feat(core): require Default for *LockState, add IntervalRwLockCore::INIT

Author: yvt

src/core/mod.rs

@@ -41,22 +41,25 @@ pub trait IntervalRwLockCore {
 
     /// The storage for per-lock data. Dropping it while it has an associated
     /// lock will cause a panic.
-    type ReadLockState;
+    type ReadLockState: Default;
 
     /// Ditto for writer locks.
-    type WriteLockState;
+    type WriteLockState: Default;
 
     /// Ditto for non-blocking reader locks.
-    type TryReadLockState;
+    type TryReadLockState: Default;
 
     /// Ditto for non-blocking writer locks.
-    type TryWriteLockState;
+    type TryWriteLockState: Default;
 
     /// Created by a `LockCallback` implementation when a lock operation is
     /// blocked in the middle. It will later be passed to [`UnlockCallback::
     /// complete`] when the lock completes.
     type InProgress;
 
+    /// The initializer.
+    const INIT: Self;
+
     /// Acquire a reader lock.
     fn lock_read<Callback: LockCallback<Self::InProgress>>(
         self: Pin<&mut Self>,

src/core/rbtree.rs

@@ -352,6 +352,8 @@ where
     type TryWriteLockState = TryWriteLockState<Index, Priority, InProgress>;
     type InProgress = InProgress;
 
+    const INIT: Self = Self::new();
+
     fn lock_read<Callback: LockCallback<Self::InProgress>>(
         self: Pin<&mut Self>,
         range: Range<Self::Index>,