YOUChain solidity compiler
npm install youchain-solcJavaScript bindings for the Solidity compiler.
Uses the Emscripten compiled Solidity found in the solc-bin repository.
0.4.26 (2020-01-16)
Remove opcode DIFFICULTY.
About swarm hash: source filename irrelevant metadata, so to generate a more consistent swarm hash.
0.5.16 (2020-02-03)
Delete token units szabo and finney.
To use the latest stable version of the Solidity compiler via Node.js you can install it via npm:
``bash`
npm install youchain-solc
If this package is installed globally (npm install -g youchain-solc), a command-line tool called solcjs will be available.
To see all the supported features, execute:
`bash`
youchain-solcjs --help
There are two ways to use youchain-solc:
1. Through a high-level API giving a uniform interface to all compiler versions
2. Through a low-level API giving access to all the compiler interfaces, which depend on the version of the compiler
#### High-level API
The high-level API consists of a single method, compile, which expects the Compiler Standard Input and Output JSON.
It also accepts an optional callback function to resolve unmet dependencies. This callback receives a path and must synchronously return either an error or the content of the dependency as a string.
It cannot be used together with callback-based, asynchronous, filesystem access. A workaround is to collect the names of dependencies, return an error, and keep re-running the compiler until all
of them are resolved.
#### Example usage without the import callback
Example:
`javascript
var solc = require("youchain-solc");
var input = {
language: "Solidity",
sources: {
"test.sol": {
content: "contract C { function f() public { } }"
}
},
settings: {
outputSelection: {
"*": {
"": [""]
}
}
}
};
var output = JSON.parse(solc.compile(JSON.stringify(input)));
// output here contains the JSON output as specified in the documentation`
for (var contractName in output.contracts["test.sol"]) {
console.log(
contractName +
": " +
output.contracts["test.sol"][contractName].evm.bytecode.object
);
}
#### Example usage with import callback
`javascript
var solc = require("youchain-solc");
var input = {
language: "Solidity",
sources: {
"test.sol": {
content: 'import "lib.sol"; contract C { function f() public { L.f(); } }'
}
},
settings: {
outputSelection: {
"*": {
"": [""]
}
}
}
};
function findImports(path) {
if (path === "lib.sol")
return {
contents:
"library L { function f() internal returns (uint) { return 7; } }"
};
else return { error: "File not found" };
}
var output = JSON.parse(solc.compile(JSON.stringify(input), findImports));
// output here contains the JSON output as specified in the documentation`
for (var contractName in output.contracts["test.sol"]) {
console.log(
contractName +
": " +
output.contracts["test.sol"][contractName].evm.bytecode.object
);
}
Note:
If you are using Electron, nodeIntegration is on for BrowserWindow by default. If it is on, Electron will provide a require method which will not behave as expected and this may cause calls, such as require('youchain-solc'), to fail.
To turn off nodeIntegration, use the following:
`javascript`
new BrowserWindow({
webPreferences: {
nodeIntegration: false
}
});
In order to compile contracts using a specific version of Solidity, the solc.loadRemoteVersion(version, callback) method is available. This returns a new youchain-solc object that uses a version of the compiler specified.
You can also load the "binary" manually and use setupMethods to create the familiar wrapper functions described above:var solc = solc.setupMethods(require("/my/local/soljson.js")).
By default, the npm version is only created for releases. This prevents people from deploying contracts with non-release versions because they are less stable and harder to verify. If you would like to use the latest development snapshot (at your own risk!), you may use the following example code.
`javascript
var solc = require("youchain-solc");
// getting the development snapshot
solc.loadRemoteVersion("latest", function(err, solcSnapshot) {
if (err) {
// An error was encountered, display and quit
} else {
// NOTE: Use solcSnapshot here with the same interface solc has`
}
});
When using libraries, the resulting bytecode will contain placeholders for the real addresses of the referenced libraries. These have to be updated, via a process called linking, before deploying the contract.
The linker module (require('youchain-solc/linker')) offers helpers to accomplish this.
The linkBytecode method provides a simple helper for linking:
`javascript
var linker = require("youchain-solc/linker");
bytecode = linker.linkBytecode(bytecode, { MyLibrary: "0x123456..." });
`
As of Solidity 0.4.25 the compiler supports standard JSON input and output which outputs a _link references_ map. This gives a map of library names to offsets in the bytecode to replace the addresses at. It also doesn't have the limitation on library file and contract name lengths.
There is a method available in the linker module called findLinkReferences which can find such link references in bytecode produced by an older compiler:
`javascript
var linker = require("youchain-solc/linker");
var linkReferences = linker.findLinkReferences(bytecode);
`
The ABI generated by Solidity versions can differ slightly, due to new features introduced. There is a tool included which aims to translate the ABI generated by an older Solidity version to conform to the latest standard.
It can be used as:
`javascript
var abi = require("youchain-solc/abi");
var inputABI = [
{
constant: false,
inputs: [],
name: "hello",
outputs: [{ name: "", type: "string" }],
payable: false,
type: "function"
}
];
var outputABI = abi.update("0.3.6", inputABI);
// Output contains: [{"constant":false,"inputs":[],"name":"hello","outputs":[{"name":"","type":"string"}],"payable":true,"type":"function"},{"type":"fallback","payable":true}]
`
There is a helper available to format old JSON assembly output into a text familiar to earlier users of Remix IDE.
`
var translate = require('youchain-solc/translate')
// assemblyJSON refers to the JSON of the given assembly and sourceCode is the source of which the assembly was generated from
var output = translate.prettyPrintLegacyAssemblyJSON(assemblyJSON, sourceCode)
`
Add the version of youchain-solc you want to use into index.html:
`html`
src="https://youchainhq.github.io/solc-bin/bin/{{ YOUCHAIN-SOLC VERSION }}.js"
>
(Alternatively use https://youchainhq.github.io/solc-bin/bin/soljson-latest.js to get the latest version.)
This will load youchain-solc into the global variable window.Module. Then use this inside Javascript as:
`javascript`
var wrapper = require("youchain-solc/wrapper");
var solc = wrapper(window.Module);
Or in ES6 syntax:
`javascript`
import * as wrapper from "youchain-solc/wrapper";
const solc = wrapper(window.Module);
Alternatively, to iterate the releases, one can load list.js from solc-bin:
`html`
src="https://youchainhq.github.io/solc-bin/bin/list.js"
>
This will result in two global variables, window.soljsonReleases listing all releases and window.soljsonSources` listing all nightly builds and releases.