const-oid: add ObjectIdentifier::parent

const-oid/src/lib.rs

@@ -105,10 +105,10 @@ impl ObjectIdentifier {
     }
 
     /// Parse an OID from a slice of [`Arc`] values (i.e. integers).
-    pub fn from_arcs<'a>(arcs: impl IntoIterator<Item = &'a Arc>) -> Result<Self> {
+    pub fn from_arcs(arcs: impl IntoIterator<Item = Arc>) -> Result<Self> {
         let mut encoder = Encoder::new();
 
-        for &arc in arcs {
+        for arc in arcs {
             encoder = encoder.arc(arc)?;
         }
 
@@ -158,6 +158,17 @@ impl ObjectIdentifier {
         Arcs::new(self)
     }
 
+    /// Get the length of this [`ObjectIdentifier`] in arcs.
+    pub fn len(&self) -> usize {
+        self.arcs().count()
+    }
+
+    /// Get the parent OID of this one (if applicable).
+    pub fn parent(&self) -> Option<Self> {
+        let num_arcs = self.len().checked_sub(1)?;
+        Self::from_arcs(self.arcs().take(num_arcs)).ok()
+    }
+
     /// Push an additional arc onto this OID, returning the child OID.
     pub const fn push_arc(self, arc: Arc) -> Result<Self> {
         // TODO(tarcieri): use `?` when stable in `const fn`

const-oid/tests/lib.rs

@@ -115,24 +115,24 @@ fn display() {
 
 #[test]
 fn try_from_u32_slice() {
-    let oid1 = ObjectIdentifier::from_arcs(&[1, 2, 840, 10045, 2, 1]).unwrap();
+    let oid1 = ObjectIdentifier::from_arcs([1, 2, 840, 10045, 2, 1]).unwrap();
     assert_eq!(oid1.arc(0).unwrap(), 1);
     assert_eq!(oid1.arc(1).unwrap(), 2);
     assert_eq!(EXAMPLE_OID_1, oid1);
 
-    let oid2 = ObjectIdentifier::from_arcs(&[2, 16, 840, 1, 101, 3, 4, 1, 42]).unwrap();
+    let oid2 = ObjectIdentifier::from_arcs([2, 16, 840, 1, 101, 3, 4, 1, 42]).unwrap();
     assert_eq!(oid2.arc(0).unwrap(), 2);
     assert_eq!(oid2.arc(1).unwrap(), 16);
     assert_eq!(EXAMPLE_OID_2, oid2);
 
     // Too short
-    assert!(ObjectIdentifier::from_arcs(&[1, 2]).is_err());
+    assert!(ObjectIdentifier::from_arcs([1, 2]).is_err());
 
     // Invalid first arc
-    assert!(ObjectIdentifier::from_arcs(&[3, 2, 840, 10045, 3, 1, 7]).is_err());
+    assert!(ObjectIdentifier::from_arcs([3, 2, 840, 10045, 3, 1, 7]).is_err());
 
     // Invalid second arc
-    assert!(ObjectIdentifier::from_arcs(&[1, 40, 840, 10045, 3, 1, 7]).is_err());
+    assert!(ObjectIdentifier::from_arcs([1, 40, 840, 10045, 3, 1, 7]).is_err());
 }
 
 #[test]
@@ -167,11 +167,19 @@ fn parse_invalid_second_arc() {
     );
 }
 
+#[test]
+fn parent() {
+    let oid = ObjectIdentifier::new("1.2.3.4").unwrap();
+    let parent = oid.parent().unwrap();
+    assert_eq!(parent, ObjectIdentifier::new("1.2.3").unwrap());
+    assert_eq!(parent.parent(), None);
+}
+
 #[test]
 fn push_arc() {
-    let oid = ObjectIdentifier::new_unwrap("1.2.3");
+    let oid = ObjectIdentifier::new("1.2.3").unwrap();
     assert_eq!(
         oid.push_arc(4).unwrap(),
-        ObjectIdentifier::new_unwrap("1.2.3.4")
+        ObjectIdentifier::new("1.2.3.4").unwrap()
     );
 }