refactor generational box into multiple files

packages/generational-box/src/references.rs

@@ -0,0 +1,169 @@
+use std::{
+    marker::PhantomData,
+    ops::{Deref, DerefMut},
+};
+
+use crate::{Mappable, MappableMut, MemoryLocationBorrowInfo};
+
+/// A reference to a value in a generational box.
+pub struct GenerationalRef<T: 'static, R: Mappable<T>> {
+    inner: R,
+    phantom: PhantomData<T>,
+    #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+    borrow: GenerationalRefBorrowInfo,
+}
+
+impl<T: 'static, R: Mappable<T>> GenerationalRef<T, R> {
+    pub(crate) fn new(
+        inner: R,
+        #[cfg(any(debug_assertions, feature = "debug_borrows"))] borrow: GenerationalRefBorrowInfo,
+    ) -> Self {
+        Self {
+            inner,
+            phantom: PhantomData,
+            #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+            borrow,
+        }
+    }
+}
+
+impl<T: 'static, R: Mappable<T>> Mappable<T> for GenerationalRef<T, R> {
+    type Mapped<U: 'static> = GenerationalRef<U, R::Mapped<U>>;
+
+    fn map<U: 'static>(_self: Self, f: impl FnOnce(&T) -> &U) -> Self::Mapped<U> {
+        GenerationalRef {
+            inner: R::map(_self.inner, f),
+            phantom: PhantomData,
+            #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+            borrow: GenerationalRefBorrowInfo {
+                borrowed_at: _self.borrow.borrowed_at,
+                borrowed_from: _self.borrow.borrowed_from,
+            },
+        }
+    }
+
+    fn try_map<U: 'static>(
+        _self: Self,
+        f: impl FnOnce(&T) -> Option<&U>,
+    ) -> Option<Self::Mapped<U>> {
+        let Self {
+            inner,
+            #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+            borrow,
+            ..
+        } = _self;
+        R::try_map(inner, f).map(|inner| GenerationalRef {
+            inner,
+            phantom: PhantomData,
+            #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+            borrow: GenerationalRefBorrowInfo {
+                borrowed_at: borrow.borrowed_at,
+                borrowed_from: borrow.borrowed_from,
+            },
+        })
+    }
+}
+
+impl<T: 'static, R: Mappable<T>> Deref for GenerationalRef<T, R> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        self.inner.deref()
+    }
+}
+
+#[cfg(any(debug_assertions, feature = "debug_borrows"))]
+pub(crate) struct GenerationalRefBorrowInfo {
+    pub(crate) borrowed_at: &'static std::panic::Location<'static>,
+    pub(crate) borrowed_from: &'static MemoryLocationBorrowInfo,
+}
+
+#[cfg(any(debug_assertions, feature = "debug_borrows"))]
+impl Drop for GenerationalRefBorrowInfo {
+    fn drop(&mut self) {
+        self.borrowed_from
+            .borrowed_at
+            .write()
+            .retain(|location| std::ptr::eq(*location, self.borrowed_at as *const _));
+    }
+}
+
+/// A mutable reference to a value in a generational box.
+pub struct GenerationalRefMut<T: 'static, W: MappableMut<T>> {
+    inner: W,
+    phantom: PhantomData<T>,
+    #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+    borrow: GenerationalRefMutBorrowInfo,
+}
+
+impl<T: 'static, R: MappableMut<T>> GenerationalRefMut<T, R> {
+    pub(crate) fn new(
+        inner: R,
+        #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+        borrow: GenerationalRefMutBorrowInfo,
+    ) -> Self {
+        Self {
+            inner,
+            phantom: PhantomData,
+            #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+            borrow,
+        }
+    }
+}
+
+impl<T: 'static, W: MappableMut<T>> MappableMut<T> for GenerationalRefMut<T, W> {
+    type Mapped<U: 'static> = GenerationalRefMut<U, W::Mapped<U>>;
+
+    fn map<U: 'static>(_self: Self, f: impl FnOnce(&mut T) -> &mut U) -> Self::Mapped<U> {
+        GenerationalRefMut {
+            inner: W::map(_self.inner, f),
+            phantom: PhantomData,
+            #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+            borrow: _self.borrow,
+        }
+    }
+
+    fn try_map<U: 'static>(
+        _self: Self,
+        f: impl FnOnce(&mut T) -> Option<&mut U>,
+    ) -> Option<Self::Mapped<U>> {
+        let Self {
+            inner,
+            #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+            borrow,
+            ..
+        } = _self;
+        W::try_map(inner, f).map(|inner| GenerationalRefMut {
+            inner,
+            phantom: PhantomData,
+            #[cfg(any(debug_assertions, feature = "debug_borrows"))]
+            borrow,
+        })
+    }
+}
+
+impl<T: 'static, W: MappableMut<T>> Deref for GenerationalRefMut<T, W> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        self.inner.deref()
+    }
+}
+
+impl<T: 'static, W: MappableMut<T>> DerefMut for GenerationalRefMut<T, W> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        self.inner.deref_mut()
+    }
+}
+
+#[cfg(any(debug_assertions, feature = "debug_borrows"))]
+pub(crate) struct GenerationalRefMutBorrowInfo {
+    pub(crate) borrowed_from: &'static MemoryLocationBorrowInfo,
+}
+
+#[cfg(any(debug_assertions, feature = "debug_borrows"))]
+impl Drop for GenerationalRefMutBorrowInfo {
+    fn drop(&mut self) {
+        self.borrowed_from.borrowed_mut_at.write().take();
+    }
+}