Solium is a linter for Solidity which uses Abstract Syntax Trees and allows the user to enable/disable existing rules and add their own ones!

It internally uses solparse to parse your solidity code into a Spider Monkey compliant AST

Solium aims to comply with the official Solidity Style Guide. Follow our blog in order to stay up to date with the latest news.

Install

npm install -g solium

Usage

In the root directory of your DApp, run the following:

solium --init

This creates .soliumrc.json and .soliumignore inside your root directory, which have the configuration for the enabled and custom rules and files and folders to ignore while running the linter respectively.

You can disable a particular rule by setting its value to false in .soliumrc.json

In order to lint a specific file, use:

solium --file foobar.sol

To run the linter over your entire project, use the following command in your root directory:

solium --dir .

This lints all the files inside your project with .sol extension.

Additional Options

Use solium --watch to enable Hot loading (Hot swapping).
Use solium --reporter=gcc or solium --reporter=pretty to configure the output
Use solium --dir <DIRECTORY_NAME> to run the linter over a particular directory

Plugging in your custom rules

-> Open up the .soliumrc.json configuration file and set the value of custom-rules-filename to the path of the file that defines your rules. You can either provide an absolute path or a path relative to the directory in which .soliumrc.json resides. For example: "custom-rules-filename": "./my-rules.js"

The format for writing your custom rule file (for example, my-rules.js) is:

module.exports = {
  'my-rule-name-1': function (context) {

    //Solium internally uses EventEmitter and emits an event every time it enters or leaves a node during the Depth First Traversal of the AST
    context.on ('IfStatement', function (emittedObject) {
    
      //exit property is set to true if we are leaving the node
      if (emittedObject.exit) {
        return;
      }
      
      //View the node representing an If Statement 
      console.log (emittedObject.node);
      
      //report an error
      context.report ({
        node: emittedObject.node,
        message: 'I JUST ENTERED AN IF STATEMENT!!',
        location: { //optional
          line: 1,  //optional
          column: 2 //optional
        }
      });
      
    });
  },
  
  'my-rule-name-2': function (context) {
    context.on ('ContractStatement', function (emittedObject) {
      //similarly define this rule to do something with Contract Declarations
    });
  }
};

NOTE: The best way to know which event you're looking for is to simply install solparse or solidity-parser, then parse your code into the AST and see the value of the type field of the node that you wish to target.

See the existing rules to get an idea of how the rules are making use of the context object being provided to them.

-> Then, inside the rules object in the same file, set your rule names to true. For instance:

"rules": {
  "my-rule-name-1": true,
  "my-rule-name-2": true
}

NOTE: If you write a rule whose name clashes with the name of a pre-defined rule, your custom rule overrides the pre-defined one.

Integrate Solium in your app

To access Solium's API, first install it:

npm install --save solium

Usage

let Solium = require ('solium'),
  sourceCode = 'contract fOO_bar { function HELLO_WORLD () {} }';
  //sourceCode can alternatively be a Buffer object
    
let errorObjects = Solium.lint (sourceCode, {
  'custom-rules-filename': null,  //see above if you wish to add custom rules
  rules: {
    camelcase: true,
    mixedcase: true
  }
});

errorObjects.forEach ((err) => {
  console.log (err);
});