Add trivial helper method to get the label count in a `Name`

[dnssec-prover] / src / rr.rs

diff --git a/src/rr.rs b/src/rr.rs
index c3367a642d3f38044b9226ad20e80360a4fb5a92..1755685cabb527075526cb8ec14a28d490117c1a 100644 (file)
--- a/src/rr.rs
+++ b/src/rr.rs
@@ -23,6 +23,27 @@ pub struct Name(String);
 impl Name {
        /// Gets the underlying human-readable domain name
        pub fn as_str(&self) -> &str { &self.0 }
+       /// Gets the number of labels in this name
+       pub fn labels(&self) -> u8 {
+               if self.as_str() == "." {
+                       0
+               } else {
+                       self.as_str().chars().filter(|c| *c == '.').count() as u8
+               }
+       }
+       /// Gets a string containing the last `n` labels in this [`Name`] (which is also a valid name).
+       pub fn trailing_n_labels(&self, n: u8) -> Option<&str> {
+               let labels = self.labels();
+               if n > labels {
+                       None
+               } else if n == labels {
+                       Some(self.as_str())
+               } else if n == 0 {
+                       Some(".")
+               } else {
+                       self.as_str().splitn(labels as usize - n as usize + 1, ".").last()
+               }
+       }
 }
 impl core::ops::Deref for Name {
        type Target = str;