NFT/ 数字藏品开发逻辑，NFT/ 数字藏品系统开发源码实例

　数字藏品（Non-fungible toke）即非同质化代币，是指使用区块链技术，对应特定的作品、艺术品生成的唯一数字凭证，在保护其数字版权的基础上，实现真实可信的数字化发行、购买、收藏和使用。每个 NFT 商品都是唯一的，承载了独特的数字资产价值。

　　数字藏品为数字出版物的一种新形态，并分为区块链作品版权和区块链数字出版产品两种产品类型。

　　///inheritdoc IUniswapV3Factory

　　function enableFeeAmount(uint24 fee,int24 tickSpacing)public override{

　　require(msg.sender==owner);

　　require(fee<1000000);

　　//tick spacing is capped at 16384 to prevent the situation where tickSpacing is so large that

　　//TickBitmap#nextInitializedTickWithinOneWord overflows int24 container from a valid tick

　　//16384 ticks represents a>5x price change with ticks of 1 bips

　　require(tickSpacing>0&&tickSpacing<16384);

　　require(feeAmountTickSpacing[fee]==0);

　　feeAmountTickSpacing[fee]=tickSpacing;

　　emit FeeAmountEnabled(fee,tickSpacing);

　　}

　　using LowGasSafeMath for uint256;

　　using LowGasSafeMath for int256;

　　using SafeCast for uint256;

　　using SafeCast for int256;

　　using Tick for mapping(int24=>Tick.Info);

　　using TickBitmap for mapping(int16=>uint256);

　　using Position for mapping(bytes32=>Position.Info);

　　using Position for Position.Info;

　　using Oracle for Oracle.Observation[65535];

　　///inheritdoc IUniswapV3PoolImmutables

　　address public immutable override factory;

　　///inheritdoc IUniswapV3PoolImmutables

　　address public immutable override token0;

　　///inheritdoc IUniswapV3PoolImmutables

　　address public immutable override token1;

　　///inheritdoc IUniswapV3PoolImmutables

　　uint24 public immutable override fee;

　　///inheritdoc IUniswapV3PoolImmutables

　　int24 public immutable override tickSpacing;//刻度间隔

　　///inheritdoc IUniswapV3PoolImmutables

　　uint128 public immutable override maxLiquidityPerTick;//可使用范围内任何刻度的头寸流动性的最大金额

　　struct Slot0{　　//the current price

　　uint160 sqrtPriceX96;

　　//the current tick

　　int24 tick;

　　//the most-recently updated index of the observations array

　　uint16 observationIndex;

　　//the current maximum number of observations that are being stored

　　uint16 observationCardinality;

　　//the next maximum number of observations to store,triggered in observations.write

　　uint16 observationCardinalityNext;

　　//the current protocol fee as a percentage of the swap fee taken on withdrawal

　　//represented as an integer denominator(1/x)%

　　uint8 feeProtocol;

　　//whether the pool is locked

　　bool unlocked;

　　}

　　///inheritdoc IUniswapV3PoolState

　　Slot0 public override slot0;