73 lines
2.8 KiB
TypeScript
73 lines
2.8 KiB
TypeScript
import BigNumber from 'bignumber.js';
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import * as _ from 'lodash';
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import * as Web3 from 'web3';
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import * as SolidityCoder from 'web3/lib/solidity/coder';
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import { AbiType, ContractEventArgs, DecodedLogArgs, LogWithDecodedArgs, RawLog, SolidityTypes } from '../types';
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export class AbiDecoder {
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private _savedABIs: Web3.AbiDefinition[] = [];
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private _methodIds: { [signatureHash: string]: Web3.EventAbi } = {};
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private static _padZeros(address: string) {
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let formatted = address;
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if (_.startsWith(formatted, '0x')) {
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formatted = formatted.slice(2);
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}
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formatted = _.padStart(formatted, 40, '0');
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return `0x${formatted}`;
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}
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constructor(abiArrays: Web3.AbiDefinition[][]) {
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_.map(abiArrays, this._addABI.bind(this));
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}
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// This method can only decode logs from the 0x & ERC20 smart contracts
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public tryToDecodeLogOrNoop<ArgsType extends ContractEventArgs>(
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log: Web3.LogEntry,
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): LogWithDecodedArgs<ArgsType> | RawLog {
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const methodId = log.topics[0];
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const event = this._methodIds[methodId];
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if (_.isUndefined(event)) {
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return log;
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}
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const logData = log.data;
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const decodedParams: DecodedLogArgs = {};
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let dataIndex = 0;
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let topicsIndex = 1;
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const nonIndexedInputs = _.filter(event.inputs, input => !input.indexed);
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const dataTypes = _.map(nonIndexedInputs, input => input.type);
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const decodedData = SolidityCoder.decodeParams(dataTypes, logData.slice('0x'.length));
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_.map(event.inputs, (param: Web3.EventParameter) => {
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// Indexed parameters are stored in topics. Non-indexed ones in decodedData
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let value = param.indexed ? log.topics[topicsIndex++] : decodedData[dataIndex++];
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if (param.type === SolidityTypes.Address) {
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value = AbiDecoder._padZeros(new BigNumber(value).toString(16));
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} else if (
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param.type === SolidityTypes.Uint256 ||
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param.type === SolidityTypes.Uint8 ||
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param.type === SolidityTypes.Uint
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) {
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value = new BigNumber(value);
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}
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decodedParams[param.name] = value;
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});
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return {
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...log,
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event: event.name,
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args: decodedParams,
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};
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}
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private _addABI(abiArray: Web3.AbiDefinition[]): void {
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_.map(abiArray, (abi: Web3.AbiDefinition) => {
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if (abi.type === AbiType.Event) {
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const signature = `${abi.name}(${_.map(abi.inputs, input => input.type).join(',')})`;
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const signatureHash = new Web3().sha3(signature);
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this._methodIds[signatureHash] = abi;
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}
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});
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this._savedABIs = this._savedABIs.concat(abiArray);
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}
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}
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