Made Amount more generic.

masp_primitives/Cargo.toml

@@ -36,6 +36,9 @@ sha2 = "0.9"
 # - Metrics
 memuse = "0.2.1"
 
+# - Checked arithmetic
+num-traits = "0.2.14"
+
 # - Secret management
 subtle = "2.2.3"
 

masp_primitives/src/convert.rs

@@ -3,7 +3,7 @@ use crate::{
         pedersen_hash::{pedersen_hash, Personalization},
         Node, ValueCommitment,
     },
-    transaction::components::amount::Amount,
+    transaction::components::amount::{Amount, I64Amt},
 };
 use borsh::{BorshDeserialize, BorshSerialize};
 use group::{Curve, GroupEncoding};
@@ -16,7 +16,7 @@ use std::{
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct AllowedConversion {
     /// The asset type that the note represents
-    assets: Amount,
+    assets: I64Amt,
     /// Memorize generator because it's expensive to recompute
     generator: jubjub::ExtendedPoint,
 }
@@ -71,15 +71,15 @@ impl AllowedConversion {
     }
 }
 
-impl From<AllowedConversion> for Amount {
-    fn from(allowed_conversion: AllowedConversion) -> Amount {
+impl From<AllowedConversion> for I64Amt {
+    fn from(allowed_conversion: AllowedConversion) -> I64Amt {
         allowed_conversion.assets
     }
 }
 
-impl From<Amount> for AllowedConversion {
+impl From<I64Amt> for AllowedConversion {
     /// Produces an asset generator without cofactor cleared
-    fn from(assets: Amount) -> Self {
+    fn from(assets: I64Amt) -> Self {
         let mut asset_generator = jubjub::ExtendedPoint::identity();
         for (asset, value) in assets.components() {
             // Compute the absolute value (failing if -i64::MAX is
@@ -199,11 +199,11 @@ mod tests {
     #[test]
     fn test_homomorphism() {
         // Left operand
-        let a = Amount::from_pair(zec(), 5).unwrap()
-            + Amount::from_pair(btc(), 6).unwrap()
-            + Amount::from_pair(xan(), 7).unwrap();
+        let a = Amount::from_pair(zec(), 5i64).unwrap()
+            + Amount::from_pair(btc(), 6i64).unwrap()
+            + Amount::from_pair(xan(), 7i64).unwrap();
         // Right operand
-        let b = Amount::from_pair(zec(), 2).unwrap() + Amount::from_pair(xan(), 10).unwrap();
+        let b = Amount::from_pair(zec(), 2i64).unwrap() + Amount::from_pair(xan(), 10i64).unwrap();
         // Test homomorphism
         assert_eq!(
             AllowedConversion::from(a.clone() + b.clone()),
@@ -213,9 +213,9 @@ mod tests {
     #[test]
     fn test_serialization() {
         // Make conversion
-        let a: AllowedConversion = (Amount::from_pair(zec(), 5).unwrap()
-            + Amount::from_pair(btc(), 6).unwrap()
-            + Amount::from_pair(xan(), 7).unwrap())
+        let a: AllowedConversion = (Amount::from_pair(zec(), 5i64).unwrap()
+            + Amount::from_pair(btc(), 6i64).unwrap()
+            + Amount::from_pair(xan(), 7i64).unwrap())
         .into();
         // Serialize conversion
         let mut data = Vec::new();

masp_primitives/src/sapling/prover.rs

@@ -8,7 +8,7 @@ use crate::{
         redjubjub::{PublicKey, Signature},
         Node,
     },
-    transaction::components::{Amount, GROTH_PROOF_SIZE},
+    transaction::components::{I64Amt, GROTH_PROOF_SIZE},
 };
 
 use super::{Diversifier, PaymentAddress, ProofGenerationKey, Rseed};
@@ -73,7 +73,7 @@ pub trait TxProver {
     fn binding_sig(
         &self,
         ctx: &mut Self::SaplingProvingContext,
-        amount: &Amount,
+        amount: &I64Amt,
         sighash: &[u8; 32],
     ) -> Result<Signature, ()>;
 }
@@ -92,7 +92,7 @@ pub mod mock {
             redjubjub::{PublicKey, Signature},
             Diversifier, Node, PaymentAddress, ProofGenerationKey, Rseed,
         },
-        transaction::components::{Amount, GROTH_PROOF_SIZE},
+        transaction::components::{I64Amt, GROTH_PROOF_SIZE},
     };
 
