chore!: Serialize, Deserialize and NoteInterface as Traits (#4135)

Closes: #3756,
#2838


Taking advantage of @jfecher's fantastic work in
noir-lang/noir#4000, implemented `Serialize<N>`
and `Deserialize<N>`. Together with `NoteInterface`, they make possible
getting rid of all the serialization interfaces, which greatly simplify
how the storage is handled and opens the door to further improvements.
~~Still some clutter to go, the lengths are still needed in some
places.~~


![Brace yourself](https://i.imgflip.com/8crkve.jpg)

I'm so sorry.

---------

Co-authored-by: sirasistant <sirasistant@gmail.com>

boxes/token/src/contracts/src/main.nr

@@ -24,11 +24,6 @@ contract Token {
         context::{PrivateContext, PublicContext, Context},
         hash::{compute_secret_hash},
         state_vars::{map::Map, public_state::PublicState, set::Set},
-        types::type_serialization::{
-                field_serialization::{FieldSerializationMethods, FIELD_SERIALIZED_LEN},
-                bool_serialization::{BoolSerializationMethods, BOOL_SERIALIZED_LEN},
-                address_serialization::{AddressSerializationMethods, AZTEC_ADDRESS_SERIALIZED_LEN},
-        },
         protocol_types::{
             abis::function_selector::FunctionSelector,
             address::AztecAddress,
@@ -45,29 +40,28 @@ contract Token {
     // docs:end:import_authwit
 
     use crate::types::{
-        transparent_note::{TransparentNote, TransparentNoteMethods, TRANSPARENT_NOTE_LEN},
-        token_note::{TokenNote, TokenNoteMethods, TOKEN_NOTE_LEN},
+        transparent_note::TransparentNote,
+        token_note::{TokenNote, TOKEN_NOTE_LEN},
         balances_map::{BalancesMap},
-        safe_u120_serialization::{SafeU120SerializationMethods, SAFE_U120_SERIALIZED_LEN}
     };
     // docs:end::imports
 
     // docs:start:storage_struct
     struct Storage {
         // docs:start:storage_admin
-        admin: PublicState<AztecAddress, AZTEC_ADDRESS_SERIALIZED_LEN>,
+        admin: PublicState<AztecAddress>,
         // docs:end:storage_admin
         // docs:start:storage_minters
-        minters: Map<AztecAddress, PublicState<bool, BOOL_SERIALIZED_LEN>>,
+        minters: Map<AztecAddress, PublicState<bool>>,
         // docs:end:storage_minters
         // docs:start:storage_balances
         balances: BalancesMap,
         // docs:end:storage_balances
-        total_supply: PublicState<SafeU120, SAFE_U120_SERIALIZED_LEN>,
+        total_supply: PublicState<SafeU120>,
         // docs:start:storage_pending_shields
-        pending_shields: Set<TransparentNote, TRANSPARENT_NOTE_LEN>,
+        pending_shields: Set<TransparentNote>,
         // docs:end:storage_pending_shields
-        public_balances: Map<AztecAddress, PublicState<SafeU120, SAFE_U120_SERIALIZED_LEN>>,
+        public_balances: Map<AztecAddress, PublicState<SafeU120>>,
     }
     // docs:end:storage_struct
 
@@ -79,7 +73,6 @@ contract Token {
                 admin: PublicState::new(
                     context,
                     1,
-                    AddressSerializationMethods,
                 ),
                 // docs:end:storage_admin_init
                 // docs:start:storage_minters_init
@@ -90,7 +83,6 @@ contract Token {
                         PublicState::new(
                             context,
                             slot,
-                            BoolSerializationMethods,
                         )
                     },
                 ),
@@ -101,10 +93,9 @@ contract Token {
                 total_supply: PublicState::new(
                     context,
                     4,
-                    SafeU120SerializationMethods,
                 ),
                 // docs:start:storage_pending_shields_init
-                pending_shields: Set::new(context, 5, TransparentNoteMethods),
+                pending_shields: Set::new(context, 5),
                 // docs:end:storage_pending_shields_init
                 public_balances: Map::new(
                     context,
@@ -113,7 +104,6 @@ contract Token {
                         PublicState::new(
                             context,
                             slot,
-                            SafeU120SerializationMethods,
                         )
                     },
                 ),
@@ -385,9 +375,9 @@ contract Token {
     ) -> pub [Field; 4] {
         let note_header = NoteHeader::new(contract_address, nonce, storage_slot);
         if (storage_slot == 5) {
-            note_utils::compute_note_hash_and_nullifier(TransparentNoteMethods, note_header, serialized_note)
+            note_utils::compute_note_hash_and_nullifier(TransparentNote::deserialize, note_header, serialized_note)
         } else {
-            note_utils::compute_note_hash_and_nullifier(TokenNoteMethods, note_header, serialized_note)
+            note_utils::compute_note_hash_and_nullifier(TokenNote::deserialize, note_header, serialized_note)
         }
     }
     // docs:end:compute_note_hash_and_nullifier

