Complete Rust Language Support (P1-Days3-4)

Add comprehensive Rust examples and documentation:
- 5 Rust examples (Result, trait, async, error, tests)
- Complete Rust language guide
- Update examples README with Rust section
- 6 new tests (5 examples + 1 structure)

Examples:
- 01-function-result: Result<T,E> with error handling
- 02-struct-trait: Struct with Display trait impl
- 03-async-tokio: Async function with tokio runtime
- 04-error-handling: Custom error with thiserror
- 05-test-generation: #[test] and #[cfg(test)] modules

Documentation covers:
- Ownership and borrowing patterns
- Lifetime annotations ('a, 'static, 'b)
- Generic types with trait bounds
- Traits and implementations
- Result and Option idioms
- Async/await with tokio
- Pattern matching
- Error types (thiserror)
- Builder and newtype patterns
- Testing (#[test], #[cfg(test)])
- Cargo integration (check, clippy, test)
- Style conventions
- Best practices for Rust prompts

All examples run successfully ✅

Component: examples/rust/, docs/user-guide/rust-guide.md
Tests: 6 tests added to test_examples.py
Status: ✅ P1 Rust Support COMPLETE

Author: rand

docs/user-guide/rust-guide.md

@@ -22,6 +22,16 @@ Python-specific examples:
 4. **[04-fastapi-endpoint.py](python/04-fastapi-endpoint.py)** - FastAPI endpoint with Pydantic
 5. **[05-test-generation.py](python/05-test-generation.py)** - Pytest test generation
 
+## Basic Examples - Rust
+
+Rust-specific examples:
+
+1. **[01-function-result.py](rust/01-function-result.py)** - Function with Result type and error handling
+2. **[02-struct-trait.py](rust/02-struct-trait.py)** - Struct with Display trait implementation
+3. **[03-async-tokio.py](rust/03-async-tokio.py)** - Async function with tokio runtime
+4. **[04-error-handling.py](rust/04-error-handling.py)** - Custom error type with thiserror
+5. **[05-test-generation.py](rust/05-test-generation.py)** - Test generation with #[test]
+
 ## Advanced Examples
 
 Complex real-world scenarios:

examples/README.md

@@ -0,0 +1,60 @@
+"""Example 1: Rust Function with Result Type.
+
+Demonstrates:
+- Function generation with Result type
+- Error handling patterns
+- Type safety with Rust
+
+Usage:
+    python examples/rust/01-function-result.py
+"""
+
+from maze.config import Config
+from maze.core.pipeline import Pipeline
+
+
+def main():
+    """Generate Rust function with Result type."""
+    print("Rust Example 1: Function with Result Type")
+    print("=" * 60)
+
+    config = Config()
+    config.project.language = "rust"
+    config.constraints.syntactic_enabled = True
+    config.constraints.type_enabled = True
+
+    pipeline = Pipeline(config)
+
+    prompt = """Create a Rust function called 'divide':
+    - Parameters: a: f64, b: f64
+    - Returns: Result<f64, String>
+    - Returns Err if b is 0.0
+    - Returns Ok(a / b) otherwise
+    - Include error message in Err
+    - Add documentation comment"""
+
+    print(f"\nPrompt: {prompt}\n")
+    print("Generating...")
+
+    result = pipeline.run(prompt)
+
+    print(f"\nResult:")
+    print(f"  Success: {result.success}")
+    print(f"  Duration: {result.total_duration_ms:.0f}ms")
+
+    print(f"\nGenerated Code:")
+    print("-" * 60)
+    print(result.code)
+    print("-" * 60)
+
+    if result.validation:
+        print(f"\nValidation:")
+        print(f"  Syntax Valid: {result.validation.syntax_valid}")
+        print(f"  Errors: {result.validation.errors_found}")
+
+    pipeline.close()
+    print("\n✅ Example complete!")
+
+
+if __name__ == "__main__":
+    main()

examples/rust/01-function-result.py

@@ -0,0 +1,51 @@
+"""Example 2: Rust Struct with Trait Implementation.
+
+Demonstrates:
+- Struct definition
+- Trait implementation
+- Method generation
+
+Usage:
+    python examples/rust/02-struct-trait.py
+"""
+
+from maze.config import Config
+from maze.core.pipeline import Pipeline
+
+
+def main():
+    """Generate Rust struct with trait implementation."""
+    print("Rust Example 2: Struct with Trait Implementation")
+    print("=" * 60)
+
+    config = Config()
+    config.project.language = "rust"
+    config.constraints.type_enabled = True
+
+    pipeline = Pipeline(config)
+
+    prompt = """Create Rust struct 'Point' and implement Display:
+    - Struct Point with x: f64, y: f64 fields
+    - Implement std::fmt::Display trait
+    - Format as "(x, y)"
+    - Add impl block with new() constructor
+    - Include documentation comments"""
+
+    print(f"\nGenerating Point struct with Display...\n")
+
+    result = pipeline.run(prompt)
+
+    print(f"Status: {'✅ Success' if result.success else '❌ Failed'}")
+    print(f"Duration: {result.total_duration_ms:.0f}ms")
+
+    print(f"\nGenerated Code:")
+    print("-" * 60)
+    print(result.code)
+    print("-" * 60)
+
+    pipeline.close()
+    print("\n✅ Example complete!")
+
+
+if __name__ == "__main__":
+    main()

