fp_library/types/

arc_ptr.rs

//! Thread-safe reference-counted pointer abstraction using [`Arc`](std::sync::Arc).
//!
//! Provides trait implementations for using `Arc` in the library's pointer abstraction hierarchy.
//!
//! ### Examples
//!
//! ```
//! use fp_library::{brands::*, functions::*};
//!
//! let ptr = send_ref_counted_pointer_new::<ArcBrand, _>(42);
//! assert_eq!(*ptr, 42);
//! ```

#[fp_macros::document_module]
mod inner {
	use crate::{
		brands::ArcBrand,
		classes::{
			Pointer, RefCountedPointer, SendRefCountedPointer, SendUnsizedCoercible,
			UnsizedCoercible,
		},
	};
	use fp_macros::document_parameters;
	use std::sync::Arc;

	impl Pointer for ArcBrand {
		type Of<T: ?Sized> = Arc<T>;

		/// Wraps a sized value in an `Arc`.
		///
		/// ### Type Signature
		///
		#[document_signature]
		///
		/// ### Type Parameters
		///
		#[document_type_parameters("The type of the value to wrap.")]
		///
		/// ### Parameters
		///
		#[document_parameters("The value to wrap.")]
		///
		/// ### Returns
		///
		/// The value wrapped in an `Arc`.
		///
		/// ### Examples
		///
		/// ```
		/// use fp_library::{brands::*, functions::*};
		///
		/// let ptr = pointer_new::<ArcBrand, _>(42);
		/// assert_eq!(*ptr, 42);
		/// ```
		fn new<T>(value: T) -> Arc<T> {
			Arc::new(value)
		}
	}

	impl RefCountedPointer for ArcBrand {
		type CloneableOf<T: ?Sized> = Arc<T>;

		/// Wraps a sized value in an `Arc`.
		///
		/// ### Type Signature
		///
		#[document_signature]
		///
		/// ### Type Parameters
		///
		#[document_type_parameters("The type of the value to wrap.")]
		///
		/// ### Parameters
		///
		#[document_parameters("The value to wrap.")]
		///
		/// ### Returns
		///
		/// The value wrapped in an `Arc`.
		///
		/// ### Examples
		///
		/// ```
		/// use fp_library::{brands::*, functions::*};
		///
		/// let ptr = ref_counted_pointer_new::<ArcBrand, _>(42);
		/// assert_eq!(*ptr, 42);
		/// ```
		fn cloneable_new<T>(value: T) -> Arc<T> {
			Arc::new(value)
		}

		/// Attempts to unwrap the inner value if this is the sole reference.
		///
		/// ### Type Signature
		///
		#[document_signature]
		///
		/// ### Type Parameters
		///
		#[document_type_parameters("The type of the wrapped value.")]
		///
		/// ### Parameters
		///
		#[document_parameters("The pointer to attempt to unwrap.")]
		///
		/// ### Returns
		///
		/// `Ok(value)` if this is the sole reference, otherwise `Err(ptr)`.
		///
		/// ### Examples
		///
		/// ```
		/// use fp_library::{brands::*, functions::*};
		///
		/// let ptr = ref_counted_pointer_new::<ArcBrand, _>(42);
		/// assert_eq!(try_unwrap::<ArcBrand, _>(ptr), Ok(42));
		/// ```
		fn try_unwrap<T>(ptr: Arc<T>) -> Result<T, Arc<T>> {
			Arc::try_unwrap(ptr)
		}
	}

	impl SendRefCountedPointer for ArcBrand {
		type SendOf<T: ?Sized + Send + Sync> = Arc<T>;

