move pod data's deserialization to RecursivePod trait (#294), expose get_common_data (#300)

src/backends/plonky2/emptypod.rs

@@ -158,23 +158,6 @@ impl EmptyPod {
         })
         .map_err(|e| Error::custom(format!("EmptyPod proof verification failure: {:?}", e)))
     }
-
-    pub(crate) fn deserialize(
-        params: Params,
-        id: PodId,
-        vds_root: Hash,
-        data: serde_json::Value,
-    ) -> Result<Box<dyn RecursivePod>> {
-        let data: Data = serde_json::from_value(data)?;
-        let circuit_data = &*STANDARD_REC_MAIN_POD_CIRCUIT_DATA;
-        let proof = deserialize_proof(&circuit_data.common, &data.proof)?;
-        Ok(Box::new(Self {
-            params,
-            id,
-            vds_root,
-            proof,
-        }))
-    }
 }
 
 #[derive(Serialize, Deserialize)]
@@ -220,6 +203,22 @@ impl RecursivePod for EmptyPod {
     fn vds_root(&self) -> Hash {
         self.vds_root
     }
+    fn deserialize_data(
+        params: Params,
+        data: serde_json::Value,
+        vds_root: Hash,
+        id: PodId,
+    ) -> Result<Box<dyn RecursivePod>, Box<DynError>> {
+        let data: Data = serde_json::from_value(data)?;
+        let circuit_data = &*STANDARD_REC_MAIN_POD_CIRCUIT_DATA;
+        let proof = deserialize_proof(&circuit_data.common, &data.proof)?;
+        Ok(Box::new(Self {
+            params,
+            id,
+            vds_root,
+            proof,
+        }))
+    }
 }
 
 #[cfg(test)]

src/backends/plonky2/mainpod/mod.rs

@@ -581,7 +581,7 @@ pub struct MainPod {
 // a serialized proof. At some point in the future, this data may be available
 // as a constant or with static initialization, but in the meantime we can
 // generate it on-demand.
-fn get_common_data(params: &Params) -> Result<CommonCircuitData<F, D>, Error> {
+pub fn get_common_data(params: &Params) -> Result<CommonCircuitData<F, D>, Error> {
     // TODO: Cache this somehow
     // https://github.com/0xPARC/pod2/issues/247
     let rec_circuit_data = &*STANDARD_REC_MAIN_POD_CIRCUIT_DATA;
@@ -643,24 +643,6 @@ impl MainPod {
     pub fn params(&self) -> &Params {
         &self.params
     }
-
-    pub(crate) fn deserialize(
-        params: Params,
-        id: PodId,
-        vds_root: Hash,
-        data: serde_json::Value,
-    ) -> Result<Box<dyn RecursivePod>> {
-        let data: Data = serde_json::from_value(data)?;
-        let common = get_common_data(&params)?;
-        let proof = deserialize_proof(&common, &data.proof)?;
-        Ok(Box::new(Self {
-            params,
-            id,
-            vds_root,
-            proof,
-            public_statements: data.public_statements,
-        }))
-    }
 }
 
 impl Pod for MainPod {
@@ -706,6 +688,23 @@ impl RecursivePod for MainPod {
     fn vds_root(&self) -> Hash {
         self.vds_root
     }
+    fn deserialize_data(
+        params: Params,
+        data: serde_json::Value,
+        vds_root: Hash,
+        id: PodId,
+    ) -> Result<Box<dyn RecursivePod>, Box<DynError>> {
+        let data: Data = serde_json::from_value(data)?;
+        let common = get_common_data(&params)?;
+        let proof = deserialize_proof(&common, &data.proof)?;
+        Ok(Box::new(Self {
+            params,
+            id,
+            vds_root,
+            proof,
+            public_statements: data.public_statements,
+        }))
+    }
 }
 
 #[cfg(test)]

src/backends/plonky2/mock/emptypod.rs

@@ -46,14 +46,6 @@ impl MockEmptyPod {
         }
         Ok(())
     }
-    pub(crate) fn deserialize(
-        params: Params,
-        id: PodId,
-        _vds_root: Hash,
-        _data: serde_json::Value,
-    ) -> Result<Box<dyn RecursivePod>> {
-        Ok(Box::new(Self { params, id }))
-    }
 }
 
 impl Pod for MockEmptyPod {
@@ -88,6 +80,14 @@ impl RecursivePod for MockEmptyPod {
     fn vds_root(&self) -> Hash {
         panic!("MockEmptyPod can't be verified in a recursive MainPod circuit");
     }
+    fn deserialize_data(
+        params: Params,
+        _data: serde_json::Value,
+        _vds_root: Hash,
+        id: PodId,
+    ) -> Result<Box<dyn RecursivePod>, Box<DynError>> {
+        Ok(Box::new(Self { params, id }))
+    }
 }
 
