探索如何在武汉链（基于ETH）的一个合约中实现同质化与非同质化功能区块链

id:BSN_2021
公众号：BSN研习社

目标：跟大家一块去研究下1155标准中提供的案例章节流程：核心文件核心方法汇总

在eip-1155中看到如下图所示一段内容，并提供了一个案例，因此今天跟大家去研究一下内部的实现细节。

文章图片

一、核心文件
其主要涉及两个文件ERC1155MixedFungibleMintable.sol和ERC1155MixedFungible .sol，如下：
文件ERC1155MixedFungible .sol内容如下：

pragma solidity ^0.5.0; import "./ERC1155.sol"; /** @dev Extension to ERC1155 for Mixed Fungible and Non-Fungible Items support The main benefit is sharing of common type information, just like you do when creating a fungible id. */ contract ERC1155MixedFungible is ERC1155 {// Use a split bit implementation. Store the type in the upper 128 bits.. // 十进制：115792089237316195423570985008687907852929702298719625575994209400481361428480 // 十六进制：ffffffffffffffffffffffffffffffff00000000000000000000000000000000 // 二进制： // 11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 // 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 uint256 public constant TYPE_MASK = uint256(uint128(~0)) << 128; // ..and the non-fungible index in the lower 128 // 十进制:340282366920938463463374607431768211455 // 十六进制:ffffffffffffffffffffffffffffffff // 二进制: // 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 // 11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 uint256 public constant NF_INDEX_MASK = uint128(~0); // The top bit is a flag to tell if this is a NFI. // 十进制: 57896044618658097711785492504343953926634992332820282019728792003956564819968 // 十六进制: 8000000000000000000000000000000000000000000000000000000000000000 // 二进制: // 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 // 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 uint256 public constant TYPE_NF_BIT = 1 << 255; mapping (uint256 => address) nfOwners; // Only to make code clearer. Should not be functions function isNonFungible(uint256 _id) public pure returns(bool) { return _id & TYPE_NF_BIT == TYPE_NF_BIT; } function isFungible(uint256 _id) public pure returns(bool) { return _id & TYPE_NF_BIT == 0; } function getNonFungibleIndex(uint256 _id) public pure returns(uint256) { return _id & NF_INDEX_MASK; } function getNonFungibleBaseType(uint256 _id) public pure returns(uint256) { return _id & TYPE_MASK; } function isNonFungibleBaseType(uint256 _id) public pure returns(bool) { // A base type has the NF bit but does not have an index. return (_id & TYPE_NF_BIT == TYPE_NF_BIT) && (_id & NF_INDEX_MASK == 0); } function isNonFungibleItem(uint256 _id) public pure returns(bool) { // A base type has the NF bit but does has an index. return (_id & TYPE_NF_BIT == TYPE_NF_BIT) && (_id & NF_INDEX_MASK != 0); } function ownerOf(uint256 _id) public view returns (address) { return nfOwners[_id]; }// override function safeTransferFrom(address _from, address _to, uint256 _id, uint256 _value, bytes calldata _data) external {require(_to != address(0x0), "cannot send to zero address"); require(_from == msg.sender || operatorApproval[_from][msg.sender] == true, "Need operator approval for 3rd party transfers."); if (isNonFungible(_id)) { require(nfOwners[_id] == _from); nfOwners[_id] = _to; // You could keep balance of NF type in base type id like so: // uint256 baseType = getNonFungibleBaseType(_id); // balances[baseType][_from] = balances[baseType][_from].sub(_value); // balances[baseType][_to]= balances[baseType][_to].add(_value); } else { balances[_id][_from] = balances[_id][_from].sub(_value); balances[_id][_to]= balances[_id][_to].add(_value); }emit TransferSingle(msg.sender, _from, _to, _id, _value); if (_to.isContract()) { _doSafeTransferAcceptanceCheck(msg.sender, _from, _to, _id, _value, _data); } }// override function safeBatchTransferFrom(address _from, address _to, uint256[] calldata _ids, uint256[] calldata _values, bytes calldata _data) external {require(_to != address(0x0), "cannot send to zero address"); require(_ids.length == _values.length, "Array length must match"); // Only supporting a global operator approval allows us to do only 1 check and not to touch storage to handle allowances. require(_from == msg.sender || operatorApproval[_from][msg.sender] == true, "Need operator approval for 3rd party transfers."); for (uint256 i = 0; i < _ids.length; ++i) { // Cache value to local variable to reduce read costs. uint256 id = _ids[i]; uint256 value = https://www.it610.com/article/_values[i]; if (isNonFungible(id)) { require(nfOwners[id] == _from); nfOwners[id] = _to; } else { balances[id][_from] = balances[id][_from].sub(value); balances[id][_to]= value.add(balances[id][_to]); } }emit TransferBatch(msg.sender, _from, _to, _ids, _values); if (_to.isContract()) { _doSafeBatchTransferAcceptanceCheck(msg.sender, _from, _to, _ids, _values, _data); } }function balanceOf(address _owner, uint256 _id) external view returns (uint256) { if (isNonFungibleItem(_id)) return nfOwners[_id] == _owner ? 1 : 0; return balances[_id][_owner]; }function balanceOfBatch(address[] calldata _owners, uint256[] calldata _ids) external view returns (uint256[] memory) {require(_owners.length == _ids.length); uint256[] memory balances_ = new uint256[](_owners.length); for (uint256 i = 0; i < _owners.length; ++i) { uint256 id = _ids[i]; if (isNonFungibleItem(id)) { balances_[i] = nfOwners[id] == _owners[i] ? 1 : 0; } else { balances_[i] = balances[id][_owners[i]]; } }return balances_; } }

