Replace serde macros with generic visitor module

Co-authored-by: Elichai Turkel <elichai.turkel@gmail.com>
Co-authored-by: Sebastian Geisler <sebastian@blockstream.io>

src/key.rs

@@ -213,7 +213,32 @@ impl SecretKey {
     }
 }
 
-serde_impl!(SecretKey, constants::SECRET_KEY_SIZE);
+#[cfg(feature = "serde")]
+impl ::serde::Serialize for SecretKey {
+    fn serialize<S: ::serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        if s.is_human_readable() {
+            s.collect_str(self)
+        } else {
+            s.serialize_bytes(&self[..])
+        }
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de> ::serde::Deserialize<'de> for SecretKey {
+    fn deserialize<D: ::serde::Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        if d.is_human_readable() {
+            d.deserialize_str(super::serde_util::HexVisitor::new(
+                "a hex string representing 32 byte SecretKey"
+            ))
+        } else {
+            d.deserialize_bytes(super::serde_util::BytesVisitor::new(
+                "raw 32 bytes SecretKey",
+                SecretKey::from_slice
+            ))
+        }
+    }
+}
 
 impl PublicKey {
     /// Obtains a raw const pointer suitable for use with FFI functions
@@ -402,7 +427,32 @@ impl From<ffi::PublicKey> for PublicKey {
     }
 }
 
-serde_impl_from_slice!(PublicKey);
+#[cfg(feature = "serde")]
+impl ::serde::Serialize for PublicKey {
+    fn serialize<S: ::serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        if s.is_human_readable() {
+            s.collect_str(self)
+        } else {
+            s.serialize_bytes(&self.serialize())
+        }
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de> ::serde::Deserialize<'de> for PublicKey {
+    fn deserialize<D: ::serde::Deserializer<'de>>(d: D) -> Result<PublicKey, D::Error> {
+        if d.is_human_readable() {
+            d.deserialize_str(super::serde_util::HexVisitor::new(
+                "an ASCII hex string representing a public key"
+            ))
+        } else {
+            d.deserialize_bytes(super::serde_util::BytesVisitor::new(
+                "a bytestring representing a public key",
+                PublicKey::from_slice
+            ))
+        }
+    }
+}
 
 impl PartialOrd for PublicKey {
     fn partial_cmp(&self, other: &PublicKey) -> Option<::core::cmp::Ordering> {
@@ -846,8 +896,20 @@ mod test {
         let pk = PublicKey::from_secret_key(&s, &sk);
 
         assert_tokens(&sk.compact(), &[Token::BorrowedBytes(&SK_BYTES[..])]);
+        assert_tokens(&sk.compact(), &[Token::Bytes(&SK_BYTES)]);
+        assert_tokens(&sk.compact(), &[Token::ByteBuf(&SK_BYTES)]);
+
         assert_tokens(&sk.readable(), &[Token::BorrowedStr(SK_STR)]);
+        assert_tokens(&sk.readable(), &[Token::Str(SK_STR)]);
+        assert_tokens(&sk.readable(), &[Token::String(SK_STR)]);
+
         assert_tokens(&pk.compact(), &[Token::BorrowedBytes(&PK_BYTES[..])]);
+        assert_tokens(&pk.compact(), &[Token::Bytes(&PK_BYTES)]);
+        assert_tokens(&pk.compact(), &[Token::ByteBuf(&PK_BYTES)]);
+
         assert_tokens(&pk.readable(), &[Token::BorrowedStr(PK_STR)]);
+        assert_tokens(&pk.readable(), &[Token::Str(PK_STR)]);
+        assert_tokens(&pk.readable(), &[Token::String(PK_STR)]);
+
     }
 }

src/lib.rs

@@ -147,6 +147,8 @@ pub mod key;
 pub mod schnorrsig;
 #[cfg(feature = "recovery")]
 pub mod recovery;
+#[cfg(feature = "serde")]
+mod serde_util;
 
 pub use key::SecretKey;
 pub use key::PublicKey;
@@ -435,21 +437,21 @@ impl ::serde::Serialize for Signature {
         } else {
             s.serialize_bytes(&self.serialize_der())
         }
-
     }
 }
 
