如何经过solc编译solidity编写的以太坊智能合约

时间 2019-11-13

标签如何经过 solc 编译 solidity 编写以太智能合约繁體版

原文原文链接

solc：solidity的编译器

solidity编写的以太坊智能合约可经过命令行编译工具solc来进行编译，成为以太坊虚拟机中的代码。solc编译后最终部署到链上造成咱们所见到的各类智能合约。html

做为一个solidity命令行编译工具，咱们来看看官网都怎么说solc。node

solc的安装很简单：git

npm install -g solc
//或者
npm install -g solc-cli
//或者
sudo apt-get install solc

安装完成后咱们来看，solc --help，solc --help命令显示全部的solc命令选项。编译器能够生成各类输出，好比最终的二进制合约文件、语法树的汇编或者须要预计的要花费的gas等。solc --bin sourceFile.sol，能够编译后输出一个名为sourceFile.sol的智能合约文件。若是你想从solc得到更丰富的一些输出变量，你可使用solc -o outputDirectory --bin --ast --asm sourceFile.sol。github

你在部署以太坊智能合约以前能够用solc --optimize --bin sourceFile.sol优化一下。默认状况下solc编译器会帮你优化200次。你也能够设置 --runs=1，这样就按照最小化的方式进行编译，若是你但愿屡次交易不太在意成本，那你能够设置成你想要的次数:)。mongodb

命令行编译器会自动读取须要导入的文件，也能够经过使用prefix = path来指定路径，例如：express

solc github.com/ethereum/dapp-bin/=/usr/local/lib/dapp-bin/ =/usr/local/lib/fallback file.solnpm

这样编译器就会从指定目录github.com/ethereum/dapp-bin/下的/usr/local/lib/dapp-bin/目录开始搜索，若是没有找到文件，它将查看/usr/local/lib/fallback。solc将只读取你指定的这两个路径的，所以像import "/etc/passwd";必需要经过/=从新映射才起做用。若是有多个匹配，则选择具备最长公共前缀的进行匹配。json

出于安全上的考虑，编译器限制了它能够访问的一些目录。在命令行中指定的源文件的路径（及其子目录）和命令行指定的路径外其余全部内容都会被拒绝。--allow-paths /sample/path,/another/sample/path来切换。安全

若是智能合约使用了libraries，你会注意到字节码包含了__LibraryName______的子字符串。您可使用solc做为连接器，这意味着它将在这些点为您插入库地址。app

能够经过添加库--libraries "Math:0x12345678901234567890 Heap:0xabcdef0123456"到您的命令，以提供每一个库的地址，或者使用文件中的说明字符串（每行一个库），并使用--libraries fileName运行solc。

若是用选项--link调用Solc，则全部输入文件都被解释为未连接的二进制文件（HEX编码），在上面给出的__LibraryName____格式中，将其连接到适当地址（若是从stdin读取输入，则将其写入stdout）。在这种状况下，除了库外，全部选项都被忽略（包括-o）。