 #[cfg(test)]

src/backends/plonky2/mock/mainpod.rs

@@ -190,32 +190,6 @@ impl MockMainPod {
         })
     }
 
-    // MockMainPods include some internal private state which is necessary
-    // for verification. In non-mock Pods, this state will not be necessary,
-    // as the public statements can be verified using a ZK proof.
-    pub(crate) fn deserialize(
-        params: Params,
-        id: PodId,
-        vds_root: Hash,
-        data: serde_json::Value,
-    ) -> Result<Box<dyn RecursivePod>> {
-        let Data {
-            public_statements,
-            operations,
-            statements,
-            merkle_proofs,
-        } = serde_json::from_value(data)?;
-        Ok(Box::new(Self {
-            params,
-            id,
-            vds_root,
-            public_statements,
-            operations,
-            statements,
-            merkle_proofs,
-        }))
-    }
-
     fn _verify(&self) -> Result<()> {
         // 1. TODO: Verify input pods
 
@@ -331,6 +305,31 @@ impl RecursivePod for MockMainPod {
     fn vds_root(&self) -> Hash {
         self.vds_root
     }
+    // MockMainPods include some internal private state which is necessary
+    // for verification. In non-mock Pods, this state will not be necessary,
+    // as the public statements can be verified using a ZK proof.
+    fn deserialize_data(
+        params: Params,
+        data: serde_json::Value,
+        vds_root: Hash,
+        id: PodId,
+    ) -> Result<Box<dyn RecursivePod>, Box<DynError>> {
+        let Data {
+            public_statements,
+            operations,
+            statements,
+            merkle_proofs,
+        } = serde_json::from_value(data)?;
+        Ok(Box::new(Self {
+            params,
+            id,
+            vds_root,
+            public_statements,
+            operations,
+            statements,
+            merkle_proofs,
+        }))
+    }
 }
 
 #[cfg(test)]

src/middleware/mod.rs

@@ -796,6 +796,7 @@ pub trait Pod: fmt::Debug + DynClone + Any {
     /// Return this Pods data serialized into a json value.  This serialization can skip `params,
     /// id, vds_root`
     fn serialize_data(&self) -> serde_json::Value;
+
     /// Extract key-values from ValueOf public statements
     fn kvs(&self) -> HashMap<AnchoredKey, Value> {
         self.pub_statements()
@@ -830,6 +831,16 @@ pub trait RecursivePod: Pod {
     fn verifier_data(&self) -> VerifierOnlyCircuitData;
     fn proof(&self) -> Proof;
     fn vds_root(&self) -> Hash;
+
+    /// Returns the deserialized RecursivePod.
+    fn deserialize_data(
+        params: Params,
+        data: serde_json::Value,
+        vds_root: Hash,
+        id: PodId,
+    ) -> Result<Box<dyn RecursivePod>, Box<DynError>>
+    where
+        Self: Sized;
 }
 
 // impl Clone for Box<dyn RecursivePod>

src/middleware/pod_deserialization.rs

@@ -3,16 +3,14 @@ use std::{
     sync::{LazyLock, Mutex},
 };
 
-use crate::middleware::{
+use crate::middleware::{DynError, Error, Hash, Params, Pod, PodId, PodType, RecursivePod, Result};
-    BackendResult, Error, Hash, Params, Pod, PodId, PodType, RecursivePod, Result,
-};
 
 type DeserializeFn = fn(
     params: Params,
-    id: PodId,
-    vds_root: Hash,
     data: serde_json::Value,
-) -> BackendResult<Box<dyn RecursivePod>>;
+    vds_root: Hash,
+    id: PodId,
+) -> Result<Box<dyn RecursivePod>, Box<DynError>>;
 
 static DESERIALIZERS: LazyLock<Mutex<HashMap<usize, DeserializeFn>>> =
     LazyLock::new(backend::deserializers_default);
@@ -41,7 +39,7 @@ pub fn deserialize_pod(
                 pod_type
             )))?;
 
-    deserialize_fn(params, id, vds_root, data)
+    deserialize_fn(params, data, vds_root, id)
         .map_err(|e| Error::custom(format!("deserialize error: {:?}", e)))
 }
 
@@ -65,10 +63,10 @@ mod backend {
 
     pub(super) fn deserializers_default() -> Mutex<HashMap<usize, DeserializeFn>> {
         let mut map: HashMap<usize, DeserializeFn> = HashMap::new();
-        map.insert(PodType::Empty as usize, EmptyPod::deserialize);
+        map.insert(PodType::Empty as usize, EmptyPod::deserialize_data);
-        map.insert(PodType::Main as usize, MainPod::deserialize);
+        map.insert(PodType::Main as usize, MainPod::deserialize_data);
-        map.insert(PodType::MockEmpty as usize, MockEmptyPod::deserialize);
+        map.insert(PodType::MockEmpty as usize, MockEmptyPod::deserialize_data);
-        map.insert(PodType::MockMain as usize, MockMainPod::deserialize);
+        map.insert(PodType::MockMain as usize, MockMainPod::deserialize_data);
         Mutex::new(map)
     }