mehen

Rust-powered CLI for detecting heuristic source code metrics at scale: complexity, maintainability, lines of code, and more.

Designed for fast, deterministic analysis over large codebases, helping both human and AI engineers track how complexity evolves over time.

Install

npm install mehen

Or run without installing:

npx -y mehen --help
bunx mehen --help

Also available on PyPI:

uvx mehen --help

Supported Languages

• Python (.py)
• TypeScript (.ts)
• TSX (.tsx)
• Rust (.rs)
• Go (.go)

Usage

Analyze metrics for a directory:

npx -y mehen -m -p src

Export metrics as JSON:

npx -y mehen -m -p src -O json -o ./metrics

Other supported output formats: YAML, TOML, CBOR.

What Mehen Computes

• Cyclomatic complexity -- control flow complexity
• Cognitive complexity -- human-perceived complexity with nesting
• Maintainability Index -- overall maintainability score
• Halstead metrics -- volume, difficulty, effort, bugs prediction
• ABC metric -- assignments, branches, conditionals
• LOC family -- SLOC, PLOC, LLOC, CLOC, blanks
• NArgs / NOM / NExit -- arguments, methods, exit points
• NPA / NPM / WMC -- public attributes, public methods, weighted methods per class

CI Integration

mehen ships a GitHub Action that computes changed-file metric trends on pull requests, compares against the base branch, and posts a summary comment:

permissions:
  contents: read
  pull-requests: write
  issues: write

steps:
  - uses: actions/checkout@v5
    with:
      fetch-depth: 0

  - uses: ophidiarium/mehen@v1
    with:
      paths: src
      thresholds: |
        cyclomatic=5
        cognitive=4

The action is backed by mehen diff, so polyglot repositories can pass multiple roots and let mehen pick supported languages from changed files.

Platforms

Native binaries are provided for:

| OS | x64 | arm64 | |---|---|---| | Linux (glibc) | @mehen/linux-x64-gnu | @mehen/linux-arm64-gnu | | Linux (musl) | @mehen/linux-x64-musl | @mehen/linux-arm64-musl | | macOS | @mehen/darwin-x64 | @mehen/darwin-arm64 | | Windows | @mehen/win32-x64 | @mehen/win32-arm64 |

The correct binary is selected automatically at runtime.

Requires Node.js >= 18.

Links

• GitHub
• Issues
• PyPI package

License

MPL-2.0