impl: add PartialEq and PartialOrd instances for byte arrays [u8; N]

Add instances for `[u8; N]` and `&[u8; N]`, for convenience.

Closes #191

Author: joshtriplett

src/impls.rs

@@ -18,6 +18,26 @@ macro_rules! impl_partial_eq {
     };
 }
 
+macro_rules! impl_partial_eq_n {
+    ($lhs:ty, $rhs:ty) => {
+        impl<'a, 'b, const N: usize> PartialEq<$rhs> for $lhs {
+            #[inline]
+            fn eq(&self, other: &$rhs) -> bool {
+                let other: &[u8] = other.as_ref();
+                PartialEq::eq(self.as_bytes(), other)
+            }
+        }
+
+        impl<'a, 'b, const N: usize> PartialEq<$lhs> for $rhs {
+            #[inline]
+            fn eq(&self, other: &$lhs) -> bool {
+                let this: &[u8] = self.as_ref();
+                PartialEq::eq(this, other.as_bytes())
+            }
+        }
+    };
+}
+
 #[cfg(feature = "alloc")]
 macro_rules! impl_partial_eq_cow {
     ($lhs:ty, $rhs:ty) => {
@@ -59,6 +79,26 @@ macro_rules! impl_partial_ord {
     };
 }
 
+macro_rules! impl_partial_ord_n {
+    ($lhs:ty, $rhs:ty) => {
+        impl<'a, 'b, const N: usize> PartialOrd<$rhs> for $lhs {
+            #[inline]
+            fn partial_cmp(&self, other: &$rhs) -> Option<Ordering> {
+                let other: &[u8] = other.as_ref();
+                PartialOrd::partial_cmp(self.as_bytes(), other)
+            }
+        }
+
+        impl<'a, 'b, const N: usize> PartialOrd<$lhs> for $rhs {
+            #[inline]
+            fn partial_cmp(&self, other: &$lhs) -> Option<Ordering> {
+                let this: &[u8] = self.as_ref();
+                PartialOrd::partial_cmp(this, other.as_bytes())
+            }
+        }
+    };
+}
+
 #[cfg(feature = "alloc")]
 mod bstring {
     use core::{cmp::Ordering, fmt, hash, ops, str::FromStr};
@@ -368,6 +408,8 @@ mod bstring {
     impl_partial_eq!(BString, &'a str);
     impl_partial_eq!(BString, BStr);
     impl_partial_eq!(BString, &'a BStr);
+    impl_partial_eq_n!(BString, [u8; N]);
+    impl_partial_eq_n!(BString, &'a [u8; N]);
 
     impl hash::Hash for BString {
         #[inline]
@@ -398,6 +440,8 @@ mod bstring {
     impl_partial_ord!(BString, &'a str);
     impl_partial_ord!(BString, BStr);
     impl_partial_ord!(BString, &'a BStr);
+    impl_partial_ord_n!(BString, [u8; N]);
+    impl_partial_ord_n!(BString, &'a [u8; N]);
 }
 
 mod bstr {
@@ -821,6 +865,8 @@ mod bstr {
     impl_partial_eq!(BStr, &'a [u8]);
     impl_partial_eq!(BStr, str);
     impl_partial_eq!(BStr, &'a str);
+    impl_partial_eq_n!(BStr, [u8; N]);
+    impl_partial_eq_n!(BStr, &'a [u8; N]);
 
     #[cfg(feature = "alloc")]
     impl_partial_eq!(BStr, Vec<u8>);
@@ -862,6 +908,8 @@ mod bstr {
     impl_partial_ord!(BStr, &'a [u8]);
     impl_partial_ord!(BStr, str);
     impl_partial_ord!(BStr, &'a str);
+    impl_partial_ord_n!(BStr, [u8; N]);
+    impl_partial_ord_n!(BStr, &'a [u8; N]);
 
     #[cfg(feature = "alloc")]
     impl_partial_ord!(BStr, Vec<u8>);
@@ -1276,3 +1324,23 @@ fn test_cows_regression() {
     let c4 = "goodbye str";
     assert_ne!(c3, c4);
 }
+
+#[test]
+#[cfg(feature = "alloc")]
+fn test_eq_ord() {
+    use core::cmp::Ordering;
+
+    use crate::{BStr, BString};
+
+    let b = BStr::new("hello");
+    assert_eq!(b, b"hello");
+    assert_ne!(b, b"world");
+    assert_eq!(b.partial_cmp(b"hello"), Some(Ordering::Equal));
+    assert_eq!(b.partial_cmp(b"world"), Some(Ordering::Less));
+
+    let b = BString::from("hello");
+    assert_eq!(b, b"hello");
+    assert_ne!(b, b"world");
+    assert_eq!(b.partial_cmp(b"hello"), Some(Ordering::Equal));
+    assert_eq!(b.partial_cmp(b"world"), Some(Ordering::Less));
+}