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import { AbiDecoder } from '@0xproject/utils';
import { ContractAbi, DecodedLogArgs, LogEntry, LogWithDecodedArgs, RawLog } from 'ethereum-types';
const TOKEN_TYPE_COLLISION = `Token can't be marked as ERC20 and ERC721 at the same time`;
/**
* ERC20 and ERC721 have some events with different args but colliding signature.
* For exmaple:
* Transfer(_from address, _to address, _value uint256)
* Transfer(_from address, _to address, _tokenId uint256)
* Both have the signature:
* Transfer(address,address,uint256)
*
* In order to correctly decode those events we need to know the token type by address in advance.
* You can pass it by calling `this.addERC20Token(address)` or `this.addERC721Token(address)`
*/
export class CollisionResistanceAbiDecoder {
private readonly _erc20AbiDecoder: AbiDecoder;
private readonly _erc721AbiDecoder: AbiDecoder;
private readonly _restAbiDecoder: AbiDecoder;
private readonly _knownERC20Tokens = new Set();
private readonly _knownERC721Tokens = new Set();
constructor(erc20Abi: ContractAbi, erc721Abi: ContractAbi, abis: ContractAbi[]) {
this._erc20AbiDecoder = new AbiDecoder([erc20Abi]);
this._erc721AbiDecoder = new AbiDecoder([erc721Abi]);
this._restAbiDecoder = new AbiDecoder(abis);
}
public tryToDecodeLogOrNoop<ArgsType extends DecodedLogArgs>(log: LogEntry): LogWithDecodedArgs<ArgsType> | RawLog {
if (this._knownERC20Tokens.has(log.address)) {
const maybeDecodedERC20Log = this._erc20AbiDecoder.tryToDecodeLogOrNoop(log);
return maybeDecodedERC20Log;
} else if (this._knownERC721Tokens.has(log.address)) {
const maybeDecodedERC721Log = this._erc721AbiDecoder.tryToDecodeLogOrNoop(log);
return maybeDecodedERC721Log;
} else {
const maybeDecodedLog = this._restAbiDecoder.tryToDecodeLogOrNoop(log);
return maybeDecodedLog;
}
}
// Hints the ABI decoder that a particular token address is ERC20 and events from it should be decoded as ERC20 events
public addERC20Token(address: string): void {
if (this._knownERC721Tokens.has(address)) {
throw new Error(TOKEN_TYPE_COLLISION);
}
this._knownERC20Tokens.add(address);
}
// Hints the ABI decoder that a particular token address is ERC721 and events from it should be decoded as ERC721 events
public addERC721Token(address: string): void {
if (this._knownERC20Tokens.has(address)) {
throw new Error(TOKEN_TYPE_COLLISION);
}
this._knownERC721Tokens.add(address);
}
}
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