Re-implement serialization (#201)

* Serialization tests now pass again

* Tidy up and test more edge-cases

* Use attributes rather than custom serializer for arrays

* Add JSON Schema support

* Tests for JSON Schema generation and validation

* Add comments

* Support custom predicates

* Clippy fixes

* Make deserialization/constructor functions pub(crate)

src/backends/plonky2/mainpod/operation.rs

@@ -2,14 +2,14 @@ use std::fmt;
 
 use anyhow::{anyhow, Result};
 use plonky2::field::types::Field;
+use serde::{Deserialize, Serialize};
 
-// use serde::{Deserialize, Serialize};
 use crate::{
     backends::plonky2::{mainpod::Statement, primitives::merkletree::MerkleClaimAndProof},
     middleware::{self, OperationType, Params, ToFields, F},
 };
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub enum OperationArg {
     None,
     Index(usize),
@@ -31,7 +31,7 @@ impl OperationArg {
     }
 }
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub enum OperationAux {
     None,
     MerkleProofIndex(usize),
@@ -47,7 +47,7 @@ impl ToFields for OperationAux {
     }
 }
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub struct Operation(pub OperationType, pub Vec<OperationArg>, pub OperationAux);
 
 impl Operation {

src/backends/plonky2/mainpod/statement.rs

@@ -1,13 +1,13 @@
 use std::fmt;
 
 use anyhow::{anyhow, Result};
+use serde::{Deserialize, Serialize};
 
-// use serde::{Deserialize, Serialize};
 use crate::middleware::{
     self, NativePredicate, Params, Predicate, StatementArg, ToFields, WildcardValue,
 };
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub struct Statement(pub Predicate, pub Vec<StatementArg>);
 
 impl Statement {