examples/rust/02-struct-trait.py

@@ -0,0 +1,53 @@
+"""Example 3: Async Function with Tokio.
+
+Demonstrates:
+- Async/await in Rust
+- Error handling with Result
+- External crate usage (tokio, reqwest)
+
+Usage:
+    python examples/rust/03-async-tokio.py
+"""
+
+from maze.config import Config
+from maze.core.pipeline import Pipeline
+
+
+def main():
+    """Generate async Rust function with tokio."""
+    print("Rust Example 3: Async Function with Tokio")
+    print("=" * 60)
+
+    config = Config()
+    config.project.language = "rust"
+    config.constraints.syntactic_enabled = True
+
+    pipeline = Pipeline(config)
+
+    prompt = """Create async Rust function 'fetch_user':
+    - Parameter: user_id: &str
+    - Returns: Result<User, reqwest::Error>
+    - Use reqwest to fetch from API
+    - Async function with .await
+    - Error handling with ?
+    - Assume User struct exists
+    - Include documentation"""
+
+    print(f"\nGenerating async function...\n")
+
+    result = pipeline.run(prompt)
+
+    print(f"Status: {'✅' if result.success else '❌'}")
+    print(f"Duration: {result.total_duration_ms:.0f}ms")
+
+    print(f"\nGenerated Async Function:")
+    print("-" * 60)
+    print(result.code)
+    print("-" * 60)
+
+    pipeline.close()
+    print("\n✅ Example complete!")
+
+
+if __name__ == "__main__":
+    main()

examples/rust/03-async-tokio.py

@@ -0,0 +1,52 @@
+"""Example 4: Custom Error Type with thiserror.
+
+Demonstrates:
+- Custom error enum
+- Error trait implementation
+- Using thiserror derive
+
+Usage:
+    python examples/rust/04-error-handling.py
+"""
+
+from maze.config import Config
+from maze.core.pipeline import Pipeline
+
+
+def main():
+    """Generate Rust custom error type."""
+    print("Rust Example 4: Custom Error Type")
+    print("=" * 60)
+
+    config = Config()
+    config.project.language = "rust"
+    config.constraints.type_enabled = True
+
+    pipeline = Pipeline(config)
+
+    prompt = """Create Rust error enum using thiserror:
+    - Name: AppError
+    - Variants: NotFound(String), Invalid(String), Internal
+    - Use #[derive(Error, Debug)]
+    - Use #[error("...")] for display messages
+    - Implement From<std::io::Error> for AppError
+    - Include documentation"""
+
+    print(f"\nGenerating custom error type...\n")
+
+    result = pipeline.run(prompt)
+
+    print(f"Status: {'✅' if result.success else '❌'}")
+    print(f"Duration: {result.total_duration_ms:.0f}ms")
+
+    print(f"\nGenerated Error Type:")
+    print("-" * 60)
+    print(result.code)
+    print("-" * 60)
+
+    pipeline.close()
+    print("\n✅ Example complete!")
+
+
+if __name__ == "__main__":
+    main()

examples/rust/04-error-handling.py

@@ -0,0 +1,77 @@
+"""Example 5: Rust Test Generation.
+
+Demonstrates:
+- Test function generation
+- #[test] attributes
+- #[cfg(test)] modules
+- Assert macros
+
+Usage:
+    python examples/rust/05-test-generation.py
+"""
+
+from maze.config import Config
+from maze.core.pipeline import Pipeline
+
+
+def main():
+    """Generate Rust tests."""
+    print("Rust Example 5: Test Generation")
+    print("=" * 60)
+
+    # Source code to test
+    source_code = """
+pub struct Calculator;
+
+impl Calculator {
+    pub fn add(&self, a: i32, b: i32) -> i32 {
+        a + b
+    }
+    
+    pub fn subtract(&self, a: i32, b: i32) -> i32 {
+        a - b
+    }
+}
+"""
+
+    print("Source Code to Test:")
+    print("-" * 60)
+    print(source_code)
+    print("-" * 60)
+
+    config = Config()
+    config.project.language = "rust"
+
+    pipeline = Pipeline(config)
+
+    prompt = f"""Generate Rust tests for this Calculator:
+
+{source_code}
+
+Requirements:
+- Use #[cfg(test)] module
+- Use #[test] attribute
+- Test add() method
+- Test subtract() method
+- Test edge cases (zero, negative numbers)
+- Use assert_eq! macro
+- Include module documentation"""
+
+    print("\nGenerating Rust tests...\n")
+
+    result = pipeline.run(prompt)
+
+    print(f"Status: {'✅' if result.success else '❌'}")
+    print(f"Duration: {result.total_duration_ms:.0f}ms")
+
+    print(f"\nGenerated Tests:")
+    print("-" * 60)
+    print(result.code)
+    print("-" * 60)
+
+    pipeline.close()
+    print("\n✅ Example complete!")
+
+
+if __name__ == "__main__":
+    main()