From 25e548352502deab508f3843431ca34f288f895e Mon Sep 17 00:00:00 2001
From: Juliette Cordor <me@cordor.dev>
Date: Wed, 4 Dec 2024 12:40:14 +1100
Subject: [PATCH] added new map trait that replaces LockMap

---
 Cargo.toml              |  1 +
 src/traits/lock.rs      |  5 ++++
 src/traits/map.rs       | 41 ++++++++++++++++++++++++++++++
 src/traits/map/mutex.rs | 56 +++++++++++++++++++++++++++++++++++++++++
 src/traits/mod.rs       |  2 ++
 5 files changed, 105 insertions(+)
 create mode 100644 src/traits/map.rs
 create mode 100644 src/traits/map/mutex.rs

diff --git a/Cargo.toml b/Cargo.toml
index c221491..5a43aa3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,6 +20,7 @@ members = ["quork-proc"]
 [dependencies]
 cfg-if = "1.0"
 lock_api = { version = "0.4", optional = true }
+parking_lot = { version = "0.12", optional = true }
 quork-proc = { version = "0.3", path = "quork-proc", optional = true }
 spin = { version = "0.9", optional = true }
 thiserror = { version = "1.0" }
diff --git a/src/traits/lock.rs b/src/traits/lock.rs
index f094838..24f4aff 100644
--- a/src/traits/lock.rs
+++ b/src/traits/lock.rs
@@ -1,3 +1,8 @@
+#![deprecated(
+    since = "0.8.0",
+    note = "Use the `map::Map` trait instead. This trait will be removed in the future."
+)]
+
 //! Map a Mutex Lock
 //!
 //! Can theoretically be anything but designed primarily for Mutex Locks
diff --git a/src/traits/map.rs b/src/traits/map.rs
new file mode 100644
index 0000000..8927de8
--- /dev/null
+++ b/src/traits/map.rs
@@ -0,0 +1,41 @@
+//! Provides a generalized map function
+//!
+//! This is primarily designed for mapping Mutex types, but can realistically be used for anything in future.
+
+mod mutex;
+
+#[allow(clippy::module_name_repetitions)]
+/// Map a mutex lock
+pub trait Map<'a, 'g, T: ?Sized, G: 'g> {
+    /// Maps a value of T to a value of U
+    fn map<F, U>(&'a self, f: F) -> U
+    where
+        F: FnOnce(G) -> U + 'g,
+        'a: 'g;
+}
+
+#[allow(clippy::module_name_repetitions)]
+/// Attempts to map a mutex lock
+pub trait TryMap<'a, 'g, T: ?Sized, G: 'g, E = G> {
+    /// Maps a value of T to a value of U
+    ///
+    /// # Errors
+    /// - Locking the mutex failed
+    fn try_map<F, U>(&'a self, f: F) -> Result<U, E>
+    where
+        F: FnOnce(G) -> U + 'g,
+        'a: 'g;
+}
+
+// impl<'a, 'g, T: ?Sized, G: 'g, S> TryMap<'a, 'g, T, G> for S
+// where
+//     S: Map<'a, 'g, T, G>,
+// {
+//     fn try_map<F, U>(&'a self, f: F) -> Result<U, G>
+//     where
+//         F: FnOnce(G) -> U + 'g,
+//         'a: 'g,
+//     {
+//         Ok(self.map(f))
+//     }
+// }
diff --git a/src/traits/map/mutex.rs b/src/traits/map/mutex.rs
new file mode 100644
index 0000000..98a012f
--- /dev/null
+++ b/src/traits/map/mutex.rs
@@ -0,0 +1,56 @@
+#[cfg(feature = "parking_lot")]
+impl<'a, 'g, T> super::Map<'a, 'g, T, parking_lot::MutexGuard<'g, T>> for parking_lot::Mutex<T> {
+    fn map<F, U>(&'a self, f: F) -> U
+    where
+        F: FnOnce(parking_lot::MutexGuard<'g, T>) -> U,
+        'a: 'g,
+    {
+        f(self.lock())
+    }
+}
+
+#[cfg(feature = "parking_lot")]
+#[derive(Debug, thiserror::Error)]
+#[error("Failed to lock the mutex")]
+/// Failed to lock the mutex
+pub struct LockError;
+
+#[cfg(feature = "parking_lot")]
+impl<'a, 'g, T> super::TryMap<'a, 'g, T, parking_lot::MutexGuard<'g, T>, LockError>
+    for parking_lot::Mutex<T>
+{
+    fn try_map<F, U>(&'a self, f: F) -> Result<U, LockError>
+    where
+        F: FnOnce(parking_lot::MutexGuard<'g, T>) -> U,
+        'a: 'g,
+    {
+        match self.try_lock() {
+            Some(guard) => Ok(f(guard)),
+            None => Err(LockError),
+        }
+    }
+}
+
+impl<'a, 'g, T>
+    super::TryMap<
+        'a,
+        'g,
+        T,
+        std::sync::MutexGuard<'g, T>,
+        std::sync::TryLockError<std::sync::MutexGuard<'g, T>>,
+    > for std::sync::Mutex<T>
+{
+    fn try_map<F, U>(
+        &'a self,
+        f: F,
+    ) -> Result<U, std::sync::TryLockError<std::sync::MutexGuard<'g, T>>>
+    where
+        F: FnOnce(std::sync::MutexGuard<'g, T>) -> U,
+        'a: 'g,
+    {
+        match self.try_lock() {
+            Ok(guard) => Ok(f(guard)),
+            Err(e) => Err(e),
+        }
+    }
+}
diff --git a/src/traits/mod.rs b/src/traits/mod.rs
index 42e5333..a045fe6 100644
--- a/src/traits/mod.rs
+++ b/src/traits/mod.rs
@@ -6,6 +6,7 @@ cfg_if::cfg_if! {
         pub mod flip;
         pub mod lock;
         pub mod truncate;
+        pub mod map;
     }
 }
 
@@ -20,6 +21,7 @@ pub mod prelude {
             pub use super::flip::*;
             pub use super::lock::*;
             pub use super::truncate::*;
+            pub use super::map::*;
         }
     }