ERC-7540: Asynchronous ERC-4626 Tokenized Vaults

contracts/interfaces/IERC7540.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.20;
+
+import {IERC4626} from "../interfaces/IERC4626.sol";
+
+/**
+ * @dev Interface for the ERC-7540 Asynchronous Tokenized Vaults standard.
+ * https://eips.ethereum.org/EIPS/eip-7540[ERC-7540]
+ */
+interface IERC7540 is IERC4626 {
+    struct Request {
+        uint256 amount;
+        uint256 claimable;
+    }
+
+    // Events
+    event DepositRequest(
+        address indexed controller,
+        address indexed owner,
+        uint256 indexed requestId,
+        address sender,
+        uint256 assets
+    );
+
+    event RedeemRequest(
+        address indexed controller,
+        address indexed owner,
+        uint256 indexed requestId,
+        address sender,
+        uint256 shares
+    );
+
+    event OperatorSet(address indexed controller, address indexed operator, bool approved);
+
+    event DepositProcessed(address indexed controller, uint256 indexed requestId, uint256 amount);
+
+    event RedeemProcessed(address indexed controller, uint256 indexed requestId, uint256 amount);
+
+    // Methods
+
+    /**
+     * @dev Initiates a deposit request.
+     * @param assets The amount of assets to deposit.
+     * @param controller The address of the controller managing the request.
+     * @param owner The owner of the assets.
+     * @return requestId The unique identifier for this deposit request.
+     */
+    function requestDeposit(uint256 assets, address controller, address owner) external returns (uint256 requestId);
+
+    /**
+     * @dev Initiates a redeem request.
+     * @param shares The amount of shares to redeem.
+     * @param controller The address of the controller managing the request.
+     * @param owner The owner of the shares.
+     * @return requestId The unique identifier for this redeem request.
+     */
+    function requestRedeem(uint256 shares, address controller, address owner) external returns (uint256 requestId);
+
+    /**
+     * @dev Gets the pending deposit request amount for a given controller and requestId.
+     * @param requestId The unique identifier for the request.
+     * @param controller The address of the controller.
+     * @return assets The amount of assets in the pending state.
+     */
+    function pendingDepositRequest(uint256 requestId, address controller) external view returns (uint256 assets);
+
+    /**
+     * @dev Gets the pending redeem request amount for a given controller and requestId.
+     * @param requestId The unique identifier for the request.
+     * @param controller The address of the controller.
+     * @return shares The amount of shares in the pending state.
+     */
+    function pendingRedeemRequest(uint256 requestId, address controller) external view returns (uint256 shares);
+
+    /**
+     * @dev Gets the claimable deposit request amount for a given controller and requestId.
+     * @param requestId The unique identifier for the request.
+     * @param controller The address of the controller.
+     * @return assets The amount of assets in the claimable state.
+     */
+    function claimableDepositRequest(uint256 requestId, address controller) external view returns (uint256 assets);
+
+    /**
+     * @dev Gets the claimable redeem request amount for a given controller and requestId.
+     * @param requestId The unique identifier for the request.
+     * @param controller The address of the controller.
+     * @return shares The amount of shares in the claimable state.
+     */
+    function claimableRedeemRequest(uint256 requestId, address controller) external view returns (uint256 shares);
+
+    /**
+     * @dev Sets or revokes an operator for the given controller.
+     * @param operator The address of the operator.
+     * @param approved The approval status of the operator.
+     * @return success Whether the operation was successful.
+     */
+    function setOperator(address operator, bool approved) external returns (bool success);
+
+    /**
+     * @dev Checks if an operator is approved for a controller.
+     * @param controller The address of the controller.
+     * @param operator The address of the operator.
+     * @return status Whether the operator is approved.
+     */
+    function isOperator(address controller, address operator) external view returns (bool status);
+
+    /**
+     * @dev Gets the details of a pending deposit request.
+     * @param controller The address of the controller.
+     * @param requestId The unique identifier for the deposit request.
+     * @return request The request object containing amount and claimable details.
+     */
+    function getPendingDepositRequest(
+        address controller,
+        uint256 requestId
+    ) external view returns (Request memory request);
+
+    /**
+     * @dev Gets the details of a pending redeem request.
+     * @param controller The address of the controller.
+     * @param requestId The unique identifier for the redeem request.
+     * @return request The request object containing amount and claimable details.
+     */
+    function getPendingRedeemRequest(
+        address controller,
+        uint256 requestId
+    ) external view returns (Request memory request);
+
+    /**
+     * @dev Gets the status of an operator for a given controller.
+     * @param controller The address of the controller.
+     * @param operator The address of the operator.
+     * @return status Whether the operator is approved.
+     */
+    function getOperator(address controller, address operator) external view returns (bool status);
+}

