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//! Single-threaded reference-counted pointer abstraction using [`Rc`](std::rc::Rc).
//!
//! Provides trait implementations for using `Rc` in the library's pointer abstraction hierarchy. Not thread-safe; use [`ArcBrand`](crate::brands::ArcBrand) for multi-threaded contexts. The corresponding brand is [`RcBrand`](crate::brands::RcBrand).
//!
//! ### Examples
//!
//! ```
//! use fp_library::{
//! brands::*,
//! functions::*,
//! };
//!
//! let ptr = pointer_new::<RcBrand, _>(42);
//! assert_eq!(*ptr, 42);
//! ```
#[fp_macros::document_module]
mod inner {
use {
crate::{
brands::RcBrand,
classes::{
Pointer,
RefCountedPointer,
ToDynCloneFn,
ToDynFn,
},
},
fp_macros::*,
std::{
cell::RefCell,
rc::Rc,
},
};
impl Pointer for RcBrand {
type Of<'a, T: ?Sized + 'a> = Rc<T>;
/// Wraps a sized value in an `Rc`.
#[document_signature]
///
#[document_type_parameters("The lifetime of the value.", "The type of the value to wrap.")]
///
#[document_parameters("The value to wrap.")]
///
#[document_returns("The value wrapped in an `Rc`.")]
///
#[document_examples]
///
/// ```
/// use fp_library::{
/// brands::*,
/// functions::*,
/// };
///
/// let ptr = pointer_new::<RcBrand, _>(42);
/// assert_eq!(*ptr, 42);
/// ```
fn new<'a, T: 'a>(value: T) -> Rc<T> {
Rc::new(value)
}
}
impl RefCountedPointer for RcBrand {
type Of<'a, T: ?Sized + 'a> = Rc<T>;
type TakeCellOf<'a, T: 'a> = Rc<RefCell<Option<T>>>;
/// Wraps a sized value in an `Rc`.
#[document_signature]
///
#[document_type_parameters("The lifetime of the value.", "The type of the value to wrap.")]
///
#[document_parameters("The value to wrap.")]
///
#[document_returns("The value wrapped in an `Rc`.")]
///
#[document_examples]
///
/// ```
/// use fp_library::{
/// brands::*,
/// functions::*,
/// };
///
/// let ptr = ref_counted_pointer_new::<RcBrand, _>(42);
/// assert_eq!(*ptr, 42);
/// ```
fn new<'a, T: 'a>(value: T) -> Rc<T> {
Rc::new(value)
}
/// Attempts to unwrap the inner value if this is the sole reference.
#[document_signature]
///
#[document_type_parameters(
"The lifetime of the wrapped value.",
"The type of the wrapped value."
)]
///
#[document_parameters("The pointer to attempt to unwrap.")]
///
#[document_returns("`Ok(value)` if this is the sole reference, otherwise `Err(ptr)`.")]
///
#[document_examples]
///
/// ```
/// use fp_library::{
/// brands::*,
/// functions::*,
/// };
///
/// let ptr = ref_counted_pointer_new::<RcBrand, _>(42);
/// assert_eq!(try_unwrap::<RcBrand, _>(ptr), Ok(42));
/// ```
fn try_unwrap<'a, T: 'a>(ptr: Rc<T>) -> Result<T, Rc<T>> {
Rc::try_unwrap(ptr)
}
/// Creates a new take-cell containing the given value.
#[document_signature]
///
#[document_type_parameters("The lifetime of the value.", "The type of the value to store.")]
///
#[document_parameters("The value to store in the cell.")]
///
#[document_returns("A new `Rc<RefCell<Option<T>>>` containing the value.")]
///
#[document_examples]
///
/// ```
/// use fp_library::{
/// brands::*,
/// classes::*,
/// };
///
/// let cell = RcBrand::take_cell_new(42);
/// assert_eq!(RcBrand::take_cell_take(&cell), Some(42));
/// ```
fn take_cell_new<'a, T: 'a>(value: T) -> Rc<RefCell<Option<T>>> {
Rc::new(RefCell::new(Some(value)))
}
/// Takes the value out of the cell, leaving `None` behind.
#[document_signature]
///
#[document_type_parameters("The lifetime of the value.", "The type of the stored value.")]
///
#[document_parameters("The cell to take the value from.")]
///
#[document_returns("`Some(value)` if the cell still contains a value, `None` otherwise.")]
///
#[document_examples]
///
/// ```
/// use fp_library::{
/// brands::*,
/// classes::*,
/// };
///
/// let cell = RcBrand::take_cell_new(42);
/// assert_eq!(RcBrand::take_cell_take(&cell), Some(42));
/// assert_eq!(RcBrand::take_cell_take(&cell), None);
/// ```
fn take_cell_take<'a, T: 'a>(cell: &Rc<RefCell<Option<T>>>) -> Option<T> {
cell.borrow_mut().take()
}
}
impl ToDynFn for RcBrand {
/// Coerces a sized closure to a `dyn Fn` wrapped in an `Rc`.