2.文件ERC1155MixedFungibleMintable.sol内容如下：

pragma solidity ^0.5.0; import "./ERC1155MixedFungible.sol"; /** @dev Mintable form of ERC1155 Shows how easy it is to mint new items */ contract ERC1155MixedFungibleMintable is ERC1155MixedFungible {uint256 nonce; mapping (uint256 => address) public creators; mapping (uint256 => uint256) public maxIndex; modifier creatorOnly(uint256 _id) { require(creators[_id] == msg.sender); _; }// This function only creates the type. function create( string calldata _uri, bool_isNF) external returns(uint256 _type) {// Store the type in the upper 128 bits _type = (++nonce << 128); // Set a flag if this is an NFI. if (_isNF) _type = _type | TYPE_NF_BIT; // This will allow restricted access to creators. creators[_type] = msg.sender; // emit a Transfer event with Create semantic to help with discovery. emit TransferSingle(msg.sender, address(0x0), address(0x0), _type, 0); if (bytes(_uri).length > 0) emit URI(_uri, _type); }function mintNonFungible(uint256 _type, address[] calldata _to) external creatorOnly(_type) {// No need to check this is a nf type rather than an id since // creatorOnly() will only let a type pass through. require(isNonFungible(_type)); // Index are 1-based. uint256 index = maxIndex[_type] + 1; maxIndex[_type] = _to.length.add(maxIndex[_type]); for (uint256 i = 0; i < _to.length; ++i) { address dst = _to[i]; uint256 id= _type | index + i; nfOwners[id] = dst; // You could use base-type id to store NF type balances if you wish. // balances[_type][dst] = quantity.add(balances[_type][dst]); emit TransferSingle(msg.sender, address(0x0), dst, id, 1); if (dst.isContract()) { _doSafeTransferAcceptanceCheck(msg.sender, msg.sender, dst, id, 1, ''); } } }function mintFungible(uint256 _id, address[] calldata _to, uint256[] calldata _quantities) external creatorOnly(_id) {require(isFungible(_id)); for (uint256 i = 0; i < _to.length; ++i) {address to = _to[i]; uint256 quantity = _quantities[i]; // Grant the items to the caller balances[_id][to] = quantity.add(balances[_id][to]); // Emit the Transfer/Mint event. // the 0x0 source address implies a mint // It will also provide the circulating supply info. emit TransferSingle(msg.sender, address(0x0), to, _id, quantity); if (to.isContract()) { _doSafeTransferAcceptanceCheck(msg.sender, msg.sender, to, _id, quantity, ''); } } } }

二、核心方法
先看一下几个内置的状态变量，如下：
TYPE_NF_BIT= 100xxx000 000xxx000
TYPE_MASK= 111xxx111 000xxx000
NF_INDEX_MASK=000xxx000 111xxx111
【探索如何在武汉链（基于ETH）的一个合约中实现同质化与非同质化功能】主要的几个方法，详解如下：
创建类型 create(string calldata _uri,bool _isNF)：
关键逻辑：首先，通过nonce自增然后左移128位生成_type 类别唯一标识（tokenid）。接下来，判断是否是非同质化，是则与TYPE_NF_BIT按位或（注：其结果最高位标识为1开头），否则直接返回_type。
示例：前128位，后128位。
nft_type：100xxx001 000xxx000；
ft_type: 000xxx001 000xxx000；
铸造非同质化 mintNonFungible(uint256 _type, address[] calldata _to)
关键逻辑：首先，要求_type符合非同质化条件，即判断_type按位与TYPE_NF_BIT是否等于TYPE_NF_BIT。接下来，获取最新的索引值index，然后根据规则（将_type与index+i按位或）生成唯一标识，并与对应的address进行映射。
示例：
非同质化条件：100xxx001 000xxx000 & TYPE_NF_BIT == TYPE_NF_BIT ；
生成tokenId的规则：id = _type | index +i。即 100xxx001 000xxx000 | 001 => 100xxx001 000xxx001 ；
铸造同质化mintFungible(uint256 _id, address[] calldata _to, uint256[] calldata _quantities)
关键逻辑：首先，要求符合同质化条件，即判断_type按位与TYPE_NF_BIT是否等于0；接下来，计算最新的数量，并与对应的address进行映射。
示例：
同质化条件：000xxx001 000xxx000 & TYPE_NF_BIT == 0；
转移 safeTransferFrom(address _from, address _to, uint256 _id, uint256 _value, bytes calldata _data)
关键逻辑：根据_id判断是否是非同质化标识，即判断_type按位与TYPE_NF_BIT是否等于TYPE_NF_BIT，然后返回对应的结果。
获取余额balanceOf(address _owner, uint256 _id) external view returns (uint256)
关键逻辑：根据_id判断是否是非同质化标识，即判断_id按位与TYPE_NF_BIT是否等于TYPE_NF_BIT，并且_id按位与NF_INDEX_MASK 等于零。然后返回对应的结果。注：非同质化的数量为0或1；
三、汇总
关键的几个方法看完后，可以发现技术上没有太大的难度，主要是运用了标识位拆分（Split ID bits）以及位运算进行巧妙的设计。即将tokenid uint256分为两部分（前128位和后128位）。当非同质化时前128位标识类型，后面128为代表索引或id，即。当同质化时前128位标识id，后128位为零，即；
通俗点的来说，当调用create方法时，非同质化生成的为类别（或系列）标识，然后再生成该类别下的唯一标识，即nf-tokenID。同质化生成的即为唯一标识,即f-tokenID。
引用资源地址：
https://eips.ethereum.org/EIP...
https://github.com/enjin/erc-...