1 files changed, 31 insertions, 0 deletions
diff --git a/third_party/rust/indexmap/src/util.rs b/third_party/rust/indexmap/src/util.rs
new file mode 100644
index 0000000000..a24dfafde7
--- /dev/null
+++ b/third_party/rust/indexmap/src/util.rs
@@ -0,0 +1,31 @@
+use core::ops::{Bound, Range, RangeBounds};
+
+pub(crate) fn third<A, B, C>(t: (A, B, C)) -> C {
+    t.2
+}
+
+pub(crate) fn simplify_range<R>(range: R, len: usize) -> Range<usize>
+where
+    R: RangeBounds<usize>,
+{
+    let start = match range.start_bound() {
+        Bound::Unbounded => 0,
+        Bound::Included(&i) if i <= len => i,
+        Bound::Excluded(&i) if i < len => i + 1,
+        bound => panic!("range start {:?} should be <= length {}", bound, len),
+    };
+    let end = match range.end_bound() {
+        Bound::Unbounded => len,
+        Bound::Excluded(&i) if i <= len => i,
+        Bound::Included(&i) if i < len => i + 1,
+        bound => panic!("range end {:?} should be <= length {}", bound, len),
+    };
+    if start > end {
+        panic!(
+            "range start {:?} should be <= range end {:?}",
+            range.start_bound(),
+            range.end_bound()
+        );
+    }
+    start..end
+}