Support transaction signing by heterogenous lists of keypairs (#8342)

automerge

sdk/src/signers.rs

@@ -0,0 +1,97 @@
+use crate::{
+    pubkey::Pubkey,
+    signature::{KeypairUtil, Signature},
+};
+
+pub trait Signers {
+    fn pubkeys(&self) -> Vec<Pubkey>;
+    fn sign_message(&self, message: &[u8]) -> Vec<Signature>;
+}
+
+macro_rules! default_keypairs_impl {
+    () => (
+            fn pubkeys(&self) -> Vec<Pubkey> {
+                self.iter().map(|keypair| keypair.pubkey()).collect()
+            }
+
+            fn sign_message(&self, message: &[u8]) -> Vec<Signature> {
+                self.iter()
+                    .map(|keypair| keypair.sign_message(message))
+                    .collect()
+            }
+    );
+}
+
+impl<T: KeypairUtil> Signers for [&T] {
+    default_keypairs_impl!();
+}
+
+impl Signers for [Box<dyn KeypairUtil>] {
+    default_keypairs_impl!();
+}
+
+impl<T: KeypairUtil> Signers for [&T; 0] {
+    default_keypairs_impl!();
+}
+
+impl<T: KeypairUtil> Signers for [&T; 1] {
+    default_keypairs_impl!();
+}
+
+impl<T: KeypairUtil> Signers for [&T; 2] {
+    default_keypairs_impl!();
+}
+
+impl<T: KeypairUtil> Signers for [&T; 3] {
+    default_keypairs_impl!();
+}
+
+impl<T: KeypairUtil> Signers for [&T; 4] {
+    default_keypairs_impl!();
+}
+
+impl<T: KeypairUtil> Signers for Vec<&T> {
+    default_keypairs_impl!();
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::error;
+
+    struct Foo;
+    impl KeypairUtil for Foo {
+        fn try_pubkey(&self) -> Result<Pubkey, Box<dyn error::Error>> {
+            Ok(Pubkey::default())
+        }
+        fn try_sign_message(&self, _message: &[u8]) -> Result<Signature, Box<dyn error::Error>> {
+            Ok(Signature::default())
+        }
+    }
+
+    struct Bar;
+    impl KeypairUtil for Bar {
+        fn try_pubkey(&self) -> Result<Pubkey, Box<dyn error::Error>> {
+            Ok(Pubkey::default())
+        }
+        fn try_sign_message(&self, _message: &[u8]) -> Result<Signature, Box<dyn error::Error>> {
+            Ok(Signature::default())
+        }
+    }
+
+    #[test]
+    fn test_dyn_keypairs_compile() {
+        let xs: Vec<Box<dyn KeypairUtil>> = vec![Box::new(Foo {}), Box::new(Bar {})];
+        assert_eq!(
+            xs.sign_message(b""),
+            vec![Signature::default(), Signature::default()],
+        );
+
+        // Same as above, but less compiler magic.
+        let xs_ref: &[Box<dyn KeypairUtil>] = &xs;
+        assert_eq!(
+            Signers::sign_message(xs_ref, b""),
+            vec![Signature::default(), Signature::default()],
+        );
+    }
+}