 #[cfg(feature = "serde")]
 impl<'de> ::serde::Deserialize<'de> for Signature {
-    fn deserialize<D: ::serde::Deserializer<'de>>(d: D) -> Result<Signature, D::Error> {
+    fn deserialize<D: ::serde::Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
-        use ::serde::de::Error;
-        use str::FromStr;
         if d.is_human_readable() {
-            let sl: &str = ::serde::Deserialize::deserialize(d)?;
+            d.deserialize_str(serde_util::HexVisitor::new(
-            Signature::from_str(sl).map_err(D::Error::custom)
+                "a hex string representing a DER encoded Signature"
+            ))
         } else {
-            let sl: &[u8] = ::serde::Deserialize::deserialize(d)?;
+            d.deserialize_bytes(serde_util::BytesVisitor::new(
-            Signature::from_der(sl).map_err(D::Error::custom)
+                "raw byte stream, that represents a DER encoded Signature",
+                Signature::from_der
+            ))
         }
     }
 }
@@ -1260,7 +1262,13 @@ mod tests {
         ";
 
         assert_tokens(&sig.compact(), &[Token::BorrowedBytes(&SIG_BYTES[..])]);
+        assert_tokens(&sig.compact(), &[Token::Bytes(&SIG_BYTES)]);
+        assert_tokens(&sig.compact(), &[Token::ByteBuf(&SIG_BYTES)]);
+
         assert_tokens(&sig.readable(), &[Token::BorrowedStr(SIG_STR)]);
+        assert_tokens(&sig.readable(), &[Token::Str(SIG_STR)]);
+        assert_tokens(&sig.readable(), &[Token::String(SIG_STR)]);
+
     }
 
     #[cfg(feature = "global-context")]

src/macros.rs

@@ -43,121 +43,3 @@ macro_rules! impl_from_array_len {
         )+
     }
 }
-
-#[cfg(feature="serde")]
-/// Implements `Serialize` and `Deserialize` for a type `$t` which represents
-/// a newtype over a byte-slice over length `$len`. Type `$t` must implement
-/// the `FromStr` and `Display` trait.
-macro_rules! serde_impl(
-    ($t:ident, $len:expr) => (
-        impl ::serde::Serialize for $t {
-            fn serialize<S: ::serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
-                if s.is_human_readable() {
-                    s.collect_str(self)
-                } else {
-                    s.serialize_bytes(&self[..])
-                }
-            }
-        }
-
-        impl<'de> ::serde::Deserialize<'de> for $t {
-            fn deserialize<D: ::serde::Deserializer<'de>>(d: D) -> Result<$t, D::Error> {
-                use ::serde::de::Error;
-                use core::str::FromStr;
-
-                if d.is_human_readable() {
-                    let sl: &str = ::serde::Deserialize::deserialize(d)?;
-                    $t::from_str(sl).map_err(D::Error::custom)
-                } else {
-                    let sl: &[u8] = ::serde::Deserialize::deserialize(d)?;
-                    if sl.len() != $len {
-                        Err(D::Error::invalid_length(sl.len(), &stringify!($len)))
-                    } else {
-                        let mut ret = [0; $len];
-                        ret.copy_from_slice(sl);
-                        Ok($t(ret))
-                    }
-                }
-            }
-        }
-    )
-);
-
-#[cfg(not(feature="serde"))]
-macro_rules! serde_impl(
-    ($t:ident, $len:expr) => ()
-);
-
-#[cfg(feature = "serde")]
-macro_rules! serde_impl_from_slice {
-    ($t: ident) => {
-        impl ::serde::Serialize for $t {
-            fn serialize<S: ::serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
-                if s.is_human_readable() {
-                    s.collect_str(self)
-                } else {
-                    s.serialize_bytes(&self.serialize())
-                }
-            }
-        }
-
-        impl<'de> ::serde::Deserialize<'de> for $t {
-            fn deserialize<D: ::serde::Deserializer<'de>>(d: D) -> Result<$t, D::Error> {
-                if d.is_human_readable() {
-                    struct HexVisitor;
-
-                    impl<'de> ::serde::de::Visitor<'de> for HexVisitor {
-                        type Value = $t;
-
-                        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                            formatter.write_str("an ASCII hex string")
-                        }
-
-                        fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
-                        where
-                            E: ::serde::de::Error,
-                        {
-                            if let Ok(hex) = str::from_utf8(v) {
-                                str::FromStr::from_str(hex).map_err(E::custom)
-                            } else {
-                                Err(E::invalid_value(::serde::de::Unexpected::Bytes(v), &self))
-                            }
-                        }
-
-                        fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
-                        where
-                            E: ::serde::de::Error,
-                        {
-                            str::FromStr::from_str(v).map_err(E::custom)
-                        }
-                    }
-                    d.deserialize_str(HexVisitor)
-                } else {
-                    struct BytesVisitor;
-
-                    impl<'de> ::serde::de::Visitor<'de> for BytesVisitor {
-                        type Value = $t;
-
-                        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                            formatter.write_str("a bytestring")
-                        }
-
-                        fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
-                        where
-                            E: ::serde::de::Error,
-                        {
-                            $t::from_slice(v).map_err(E::custom)
-                        }
-                    }
-
-                    d.deserialize_bytes(BytesVisitor)
-                }
-            }
-        }
-    };
-}
-
-#[cfg(not(feature = "serde"))]
-macro_rules! serde_impl_from_slice(
-    ($t:ident) => ()
-);

