openzeppelin-contracts/contracts/utils/SlotDerivation.sol

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (utils/SlotDerivation.sol)
// This file was procedurally generated from scripts/generate/templates/SlotDerivation.js.

pragma solidity ^0.8.20;

/**
 * @dev Library for computing storage (and transient storage) locations from namespaces and deriving slots
 * corresponding to standard patterns. The derivation method for array and mapping matches the storage layout used by
 * the solidity language / compiler.
 *
 * See https://docs.soliditylang.org/en/v0.8.20/internals/layout_in_storage.html#mappings-and-dynamic-arrays[Solidity docs for mappings and dynamic arrays.].
 *
 * Example usage:
 * ```solidity
 * contract Example {
 *     // Add the library methods
 *     using StorageSlot for bytes32;
 *     using SlotDerivation for bytes32;
 *
 *     // Declare a namespace
 *     string private constant _NAMESPACE = "<namespace>" // eg. OpenZeppelin.Slot
 *
 *     function setValueInNamespace(uint256 key, address newValue) internal {
 *         _NAMESPACE.erc7201Slot().deriveMapping(key).getAddressSlot().value = newValue;
 *     }
 *
 *     function getValueInNamespace(uint256 key) internal view returns (address) {
 *         return _NAMESPACE.erc7201Slot().deriveMapping(key).getAddressSlot().value;
 *     }
 * }
 * ```
 *
 * TIP: Consider using this library along with {StorageSlot}.
 *
 * NOTE: This library provides a way to manipulate storage locations in a non-standard way. Tooling for checking
 * upgrade safety will ignore the slots accessed through this library.
 *
 * _Available since v5.1._
 */
library SlotDerivation {
    /**
     * @dev Derive an ERC-7201 slot from a string (namespace).
     */
    function erc7201Slot(string memory namespace) internal pure returns (bytes32 slot) {
        assembly ("memory-safe") {
            mstore(0x00, sub(keccak256(add(namespace, 0x20), mload(namespace)), 1))
            slot := and(keccak256(0x00, 0x20), not(0xff))
        }
    }

    /**
     * @dev Add an offset to a slot to get the n-th element of a structure or an array.
     */
    function offset(bytes32 slot, uint256 pos) internal pure returns (bytes32 result) {
        unchecked {
            return bytes32(uint256(slot) + pos);
        }
    }

    /**
     * @dev Derive the location of the first element in an array from the slot where the length is stored.
     */
    function deriveArray(bytes32 slot) internal pure returns (bytes32 result) {
        assembly ("memory-safe") {
            mstore(0x00, slot)
            result := keccak256(0x00, 0x20)
        }
    }

    /**
     * @dev Derive the location of a mapping element from the key.
     */
    function deriveMapping(bytes32 slot, address key) internal pure returns (bytes32 result) {
        assembly ("memory-safe") {
            mstore(0x00, and(key, shr(96, not(0))))
            mstore(0x20, slot)
            result := keccak256(0x00, 0x40)
        }
    }

    /**
     * @dev Derive the location of a mapping element from the key.
     */
    function deriveMapping(bytes32 slot, bool key) internal pure returns (bytes32 result) {
        assembly ("memory-safe") {
            mstore(0x00, iszero(iszero(key)))
            mstore(0x20, slot)
            result := keccak256(0x00, 0x40)
        }
    }

    /**
     * @dev Derive the location of a mapping element from the key.
     */
    function deriveMapping(bytes32 slot, bytes32 key) internal pure returns (bytes32 result) {
        assembly ("memory-safe") {
            mstore(0x00, key)
            mstore(0x20, slot)
            result := keccak256(0x00, 0x40)
        }
    }

    /**
     * @dev Derive the location of a mapping element from the key.
     */
    function deriveMapping(bytes32 slot, uint256 key) internal pure returns (bytes32 result) {
        assembly ("memory-safe") {
            mstore(0x00, key)
            mstore(0x20, slot)
            result := keccak256(0x00, 0x40)
        }
    }

    /**
     * @dev Derive the location of a mapping element from the key.
     */
    function deriveMapping(bytes32 slot, int256 key) internal pure returns (bytes32 result) {
        assembly ("memory-safe") {
            mstore(0x00, key)
            mstore(0x20, slot)
            result := keccak256(0x00, 0x40)
        }
    }

    /**
     * @dev Derive the location of a mapping element from the key.
     */
    function deriveMapping(bytes32 slot, string memory key) internal pure returns (bytes32 result) {
        assembly ("memory-safe") {
            let length := mload(key)
            let begin := add(key, 0x20)
            let end := add(begin, length)
            let cache := mload(end)
            mstore(end, slot)
            result := keccak256(begin, add(length, 0x20))
            mstore(end, cache)
        }
    }

    /**
     * @dev Derive the location of a mapping element from the key.
     */
    function deriveMapping(bytes32 slot, bytes memory key) internal pure returns (bytes32 result) {
        assembly ("memory-safe") {
            let length := mload(key)
            let begin := add(key, 0x20)
            let end := add(begin, length)
            let cache := mload(end)
            mstore(end, slot)
            result := keccak256(begin, add(length, 0x20))
            mstore(end, cache)
        }
    }
}