feat: Use DecodeOwned for improved ergonomic (#74)

pallas-codec/src/lib.rs

@@ -11,20 +11,19 @@ pub trait Fragment: Sized {
     fn write_cbor<W: Write>(&self, write: W) -> Result<(), minicbor::encode::Error<W::Error>>;
 }
 
-#[macro_export]
-macro_rules! impl_fragment {
-    ($Struct:ty) => {
-        impl $crate::Fragment for $Struct {
-            fn read_cbor(buffer: &[u8]) -> Result<Self, decode::Error> {
-                $crate::minicbor::decode(buffer)
-            }
+pub trait DecodeOwned: for<'b> minicbor::Decode<'b> {}
 
-            fn write_cbor<W: encode::Write>(
-                &self,
-                write: W,
-            ) -> Result<(), encode::Error<W::Error>> {
-                $crate::minicbor::encode(self, write)
-            }
-        }
-    };
+impl<T> DecodeOwned for T where T: for<'b> minicbor::Decode<'b> {}
+
+impl<T> Fragment for T
+where
+    T: DecodeOwned + minicbor::Encode,
+{
+    fn read_cbor(buffer: &[u8]) -> Result<Self, minicbor::decode::Error> {
+        minicbor::decode(buffer)
+    }
+
+    fn write_cbor<W: Write>(&self, write: W) -> Result<(), minicbor::encode::Error<W::Error>> {
+        minicbor::encode(self, write)
+    }
 }

pallas-miniprotocols/src/blockfetch/mod.rs

@@ -4,7 +4,6 @@ use crate::machines::{Agent, MachineOutput, Transition};
 
 use crate::common::Point;
 
-use pallas_codec::impl_fragment;
 use pallas_codec::minicbor::{decode, encode, Decode, Decoder, Encode, Encoder};
 
 #[derive(Debug, PartialEq, Clone)]
@@ -90,8 +89,6 @@ impl<'b> Decode<'b> for Message {
     }
 }
 
-impl_fragment!(Message);
-
 pub trait Observer {
     fn on_block_received(&self, body: Vec<u8>) -> Result<(), Box<dyn std::error::Error>> {
         log::debug!("block received, sice: {}", body.len());

pallas-miniprotocols/src/chainsync/codec.rs

@@ -1,8 +1,5 @@
 use crate::common::Point;
-use pallas_codec::{
-    impl_fragment,
-    minicbor::{decode, encode, Decode, Decoder, Encode, Encoder},
-};
+use pallas_codec::minicbor::{decode, encode, Decode, Decoder, Encode, Encoder};
 
 use super::{BlockContent, HeaderContent, Message, SkippedContent, Tip};
 
@@ -165,8 +162,6 @@ impl Encode for HeaderContent {
     }
 }
 
-impl_fragment!(Message<HeaderContent>);
-
 impl<'b> Decode<'b> for BlockContent {
     fn decode(d: &mut Decoder<'b>) -> Result<Self, decode::Error> {
         d.tag()?;
@@ -181,8 +176,6 @@ impl Encode for BlockContent {
     }
 }
 
-impl_fragment!(Message<BlockContent>);
-
 impl<'b> Decode<'b> for SkippedContent {
     fn decode(d: &mut Decoder<'b>) -> Result<Self, decode::Error> {
         d.skip()?;
@@ -195,5 +188,3 @@ impl Encode for SkippedContent {
         todo!()
     }
 }
-
-impl_fragment!(Message<SkippedContent>);

pallas-miniprotocols/src/handshake/n2c.rs

@@ -1,10 +1,7 @@
 use core::panic;
 use std::collections::HashMap;
 
-use pallas_codec::{
-    impl_fragment,
-    minicbor::{decode, encode, Decode, Decoder, Encode, Encoder},
-};
+use pallas_codec::minicbor::{decode, encode, Decode, Decoder, Encode, Encoder};
 
 use crate::machines::{Agent, MachineOutput};
 
@@ -122,8 +119,6 @@ impl<'b> Decode<'b> for Message {
     }
 }
 
-impl_fragment!(Message);
-
 #[derive(Debug, PartialEq, Eq)]
 pub enum State {
     Propose,

pallas-miniprotocols/src/handshake/n2n.rs

@@ -1,10 +1,7 @@
 use core::panic;
 use std::collections::HashMap;
 
-use pallas_codec::{
-    impl_fragment,
-    minicbor::{decode, encode, Decode, Encode, Encoder},
-};
+use pallas_codec::minicbor::{decode, encode, Decode, Encode, Encoder};
 
 use crate::machines::{Agent, MachineOutput};
 
@@ -136,8 +133,6 @@ impl<'b> Decode<'b> for Message {
     }
 }
 
-impl_fragment!(Message);
-
 #[derive(Debug, PartialEq, Eq)]
 pub enum State {
     Propose,

pallas-miniprotocols/src/localstate/queries.rs

@@ -1,9 +1,6 @@
-use pallas_codec::{
-    impl_fragment,
-    minicbor::{data::Cbor, decode, encode, Decode, Decoder, Encode, Encoder},
-};
+use pallas_codec::minicbor::{data::Cbor, decode, encode, Decode, Decoder, Encode, Encoder};
 
-use super::{Message, Query};
+use super::Query;
 
 #[derive(Debug, Clone)]
 pub struct BlockQuery {}
@@ -69,5 +66,3 @@ impl Query for QueryV10 {
     type Request = RequestV10;
     type Response = GenericResponse;
 }
-
-impl_fragment!(Message<QueryV10>);

pallas-miniprotocols/src/txsubmission/mod.rs

@@ -2,10 +2,7 @@ use std::fmt::Debug;
 
 use itertools::Itertools;
 use log::debug;
-use pallas_codec::{
-    impl_fragment,
-    minicbor::{decode, encode, Decode, Decoder, Encode, Encoder},
-};
+use pallas_codec::minicbor::{decode, encode, Decode, Decoder, Encode, Encoder};
 
 use crate::machines::{Agent, MachineError, MachineOutput, Transition};
 
@@ -142,8 +139,6 @@ impl<'b> Decode<'b> for Message {
     }
 }
 
-impl_fragment!(Message);
-
 /// A very basic tx provider agent with a fixed set of tx to submit
 ///
 /// This provider takes a set of tx from a vec as the single, static source of