boxes/token/src/contracts/src/types.nr

@@ -2,4 +2,3 @@ mod transparent_note;
 mod balance_set;
 mod balances_map;
 mod token_note;
-mod safe_u120_serialization;

boxes/token/src/contracts/src/types/balance_set.nr

@@ -13,23 +13,19 @@ use dep::aztec::note::{
     note_getter_options::{NoteGetterOptions, SortOrder},
     note_viewer_options::NoteViewerOptions
 };
-use dep::aztec::note::{
-    note_header::NoteHeader,
-    note_interface::NoteInterface,
-    utils::compute_note_hash_for_read_or_nullify,
-};
-use crate::types::token_note::{TokenNote, TOKEN_NOTE_LEN, TokenNoteMethods};
+
+use crate::types::token_note::TokenNote;
 
 // A set implementing standard manipulation of balances.
 // Does not require spending key, but only knowledge.
 // Spending key requirement should be enforced by the contract using this.
 struct BalanceSet {
     owner: AztecAddress,
-    set: Set<TokenNote, TOKEN_NOTE_LEN>
+    set: Set<TokenNote>
 }
 
 impl BalanceSet {
-  pub fn new(set: Set<TokenNote, TOKEN_NOTE_LEN>, owner: AztecAddress) -> Self {
+  pub fn new(set: Set<TokenNote>, owner: AztecAddress) -> Self {
     Self {
         owner,
         set,

boxes/token/src/contracts/src/types/balances_map.nr

@@ -4,11 +4,11 @@ use crate::types::balance_set::BalanceSet;
 use dep::aztec::hash::pedersen_hash;
 use dep::aztec::protocol_types::address::AztecAddress;
 
-use crate::types::token_note::{TokenNote, TOKEN_NOTE_LEN, TokenNoteMethods};
+use crate::types::token_note::TokenNote;
 use dep::aztec::state_vars::{map::Map, set::Set};
 
 struct BalancesMap {
-    store: Map<AztecAddress, Set<TokenNote, TOKEN_NOTE_LEN>>,
+    store: Map<AztecAddress, Set<TokenNote>>,
 }
 
 impl BalancesMap {
@@ -20,7 +20,6 @@ impl BalancesMap {
             Set {
                 context,
                 storage_slot,
-                note_interface: TokenNoteMethods,
             }
         });
         Self {

boxes/token/src/contracts/src/types/token_note.nr

@@ -14,6 +14,7 @@ use dep::aztec::{
     state_vars::set::Set,
     log::emit_encrypted_log,
     hash::pedersen_hash,
+    protocol_types::traits::{Serialize, Deserialize},
 };
 use dep::aztec::oracle::{
     rand::rand,
@@ -39,30 +40,25 @@ struct TokenNote {
     header: NoteHeader,
 }
 
-impl TokenNote {
-    pub fn new(amount: SafeU120, owner: AztecAddress) -> Self {
-        Self {
-            amount,
-            owner,
-            randomness: rand(),
-            header: NoteHeader::empty(),
-        }
-    }
-
-    pub fn serialize(self) -> [Field; TOKEN_NOTE_LEN] {
+impl Serialize<TOKEN_NOTE_LEN> for TokenNote {
+    fn serialize(self) -> [Field; TOKEN_NOTE_LEN] {
         [self.amount.value as Field, self.owner.to_field(), self.randomness]
     }
+}
 
