openpgp: New type ID.

  - ID is either a KeyID or a Fingerprint.

  - Fixes #282.

2 files changed, 62 insertions, 0 deletions

diff --git a/openpgp/src/id.rs b/openpgp/src/id.rs
new file mode 100644
index 00000000..eafc3b20
--- /dev/null
+++ b/openpgp/src/id.rs
@@ -0,0 +1,60 @@
+use std::convert::TryFrom;
+
+use crate::{
+    Error,
+    Fingerprint,
+    KeyID,
+    Result,
+};
+
+/// Identifies OpenPGP keys.
+///
+/// An `ID` is either a `Fingerprint` or a `KeyID`.
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
+pub enum ID {
+    /// A Fingerprint.
+    Fingerprint(Fingerprint),
+    /// A KeyID.
+    KeyID(KeyID),
+}
+
+impl std::fmt::Display for ID {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self {
+            ID::Fingerprint(v) => v.fmt(f),
+            ID::KeyID(v) => v.fmt(f),
+        }
+    }
+}
+
+impl From<KeyID> for ID {
+    fn from(i: KeyID) -> Self {
+        ID::KeyID(i)
+    }
+}
+
+impl From<ID> for KeyID {
+    fn from(i: ID) -> Self {
+        match i {
+            ID::Fingerprint(i) => i.into(),
+            ID::KeyID(i) => i,
+        }
+    }
+}
+
+impl From<Fingerprint> for ID {
+    fn from(i: Fingerprint) -> Self {
+        ID::Fingerprint(i)
+    }
+}
+
+impl TryFrom<ID> for Fingerprint {
+    type Error = failure::Error;
+    fn try_from(i: ID) -> Result<Self> {
+        match i {
+            ID::Fingerprint(i) => Ok(i),
+            ID::KeyID(i) => Err(Error::InvalidOperation(
+                format!("Cannot convert keyid {} to fingerprint", i)).into()),
+        }
+    }
+}
diff --git a/openpgp/src/lib.rs b/openpgp/src/lib.rs
index 603d0744..058af071 100644
--- a/openpgp/src/lib.rs
+++ b/openpgp/src/lib.rs
@@ -145,6 +145,8 @@ use crate::types::{
 
 mod fingerprint;
 mod keyid;
+mod id;
+pub use id::ID;
 
 #[cfg(test)]
 mod tests;