contracts/mocks/docs/ERC7540Fees.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.20;
+
+import {IERC4626} from "../../interfaces/IERC4626.sol";
+import {IERC20} from "../../token/ERC20/IERC20.sol";
+import {ERC7540} from "../../token/ERC20/extensions/ERC7540.sol";
+import {ERC4626} from "../../token/ERC20/extensions/ERC4626.sol";
+import {SafeERC20} from "../../token/ERC20/utils/SafeERC20.sol";
+import {Math} from "../../utils/math/Math.sol";
+
+/**
+ * @dev ERC-7540 vault with entry/exit fees expressed in basis points.
+ *
+ * NOTE: This contract charges fees in terms of assets, not shares. The fees are calculated
+ * based on the amount of assets being deposited or withdrawn, not the shares being minted or redeemed.
+ * This is an opinionated design decision that should be taken into account when integrating.
+ *
+ * WARNING: This contract is for demonstration purposes and has not been audited. Use it with caution.
+ */
+abstract contract ERC7540Fees is ERC7540 {
+    using SafeERC20 for IERC20;
+    using Math for uint256;
+
+    uint256 private constant _BASIS_POINT_SCALE = 1e4;
+
+    function previewDeposit(uint256 assets) public view virtual override(ERC4626, IERC4626) returns (uint256) {
+        uint256 fee = _feeOnTotal(assets, _entryFeeBasisPoints());
+        return super.previewDeposit(assets - fee);
+    }
+
+    function previewRedeem(uint256 shares) public view virtual override(ERC4626, IERC4626) returns (uint256) {
+        uint256 assets = super.previewRedeem(shares);
+        uint256 fee = _feeOnTotal(assets, _exitFeeBasisPoints());
+        return assets - fee;
+    }
+
+    function _deposit(address caller, address receiver, uint256 assets, uint256 shares) internal virtual override {
+        uint256 fee = _feeOnTotal(assets, _entryFeeBasisPoints());
+        address recipient = _entryFeeRecipient();
+
+        super._deposit(caller, receiver, assets - fee, shares);
+
+        if (fee > 0 && recipient != address(this)) {
+            IERC20(asset()).safeTransfer(recipient, fee);
+        }
+    }
+
+    function _withdraw(
+        address caller,
+        address receiver,
+        address owner,
+        uint256 assets,
+        uint256 shares
+    ) internal virtual override {
+        uint256 fee = _feeOnRaw(assets, _exitFeeBasisPoints());
+        address recipient = _exitFeeRecipient();
+
+        super._withdraw(caller, receiver, owner, assets - fee, shares);
+
+        if (fee > 0 && recipient != address(this)) {
+            IERC20(asset()).safeTransfer(recipient, fee);
+        }
+    }
+
+    function _entryFeeBasisPoints() internal view virtual returns (uint256) {
+        return 0; // replace with e.g. 100 for 1%
+    }
+
+    function _exitFeeBasisPoints() internal view virtual returns (uint256) {
+        return 0; // replace with e.g. 100 for 1%
+    }
+
+    function _entryFeeRecipient() internal view virtual returns (address) {
+        return address(0); // replace with e.g. a treasury address
+    }
+
+    function _exitFeeRecipient() internal view virtual returns (address) {
+        return address(0); // replace with e.g. a treasury address
+    }
+
+    function _feeOnRaw(uint256 assets, uint256 feeBasisPoints) private pure returns (uint256) {
+        return assets.mulDiv(feeBasisPoints, _BASIS_POINT_SCALE, Math.Rounding.Ceil);
+    }
+
+    function _feeOnTotal(uint256 assets, uint256 feeBasisPoints) private pure returns (uint256) {
+        return assets.mulDiv(feeBasisPoints, feeBasisPoints + _BASIS_POINT_SCALE, Math.Rounding.Ceil);
+    }
+}

