Add Limit struct.

Fixes #9286.

crates/limit/src/lib.rs

@@ -0,0 +1,31 @@
+//! limit defines a struct to enforce limits.
+
+/// Represents a struct used to enforce a numerical limit.
+pub struct Limit {
+    upper_bound: usize,
+}
+
+impl Limit {
+    /// Creates a new limit.
+    #[inline]
+    pub const fn new(upper_bound: usize) -> Self {
+        Self { upper_bound }
+    }
+
+    /// Gets the underlying numeric limit.
+    #[inline]
+    pub const fn inner(&self) -> usize {
+        self.upper_bound
+    }
+
+    /// Checks whether the given value is below the limit.
+    /// Returns `Ok` when `other` is below `self`, and `Err` otherwise.
+    #[inline]
+    pub const fn check(&self, other: usize) -> Result<(), ()> {
+        if other > self.upper_bound {
+            Err(())
+        } else {
+            Ok(())
+        }
+    }
+}