#[document_signature]
///
#[document_type_parameters(
"The lifetime of the closure.",
"The input type of the function.",
"The output type of the function."
)]
///
#[document_parameters("The closure to coerce.")]
///
#[document_returns("The closure wrapped in an `Rc` as a trait object.")]
#[document_examples]
///
/// ```
/// use fp_library::{
/// brands::*,
/// classes::*,
/// };
///
/// let f = <RcBrand as ToDynFn>::new(|x: i32| x + 1);
/// assert_eq!(f(1), 2);
/// ```
fn new<'a, A: 'a, B: 'a>(f: impl 'a + Fn(A) -> B) -> Rc<dyn 'a + Fn(A) -> B> {
Rc::new(f)
}
/// Coerces a sized by-reference closure to a `dyn Fn(&A) -> B` wrapped in an `Rc`.
#[document_signature]
///
#[document_type_parameters(
"The lifetime of the closure.",
"The input type (the closure receives `&A`).",
"The output type of the function."
)]
///
#[document_parameters("The closure to coerce.")]
///
#[document_returns("The closure wrapped in an `Rc` as a by-reference trait object.")]
#[document_examples]
///
/// ```
/// use fp_library::{
/// brands::*,
/// classes::*,
/// };
///
/// let f = <RcBrand as ToDynFn>::ref_new(|x: &i32| *x + 1);
/// assert_eq!(f(&1), 2);
/// ```
fn ref_new<'a, A: 'a, B: 'a>(f: impl 'a + Fn(&A) -> B) -> Rc<dyn 'a + Fn(&A) -> B> {
Rc::new(f)
}
}
impl ToDynCloneFn for RcBrand {
/// Coerces a sized closure to a `dyn Fn` wrapped in an `Rc`.
#[document_signature]
///
#[document_type_parameters(
"The lifetime of the closure.",
"The input type of the function.",
"The output type of the function."
)]
///
#[document_parameters("The closure to coerce.")]
///
#[document_returns("The closure wrapped in an `Rc` as a trait object.")]
///
#[document_examples]
///
/// ```
/// use fp_library::{
/// brands::*,
/// functions::*,
/// };
///
/// let f = to_dyn_clone_fn::<RcBrand, _, _>(|x: i32| x + 1);
/// assert_eq!(f(1), 2);
/// ```
fn new<'a, A: 'a, B: 'a>(f: impl 'a + Fn(A) -> B) -> Rc<dyn 'a + Fn(A) -> B> {
Rc::new(f)
}
/// Coerces a sized by-reference closure to a `dyn Fn(&A) -> B` wrapped in an `Rc`.
#[document_signature]
///
#[document_type_parameters(
"The lifetime of the closure.",
"The input type (the closure receives `&A`).",
"The output type of the function."
)]
///
#[document_parameters("The closure to coerce.")]
///
#[document_returns("The closure wrapped in an `Rc` as a by-reference trait object.")]
///
#[document_examples]
///
/// ```
/// use fp_library::{
/// brands::*,
/// classes::*,
/// };
///
/// let f = <RcBrand as ToDynCloneFn>::ref_new(|x: &i32| *x + 1);
/// assert_eq!(f(&1), 2);
/// ```
fn ref_new<'a, A: 'a, B: 'a>(f: impl 'a + Fn(&A) -> B) -> Rc<dyn 'a + Fn(&A) -> B> {
Rc::new(f)
}
}
}
#[cfg(test)]
mod tests {
use crate::{
brands::RcBrand,
classes::{
RefCountedPointer,
pointer::new as pointer_new,
ref_counted_pointer::new as ref_counted_pointer_new,
},
};
/// Tests that `Pointer::new` correctly creates an `Rc` wrapping the value.
#[test]
fn test_rc_pointer_new() {
let ptr = pointer_new::<RcBrand, _>(42);
assert_eq!(*ptr, 42);
}
/// Tests that `RefCountedPointer::new` correctly creates an `Rc` wrapping the value.
#[test]
fn test_rc_ref_counted_new() {
let ptr = ref_counted_pointer_new::<RcBrand, _>(42);
assert_eq!(*ptr, 42);
}
/// Tests that cloning the pointer works as expected (shared ownership).
#[test]
fn test_rc_clone() {
let ptr = ref_counted_pointer_new::<RcBrand, _>(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_rc_try_unwrap() {
let ptr = ref_counted_pointer_new::<RcBrand, _>(42);
assert_eq!(RcBrand::try_unwrap(ptr), Ok(42));
let ptr = ref_counted_pointer_new::<RcBrand, _>(42);
let _clone = ptr.clone();
assert!(RcBrand::try_unwrap(ptr).is_err());
}
}