Merge #171: Create explicit empty and null values for some types

349de41 Create explicit empty and null values for some types (Steven Roose)

Pull request description:

  IMO these are different than f.e. the Default impls on TxOut etc, because these types actually in many actual production cases want to be set to the empty or none value. As opposed to Default on other types that only exist to aid in test scenarios or so to avoid having to set the fields.

ACKs for top commit:
  apoelstra:
    ACK 349de41

Tree-SHA512: 3d91f9cf1d944ce15186ecd990dde874d6aad624bdcc7a0e91e9bcd540ef9aeef0289dbc717f165f13b32eafab63d7ddc610b970fc05bac6239606b46fd79460

Author: apoelstra

src/transaction.rs

@@ -34,7 +34,7 @@ use secp256k1_zkp::{
 };
 
 /// Description of an asset issuance in a transaction input
-#[derive(Copy, Clone, Debug, Default, Eq, Hash, PartialEq, PartialOrd, Ord)]
+#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
 pub struct AssetIssuance {
     /// Zero for a new asset issuance; otherwise a blinding factor for the input
     pub asset_blinding_nonce: Tweak,
@@ -47,6 +47,15 @@ pub struct AssetIssuance {
 }
 
 impl AssetIssuance {
+    /// Create a null issuance.
+    pub fn null() -> Self {
+        AssetIssuance {
+            asset_blinding_nonce: ZERO_TWEAK,
+            asset_entropy: [0; 32],
+            amount: confidential::Value::Null,
+            inflation_keys: confidential::Value::Null,
+        }
+    }
 
     /// Checks whether the [`AssetIssuance`] is null
     pub fn is_null(&self) -> bool {
@@ -56,6 +65,12 @@ impl AssetIssuance {
 serde_struct_impl!(AssetIssuance, asset_blinding_nonce, asset_entropy, amount, inflation_keys);
 impl_consensus_encoding!(AssetIssuance, asset_blinding_nonce, asset_entropy, amount, inflation_keys);
 
+impl Default for AssetIssuance {
+    fn default() -> Self {
+        Self::null()
+    }
+}
+
 /// A reference to a transaction output
 #[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
 pub struct OutPoint {
@@ -343,7 +358,7 @@ impl std::error::Error for RelativeLockTimeError {
 
 
 /// Transaction input witness
-#[derive(Clone, Default, PartialEq, Eq, Debug, Hash, PartialOrd, Ord)]
+#[derive(Clone, PartialEq, Eq, Debug, Hash, PartialOrd, Ord)]
 pub struct TxInWitness {
     /// Amount rangeproof
     pub amount_rangeproof: Option<Box<RangeProof>>,
@@ -358,6 +373,16 @@ serde_struct_impl!(TxInWitness, amount_rangeproof, inflation_keys_rangeproof, sc
 impl_consensus_encoding!(TxInWitness, amount_rangeproof, inflation_keys_rangeproof, script_witness, pegin_witness);
 
 impl TxInWitness {
+    /// Create an empty input witness.
+    pub fn empty() -> Self {
+        TxInWitness {
+            amount_rangeproof: None,
+            inflation_keys_rangeproof: None,
+            script_witness: Vec::new(),
+            pegin_witness: Vec::new(),
+        }
+    }
+
     /// Whether this witness is null
     pub fn is_empty(&self) -> bool {
         self.amount_rangeproof.is_none() &&
@@ -367,6 +392,12 @@ impl TxInWitness {
     }
 }
 
+impl Default for TxInWitness {
+    fn default() -> Self {
+        Self::empty()
+    }
+}
+
 
 /// Parsed data from a transaction input's pegin witness
 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
@@ -604,7 +635,7 @@ impl TxIn {
 }
 
 /// Transaction output witness
-#[derive(Clone, Default, PartialEq, Eq, Debug, Hash, PartialOrd, Ord)]
+#[derive(Clone, PartialEq, Eq, Debug, Hash, PartialOrd, Ord)]
 pub struct TxOutWitness {
     /// Surjection proof showing that the asset commitment is legitimate
     // We Box it because surjection proof internally is an array [u8; N] that
@@ -619,6 +650,14 @@ serde_struct_impl!(TxOutWitness, surjection_proof, rangeproof);
 impl_consensus_encoding!(TxOutWitness, surjection_proof, rangeproof);
 
 impl TxOutWitness {
+    /// Create an empty output witness.
+    pub fn empty() -> Self {
+        TxOutWitness {
+            surjection_proof: None,
+            rangeproof: None,
+        }
+    }
+
     /// Whether this witness is null
     pub fn is_empty(&self) -> bool {
         self.surjection_proof.is_none() && self.rangeproof.is_none()
@@ -635,6 +674,12 @@ impl TxOutWitness {
     }
 }
 
+impl Default for TxOutWitness {
+    fn default() -> Self {
+        Self::empty()
+    }
+}
+
 /// Information about a pegout
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct PegoutData<'txo> {
@@ -690,7 +735,6 @@ impl Decodable for TxOut {
 }
 
 impl TxOut {
-
     /// Create a new fee output.
     pub fn new_fee(amount: u64, asset: AssetId) -> TxOut {
         TxOut {