[UniswapV2] UniswapV2Factory.sol

Variables

feeTo

Accumulate liquidity token for protocol fee.

feeToSetter

Address that can change the feeTo .

getPair

To get the address of exchange pairs. Ex: getPair[<tokenA address>][<tokenB address>] .

allPairs

Array of exchange pairs created by this factory.

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Functions

createPair

1. Get consistent order of token addresses.
   

   (address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
   

2. Check if address of pair is zero. It means that there is not existing pool for token0 & token1 .
   

   require(getPair[token0][token1] == address(0), 'UniswapV2: PAIR_EXISTS'); // single check is sufficient
   

3. Initialize the pair of token0 and token . Add pair to the allPairs array.
   

   IUniswapV2Pair(pair).initialize(token0, token1);
           getPair[token0][token1] = pair;
           getPair[token1][token0] = pair; // populate mapping in the reverse direction
           allPairs.push(pair);
           emit PairCreated(token0, token1, pair, allPairs.length);
   

setFeeTo & setFeeToSetter

If msg.sender is feeToSetter , we can change and control the feeTo .