		/// Wraps a sized value in an `Arc`.
		///
		/// ### Type Signature
		///
		#[document_signature]
		///
		/// ### Type Parameters
		///
		#[document_type_parameters("The type of the value to wrap.")]
		///
		/// ### Parameters
		///
		#[document_parameters("The value to wrap.")]
		///
		/// ### Returns
		///
		/// The value wrapped in an `Arc`.
		///
		/// ### Examples
		///
		/// ```
		/// use fp_library::{brands::*, functions::*};
		///
		/// let ptr = send_ref_counted_pointer_new::<ArcBrand, _>(42);
		/// assert_eq!(*ptr, 42);
		/// ```
		fn send_new<T: Send + Sync>(value: T) -> Arc<T> {
			Arc::new(value)
		}
	}

	impl UnsizedCoercible for ArcBrand {
		/// Coerces a sized closure to a `dyn Fn` wrapped in an `Arc`.
		///
		/// ### Type Signature
		///
		#[document_signature]
		///
		/// ### Type Parameters
		///
		#[document_type_parameters(
			"The lifetime of the closure.",
			"The input type of the function.",
			"The output type of the function."
		)]
		///
		/// ### Parameters
		///
		#[document_parameters("The closure to coerce.")]
		///
		/// ### Returns
		///
		/// The closure wrapped in an `Arc` as a trait object.
		///
		/// ### Examples
		///
		/// ```
		/// use fp_library::{brands::*, functions::*};
		///
		/// let f = coerce_fn::<ArcBrand, _, _, _>(|x: i32| x + 1);
		/// assert_eq!(f(1), 2);
		/// ```
		fn coerce_fn<'a, A, B>(f: impl 'a + Fn(A) -> B) -> Arc<dyn 'a + Fn(A) -> B> {
			Arc::new(f)
		}
	}

	impl SendUnsizedCoercible for ArcBrand {
		/// Coerces a sized Send+Sync closure to a `dyn Fn + Send + Sync` wrapped in an `Arc`.
		///
		/// ### Type Signature
		///
		#[document_signature]
		///
		/// ### Type Parameters
		///
		#[document_type_parameters(
			"The lifetime of the closure.",
			"The input type of the function.",
			"The output type of the function."
		)]
		///
		/// ### Parameters
		///
		#[document_parameters("The closure to coerce.")]
		///
		/// ### Returns
		///
		/// The closure wrapped in an `Arc` as a thread-safe trait object.
		///
		/// ### Examples
		///
		/// ```
		/// use fp_library::{brands::*, functions::*};
		///
		/// let f = coerce_send_fn::<ArcBrand, _, _, _>(|x: i32| x + 1);
		/// assert_eq!(f(1), 2);
		/// ```
		fn coerce_send_fn<'a, A, B>(
			f: impl 'a + Fn(A) -> B + Send + Sync
		) -> Arc<dyn 'a + Fn(A) -> B + Send + Sync> {
			Arc::new(f)
		}
	}
}

#[cfg(test)]
mod tests {
	use crate::{
		brands::ArcBrand,
		classes::{
			RefCountedPointer, pointer::new, ref_counted_pointer::cloneable_new,
			send_ref_counted_pointer::send_new,
		},
	};

	/// Tests that `pointer_new` correctly creates an `Arc` wrapping the value.
	#[test]
	fn test_arc_new() {
		let ptr = new::<ArcBrand, _>(42);
		assert_eq!(*ptr, 42);
	}

	/// Tests that `ref_counted_pointer_new` correctly creates an `Arc` wrapping the value.
	#[test]
	fn test_arc_cloneable_new() {
		let ptr = cloneable_new::<ArcBrand, _>(42);
		assert_eq!(*ptr, 42);
	}

	/// Tests that `send_ref_counted_pointer_new` correctly creates an `Arc` wrapping the value.
	#[test]
	fn test_arc_send_new() {
		let ptr = send_new::<ArcBrand, _>(42);
		assert_eq!(*ptr, 42);
	}

	/// Tests that cloning the pointer works as expected (shared ownership).
	#[test]
	fn test_arc_clone() {
		let ptr = cloneable_new::<ArcBrand, _>(42);
		let clone = ptr.clone();
		assert_eq!(*clone, 42);
	}

	/// Tests `try_unwrap` behavior:
	/// - Returns `Ok(value)` when there is only one reference.
	/// - Returns `Err(ptr)` when there are multiple references.
	#[test]
	fn test_arc_try_unwrap() {
		let ptr = cloneable_new::<ArcBrand, _>(42);
		assert_eq!(ArcBrand::try_unwrap(ptr), Ok(42));

		let ptr = cloneable_new::<ArcBrand, _>(42);
		let _clone = ptr.clone();
		assert!(ArcBrand::try_unwrap(ptr).is_err());
	}
}