> For the complete documentation index, see [llms.txt](https://docs.dragonswap.app/dragonswap/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.dragonswap.app/dragonswap/resources/developer-resources/smart-contracts/dragonswapv2/smart-router/interfaces/itokenvalidator.md).

# ITokenValidator

Validates tokens by flash borrowing from the token/ pool on V1.

Returns Status.FOT if we detected a fee is taken on transfer. Status.STF if transfer failed for the token. Status.UNKN if we did not detect any issues with the token.

A return value of Status.UNKN does not mean the token is definitely not a fee on transfer token or definitely has no problems with its transfer. It just means we cant say for sure that it has any issues.

*We can not guarantee the result of this lens is correct for a few reasons:*

*1/ Some tokens take fees or allow transfers under specific conditions, for example some have an allowlist*

*of addresses that do/dont require fees. Therefore the result is not guaranteed to be correct*

*in all circumstances.*

*2/ It is possible that the token does not have any pools on V1 therefore we are not able to perform*

*a flashloan to test the token.*

*These functions are not marked view because they rely on calling non-view functions and reverting to compute the result.*

### Functions <a href="#functions" id="functions"></a>

#### validate <a href="#validate" id="validate"></a>

Validates a token by detecting if its transferable or takes a fee on transfer

```solidity
function validate(address token, address[] calldata baseTokens, uint256 amountToBorrow) external returns (Status);
```

**Parameters**

| Name             | Type        | Description                                                                                       |
| ---------------- | ----------- | ------------------------------------------------------------------------------------------------- |
| `token`          | `address`   | The address of the token to check for fee on transfer                                             |
| `baseTokens`     | `address[]` | The addresses of the tokens to try pairing with token when looking for a pool to flash loan from. |
| `amountToBorrow` | `uint256`   | The amount to try flash borrowing from the pools                                                  |

**Returns**

| Name     | Type     | Description             |
| -------- | -------- | ----------------------- |
| `<none>` | `Status` | The status of the token |

#### batchValidate <a href="#batchvalidate" id="batchvalidate"></a>

Validates each token by detecting if its transferable or takes a fee on transfer

```solidity
function batchValidate(address[] calldata tokens, address[] calldata baseTokens, uint256 amountToBorrow)
    external
    returns (Status[] memory);
```

**Parameters**

| Name             | Type        | Description                                                                                       |
| ---------------- | ----------- | ------------------------------------------------------------------------------------------------- |
| `tokens`         | `address[]` | The addresses of the tokens to check for fee on transfer                                          |
| `baseTokens`     | `address[]` | The addresses of the tokens to try pairing with token when looking for a pool to flash loan from. |
| `amountToBorrow` | `uint256`   | The amount to try flash borrowing from the pools                                                  |

**Returns**

| Name     | Type       | Description             |
| -------- | ---------- | ----------------------- |
| `<none>` | `Status[]` | The status of the token |

### Enums <a href="#enums" id="enums"></a>

#### Status <a href="#status" id="status"></a>

```solidity
enum Status {
    UNKN,
    FOT,
    STF
}
```


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