若是用--standard-json调用SOLC，它就将标准的JSON输入（以下所述），并返回JSON输出。

#solc编译器输入输出JSON描述

这些JSON格式经过编译器API使用，能够经过SOLC得到。内容都是能够修改的，一些对象是可选的（如前所述），其目的是向后兼容。

编译器的API须要一个JSON格式的输入，而后以JSON格式输出编译结果。

注意不容许注释。下面示例中的注释，是官网为了学习者更好的理解标注的。

输入格式说明：

{
  // Required: Source code language, such as "Solidity", "serpent", "lll", "assembly", etc.
  language: "Solidity",
  // Required
  sources:
  {
    // The keys here are the "global" names of the source files,
    // imports can use other files via remappings (see below).
    "myFile.sol":
    {
      // Optional: keccak256 hash of the source file
      // It is used to verify the retrieved content if imported via URLs.
      "keccak256": "0x123...",
      // Required (unless "content" is used, see below): URL(s) to the source file.
      // URL(s) should be imported in this order and the result checked against the
      // keccak256 hash (if available). If the hash doesn't match or none of the
      // URL(s) result in success, an error should be raised.
      "urls":
      [
        "bzzr://56ab...",
        "ipfs://Qma...",
        "file:///tmp/path/to/file.sol"
      ]
    },
    "mortal":
    {
      // Optional: keccak256 hash of the source file
      "keccak256": "0x234...",
      // Required (unless "urls" is used): literal contents of the source file
      "content": "contract mortal is owned { function kill() { if (msg.sender == owner) selfdestruct(owner); } }"
    }
  },
  // Optional
  settings:
  {
    // Optional: Sorted list of remappings
    remappings: [ ":g/dir" ],
    // Optional: Optimizer settings
    optimizer: {
      // disabled by default
      enabled: true,
      // Optimize for how many times you intend to run the code.
      // Lower values will optimize more for initial deployment cost, higher values will optimize more for high-frequency usage.
      runs: 200
    },
    evmVersion: "byzantium", // Version of the EVM to compile for. Affects type checking and code generation. Can be homestead, tangerineWhistle, spuriousDragon, byzantium or constantinople
    // Metadata settings (optional)
    metadata: {
      // Use only literal content and not URLs (false by default)
      useLiteralContent: true
    },
    // Addresses of the libraries. If not all libraries are given here, it can result in unlinked objects whose output data is different.
    libraries: {
      // The top level key is the the name of the source file where the library is used.
      // If remappings are used, this source file should match the global path after remappings were applied.
      // If this key is an empty string, that refers to a global level.
      "myFile.sol": {
        "MyLib": "0x123123..."
      }
    }
    // The following can be used to select desired outputs.
    // If this field is omitted, then the compiler loads and does type checking, but will not generate any outputs apart from errors.
    // The first level key is the file name and the second is the contract name, where empty contract name refers to the file itself,
    // while the star refers to all of the contracts.
    //
    // The available output types are as follows:
    //   abi - ABI
    //   ast - AST of all source files
    //   legacyAST - legacy AST of all source files
    //   devdoc - Developer documentation (natspec)
    //   userdoc - User documentation (natspec)
    //   metadata - Metadata
    //   ir - New assembly format before desugaring
    //   evm.assembly - New assembly format after desugaring
    //   evm.legacyAssembly - Old-style assembly format in JSON
    //   evm.bytecode.object - Bytecode object
    //   evm.bytecode.opcodes - Opcodes list
    //   evm.bytecode.sourceMap - Source mapping (useful for debugging)
    //   evm.bytecode.linkReferences - Link references (if unlinked object)
    //   evm.deployedBytecode* - Deployed bytecode (has the same options as evm.bytecode)
    //   evm.methodIdentifiers - The list of function hashes
    //   evm.gasEstimates - Function gas estimates
    //   ewasm.wast - eWASM S-expressions format (not supported atm)
    //   ewasm.wasm - eWASM binary format (not supported atm)
    //
    // Note that using a using `evm`, `evm.bytecode`, `ewasm`, etc. will select every
    // target part of that output. Additionally, `*` can be used as a wildcard to request everything.
    //
    outputSelection: {
      // Enable the metadata and bytecode outputs of every single contract.
      "*": {
        "*": [ "metadata", "evm.bytecode" ]
      },
      // Enable the abi and opcodes output of MyContract defined in file def.
      "def": {
        "MyContract": [ "abi", "evm.bytecode.opcodes" ]
      },
      // Enable the source map output of every single contract.
      "*": {
        "*": [ "evm.bytecode.sourceMap" ]
      },
      // Enable the legacy AST output of every single file.
      "*": {
        "": [ "legacyAST" ]
      }
    }
  }
}

