der: const Any::to_ref, BytesOwned::to_ref

der/src/asn1/any.rs

@@ -233,6 +233,14 @@ mod allocating {
                 value: BytesOwned::default(),
             }
         }
+
+        /// Create a new [`AnyRef`] from the provided [`Any`] owned tag and bytes.
+        pub const fn to_ref(&self) -> AnyRef<'_> {
+            AnyRef {
+                tag: self.tag,
+                value: self.value.to_ref(),
+            }
+        }
     }
 
     impl Choice<'_> for Any {
@@ -272,7 +280,7 @@ mod allocating {
     impl<'a> From<&'a Any> for AnyRef<'a> {
         fn from(any: &'a Any) -> AnyRef<'a> {
             // Ensured to parse successfully in constructor
-            AnyRef::new(any.tag, any.value.as_slice()).expect("invalid ANY")
+            any.to_ref()
         }
     }
 

der/src/bytes_owned.rs

@@ -31,18 +31,26 @@ impl BytesOwned {
     }
 
     /// Borrow the inner byte slice
-    pub fn as_slice(&self) -> &[u8] {
+    pub const fn as_slice(&self) -> &[u8] {
         &self.inner
     }
 
     /// Get the [`Length`] of this [`BytesRef`]
-    pub fn len(&self) -> Length {
+    pub const fn len(&self) -> Length {
         self.length
     }
 
     /// Is this [`BytesOwned`] empty?
-    pub fn is_empty(&self) -> bool {
-        self.len() == Length::ZERO
+    pub const fn is_empty(&self) -> bool {
+        self.len().is_zero()
+    }
+
+    /// Create [`BytesRef`] from allocated [`BytesOwned`].
+    pub const fn to_ref(&self) -> BytesRef<'_> {
+        BytesRef {
+            length: self.length,
+            inner: &self.inner,
+        }
     }
 }
 

der/src/length.rs

@@ -52,8 +52,9 @@ impl Length {
     }
 
     /// Is this length equal to zero?
-    pub fn is_zero(self) -> bool {
-        self == Self::ZERO
+    pub const fn is_zero(self) -> bool {
+        let value = self.0;
+        value == 0
     }
 
     /// Get the length of DER Tag-Length-Value (TLV) encoded data if `self`