressHex('tokenTAddress', tokenTAddress);
+        assert.isETHAddressHex('feeRecipient', feeRecipient);
+        assert.isBigNumber('valueM', valueM);
+        assert.isBigNumber('valueT', valueT);
+        assert.isBigNumber('makerFee', makerFee);
+        assert.isBigNumber('takerFee', takerFee);
+        assert.isBigNumber('expiration', expiration);
+        assert.isBigNumber('salt', salt);
+
+        const orderParts = [
+            {value: exchangeContractAddr, type: SolidityTypes.address},
+            {value: makerAddr, type: SolidityTypes.address},
+            {value: takerAddr, type: SolidityTypes.address},
+            {value: tokenMAddress, type: SolidityTypes.address},
+            {value: tokenTAddress, type: SolidityTypes.address},
+            {value: feeRecipient, type: SolidityTypes.address},
+            {value: this.bigNumberToBN(valueM), type: SolidityTypes.uint256},
+            {value: this.bigNumberToBN(valueT), type: SolidityTypes.uint256},
+            {value: this.bigNumberToBN(makerFee), type: SolidityTypes.uint256},
+            {value: this.bigNumberToBN(takerFee), type: SolidityTypes.uint256},
+            {value: this.bigNumberToBN(expiration), type: SolidityTypes.uint256},
+            {value: this.bigNumberToBN(salt), type: SolidityTypes.uint256},
+        ];
+        const types = _.map(orderParts, o => o.type);
+        const values = _.map(orderParts, o => o.value);
+        const hashBuff = ethABI.soliditySHA3(types, values);
+        const hashHex = ethUtil.bufferToHex(hashBuff);
+        return hashHex;
+    }
+    /**
      * Verifies that the elliptic curve signature `signature` was generated
      * by signing `data` with the private key corresponding to the `signerAddressHex` address.
      */
@@ -80,6 +126,15 @@ export class ZeroEx {
         const baseUnitAmount = amount.times(unit);
         return baseUnitAmount;
     }
+    /**
+     * Converts BigNumber instance to BN
+     * The only we convert to BN is to remain compatible with `ethABI. soliditySHA3 ` that
+     * expects values of Solidity type `uint` to be of type `BN`.
+     * We do not use BN anywhere else in the codebase.
+     */
+    private static bigNumberToBN(value: BigNumber.BigNumber) {
+        return new BN(value.toString(), 10);
+    }
     constructor(web3: Web3) {
         this.web3Wrapper = new Web3Wrapper(web3);
         this.exchange = new ExchangeWrapper(this.web3Wrapper);
diff --git a/src/ts/globals.d.ts b/src/ts/globals.d.ts
index 04328509a..30225d0d8 100644
--- a/src/ts/globals.d.ts
+++ b/src/ts/globals.d.ts
@@ -1,4 +1,5 @@
 declare module 'chai-bignumber';
+declare module 'bn.js';
 
 declare interface Schema {
     id: string;
@@ -51,3 +52,7 @@ declare function promisify(original: any, settings?: any): ((...arg: any[]) => P
 declare module 'es6-promisify' {
     export = promisify;
 }
+
+declare module 'ethereumjs-abi' {
+    const soliditySHA3: (argTypes: string[], args: any[]) => Buffer;
+}
diff --git a/src/ts/types.ts b/src/ts/types.ts
index 01380af02..04123782e 100644
--- a/src/ts/types.ts
+++ b/src/ts/types.ts
@@ -1,4 +1,5 @@
 import * as _ from 'lodash';
+import * as BigNumber from 'bignumber.js';
 
 // Utility function to create a K:V from a list of strings
 // Adapted from: https://basarat.gitbooks.io/typescript/content/docs/types/literal-types.html
@@ -28,3 +29,9 @@ export interface ECSignature {
 export interface ExchangeContract {
     isValidSignature: any;
 }
+
+export const SolidityTypes = strEnum([
+    'address',
+    'uint256',
+]);
+export type SolidityTypes = keyof typeof SolidityTypes;
diff --git a/src/ts/utils/constants.ts b/src/ts/utils/constants.ts
new file mode 100644
index 000000000..60af7b674
--- /dev/null
+++ b/src/ts/utils/constants.ts
@@ -0,0 +1,3 @@
+export const constants = {
+    NULL_ADDRESS: '0x0000000000000000000000000000000000000000',
+}