SentinelList

A library for linked lists in Solidity

The library comes with linked lists in different flavors:

• SentinelList: A linked list for addresses
• SentinelList4337: An ERC-4337 compliant linked list for addresses
• SentinelListBytes32: A linked list for bytes32

Using the library

In a contract, you can use the SentinelList library to store a linked list of addresses:

import {SentinelListLib} from "sentinellist/SentinelList.sol";

contract Example {
    using SentinelListLib for SentinelListLib.SentinelList;

    // Declare a variable to store the data
    // Note: this can also be in a mapping or other data structure
    SentinelListLib.SentinelList list;

    function set(address newAddress) external {
        // Store the data
        list.push(newAddress);
    }

    function get(uint256 size) external view returns (address[] memory addressArray) {
        // Retrieve the data
        (addressArray,) = list.getEntriesPaginated(SENTINEL, size);
    }
}

Available functions

SentinelListLib

• init(SentinelList storage self): Initialize the list (required before using the list and will revert if the list is already initialized)
• alreadyInitialized(SentinelList storage self): Check if the list is already initialized
• getNext(SentinelList storage self, address entry): Get the next entry in the list
• push(SentinelList storage self, address newEntry): Add a new entry to the list
• pop(SentinelList storage self, address prevEntry, address popEntry): Remove an entry from the list
• popAll(SentinelList storage self): Remove all entries from the list
• contains(SentinelList storage self, address entry): Check if an entry is in the list
• getEntriesPaginated(SentinelList storage self, address start, uint256 size): Get a paginated list of entries from start with a maximum of size entries

SentinelList4337Lib

• init(SentinelList storage self, address account): Initialize the list (required before using the list and will revert if the list is already initialized)
• alreadyInitialized(SentinelList storage self, address account): Check if the list is already initialized
• getNext(SentinelList storage self, address account, address entry): Get the next entry in the list
• push(SentinelList storage self, address account, address newEntry): Add a new entry to the list
• pop(SentinelList storage self, address account, address prevEntry, address popEntry): Remove an entry from the list
• popAll(SentinelList storage self, address account): Remove all entries from the list
• contains(SentinelList storage self, address account, address entry): Check if an entry is in the list
• getEntriesPaginated(SentinelList storage self, address account, address start, uint256 size): Get a paginated list of entries from start with a maximum of size entries

LinkedBytes32Lib

• init(LinkedBytes32 storage self): Initialize the list (required before using the list and will revert if the list is already initialized)
• alreadyInitialized(LinkedBytes32 storage self): Check if the list is already initialized
• getNext(LinkedBytes32 storage self, bytes32 entry): Get the next entry in the list
• push(LinkedBytes32 storage self, bytes32 newEntry): Add a new entry to the list
• pop(LinkedBytes32 storage self, bytes32 prevEntry, bytes32 popEntry): Remove an entry from the list
• popAll(LinkedBytes32 storage self): Remove all entries from the list
• contains(LinkedBytes32 storage self, bytes32 entry): Check if an entry is in the list
• getEntriesPaginated(LinkedBytes32 storage self, bytes32 start, uint256 size): Get a paginated list of entries from start with a maximum of size entries

Using this repo

To install the dependencies, run:

forge install

To build the project, run:

forge build

To run the tests, run:

forge test

Contributing

For feature or change requests, feel free to open a PR, start a discussion or get in touch with us.

Credits

• Safe and Richard: For the initial implementation in the Safe Smart Account