src/schnorrsig.rs

@@ -18,7 +18,33 @@ use {Message, Signing, Verification};
 pub struct Signature([u8; constants::SCHNORRSIG_SIGNATURE_SIZE]);
 impl_array_newtype!(Signature, u8, constants::SCHNORRSIG_SIGNATURE_SIZE);
 impl_pretty_debug!(Signature);
-serde_impl!(Signature, constants::SCHNORRSIG_SIGNATURE_SIZE);
+
+#[cfg(feature = "serde")]
+impl ::serde::Serialize for Signature {
+    fn serialize<S: ::serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        if s.is_human_readable() {
+            s.collect_str(self)
+        } else {
+            s.serialize_bytes(&self[..])
+        }
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de> ::serde::Deserialize<'de> for Signature {
+    fn deserialize<D: ::serde::Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        if d.is_human_readable() {
+            d.deserialize_str(super::serde_util::HexVisitor::new(
+                "a hex string representing 64 byte schnorr signature"
+            ))
+        } else {
+            d.deserialize_bytes(super::serde_util::BytesVisitor::new(
+                "raw 64 bytes schnorr signature",
+                Signature::from_slice
+            ))
+        }
+    }
+}
 
 impl fmt::LowerHex for Signature {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
@@ -376,7 +402,32 @@ impl From<::key::PublicKey> for PublicKey {
     }
 }
 
-serde_impl_from_slice!(PublicKey);
+#[cfg(feature = "serde")]
+impl ::serde::Serialize for PublicKey {
+    fn serialize<S: ::serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        if s.is_human_readable() {
+            s.collect_str(self)
+        } else {
+            s.serialize_bytes(&self.serialize())
+        }
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de> ::serde::Deserialize<'de> for PublicKey {
+    fn deserialize<D: ::serde::Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        if d.is_human_readable() {
+            d.deserialize_str(super::serde_util::HexVisitor::new(
+                "a hex string representing 32 byte schnorr public key"
+            ))
+        } else {
+            d.deserialize_bytes(super::serde_util::BytesVisitor::new(
+                "raw 32 bytes schnorr public key",
+                PublicKey::from_slice
+            ))
+        }
+    }
+}
 
 impl<C: Signing> Secp256k1<C> {
     fn schnorrsig_sign_helper(

src/serde_util.rs

@@ -0,0 +1,76 @@
+use core::fmt;
+use core::marker::PhantomData;
+use core::str::{self, FromStr};
+use serde::de;
+
+pub struct HexVisitor<T> {
+    expectation: &'static str,
+    _pd: PhantomData<T>,
+}
+
+impl<T> HexVisitor<T> {
+    pub fn new(expectation: &'static str) -> Self {
+        HexVisitor {
+            expectation,
+            _pd: PhantomData,
+        }
+    }
+}
+
+impl<'de, T> de::Visitor<'de> for HexVisitor<T>
+where
+    T: FromStr,
+    <T as FromStr>::Err: fmt::Display,
+{
+    type Value = T;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str(self.expectation)
+    }
+
+    fn visit_bytes<E: de::Error>(self, v: &[u8]) -> Result<Self::Value, E> {
+        if let Ok(hex) = str::from_utf8(v) {
+            FromStr::from_str(hex).map_err(E::custom)
+        } else {
+            Err(E::invalid_value(de::Unexpected::Bytes(v), &self))
+        }
+    }
+
+    fn visit_str<E: de::Error>(self, v: &str) -> Result<Self::Value, E> {
+        FromStr::from_str(v).map_err(E::custom)
+    }
+}
+
+pub struct BytesVisitor<F> {
+    expectation: &'static str,
+    parse_fn: F,
+}
+
+impl<F, T, Err> BytesVisitor<F>
+where
+    F: FnOnce(&[u8]) -> Result<T, Err>,
+    Err: fmt::Display,
+{
+    pub fn new(expectation: &'static str, parse_fn: F) -> Self {
+        BytesVisitor {
+            expectation,
+            parse_fn,
+        }
+    }
+}
+
+impl<'de, F, T, Err> de::Visitor<'de> for BytesVisitor<F>
+where
+    F: FnOnce(&[u8]) -> Result<T, Err>,
+    Err: fmt::Display,
+{
+    type Value = T;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str(self.expectation)
+    }
+
+    fn visit_bytes<E: de::Error>(self, v: &[u8]) -> Result<Self::Value, E> {
+        (self.parse_fn)(v).map_err(E::custom)
+    }
+}