Move SerializeForVersion to dto module and remove wrapper structs around common types

crates/rpc/src/dto.rs

@@ -1,6 +1,6 @@
 #![allow(unused)]
 
-use serde::de::{Error, IntoDeserializer};
+use serde::de::{Error as SerdeError, IntoDeserializer};
 
 mod block;
 mod class;
@@ -12,8 +12,6 @@ mod simulation;
 mod state_update;
 mod transaction;
 
-pub mod serialize;
-
 pub use block::*;
 pub use class::*;
 pub use event::*;
@@ -26,6 +24,135 @@ pub use transaction::*;
 
 use crate::RpcVersion;
 
+#[derive(Copy, Clone)]
+#[cfg_attr(test, derive(Default))]
+pub struct Serializer {
+    pub version: RpcVersion,
+}
+
+pub struct SerializeStruct {
+    pub version: RpcVersion,
+    fields: serde_json::Map<String, Ok>,
+}
+
+type BaseSerializer = serde_json::value::Serializer;
+pub(crate) type Ok = <BaseSerializer as serde::Serializer>::Ok;
+pub(crate) type Error = <BaseSerializer as serde::Serializer>::Error;
+
+pub trait SerializeForVersion {
+    fn serialize(&self, serializer: Serializer) -> Result<Ok, Error>;
+}
+
+// This blanket implementation should be removed once all existing DTOs have
+// been migrated.
+impl<T> SerializeForVersion for T
+where
+    T: serde::Serialize,
+{
+    fn serialize(&self, _serializer: Serializer) -> Result<Ok, Error> {
+        self.serialize(BaseSerializer {})
+    }
+}
+
+impl Serializer {
+    pub fn new(version: RpcVersion) -> Self {
+        Self { version }
+    }
+
+    pub fn serialize(self, value: &dyn SerializeForVersion) -> Result<Ok, Error> {
+        value.serialize(self)
+    }
+
+    pub fn serialize_str(self, value: &str) -> Result<Ok, Error> {
+        use serde::Serializer;
+        BaseSerializer {}.serialize_str(value)
+    }
+
+    pub fn serialize_u64(self, value: u64) -> Result<Ok, Error> {
+        use serde::Serializer;
+        BaseSerializer {}.serialize_u64(value)
+    }
+
+    pub fn serialize_bool(self, value: bool) -> Result<Ok, Error> {
+        use serde::Serializer;
+        BaseSerializer {}.serialize_bool(value)
+    }
+
+    pub fn serialize_struct(self) -> Result<SerializeStruct, Error> {
+        Ok(SerializeStruct {
+            version: self.version,
+            fields: Default::default(),
+        })
+    }
+
+    pub fn serialize_iter(
+        self,
+        len: usize,
+        values: &mut dyn Iterator<Item = impl SerializeForVersion>,
+    ) -> Result<Ok, Error> {
+        use serde::ser::SerializeSeq;
+        use serde::Serializer;
+
+        let mut serializer = BaseSerializer {}.serialize_seq(Some(len))?;
+        for value in values {
+            let value = self.serialize(&value)?;
+            serializer.serialize_element(&value)?;
+        }
+        serializer.end()
+    }
+}
+
+impl SerializeStruct {
+    pub fn serialize_field(
+        &mut self,
+        key: &'static str,
+        value: &dyn SerializeForVersion,
+    ) -> Result<(), Error> {
+        let value = value.serialize(Serializer::new(self.version))?;
+        self.fields.insert(key.to_owned(), value);
+        Ok(())
+    }
+
+    pub fn serialize_iter(
+        &mut self,
+        key: &'static str,
+        len: usize,
+        values: &mut dyn Iterator<Item = impl SerializeForVersion>,
+    ) -> Result<(), Error> {
+        let seq = Serializer::new(self.version).serialize_iter(len, values)?;
+        self.serialize_field(key, &seq)
+    }
+
+    /// Skips serialization if its [`None`].
+    pub fn serialize_optional(
+        &mut self,
+        key: &'static str,
+        value: Option<impl SerializeForVersion>,
+    ) -> Result<(), Error> {
+        if let Some(value) = value {
+            self.serialize_field(key, &value)?;
+        }
+
+        Ok(())
+    }
+
+    pub fn flatten(&mut self, value: &dyn SerializeForVersion) -> Result<(), Error> {