-    pub fn deserialize(serialized_note: [Field; TOKEN_NOTE_LEN]) -> Self {
+impl Deserialize<TOKEN_NOTE_LEN> for TokenNote {
+    fn deserialize(serialized_note: [Field; TOKEN_NOTE_LEN]) -> Self {
         Self {
             amount: SafeU120::new(serialized_note[0]),
             owner: AztecAddress::from_field(serialized_note[1]),
             randomness: serialized_note[2],
             header: NoteHeader::empty(),
         }
     }
+}
 
-    pub fn compute_note_hash(self) -> Field {
+impl NoteInterface for TokenNote {
+      fn compute_note_hash(self) -> Field {
         // TODO(#1205) Should use a non-zero generator index.
         pedersen_hash([
             self.amount.value as Field, 
@@ -72,8 +68,8 @@ impl TokenNote {
     }
 
     // docs:start:nullifier
-    pub fn compute_nullifier(self, context: &mut PrivateContext) -> Field {
-        let note_hash_for_nullify = compute_note_hash_for_read_or_nullify(TokenNoteMethods, self);
+    fn compute_nullifier(self, context: &mut PrivateContext) -> Field {
+        let note_hash_for_nullify = compute_note_hash_for_read_or_nullify(self);
         let secret = context.request_nullifier_secret_key(self.owner);
         // TODO(#1205) Should use a non-zero generator index.
         pedersen_hash([
@@ -84,8 +80,8 @@ impl TokenNote {
     }
     // docs:end:nullifier
 
-    pub fn compute_nullifier_without_context(self) -> Field {
-        let note_hash_for_nullify = compute_note_hash_for_read_or_nullify(TokenNoteMethods, self);
+    fn compute_nullifier_without_context(self) -> Field {
+        let note_hash_for_nullify = compute_note_hash_for_read_or_nullify(self);
         let secret = get_nullifier_secret_key(self.owner);
         // TODO(#1205) Should use a non-zero generator index.
         pedersen_hash([
@@ -95,12 +91,16 @@ impl TokenNote {
         ],0)
     }
 
-    pub fn set_header(&mut self, header: NoteHeader) {
+    fn set_header(&mut self, header: NoteHeader) {
         self.header = header;
     }
 
+    fn get_header(self) -> NoteHeader {
+        self.header
+    }
+
     // Broadcasts the note as an encrypted log on L1.
-    pub fn broadcast(self, context: &mut PrivateContext, slot: Field) {
+    fn broadcast(self, context: &mut PrivateContext, slot: Field) {
       // We only bother inserting the note if non-empty to save funds on gas.
       if !self.amount.is_zero() {
           let encryption_pub_key = get_public_key(self.owner);
@@ -115,46 +115,13 @@ impl TokenNote {
   }
 }
 
-fn deserialize(serialized_note: [Field; TOKEN_NOTE_LEN]) -> TokenNote {
-    TokenNote::deserialize(serialized_note)
-}
-
-fn serialize(note: TokenNote) -> [Field; TOKEN_NOTE_LEN] {
-    note.serialize()
-}
-
-fn compute_note_hash(note: TokenNote) -> Field {
-    note.compute_note_hash()
-}
-
-fn compute_nullifier(note: TokenNote, context: &mut PrivateContext) -> Field {
-    note.compute_nullifier(context)
-}
-
-fn compute_nullifier_without_context(note: TokenNote) -> Field {
-    note.compute_nullifier_without_context()
-}
-
-fn get_header(note: TokenNote) -> NoteHeader {
-    note.header
-}
-
-fn set_header(note: &mut TokenNote, header: NoteHeader) {
-    note.set_header(header)
-}
-
-// Broadcasts the note as an encrypted log on L1.
-fn broadcast(context: &mut PrivateContext, slot: Field, note: TokenNote) {
-    note.broadcast(context, slot);
+impl TokenNote {
+    pub fn new(amount: SafeU120, owner: AztecAddress) -> Self {
+        Self {
+            amount,
+            owner,
+            randomness: rand(),
+            header: NoteHeader::empty(),
+        }
+    }
 }
-
-global TokenNoteMethods = NoteInterface {
-    deserialize,
-    serialize,
-    compute_note_hash,
-    compute_nullifier,
-    compute_nullifier_without_context,
-    get_header,
-    set_header,
-    broadcast,
-};