1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
import { AssetProxyId, ExchangeContractErrs } from '@0x/types';
import { BigNumber } from '@0x/utils';
import { AbstractBalanceAndProxyAllowanceLazyStore } from './abstract/abstract_balance_and_proxy_allowance_lazy_store';
import { assetDataUtils } from './asset_data_utils';
import { constants } from './constants';
import { TradeSide, TransferType } from './types';
enum FailureReason {
Balance = 'balance',
ProxyAllowance = 'proxyAllowance',
}
const ERR_MSG_MAPPING = {
[FailureReason.Balance]: {
[TradeSide.Maker]: {
[TransferType.Trade]: ExchangeContractErrs.InsufficientMakerBalance,
[TransferType.Fee]: ExchangeContractErrs.InsufficientMakerFeeBalance,
},
[TradeSide.Taker]: {
[TransferType.Trade]: ExchangeContractErrs.InsufficientTakerBalance,
[TransferType.Fee]: ExchangeContractErrs.InsufficientTakerFeeBalance,
},
},
[FailureReason.ProxyAllowance]: {
[TradeSide.Maker]: {
[TransferType.Trade]: ExchangeContractErrs.InsufficientMakerAllowance,
[TransferType.Fee]: ExchangeContractErrs.InsufficientMakerFeeAllowance,
},
[TradeSide.Taker]: {
[TransferType.Trade]: ExchangeContractErrs.InsufficientTakerAllowance,
[TransferType.Fee]: ExchangeContractErrs.InsufficientTakerFeeAllowance,
},
},
};
/**
* An exchange transfer simulator which simulates asset transfers exactly how the
* 0x exchange contract would do them.
*/
export class ExchangeTransferSimulator {
private readonly _store: AbstractBalanceAndProxyAllowanceLazyStore;
private static _throwValidationError(
failureReason: FailureReason,
tradeSide: TradeSide,
transferType: TransferType,
): never {
const errMsg = ERR_MSG_MAPPING[failureReason][tradeSide][transferType];
throw new Error(errMsg);
}
/**
* Instantiate a ExchangeTransferSimulator
* @param store A class that implements AbstractBalanceAndProxyAllowanceLazyStore
* @return an instance of ExchangeTransferSimulator
*/
constructor(store: AbstractBalanceAndProxyAllowanceLazyStore) {
this._store = store;
}
/**
* Simulates transferFrom call performed by a proxy
* @param assetData Data of the asset being transferred. Includes
* it's identifying information and assetType,
* e.g address for ERC20, address & tokenId for ERC721
* @param from Owner of the transferred tokens
* @param to Recipient of the transferred tokens
* @param amountInBaseUnits The amount of tokens being transferred
* @param tradeSide Is Maker/Taker transferring
* @param transferType Is it a fee payment or a value transfer
*/
public async transferFromAsync(
assetData: string,
from: string,
to: string,
amountInBaseUnits: BigNumber,
tradeSide: TradeSide,
transferType: TransferType,
): Promise<void> {
const assetProxyId = assetDataUtils.decodeAssetProxyId(assetData);
switch (assetProxyId) {
case AssetProxyId.ERC20:
case AssetProxyId.ERC721:
// HACK: When simulating an open order (e.g taker is NULL_ADDRESS), we don't want to adjust balances/
// allowances for the taker. We do however, want to increase the balance of the maker since the maker
// might be relying on those funds to fill subsequent orders or pay the order's fees.
if (from === constants.NULL_ADDRESS && tradeSide === TradeSide.Taker) {
await this._increaseBalanceAsync(assetData, to, amountInBaseUnits);
return;
}
const balance = await this._store.getBalanceAsync(assetData, from);
const proxyAllowance = await this._store.getProxyAllowanceAsync(assetData, from);
if (proxyAllowance.isLessThan(amountInBaseUnits)) {
ExchangeTransferSimulator._throwValidationError(
FailureReason.ProxyAllowance,
tradeSide,
transferType,
);
}
if (balance.isLessThan(amountInBaseUnits)) {
ExchangeTransferSimulator._throwValidationError(FailureReason.Balance, tradeSide, transferType);
}
await this._decreaseProxyAllowanceAsync(assetData, from, amountInBaseUnits);
await this._decreaseBalanceAsync(assetData, from, amountInBaseUnits);
await this._increaseBalanceAsync(assetData, to, amountInBaseUnits);
break;
case AssetProxyId.MultiAsset:
const decodedAssetData = assetDataUtils.decodeMultiAssetData(assetData);
for (const [index, nestedAssetDataElement] of decodedAssetData.nestedAssetData.entries()) {
const amountsElement = decodedAssetData.amounts[index];
const totalAmount = amountInBaseUnits.times(amountsElement);
await this.transferFromAsync(
nestedAssetDataElement,
from,
to,
totalAmount,
tradeSide,
transferType,
);
}
break;
default:
break;
}
}
private async _decreaseProxyAllowanceAsync(
assetData: string,
userAddress: string,
amountInBaseUnits: BigNumber,
): Promise<void> {
const proxyAllowance = await this._store.getProxyAllowanceAsync(assetData, userAddress);
// HACK: This code assumes that all tokens with an UNLIMITED_ALLOWANCE_IN_BASE_UNITS set,
// are UnlimitedAllowanceTokens. This is however not true, it just so happens that all
// DummyERC20Tokens we use in tests are.
if (!proxyAllowance.eq(constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS)) {
this._store.setProxyAllowance(assetData, userAddress, proxyAllowance.minus(amountInBaseUnits));
}
}
private async _increaseBalanceAsync(
assetData: string,
userAddress: string,
amountInBaseUnits: BigNumber,
): Promise<void> {
const balance = await this._store.getBalanceAsync(assetData, userAddress);
this._store.setBalance(assetData, userAddress, balance.plus(amountInBaseUnits));
}
private async _decreaseBalanceAsync(
assetData: string,
userAddress: string,
amountInBaseUnits: BigNumber,
): Promise<void> {
const balance = await this._store.getBalanceAsync(assetData, userAddress);
this._store.setBalance(assetData, userAddress, balance.minus(amountInBaseUnits));
}
}
|
