From 300f3a1b43d13b08b2dcd01bdfb992456e3cc012 Mon Sep 17 00:00:00 2001
From: oxalica <oxalicc@pm.me>
Date: Sat, 6 May 2023 21:15:49 +0800
Subject: [PATCH 1/5] Impl `ExactSizeIterator` for `IdxRange`

---
 lib/la-arena/src/lib.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/la-arena/src/lib.rs b/lib/la-arena/src/lib.rs
index b03fa5b61d..c793fff848 100644
--- a/lib/la-arena/src/lib.rs
+++ b/lib/la-arena/src/lib.rs
@@ -176,9 +176,14 @@ impl<T> IdxRange<T> {
 
 impl<T> Iterator for IdxRange<T> {
     type Item = Idx<T>;
+
     fn next(&mut self) -> Option<Self::Item> {
         self.range.next().map(|raw| Idx::from_raw(raw.into()))
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.range.size_hint()
+    }
 }
 
 impl<T> DoubleEndedIterator for IdxRange<T> {
@@ -187,6 +192,8 @@ impl<T> DoubleEndedIterator for IdxRange<T> {
     }
 }
 
+impl<T> ExactSizeIterator for IdxRange<T> {}
+
 impl<T> fmt::Debug for IdxRange<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_tuple(&format!("IdxRange::<{}>", std::any::type_name::<T>()))

From 4e4940e21ee2bdcdeb084e6d2ed675cdac746dfe Mon Sep 17 00:00:00 2001
From: oxalica <oxalicc@pm.me>
Date: Sat, 6 May 2023 21:21:00 +0800
Subject: [PATCH 2/5] Add `Arena::alloc_many` to easily get `IdxRange`

There are no currently ways to get `IdxRange` without manually offseting
`Idx`. Providing a method for multiple-allocation simplifies this
process and makes it less error-prone.
---
 lib/la-arena/src/lib.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/lib/la-arena/src/lib.rs b/lib/la-arena/src/lib.rs
index c793fff848..bb7f21788c 100644
--- a/lib/la-arena/src/lib.rs
+++ b/lib/la-arena/src/lib.rs
@@ -312,6 +312,21 @@ impl<T> Arena<T> {
         idx
     }
 
+    /// Densely allocates multiple values, returning the values’ index range.
+    ///
+    /// ```
+    /// let mut arena = la_arena::Arena::new();
+    /// let range = arena.alloc_many(0..4);
+    ///
+    /// assert_eq!(arena[range], [0, 1, 2, 3]);
+    /// ```
+    pub fn alloc_many<II: IntoIterator<Item = T>>(&mut self, iter: II) -> IdxRange<T> {
+        let start = self.next_idx();
+        self.extend(iter);
+        let end = self.next_idx();
+        IdxRange::new(start..end)
+    }
+
     /// Returns an iterator over the arena’s elements.
     ///
     /// ```

From 86eaf536004ef348df4b3490a81ccf16aeba440f Mon Sep 17 00:00:00 2001
From: oxalica <oxalicc@pm.me>
Date: Sat, 6 May 2023 21:27:35 +0800
Subject: [PATCH 3/5] Fix typo in docs

---
 lib/la-arena/src/lib.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/la-arena/src/lib.rs b/lib/la-arena/src/lib.rs
index bb7f21788c..eac9802e3e 100644
--- a/lib/la-arena/src/lib.rs
+++ b/lib/la-arena/src/lib.rs
@@ -168,7 +168,7 @@ impl<T> IdxRange<T> {
         Idx::from_raw(RawIdx::from(self.range.start))
     }
 
-    /// Returns the start of the index range.
+    /// Returns the end of the index range.
     pub fn end(&self) -> Idx<T> {
         Idx::from_raw(RawIdx::from(self.range.end))
     }

From 665c0cb547e044e6ff744e1b2c4b84e6232c97a6 Mon Sep 17 00:00:00 2001
From: oxalica <oxalicc@pm.me>
Date: Sat, 6 May 2023 21:59:03 +0800
Subject: [PATCH 4/5] Forward `Iterator::{count,last,nth}` for `IdxRange`
 random access

---
 lib/la-arena/src/lib.rs | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/lib/la-arena/src/lib.rs b/lib/la-arena/src/lib.rs
index eac9802e3e..63827e0ba9 100644
--- a/lib/la-arena/src/lib.rs
+++ b/lib/la-arena/src/lib.rs
@@ -184,6 +184,24 @@ impl<T> Iterator for IdxRange<T> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.range.size_hint()
     }
+
+    fn count(self) -> usize
+    where
+        Self: Sized,
+    {
+        self.range.count()
+    }
+
+    fn last(self) -> Option<Self::Item>
+    where
+        Self: Sized,
+    {
+        self.range.last().map(|raw| Idx::from_raw(raw.into()))
+    }
+
+    fn nth(&mut self, n: usize) -> Option<Self::Item> {
+        self.range.nth(n).map(|raw| Idx::from_raw(raw.into()))
+    }
 }
 
 impl<T> DoubleEndedIterator for IdxRange<T> {

From add94d3b9ca53921796ad1336aa67701b6cf888a Mon Sep 17 00:00:00 2001
From: oxalica <oxalicc@pm.me>
Date: Sat, 6 May 2023 22:02:30 +0800
Subject: [PATCH 5/5] Impl `FusedIterator` for `IdxRange`

---
 lib/la-arena/src/lib.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/la-arena/src/lib.rs b/lib/la-arena/src/lib.rs
index 63827e0ba9..1f8ef01a5b 100644
--- a/lib/la-arena/src/lib.rs
+++ b/lib/la-arena/src/lib.rs
@@ -6,7 +6,7 @@
 use std::{
     cmp, fmt,
     hash::{Hash, Hasher},
-    iter::Enumerate,
+    iter::{Enumerate, FusedIterator},
     marker::PhantomData,
     ops::{Index, IndexMut, Range, RangeInclusive},
 };
@@ -212,6 +212,8 @@ impl<T> DoubleEndedIterator for IdxRange<T> {
 
 impl<T> ExactSizeIterator for IdxRange<T> {}
 
+impl<T> FusedIterator for IdxRange<T> {}
+
 impl<T> fmt::Debug for IdxRange<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_tuple(&format!("IdxRange::<{}>", std::any::type_name::<T>()))