simple union-find implementation HEAD canon

Change-Id: I32b78b3eee68205032591578fca70c366a6a6964

1 files changed, 27 insertions, 5 deletions

diff --git a/crates/core/src/utilities.rs b/crates/core/src/utilities.rs
index 583ad7c..b6bb86d 100644
--- a/crates/core/src/utilities.rs
+++ b/crates/core/src/utilities.rs
@@ -34,7 +34,7 @@ where
 }
 
 /// Extension trait for wrapping arithmetic.
-pub trait WrappingArithmeticExt {
+pub const trait WrappingArithmeticExt {
     /// Wrapping integer increment.
     fn wrapping_increment(self) -> Self;
 
@@ -50,7 +50,7 @@ pub trait WrappingArithmeticExt {
 
 macro_rules! wrapping_arithmetic_ext_impl {
     ($t:ty) => {
-        impl WrappingArithmeticExt for $t {
+        impl const WrappingArithmeticExt for $t {
             fn wrapping_increment(self) -> Self {
                 self.wrapping_add(1)
             }
@@ -84,7 +84,7 @@ wrapping_arithmetic_ext_impl!(i8);
 
 /// Extension trait for checked arithmetic that turns the output into a
 /// [`Result`].
-pub trait CheckedArithmeticExt: Sized {
+pub const trait CheckedArithmeticExt: Sized {
     /// Checked integer addition.
     ///
     /// # Errors
@@ -92,6 +92,13 @@ pub trait CheckedArithmeticExt: Sized {
     /// Returns an error if the result would have overflowed.
     fn errored_add(self, rhs: Self) -> Result<Self, IntegerOverflowError>;
 
+    /// Checked integer decrement.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the result would have overflowed.
+    fn errored_decrement(self) -> Result<Self, IntegerOverflowError>;
+
     /// Checked integer division.
     ///
     /// # Errors
@@ -99,6 +106,13 @@ pub trait CheckedArithmeticExt: Sized {
     /// Returns an error if the result would have overflowed.
     fn errored_div(self, rhs: Self) -> Result<Self, IntegerOverflowError>;
 
+    /// Checked integer increment.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the result would have overflowed.
+    fn errored_increment(self) -> Result<Self, IntegerOverflowError>;
+
     /// Checked integer multiplication.
     ///
     /// # Errors
@@ -123,7 +137,7 @@ pub trait CheckedArithmeticExt: Sized {
 
 macro_rules! checked_arithmetic_ext_impl {
     ($t:ty) => {
-        impl CheckedArithmeticExt for $t {
+        impl const CheckedArithmeticExt for $t {
             fn errored_add(
                 self,
                 rhs: Self,
@@ -131,6 +145,10 @@ macro_rules! checked_arithmetic_ext_impl {
                 self.checked_add(rhs).ok_or(IntegerOverflowError)
             }
 
+            fn errored_decrement(self) -> Result<Self, IntegerOverflowError> {
+                self.errored_sub(1)
+            }
+
             fn errored_div(
                 self,
                 rhs: Self,
@@ -138,6 +156,10 @@ macro_rules! checked_arithmetic_ext_impl {
                 self.checked_div(rhs).ok_or(IntegerOverflowError)
             }
 
+            fn errored_increment(self) -> Result<Self, IntegerOverflowError> {
+                self.errored_add(1)
+            }
+
             fn errored_mul(
                 self,
                 rhs: Self,
@@ -175,7 +197,7 @@ checked_arithmetic_ext_impl!(i16);
 checked_arithmetic_ext_impl!(i8);
 
 /// Representation of an integer overflow error.
-#[derive(PartialEq, Eq)]
+#[derive(Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "core-fmt", derive(Debug))]
 pub struct IntegerOverflowError;