+        let value = value.serialize(Serializer::new(self.version))?;
+
+        if let serde_json::Value::Object(value) = value {
+            for (k, v) in value {
+                self.fields.insert(k, v);
+            }
+        }
+
+        Ok(())
+    }
+
+    pub fn end(self) -> Result<Ok, Error> {
+        Ok(serde_json::Value::Object(self.fields))
+    }
+}
+
 pub trait DeserializeForVersion: Sized {
     fn deserialize(value: Value) -> Result<Self, serde_json::Error>;
 }
@@ -448,3 +575,108 @@ impl Map {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use serde_json::json;
+
+    use super::*;
+
+    mod serialize {
+        use super::*;
+
+        #[test]
+        fn str() {
+            let encoded = Serializer::default().serialize_str("value").unwrap();
+            assert_eq!(encoded, json!("value"));
+        }
+
+        #[test]
+        fn u64() {
+            let encoded = Serializer::default().serialize_u64(123).unwrap();
+            assert_eq!(encoded, json!(123));
+        }
+
+        #[test]
+        fn bool() {
+            let encoded_true = Serializer::default().serialize_bool(true).unwrap();
+            assert_eq!(encoded_true, json!(true));
+
+            let encoded_false = Serializer::default().serialize_bool(false).unwrap();
+            assert_eq!(encoded_false, json!(false));
+        }
+    }
+
+    mod serialize_struct {
+        use super::*;
+
+        #[test]
+        fn version_carries_over() {
+            let uut = Serializer::new(RpcVersion::PathfinderV01)
+                .serialize_struct()
+                .unwrap();
+            assert_eq!(uut.version, RpcVersion::PathfinderV01);
+        }
+
+        #[test]
+        fn optional() {
+            let mut uut = Serializer::default().serialize_struct().unwrap();
+            uut.serialize_optional("missing", None::<u64>).unwrap();
+            uut.serialize_optional("present", Some(200u64)).unwrap();
+            let encoded = uut.end().unwrap();
+            let expected = json!({"present": 200u64});
+
+            assert_eq!(encoded, expected);
+        }
+
+        #[test]
+        fn iter() {
+            let empty = vec![0u64; 0];
+            let count = vec![0u64, 1, 2, 3];
+
+            let mut uut = Serializer::default().serialize_struct().unwrap();
+            uut.serialize_iter("empty", 0, &mut empty.iter()).unwrap();
+            uut.serialize_iter("count", 0, &mut count.iter()).unwrap();
+            let encoded = uut.end().unwrap();
+            let expected = json!({
+                "count": count,
+                "empty": empty,
+            });
+
+            assert_eq!(encoded, expected);
+        }
+
+        #[test]
+        fn flatten() {
+            struct TypeX(u64);
+            impl SerializeForVersion for TypeX {
+                fn serialize(&self, serializer: Serializer) -> Result<Ok, Error> {
+                    let mut serializer = serializer.serialize_struct()?;
+                    serializer.serialize_field("x", &self.0);
+                    serializer.end()
+                }
+            }
+
+            let mut uut = Serializer::default().serialize_struct().unwrap();
+            uut.serialize_field("y", &200u64).unwrap();
+            uut.flatten(&TypeX(300)).unwrap();
+            let encoded = uut.end().unwrap();
+
+            let expected = json!({
+                "x": 300,
+                "y": 200,
+            });
+
+            assert_eq!(encoded, expected);
+        }
+
+        #[test]
+        fn field() {
+            let mut uut = Serializer::default().serialize_struct().unwrap();
+            uut.serialize_field("field", &"value").unwrap();
+            let encoded = uut.end().unwrap();
+            let expected = json!({"field": "value"});
+            assert_eq!(encoded, expected);
+        }
+    }
+}