implement the specified sparse merkletree (#82)

* wip

* prototype custom predicates 1b

* feat: implement custom pred recursion

* files reorg, add github CI for rustfmt checks

* start sparsemerkletree. impl add_leaf method, initial Leaf & Intermediate types with methods

* mt: add hash computation of all the nodes in the tree, add method to print the tree to visualize it as a graphviz

* mt: add  (till the leaf) method which is used by get,contains,prove methods

* mt: add verify (of inclusion) method

* mt: update 'down' method to reuse siblings, update get,contains,prove methods (the three use 'down' under the hood)

* Add nonexistence proofs and iterator

* Add iterator test

* migrate usage of old merkletree to the new merkletree impl in POD2 code

---------

Co-authored-by: Eduard S. <eduardsanou@posteo.net>
Co-authored-by: Ahmad <root@ahmadafuni.com>

src/backends/mock_main/mod.rs

@@ -485,7 +485,7 @@ pub mod tests {
             pk: "ZooDeel".into(),
         };
         let pay_stub_pod = pay_stub_builder.sign(&mut signer)?;
-        let kyc_builder = zu_kyc_pod_builder(&params, &gov_id_pod, &pay_stub_pod);
+        let kyc_builder = zu_kyc_pod_builder(&params, &gov_id_pod, &pay_stub_pod)?;
 
         let mut prover = MockProver {};
         let kyc_pod = kyc_builder.prove(&mut prover)?;
@@ -501,7 +501,7 @@ pub mod tests {
 
     #[test]
     fn test_mock_main_great_boy() -> Result<()> {
-        let great_boy_builder = great_boy_pod_full_flow();
+        let great_boy_builder = great_boy_pod_full_flow()?;
 
         let mut prover = MockProver {};
         let great_boy_pod = great_boy_builder.prove(&mut prover)?;
@@ -520,7 +520,7 @@ pub mod tests {
 
     #[test]
     fn test_mock_main_tickets() -> Result<()> {
-        let tickets_builder = tickets_pod_full_flow();
+        let tickets_builder = tickets_pod_full_flow()?;
         let mut prover = MockProver {};
         let proof_pod = tickets_builder.prove(&mut prover)?;
         let pod = proof_pod.pod.into_any().downcast::<MockMainPod>().unwrap();

src/backends/mock_signed.rs

@@ -2,6 +2,7 @@ use anyhow::Result;
 use std::any::Any;
 use std::collections::HashMap;
 
+use crate::constants::MAX_DEPTH;
 use crate::middleware::{
     containers::Dictionary, hash_str, AnchoredKey, Hash, Params, Pod, PodId, PodSigner, PodType,
     Statement, Value, KEY_SIGNER, KEY_TYPE,
@@ -19,7 +20,7 @@ impl PodSigner for MockSigner {
         kvs.insert(hash_str(&KEY_SIGNER), Value(pk_hash.0));
         kvs.insert(hash_str(&KEY_TYPE), Value::from(PodType::MockSigned));
 
-        let dict = Dictionary::new(&kvs);
+        let dict = Dictionary::new(&kvs)?;
         let id = PodId(dict.commitment());
         let signature = format!("{}_signed_by_{}", id, pk_hash);
         Ok(Box::new(MockSignedPod {
@@ -49,13 +50,17 @@ impl Pod for MockSignedPod {
         }
 
         // Verify id
-        let mt = MerkleTree::new(
+        let mt = match MerkleTree::new(
+            MAX_DEPTH,
             &self
                 .dict
                 .iter()
                 .map(|(&k, &v)| (k, v))
                 .collect::<HashMap<Value, Value>>(),
-        );
+        ) {
+            Ok(mt) => mt,
+            Err(_) => return false,
+        };
         let id = PodId(mt.root());
         if id != self.id {
             return false;
@@ -93,14 +98,16 @@ impl Pod for MockSignedPod {
 
 #[cfg(test)]
 pub mod tests {
-    use super::*;
-    use crate::frontend;
-    use crate::middleware::{self, F, NULL};
     use plonky2::field::types::Field;
     use std::iter;
 
+    use super::*;
+    use crate::constants::MAX_DEPTH;
+    use crate::frontend;
+    use crate::middleware::{self, F, NULL};
+
     #[test]
-    fn test_mock_signed_0() {
+    fn test_mock_signed_0() -> Result<()> {
         let params = middleware::Params::default();
         let mut pod = frontend::SignedPodBuilder::new(&params);
         pod.insert("idNumber", "4242424242");
@@ -131,7 +138,7 @@ pub mod tests {
             .map(|(AnchoredKey(_, k), v)| (Value(k.0), v))
             .chain(iter::once(bad_kv))
             .collect::<HashMap<Value, Value>>();
-        let bad_mt = MerkleTree::new(&bad_kvs_mt);
+        let bad_mt = MerkleTree::new(MAX_DEPTH, &bad_kvs_mt)?;
         bad_pod.dict.mt = bad_mt;
         assert_eq!(bad_pod.verify(), false);
 
@@ -143,8 +150,10 @@ pub mod tests {
             .map(|(AnchoredKey(_, k), v)| (Value(k.0), v))
             .chain(iter::once(bad_kv))
             .collect::<HashMap<Value, Value>>();
-        let bad_mt = MerkleTree::new(&bad_kvs_mt);
+        let bad_mt = MerkleTree::new(MAX_DEPTH, &bad_kvs_mt)?;
         bad_pod.dict.mt = bad_mt;
         assert_eq!(bad_pod.verify(), false);
+
+        Ok(())
     }
 }