4 files changed, 44 insertions, 13 deletions

diff --git a/src/contract_wrappers/exchange_wrapper.ts b/src/contract_wrappers/exchange_wrapper.ts
index f0f153c2b..3f6eb0dab 100644
--- a/src/contract_wrappers/exchange_wrapper.ts
+++ b/src/contract_wrappers/exchange_wrapper.ts
@@ -7,9 +7,13 @@ import * as ExchangeArtifacts from '../artifacts/Exchange.json';
 import {ecSignatureSchema} from '../schemas/ec_signature_schema';
 
 export class ExchangeWrapper extends ContractWrapper {
+    private exchangeContractIfExists?: ExchangeContract;
     constructor(web3Wrapper: Web3Wrapper) {
         super(web3Wrapper);
     }
+    public invalidateContractInstance(): void {
+        delete this.exchangeContractIfExists;
+    }
     public async isValidSignatureAsync(dataHex: string, ecSignature: ECSignature,
                                        signerAddressHex: string): Promise<boolean> {
         assert.isHexString('dataHex', dataHex);
@@ -19,10 +23,9 @@ export class ExchangeWrapper extends ContractWrapper {
         const senderAddressIfExists = await this.web3Wrapper.getSenderAddressIfExistsAsync();
         assert.assert(!_.isUndefined(senderAddressIfExists), ZeroExError.USER_HAS_NO_ASSOCIATED_ADDRESSES);
 
-        const contractInstance = await this.instantiateContractIfExistsAsync((ExchangeArtifacts as any));
-        const exchangeInstance = contractInstance as ExchangeContract;
+        const exchangeContract = await this.getExchangeContractAsync();
 
-        const isValidSignature = await exchangeInstance.isValidSignature.call(
+        const isValidSignature = await exchangeContract.isValidSignature.call(
             signerAddressHex,
             dataHex,
             ecSignature.v,
@@ -34,4 +37,12 @@ export class ExchangeWrapper extends ContractWrapper {
         );
         return isValidSignature;
     }
+    private async getExchangeContractAsync(): Promise<ExchangeContract> {
+        if (!_.isUndefined(this.exchangeContractIfExists)) {
+            return this.exchangeContractIfExists;
+        }
+        const contractInstance = await this.instantiateContractIfExistsAsync((ExchangeArtifacts as any));
+        this.exchangeContractIfExists = contractInstance as ExchangeContract;
+        return this.exchangeContractIfExists;
+    }
 }
diff --git a/src/contract_wrappers/token_registry_wrapper.ts b/src/contract_wrappers/token_registry_wrapper.ts
index 4d6eacb51..86bea1c5d 100644
--- a/src/contract_wrappers/token_registry_wrapper.ts
+++ b/src/contract_wrappers/token_registry_wrapper.ts
@@ -1,20 +1,23 @@
 import * as _ from 'lodash';
 import {Web3Wrapper} from '../web3_wrapper';
-import {ZeroExError, Token, TokenRegistryContract} from '../types';
+import {Token, TokenRegistryContract, TokenMetadata} from '../types';
 import {assert} from '../utils/assert';
 import {ContractWrapper} from './contract_wrapper';
 import * as TokenRegistryArtifacts from '../artifacts/TokenRegistry.json';
 
 export class TokenRegistryWrapper extends ContractWrapper {
+    private tokenRegistryContractIfExists?: TokenRegistryContract;
     constructor(web3Wrapper: Web3Wrapper) {
         super(web3Wrapper);
     }
+    public invalidateContractInstance(): void {
+        delete this.tokenRegistryContractIfExists;
+    }
     public async getTokensAsync(): Promise<Token[]> {
-        const contractInstance = await this.instantiateContractIfExistsAsync((TokenRegistryArtifacts as any));
-        const tokenRegistryContract = contractInstance as TokenRegistryContract;
+        const tokenRegistryContract = await this.getTokenRegistryContractAsync();
 
         const addresses = await tokenRegistryContract.getTokenAddresses.call();
-        const tokenMetadataPromises: Array<Promise<any[]>> = _.map(
+        const tokenMetadataPromises: Array<Promise<TokenMetadata>> = _.map(
             addresses,
             (address: string) => (tokenRegistryContract.getTokenMetaData.call(address)),
         );
@@ -30,4 +33,12 @@ export class TokenRegistryWrapper extends ContractWrapper {
         });
         return tokens;
     }
+    private async getTokenRegistryContractAsync(): Promise<TokenRegistryContract> {
+        if (!_.isUndefined(this.tokenRegistryContractIfExists)) {
+            return this.tokenRegistryContractIfExists;
+        }
+        const contractInstance = await this.instantiateContractIfExistsAsync((TokenRegistryArtifacts as any));
+        this.tokenRegistryContractIfExists = contractInstance as TokenRegistryContract;
+        return this.tokenRegistryContractIfExists;
+    }
 }
diff --git a/src/types.ts b/src/types.ts
index f5b0f3e7c..9c82c1fa6 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -37,8 +37,12 @@ export interface ERC20Contract {
 }
 
 export interface TokenRegistryContract {
-    getTokenMetaData: any;
-    getTokenAddresses: any;
+    getTokenMetaData: {
+        call: (address: string) => Promise<TokenMetadata>;
+    };
+    getTokenAddresses: {
+        call: () => Promise<string[]>;
+    };
 }
 
 export const SolidityTypes = strEnum([
@@ -47,6 +51,9 @@ export const SolidityTypes = strEnum([
 ]);
 export type SolidityTypes = keyof typeof SolidityTypes;
 
+//                          [address, name, symbol, projectUrl, decimals, ipfsHash, swarmHash]
+export type TokenMetadata = [string, string, string, string, BigNumber.BigNumber, string, string];
+
 export interface Token {
     name: string;
     address: string;
diff --git a/src/web3_wrapper.ts b/src/web3_wrapper.ts
index 97d04db8c..e65f29b56 100644
--- a/src/web3_wrapper.ts
+++ b/src/web3_wrapper.ts
@@ -9,6 +9,9 @@ export class Web3Wrapper {
         this.web3 = new Web3();
         this.web3.setProvider(web3.currentProvider);
     }
+    public setProvider(provider: Web3.Provider) {
+        this.web3.setProvider(provider);
+    }
     public isAddress(address: string): boolean {
         return this.web3.isAddress(address);
     }
@@ -49,10 +52,9 @@ export class Web3Wrapper {
     }
     public async doesContractExistAtAddressAsync(address: string): Promise<boolean> {
         const code = await promisify(this.web3.eth.getCode)(address);
-        // Regex matches 0x0, 0x00, 0x in order to accomodate poorly implemented clients
-        const zeroHexAddressRegex = /^0x0*$/i;
-        const didFindCode = _.isNull(code.match(zeroHexAddressRegex));
-        return didFindCode;
+        // Regex matches 0x0, 0x00, 0x in order to accommodate poorly implemented clients
+        const codeIsEmpty = /^0x0{0,40}$/i.test(code);
+        return !codeIsEmpty;
     }
     public async signTransactionAsync(address: string, message: string): Promise<string> {
         const signData = await promisify(this.web3.eth.sign)(address, message);