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import { schemas, SchemaValidator } from '@0xproject/json-schemas';
import { promisify } from '@0xproject/utils';
import * as _ from 'lodash';
import * as Web3 from 'web3';
import { AbiType } from './types';
export class Contract implements Web3.ContractInstance {
public address: string;
public abi: Web3.ContractAbi;
private _contract: Web3.ContractInstance;
private _defaults: Partial<Web3.TxData>;
private _validator: SchemaValidator;
// This class instance is going to be populated with functions and events depending on the ABI
// and we don't know their types in advance
[name: string]: any;
constructor(web3ContractInstance: Web3.ContractInstance, defaults: Partial<Web3.TxData>) {
this._contract = web3ContractInstance;
this.address = web3ContractInstance.address;
this.abi = web3ContractInstance.abi;
this._defaults = defaults;
this._populateEvents();
this._populateFunctions();
this._validator = new SchemaValidator();
}
private _populateFunctions(): void {
const functionsAbi = _.filter(this.abi, abiPart => abiPart.type === AbiType.Function) as Web3.FunctionAbi[];
_.forEach(functionsAbi, (functionAbi: Web3.MethodAbi) => {
if (functionAbi.constant) {
const cbStyleCallFunction = this._contract[functionAbi.name].call;
this[functionAbi.name] = {
callAsync: promisify(cbStyleCallFunction, this._contract),
};
} else {
const cbStyleFunction = this._contract[functionAbi.name];
const cbStyleEstimateGasFunction = this._contract[functionAbi.name].estimateGas;
this[functionAbi.name] = {
estimateGasAsync: promisify(cbStyleEstimateGasFunction, this._contract),
sendTransactionAsync: this._promisifyWithDefaultParams(cbStyleFunction),
};
}
});
}
private _populateEvents(): void {
const eventsAbi = _.filter(this.abi, abiPart => abiPart.type === AbiType.Event) as Web3.EventAbi[];
_.forEach(eventsAbi, (eventAbi: Web3.EventAbi) => {
this[eventAbi.name] = this._contract[eventAbi.name];
});
}
private _promisifyWithDefaultParams(fn: (...args: any[]) => void): (...args: any[]) => Promise<any> {
const promisifiedWithDefaultParams = async (...args: any[]) => {
const promise = new Promise((resolve, reject) => {
const lastArg = args[args.length - 1];
let txData: Partial<Web3.TxData> = {};
if (this._isTxData(lastArg)) {
txData = args.pop();
}
txData = {
...this._defaults,
...txData,
};
const callback = (err: Error, data: any) => {
if (_.isNull(err)) {
resolve(data);
} else {
reject(err);
}
};
args.push(txData);
args.push(callback);
fn.apply(this._contract, args);
});
return promise;
};
return promisifiedWithDefaultParams;
}
private _isTxData(lastArg: any): boolean {
const isValid = this._validator.isValid(lastArg, schemas.txDataSchema);
return isValid;
}
}
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