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…vert (#362)

* Default protocol fees to 0 if protocolFeeController reverts

* snapshots

* fix comment

* add another malicious contract

* remove useless var assignment

* make call and decode return in assembly

* fix typo in var assingmenet

* clean up tests

* update snapshots#

* check withdrawFee == 0 on tests too

* add test

* separate out fetchProtocolFees and checkProtocolFees

* manually revert in setProtocolFees

* Add success return value to fetchProtocolFEes

* Add test for FeeTooLarge passing on initialzie but not on setProtocolFees

* check low level call success

* clean up

* add comment

* simplify

* udpate snaps

* fix compiler warnings

* fix result type

* fix formatting

* Add more descriptive error message

* Change error name again

* Add comments

* update gas specs

* fix merge conflict t4ests

* fix tests

* Add tests for setProtocolFee with invalid controllers

* Add missing snaps

* Feedback changes

* fix initialize tests

* fix fmt

* Fix comment

* comments and revise order


Co-authored-by: Sara Reynolds <>

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Uniswap v4 Core

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

The contracts in this repo are in early stages - we are releasing the draft code now so that v4 can be built in public, with open feedback and meaningful community contribution. We expect this will be a months-long process, and we appreciate any kind of contribution, no matter how small.


If you’re interested in contributing please see our contribution guidelines! This includes instructions on how to compile using TSTORE and TLOAD opcodes in the Setup section.


A more detailed description of Uniswap v4 Core can be found in the draft of the Uniswap v4 Core Whitepaper.


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 (positive) or to the user (negative) 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.

Repository Structure

All contracts are held within the v4-core/contracts folder.

Note that helper contracts used by tests are held in the v4-core/contracts/test subfolder within the contracts folder. Any new test helper contracts should be added here, but all foundry tests are in the v4-core/test/foundry-tests folder.

    | IPoolManager.sol
    | ...
    | Position.sol
    | Pool.sol
    | ...

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

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

import {IPoolManager} from 'v4-core/contracts/interfaces/IPoolManager.sol';
import {ILockCallback} from 'v4-core/contracts/interfaces/callback/ILockCallback.sol';

contract MyContract is ILockCallback {
    IPoolManager poolManager;

    function doSomethingWithPools() {
        // this function will call `lockAcquired` below

    function lockAcquired(bytes calldata data) external returns (bytes memory) {
        // perform pool actions


The primary license for Uniswap V4 Core is the Business Source License 1.1 (BUSL-1.1), seeΒ LICENSE. Minus the following exceptions:

Each of these files states their license type.