> For the complete documentation index, see [llms.txt](https://docs.mellow.finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mellow.finance/resources/mellow-lrt-depreciated/validators/erc20swapvalidator.md).

# ERC20SwapValidator

### Overview

`ERC20SwapValidator` ensures that only authorized routers and tokens are used for ERC20 token swaps. It provides validation methods, mappings to track supported routers/tokens, and emits relevant events to keep track of changes.

### Key Features

* **Router and Token Support**: Controls which routers and tokens are authorized for swap operations.
* **Swap Validation**: Enforces rules for swap operations, ensuring compliance with authorized routers and tokens.
* **Error Reporting**: Raises specific errors when a swap operation fails validation.

### Error Definitions

* **InvalidLength**: Raised when the data length for a swap operation is incorrect.
* **InvalidSelector**: The function selector provided is not recognized.
* **UnsupportedToken**: The token used is not on the supported list.
* **UnsupportedRouter**: The router used is not on the supported list.

### Core Methods

1. **View Functions**
   * `isSupportedRouter(address)`: Checks if a router is supported for swaps.
   * `isSupportedToken(address)`: Checks if a token is supported for swaps.
2. **Configuration Functions**
   * `setSupportedRouter(address, bool)`: Sets a router's supported status.
   * `setSupportedToken(address, bool)`: Sets a token's supported status.
3. **Validation Function**
   * `validate(address, address, bytes)`: Validates that the swap operation complies with the rules:
     * Checks function signatures.
     * Verifies swap parameters.
     * Ensures routers and tokens are authorized.

### Events

1. **Router Updates:**
   * `ERC20SwapValidatorSetSupportedRouter(address, bool, uint256)`: Emitted when a router's support status is updated.
     * **router**: Address of the router.
     * **flag**: Boolean indicating support status.
     * **timestamp**: Timestamp of the action.
2. **Token Updates:**
   * `ERC20SwapValidatorSetSupportedToken(address, bool, uint256)`: Emitted when a token's support status is updated.
     * **token**: Address of the token.
     * **flag**: Boolean indicating support status.
     * **timestamp**: Timestamp of the action.


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