rust-patterns

rust-patterns Skill

Comprehensive Rust pattern analysis tool for detecting, suggesting, and evaluating design patterns in Rust codebases.

Overview

This skill provides three complementary modes for Rust pattern analysis:

1. Detection Mode: Scan codebase to identify existing patterns and anti-patterns
2. Suggestion Mode: Recommend patterns to address code smells and improve design
3. Evaluation Mode: Score pattern implementation quality against best practices

Complementary to: @RUST_PATTERNS.md (always-active rules) - this skill provides optional deep analysis.

Invocation

# Detection - scan codebase for patterns
/rust-patterns detect [path]

# Suggestion - recommend patterns for code smells
/rust-patterns suggest [path]

# Evaluation - score pattern implementation quality
/rust-patterns evaluate [path] [--pattern=<name>]

# Help
/rust-patterns --help

Mode 1: Detection

Purpose: Identify patterns and anti-patterns currently in the codebase.

Workflow:

1. Scan → Glob for *.rs files in target path
2. Search → Grep for pattern signatures (ownership, newtype, builder, etc.)
3. Detect Anti-patterns → Grep for .clone(), .unwrap(), Arc<Mutex>, blocking ops
4. Classify → Categorize as idiom/pattern/anti-pattern
5. Score Confidence → 0.0-1.0 based on signature strength
6. Report → JSON output with file locations and recommendations

Example:

/rust-patterns detect src/

Output Format:

{
  "scan_summary": {
    "files_scanned": 42,
    "patterns_found": 15,
    "anti_patterns_found": 8,
    "confidence_avg": 0.87
  },
  "patterns": {
    "newtype": [
      {
        "file": "src/models/stats.rs",
        "lines": "12-15",
        "confidence": 0.92,
        "code": "struct SessionId(String);",
        "note": "✅ Good: Zero-cost type safety"
      }
    ],
    "builder": [
      {
        "file": "src/store.rs",
        "lines": "45-78",
        "confidence": 0.88,
        "code": "impl DataStoreBuilder { ... }",
        "note": "✅ Good: Type-state builder pattern"
      }
    ],
    "raii": [
      {
        "file": "src/guard.rs",
        "lines": "23-35",
        "confidence": 0.95,
        "code": "impl Drop for FileGuard { ... }",
        "note": "✅ Good: Automatic cleanup"
      }
    ]
  },
  "anti_patterns": {
    "excessive_clone": [
      {
        "file": "src/app.rs",
        "lines": "45",
        "severity": "high",
        "code": ".clone().process().clone()",
        "suggestion": "Use &DataStore instead of cloning",
        "impact": "Performance: Multiple heap allocations"
      }
    ],
    "unwrap_in_production": [
      {
        "file": "src/parsers/session.rs",
        "lines": "89",
        "severity": "critical",
        "code": "serde_json::from_str(&content).unwrap()",
        "suggestion": "Use ? operator with .context()",
        "impact": "Safety: Will panic on malformed input"
      }
    ],
    "blocking_in_async": [
      {
        "file": "src/api/handlers.rs",
        "lines": "123",
        "severity": "high",
        "code": "std::fs::read(path)",
        "suggestion": "Use tokio::fs::read() or spawn_blocking",
        "impact": "Performance: Blocks async executor"
      }
    ]
  },
  "recommendations": [
    "Fix 3 critical anti-patterns before merge",
    "Consider extracting builder pattern in src/config.rs",
    "Review clone usage in src/app.rs (8 occurrences)"
  ]
}