# 🍬 Contributing to Sweet
Thank you for your interest in improving Sweet! This guide provides technical specifications for contributing to the core engine and adding support for new programming languages.
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## 🏗️ Project Architecture (Single-Pass Zero-Copy)
Sweet is built for industrial-grade performance. Unlike traditional analyzers that read files multiple times, Sweet uses a **Unified Single-Pass Engine**:
1. **Discovery**: The `ignore` walker finds files respecting `.gitignore`.
2. **Memory Mapping**: Files are mapped into memory using `memmap2` for zero-copy access.
3. **Unified Scan**: The `scanner::scan` function traverses the byte buffer **exactly once**.
- It tracks nesting depth via indentation.
- It identifies imports using language-specific keywords.
- It strips comments on-the-fly to produce a "clean" buffer for repetition analysis.
4. **Repetition Analysis**: A specialized module computes hashes of the clean buffer to find project-wide clones.
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## 🚀 Adding a New Language
Sweet uses the **Strategy Pattern** to handle language-specific rules. Adding a language is purely declarative.
### 1. Define the Language Strategy
Create a new file in `src/languages/definitions/go.rs`:
```rust
use crate::languages::Language;
pub struct Go;
impl Language for Go {
fn name(&self) -> &'static str { "Go" }
fn extensions(&self) -> &'static [&'static str] { &["go"] }
fn line_comment(&self) -> Option<&'static str> { Some("//") }
fn block_comment(&self) -> Option<(&'static str, &'static str)> { Some(("/*", "*/")) }
fn import_keywords(&self) -> &'static [&'static str] {
&["import", "import ("]
}
// Optional: Number of spaces per indent level (default: 4)
fn indent_size(&self) -> usize { 8 }
// Optional: Default thresholds specifically for this language
fn default_thresholds(&self) -> crate::Thresholds {
crate::Thresholds {
max_lines: 400,
max_imports: 20,
..Default::default()
}
}
}
```
### 2. Registration
To make the language active, you must register it in three places:
1. **Expose Module**: Add `pub mod go;` to `src/languages/definitions/mod.rs`.
2. **Register in Engine**: Add `Box::new(definitions::go::Go)` to `LanguageRegistry::new()` in `src/languages/mod.rs`.
3. **Update Config Schema**:
- Add the extension (`go`) to the `ThresholdsOverrides` struct in `src/config/thresholds.rs`.
- Update the `get()` and `extend()` methods in that same file to handle the new field.
### 3. VS Code Integration
1. **`editors/vscode/package.json`**: Add the language ID to the `languages` contribution point.
2. **`editors/vscode/src/extension.ts`**: Add the language ID to the `supportedLanguages` array to enable LSP features.
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## 🧪 Quality Standards
We enforce strict engineering standards to maintain Sweet's performance and reliability:
- **Zero-Copy First**: Avoid allocating `String` or `Vec` inside the scanner loop. Use byte slices (`&[u8]`) and offsets.
- **No Panics**: Use `Result` and `Option`. The codebase has a strict `#![deny(clippy::unwrap_used)]`.
- **Pedantic Clippy**: We use `clippy::pedantic`. All contributions must pass without warnings.
- **Performance Regression**: If your change affects the core loop, run `cargo bench` to ensure no performance loss.
### Validation Workflow
Run the pre-push hook before submitting a PR:
```bash
./hooks/pre-push
```
This ensures formatting, lints, and tests are perfect.
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## 📜 License
By contributing, you agree that your contributions will be licensed under the [MIT License](./LICENSE).