BurnerHook

A trading tax hook. It takes a cut of every trade, manages its own liquidity and burns tokens.

• Takes a cut of every trade

  On top of the normal pool fee, it keeps a share of each trade. The fee is paid out in the same trade.

  The code that does this (beforeSwap):

  function beforeSwap(address, PoolKey calldata, SwapParams calldata params, bytes calldata)
      external
      onlyPoolManager
      returns (bytes4, BeforeSwapDelta, uint24)
  {
      bool exactIn = params.amountSpecified < 0;
      uint256 fee;
      if (exactIn && !params.zeroForOne) fee = ofGross(uint256(-params.amountSpecified));
      else if (!exactIn && params.zeroForOne) fee = ofNet(uint256(params.amountSpecified));
      burn(fee);
      return (IHooks.beforeSwap.selector, toBeforeSwapDelta(fee.toInt128(), 0), 0);
  }

• Manages its own liquidity

  It adds and removes liquidity itself, so it can own part or all of the pool.

  The code that does this (unlockCallback):

  function unlockCallback(bytes calldata data) external onlyPoolManager returns (bytes memory) {
      (address from, uint256 eth, uint256 bits, uint128 minLiquidity) =
          abi.decode(data, (address, uint256, uint256, uint128));
      PoolKey memory key = poolKey();
      (uint160 price,,,) = POOL_MANAGER.getSlot0(key.toId());
      uint128 liquidity = LiquidityAmounts.getLiquidityForAmounts(
          price, TickMath.getSqrtPriceAtTick(TICK_LOWER), TickMath.getSqrtPriceAtTick(TICK_UPPER), eth, bits
      );
      if (liquidity == 0 || liquidity < minLiquidity) revert TooLittleLiquidity();
  
      (BalanceDelta delta,) = POOL_MANAGER.modifyLiquidity(
          key,
          ModifyLiquidityParams({
              tickLower: TICK_LOWER, tickUpper: TICK_UPPER, liquidityDelta: int256(uint256(liquidity)), salt: 0
          }),
          ""
      );
      eth = (-delta.amount0()).toUint128();
      bits = (-delta.amount1()).toUint128();
      POOL_MANAGER.settle{value: eth}();
      POOL_MANAGER.sync(key.currency1);
      BITS.safeTransferFrom(from, address(POOL_MANAGER), bits);
      POOL_MANAGER.settle();
      return abi.encode(eth, bits, liquidity);
  }

• Burns tokens

  It destroys some tokens (or sends them to an address nobody controls), so there are fewer of them.

  The code that does this (beforeSwap):

  function beforeSwap(address, PoolKey calldata, SwapParams calldata params, bytes calldata)
      external
      onlyPoolManager
      returns (bytes4, BeforeSwapDelta, uint24)
  {
      bool exactIn = params.amountSpecified < 0;
      uint256 fee;
      if (exactIn && !params.zeroForOne) fee = ofGross(uint256(-params.amountSpecified));
      else if (!exactIn && params.zeroForOne) fee = ofNet(uint256(params.amountSpecified));
      burn(fee);
      return (IHooks.beforeSwap.selector, toBeforeSwapDelta(fee.toInt128(), 0), 0);
  }

• Liquidity can’t be added or removed directly

  Nobody can add or remove liquidity through Uniswap directly. Liquidity only moves through the hook’s own code.

• Only the hook creates its pools

  Nobody can create a pool with this hook directly. Pools are only created through the hook’s own code.

Who controls it: Nobody. The hook has no admin functions, and the code cannot be changed.

What do these labels mean? Based on the hook’s published code.