     use super::TxProver;
@@ -169,7 +169,7 @@ pub mod mock {
         fn binding_sig(
             &self,
             _ctx: &mut Self::SaplingProvingContext,
-            _value: &Amount,
+            _value: &I64Amt,
             _sighash: &[u8; 32],
         ) -> Result<Signature, ()> {
             Err(())

masp_primitives/src/transaction.rs

@@ -25,7 +25,7 @@ use crate::{
 
 use self::{
     components::{
-        amount::Amount,
+        amount::{Amount, I64Amt},
         sapling::{
             self, ConvertDescriptionV5, OutputDescriptionV5, SpendDescription, SpendDescriptionV5,
         },
@@ -269,7 +269,7 @@ impl<A: Authorization> TransactionData<A> {
 }
 
 impl<A: Authorization> TransactionData<A> {
-    pub fn sapling_value_balance(&self) -> Amount {
+    pub fn sapling_value_balance(&self) -> I64Amt {
         self.sapling_bundle
             .as_ref()
             .map_or(Amount::zero(), |b| b.value_balance.clone())
@@ -355,7 +355,7 @@ impl Transaction {
         })
     }
 
-    fn read_amount<R: Read>(mut reader: R) -> io::Result<Amount> {
+    fn read_amount<R: Read>(mut reader: R) -> io::Result<I64Amt> {
         Amount::read(&mut reader).map_err(|_| {
             io::Error::new(
                 io::ErrorKind::InvalidData,

masp_primitives/src/transaction/builder.rs

@@ -19,7 +19,7 @@ use crate::{
     sapling::{prover::TxProver, Diversifier, Node, Note, PaymentAddress},
     transaction::{
         components::{
-            amount::{Amount, BalanceError, MAX_MONEY},
+            amount::{Amount, BalanceError, I64Amt, MAX_MONEY},
             sapling::{
                 self,
                 builder::{SaplingBuilder, SaplingMetadata},
@@ -43,10 +43,10 @@ const DEFAULT_TX_EXPIRY_DELTA: u32 = 20;
 pub enum Error<FeeError> {
     /// Insufficient funds were provided to the transaction builder; the given
     /// additional amount is required in order to construct the transaction.
-    InsufficientFunds(Amount),
+    InsufficientFunds(I64Amt),
     /// The transaction has inputs in excess of outputs and fees; the user must
     /// add a change output.
-    ChangeRequired(Amount),
+    ChangeRequired(I64Amt),
     /// An error occurred in computing the fees for a transaction.
     Fee(FeeError),
     /// An overflow or underflow occurred when computing value balances
@@ -293,13 +293,13 @@ impl<P: consensus::Parameters, R: RngCore> Builder<P, R> {
     }
 
     /// Returns the sum of the transparent, Sapling, and TZE value balances.
-    pub fn value_balance(&self) -> Result<Amount, BalanceError> {
+    pub fn value_balance(&self) -> Result<I64Amt, BalanceError> {
         let value_balances = [
             self.transparent_builder.value_balance()?,
             self.sapling_builder.value_balance(),
         ];
 
-        Ok(value_balances.into_iter().sum::<Amount>())
+        Ok(value_balances.into_iter().sum::<I64Amt>())
     }
 
     /// Builds a transaction from the configured spends and outputs.
@@ -326,7 +326,7 @@ impl<P: consensus::Parameters, R: RngCore> Builder<P, R> {
     fn build_internal<FE>(
         self,
         prover: &impl TxProver,
-        fee: Amount,
+        fee: I64Amt,
     ) -> Result<(Transaction, SaplingMetadata), Error<FE>> {
         let consensus_branch_id = BranchId::for_height(&self.params, self.target_height);
 

masp_primitives/src/transaction/components.rs

@@ -4,7 +4,7 @@ pub mod amount;
 pub mod sapling;
 pub mod transparent;
 pub use self::{
-    amount::Amount,
+    amount::{Amount, I64Amt},
     sapling::{ConvertDescription, OutputDescription, SpendDescription},
     transparent::{TxIn, TxOut},
 };