Circom Parser

A TypeScript package for parsing Circom code using ANTLR (ANother Tool for Language Recognition) grammar.

It includes built-in visitors and utilities that allow you to parse, traverse, and manipulate Circom circuits.

Installation

npm install @distributedlab/circom-parser

Usage

Custom Visitor Creation

To create your own visitor, simply extend the CircomVisitor class and override the visit methods you need.

import { CircomVisitor, AnyRuleContext } from '@distributed-lab/circom-parser';

export default class MyCircomVisitor extends CircomVisitor {
    visitAnyRule = (ctx: AnyRuleContext) => {
        // override the visit logic here
    }
}

Custom Visitor Usage

After creating your custom visitor, you can use it with the CircomParser to traverse and manipulate the parse tree.

import { getCircomParser, ParserError } from '@distributed-lab/circom-parser';

import { MyCircomVisitor } from './MyCircomVisitor';

const { parser, errorListener } = getCircomParser(source);

const templateVisitor = new MyCircomVisitor();

templateVisitor.visit(parser.circuit());

if (errorListener.hasErrors()) {
    throw new ParserError(errorListener.getErrors());
}

Reference: Built-in Visitors

You can use the built-in visitors provided in this package as a reference or starting point for your own implementations:

• CircomTemplateVisitor
• CircomIncludeVisitor
• CircomMainComponentVisitor
• CircomExpressionVisitor

Known limitations

1. Function calls inside the main component declaration or expressions are not supported.
2. Currently, all 'simple' expressions are evaluated as-is, without accounting for the module.