# Sprint 49: Multi-Language Support Implementation

This document details the implementation of multi-language support in deep_context.rs, which was completed as part of Sprint 49.

## Overview

The multi-language support implementation enhances PMAT's ability to analyze code across different programming languages. This implementation focuses specifically on integrating the C and C++ language analyzers with the deep_context.rs module, which is responsible for creating comprehensive context information for files.

## Implementation Details

### Language-Specific Analysis Functions

We've implemented dedicated language-specific analysis functions:

```rust
pub async fn analyze_c_language(
    file_path: &std::path::Path,
) -> anyhow::Result<Vec<crate::services::context::AstItem>> {
    #[cfg(feature = "c-ast")]
    {
        // Use the new comprehensive C language analyzer
        use crate::services::ast::languages::c;
        let file_context = c::analyze_c_file(file_path)
            .await
            .map_err(|e| anyhow::anyhow!("C analysis error: {}", e))?;
        
        // Return the AST items from the file context
        Ok(file_context.items)
    }
    
    #[cfg(not(feature = "c-ast"))]
    analyze_c_file(file_path).await
}

pub async fn analyze_cpp_language(
    file_path: &std::path::Path,
) -> anyhow::Result<Vec<crate::services::context::AstItem>> {
    #[cfg(feature = "cpp-ast")]
    {
        // Use the comprehensive C++ language analyzer
        use crate::services::ast::languages::cpp;
        let file_context = cpp::analyze_cpp_file(file_path)
            .await
            .map_err(|e| anyhow::anyhow!("C++ analysis error: {}", e))?;
        
        // Return the AST items from the file context
        Ok(file_context.items)
    }
    
    #[cfg(not(feature = "cpp-ast"))]
    analyze_c_file(file_path).await  // Fallback to C analysis if C++ feature is not enabled
}
```

### Language Dispatcher

The analyze_file_by_language function now distinguishes between C and C++:

```rust
pub async fn analyze_file_by_language(
    file_path: &std::path::Path,
    language: &str,
) -> anyhow::Result<Vec<crate::services::context::AstItem>> {
    match language {
        // Core languages with full AST analysis
        "rust" => analyze_rust_language(file_path).await,
        "typescript" | "javascript" => analyze_typescript_language(file_path).await,
        "python" => analyze_python_language(file_path).await,
        "go" => analyze_go_language(file_path).await,
        "c" => analyze_c_language(file_path).await,
        "cpp" => analyze_cpp_language(file_path).await,
        // Other languages...
    }
}
```

### Thread-Local Caching

For performance optimization, we've added thread-local caches for C and C++:

```rust
// Thread-local cache for unified C analysis results
thread_local! {
    static C_UNIFIED_CACHE: RefCell<FxHashMap<PathBuf, FileComplexityMetrics>> = RefCell::new(FxHashMap::default());
}

// Thread-local cache for unified C++ analysis results
thread_local! {
    static CPP_UNIFIED_CACHE: RefCell<FxHashMap<PathBuf, FileComplexityMetrics>> = RefCell::new(FxHashMap::default());
}
```

### Backward Compatibility

To maintain backward compatibility, we updated the analyze_c_file function to delegate to the new implementation:

```rust
async fn analyze_c_file(
    #[allow(unused_variables)] file_path: &Path,
) -> anyhow::Result<Vec<crate::services::context::AstItem>> {
    #[cfg(feature = "c-ast")]
    {
        // Direct delegation to the new implementation
        // This avoids code duplication and ensures consistency
        use crate::services::ast::languages::c;
        let file_context = c::analyze_c_file(file_path)
            .await
            .map_err(|e| anyhow::anyhow!("C analysis error: {}", e))?;
        
        Ok(file_context.items)
    }
    #[cfg(not(feature = "c-ast"))]
    Ok(Vec::new())
}
```

## Architecture

The implementation follows a multi-layered architecture:

1. **Language Dispatcher** (analyze_file_by_language) - Routes analysis requests based on file language
2. **Language-Specific Analyzers** (analyze_c_language, analyze_cpp_language) - Handle language-specific processing
3. **AST Visitors** (CAstVisitor, CppAstVisitor) - Extract AST information from source code
4. **Complexity Analyzers** (CComplexityAnalyzer, CppComplexityAnalyzer) - Calculate complexity metrics
5. **Caching Layer** (C_UNIFIED_CACHE, CPP_UNIFIED_CACHE) - Optimize performance with thread-local caching

## Benefits

This implementation provides several benefits:

1. **Improved Language Support** - Better analysis of C and C++ codebases
2. **Performance Optimization** - Thread-local caching reduces repeated parsing
3. **Clean Architecture** - Separate analyzers for each language
4. **Feature Isolation** - Feature flags allow selective language support
5. **Backward Compatibility** - Existing code continues to work with the new implementation

## Future Work

Potential future enhancements include:

1. Implementing Ruby language analysis
2. Enhancing the C/C++ analyzers with more detailed AST extraction
3. Adding support for more specialized language features
4. Implementing unified context annotations for all supported languages
5. Adding more sophisticated caching strategies for large projects

## Conclusion

The multi-language support implementation completes the high-severity technical debt reduction tasks planned for Sprint 49. It enhances PMAT's ability to analyze C and C++ code and provides a framework for adding support for additional languages in the future.