> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mellow.finance/llms.txt
> Use this file to discover all available pages before exploring further.

# DefaultAccessControl

### Overview

`DefaultAccessControl` contract provides a flexible role-based access control mechanism. It leverages the OpenZeppelin `AccessControlEnumerable`. The contract defines three roles —`OPERATOR`, `ADMIN_ROLE`, and `ADMIN_DELEGATE_ROLE` — each with specific permissions to control various aspects of the system.

### Key Features

* **Role Hierarchy**: Establishes a clear hierarchy of permissions through three primary roles:
  * **Admin Role**: Has the highest privileges.
  * **Admin Delegate Role**: Can manage operators.
  * **Operator Role**: Executes regular tasks but with limited authority.
* **Access Verification**: Provides methods to verify if a user meets certain permission requirements.

### Roles

* **`OPERATOR`**: A hashed identifier for the operator role.
* **`ADMIN_ROLE`**: A hashed identifier for the admin role.
* **`ADMIN_DELEGATE_ROLE`**: A hashed identifier for the admin delegate role.

### Constructor

* **`constructor(address)`**: Initializes the contract with an admin address.
  * **admin**: Address of the initial admin.
  * **Errors**:
    * `AddressZero`: Raised if the admin address is zero.

### Core Methods

1. **Role Verification**
   * `isAdmin(address)`: Checks if the sender has an admin or admin delegate role.
     * **sender**: Address to verify.
     * **Returns**: `true` if the sender is an admin or delegate, `false` otherwise.
   * `isOperator(address)`: Checks if the sender has an operator role.
     * **sender**: Address to verify.
     * **Returns**: `true` if the sender is an operator, `false` otherwise.
2. **Access Enforcement**
   * `requireAdmin(address)`: Requires the sender to be an admin or delegate.
     * **sender**: Address of the user.
     * **Errors**:
       * `Forbidden`: Raised if the sender does not have the required role.
   * `requireAtLeastOperator(address)`: Requires the sender to be at least an operator or higher.
     * **sender**: Address of the user.
     * **Errors**:
       * `Forbidden`: Raised if the sender does not have the required role.
3. **Internal Methods**
   * `_requireAdmin(address)`: Internal method for admin verification.
   * `_requireAtLeastOperator(address)`: Internal method for operator or higher verification.