Uniswap v4 Core

Uniswap v4 is a new automated market market protocol that provides extensibility and customizability to pools. v4-core hosts the core pool logic for creating pools and executing pool actions like swapping and providing liquidity.

Architecture

v4-core uses a singleton-style architecture, where all pool state is managed in the PoolManager.sol contract. Pool actions can be taken by acquiring a lock on the contract and implementing the lockAcquired callback to then proceed with any of the following actions on the pools:

• swap
• modifyPosition
• donate
• take
• settle
• mint

Only the net balances owed to the pool (negative) or to the user (positive) are tracked throughout the duration of a lock. This is the delta field held in the lock state. Any number of actions can be run on the pools, as long as the deltas accumulated during the lock reach 0 by the lock’s release. This lock and call style architecture gives callers maximum flexibility in integrating with the core code.

Additionally, a pool may be initialized with a hook contract, that can implement any of the following callbacks in the lifecycle of pool actions:

• {before,after}Initialize
• {before,after}ModifyPosition
• {before,after}Swap
• {before,after}Donate

Hooks may also elect to specify fees on swaps, or liquidity withdrawal. Much like the actions above, fees are implemented using callback functions.

The fee values, or callback logic, may be updated by the hooks dependent on their implementation. However which callbacks are executed on a pool, including the type of fee or lack of fee, cannot change after pool initialization.

Read a more in-depth overview of the design decisions in the working v4-whitepaper.

Repository Structure

All contracts are held within the core-next/contracts folder.

Note that helper contracts used by tests are held in the core-next/contracts/test subfolder within the contracts folder. Any new test helper contracts should be added here, but all foundry tests are in the core-next/test/foundry-tests folder.

contracts/
----interfaces/
    | IPoolManager.sol
    | ...
----libraries/
    | Position.sol
    | Pool.sol
    | ...
----test
...
PoolManager.sol
test/
----foundry-tests/

Local deployment and Usage

To utilize the contracts and deploy to a local testnet, you can install the code in your repo with forge:

forge install https://github.com/Uniswap/core-next

To integrate with the contracts, the interfaces are available to use:

import {IPoolManager} from 'core-next/contracts/interfaces/IPoolManager.sol';
import {ILockCallback} from 'core-next/contracts/interfaces/callback/ILockCallback.sol';

contract MyContract is ILockCallback {
    IPoolManager poolManager;

    function doSomethingWithPools() {
        // this function will call `lockAcquired` below
        poolManager.lock(...);
    }

    function lockAcquired(uint256 id, bytes calldata data) external returns (bytes memory) {
        // perform pool actions
        poolManager.swap(...)
    }
}

Contributing

If you’re interested in contributing please see the contribution guidelines!

License

The primary license for Uniswap V4 Core is the Business Source License 1.1 (BUSL-1.1), see LICENSE