contracts/mocks/token/ERC7540FeesMock.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.20;
+
+import {ERC7540Fees} from "../docs/ERC7540Fees.sol";
+import {ERC7540} from "../../token/ERC20/extensions/ERC7540.sol";
+import {IERC20} from "../../token/ERC20/IERC20.sol";
+
+abstract contract ERC7540FeesMock is ERC7540Fees {
+    uint256 private immutable _entryFeeBasisPointValue;
+    address private immutable _entryFeeRecipientValue;
+    uint256 private immutable _exitFeeBasisPointValue;
+    address private immutable _exitFeeRecipientValue;
+
+    constructor(
+        IERC20 asset,
+        uint256 entryFeeBasisPoints,
+        address entryFeeRecipient,
+        uint256 exitFeeBasisPoints,
+        address exitFeeRecipient
+    ) ERC7540(asset) {
+        _entryFeeBasisPointValue = entryFeeBasisPoints;
+        _entryFeeRecipientValue = entryFeeRecipient;
+        _exitFeeBasisPointValue = exitFeeBasisPoints;
+        _exitFeeRecipientValue = exitFeeRecipient;
+    }
+
+    function _entryFeeBasisPoints() internal view virtual override returns (uint256) {
+        return _entryFeeBasisPointValue;
+    }
+
+    function _entryFeeRecipient() internal view virtual override returns (address) {
+        return _entryFeeRecipientValue;
+    }
+
+    function _exitFeeBasisPoints() internal view virtual override returns (uint256) {
+        return _exitFeeBasisPointValue;
+    }
+
+    function _exitFeeRecipient() internal view virtual override returns (address) {
+        return _exitFeeRecipientValue;
+    }
+}

contracts/mocks/token/ERC7540LimitsMock.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.20;
+
+import {IERC20} from "../../token/ERC20/IERC20.sol";
+import {IERC4626} from "../../interfaces/IERC4626.sol";
+import {ERC7540} from "../../token/ERC20/extensions/ERC7540.sol";
+import {ERC4626} from "../../token/ERC20/extensions/ERC4626.sol";
+
+abstract contract ERC7540LimitsMock is ERC7540 {
+    uint256 private immutable _maxDeposit;
+    uint256 private immutable _maxMint;
+
+    constructor(IERC20 asset, uint256 maxDepositValue, uint256 maxMintValue) ERC7540(asset) {
+        _maxDeposit = maxDepositValue;
+        _maxMint = maxMintValue;
+    }
+
+    function maxDeposit(address) public view override(IERC4626, ERC4626) returns (uint256) {
+        return _maxDeposit;
+    }
+
+    function maxMint(address) public view override(IERC4626, ERC4626) returns (uint256) {
+        return _maxMint;
+    }
+}

contracts/mocks/token/ERC7540Mock.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.20;
+
+import {IERC20} from "../../token/ERC20/IERC20.sol";
+import {ERC20} from "../../token/ERC20/ERC20.sol";
+import {ERC7540} from "../../token/ERC20/extensions/ERC7540.sol";
+import {ERC4626} from "../../token/ERC20/extensions/ERC4626.sol";
+
+contract ERC7540Mock is ERC7540 {
+    constructor(IERC20 asset) ERC20("ERC4626Mock", "E4626M") ERC7540(asset) {}
+
+    function processPendingDeposit(uint256 requestId, address controller) external view {
+        Request memory request = getPendingDepositRequest(controller, requestId);
+        require(request.amount > 0, "No pending deposit request");
+
+        request.claimable += request.amount;
+        request.amount = 0;
+    }
+
+    function processPendingRedeem(uint256 requestId, address controller) external view {
+        Request memory request = getPendingRedeemRequest(controller, requestId);
+        require(request.amount > 0, "No pending redeem request");
+
+        request.claimable += request.amount;
+        request.amount = 0;
+    }
+
+    function _processPendingRequests(uint256 requestId, address controller) internal override {
+        Request memory depositRequest = getPendingDepositRequest(controller, requestId);
+        if (depositRequest.amount > 0) {
+            depositRequest.claimable += depositRequest.amount;
+            emit DepositProcessed(controller, requestId, depositRequest.amount);
+            depositRequest.amount = 0;
+        }
+
+        Request memory redeemRequest = getPendingRedeemRequest(controller, requestId);
+        if (redeemRequest.amount > 0) {
+            redeemRequest.claimable += redeemRequest.amount;
+            emit RedeemProcessed(controller, requestId, redeemRequest.amount);
+            redeemRequest.amount = 0;
+        }
+    }
+}

contracts/mocks/token/ERC7540OffsetMock.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.20;
+
+import {IERC20} from "../../token/ERC20/IERC20.sol";
+import {ERC7540} from "../../token/ERC20/extensions/ERC7540.sol";
+
+abstract contract ERC7540OffsetMock is ERC7540 {
+    uint8 private immutable _offset;
+
+    constructor(IERC20 asset, uint8 offset) ERC7540(asset) {
+        _offset = offset;
+    }
+
+    function _decimalsOffset() internal view override returns (uint8) {
+        return _offset;
+    }
+}