输出格式说明

{
  // Optional: not present if no errors/warnings were encountered
  errors: [
    {
      // Optional: Location within the source file.
      sourceLocation: {
        file: "sourceFile.sol",
        start: 0,
        end: 100
      ],
      // Mandatory: Error type, such as "TypeError", "InternalCompilerError", "Exception", etc.
      // See below for complete list of types.
      type: "TypeError",
      // Mandatory: Component where the error originated, such as "general", "ewasm", etc.
      component: "general",
      // Mandatory ("error" or "warning")
      severity: "error",
      // Mandatory
      message: "Invalid keyword"
      // Optional: the message formatted with source location
      formattedMessage: "sourceFile.sol:100: Invalid keyword"
    }
  ],
  // This contains the file-level outputs. In can be limited/filtered by the outputSelection settings.
  sources: {
    "sourceFile.sol": {
      // Identifier (used in source maps)
      id: 1,
      // The AST object
      ast: {},
      // The legacy AST object
      legacyAST: {}
    }
  },
  // This contains the contract-level outputs. It can be limited/filtered by the outputSelection settings.
  contracts: {
    "sourceFile.sol": {
      // If the language used has no contract names, this field should equal to an empty string.
      "ContractName": {
        // The Ethereum Contract ABI. If empty, it is represented as an empty array.
        // See https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI
        abi: [],
        // See the Metadata Output documentation (serialised JSON string)
        metadata: "{...}",
        // User documentation (natspec)
        userdoc: {},
        // Developer documentation (natspec)
        devdoc: {},
        // Intermediate representation (string)
        ir: "",
        // EVM-related outputs
        evm: {
          // Assembly (string)
          assembly: "",
          // Old-style assembly (object)
          legacyAssembly: {},
          // Bytecode and related details.
          bytecode: {
            // The bytecode as a hex string.
            object: "00fe",
            // Opcodes list (string)
            opcodes: "",
            // The source mapping as a string. See the source mapping definition.
            sourceMap: "",
            // If given, this is an unlinked object.
            linkReferences: {
              "libraryFile.sol": {
                // Byte offsets into the bytecode. Linking replaces the 20 bytes located there.
                "Library1": [
                  { start: 0, length: 20 },
                  { start: 200, length: 20 }
                ]
              }
            }
          },
          // The same layout as above.
          deployedBytecode: { },
          // The list of function hashes
          methodIdentifiers: {
            "delegate(address)": "5c19a95c"
          },
          // Function gas estimates
          gasEstimates: {
            creation: {
              codeDepositCost: "420000",
              executionCost: "infinite",
              totalCost: "infinite"
            },
            external: {
              "delegate(address)": "25000"
            },
            internal: {
              "heavyLifting()": "infinite"
            }
          }
        },
        // eWASM related outputs
        ewasm: {
          // S-expressions format
          wast: "",
          // Binary format (hex string)
          wasm: ""
        }
      }
    }
  }
}

错误类型说明：

JSONError：JSON错误，JSON输入不符合要求的格式，例如输入不是JSON对象，不支持语言，等等。
IOError：IO错误，IO和导入处理错误，如提供的源中的不可解析URL或hash不匹配。
ParserError：语法f分析错误，源代码不符合语言规则。
DocstringParsingError：文档解析错误，没法解析注释块中的NATSPEC标记。
SytRealError：语法错误，如continue 在for循环以外使用。
DeclarationError：声明错误，无效、不可解析或冲突的标识符名称。例如未找到标识符
TypeError：类型错误，如无效类型转换、无效赋值等。
UnimplementedFeatureError：编译器不支持该特性，但但愿在未来的版本中获得支持。
InternalCompilerError：编译器中触发内部错误，这应该做为一个问题来反馈。
Exception：例外，编译过程当中未知的故障，这应该做为一个问题反馈。
CompilerError：编译错误，编译器堆栈的使用无效，这应该做为一个问题来反馈。
FatalError：致命错误，这应该做为一个问题来反馈。
Warning：警告并无中止编译，但若是可能的话，应该加以处理。

原文请访问：solc

若是你但愿立刻开始学习以太坊DApp开发，推荐访问一个在线教程：

以太坊智能合约，主要介绍智能合约与dapp应用开发，适合入门。

以太坊开发，主要是介绍使用node.js、mongodb、区块链、ipfs实现去中心化电商DApp实战，适合进阶。