feat(traverse): Add era-handling utilities (#123)

pallas-traverse/src/block.rs

@@ -103,9 +103,9 @@ impl<'b> MultiEraBlock<'b> {
 
     pub fn txs(&self) -> Vec<MultiEraTx> {
         match self {
-            MultiEraBlock::AlonzoCompatible(x, _) => support::clone_alonzo_txs(x)
+            MultiEraBlock::AlonzoCompatible(x, era) => support::clone_alonzo_txs(x)
                 .into_iter()
-                .map(|x| MultiEraTx::AlonzoCompatible(Box::new(Cow::Owned(x))))
+                .map(|x| MultiEraTx::AlonzoCompatible(Box::new(Cow::Owned(x)), *era))
                 .collect(),
             MultiEraBlock::Byron(x) => support::clone_byron_txs(x)
                 .into_iter()

pallas-traverse/src/era.rs

@@ -15,3 +15,33 @@ impl Era {
         }
     }
 }
+
+// for consistency, we use the same tag convention used by the node's cbor
+// encoding
+impl TryFrom<u16> for Era {
+    type Error = crate::Error;
+
+    fn try_from(value: u16) -> Result<Self, Self::Error> {
+        match value {
+            0 => Ok(Era::Byron),
+            1 => Ok(Era::Byron),
+            2 => Ok(Era::Shelley),
+            3 => Ok(Era::Allegra),
+            4 => Ok(Era::Mary),
+            5 => Ok(Era::Alonzo),
+            x => Err(crate::Error::UnkownEra(x)),
+        }
+    }
+}
+
+impl From<Era> for u16 {
+    fn from(other: Era) -> Self {
+        match other {
+            Era::Byron => 1,
+            Era::Shelley => 2,
+            Era::Allegra => 3,
+            Era::Mary => 4,
+            Era::Alonzo => 5,
+        }
+    }
+}

pallas-traverse/src/header.rs

@@ -0,0 +1,42 @@
+use pallas_codec::minicbor;
+use pallas_crypto::hash::Hash;
+use pallas_primitives::ToHash;
+
+use crate::{Error, MultiEraHeader};
+
+impl<'b> MultiEraHeader<'b> {
+    pub fn decode(tag: u8, subtag: Option<u8>, cbor: &'b [u8]) -> Result<Self, Error> {
+        match tag {
+            0 => match subtag {
+                Some(0) => {
+                    let header = minicbor::decode(cbor).map_err(Error::invalid_cbor)?;
+                    Ok(MultiEraHeader::EpochBoundary(header))
+                }
+                _ => {
+                    let header = minicbor::decode(cbor).map_err(Error::invalid_cbor)?;
+                    Ok(MultiEraHeader::Byron(header))
+                }
+            },
+            _ => {
+                let header = minicbor::decode(cbor).map_err(Error::invalid_cbor)?;
+                Ok(MultiEraHeader::AlonzoCompatible(header))
+            }
+        }
+    }
+
+    pub fn slot(&self) -> u64 {
+        match self {
+            MultiEraHeader::EpochBoundary(x) => x.to_abs_slot(),
+            MultiEraHeader::AlonzoCompatible(x) => x.header_body.slot,
+            MultiEraHeader::Byron(x) => x.consensus_data.0.to_abs_slot(),
+        }
+    }
+
+    pub fn hash(&self) -> Hash<32> {
+        match self {
+            MultiEraHeader::EpochBoundary(x) => x.to_hash(),
+            MultiEraHeader::AlonzoCompatible(x) => x.to_hash(),
+            MultiEraHeader::Byron(x) => x.to_hash(),
+        }
+    }
+}

pallas-traverse/src/lib.rs

@@ -3,13 +3,15 @@
 use std::borrow::Cow;
 use std::fmt::Display;
 
+use pallas_codec::utils::KeepRaw;
 use pallas_crypto::hash::Hash;
 use pallas_primitives::{alonzo, byron};
 use thiserror::Error;
 
 pub mod block;
 pub mod cert;
 pub mod era;
+pub mod header;
 pub mod input;
 pub mod output;
 pub mod probe;
@@ -35,6 +37,13 @@ pub enum Feature {
     SmartContracts,
 }
 
+#[derive(Debug)]
+pub enum MultiEraHeader<'b> {
+    EpochBoundary(KeepRaw<'b, byron::EbbHead>),
+    AlonzoCompatible(KeepRaw<'b, alonzo::Header>),
+    Byron(KeepRaw<'b, byron::BlockHead>),
+}
+
 #[derive(Debug, Clone)]
 #[non_exhaustive]
 pub enum MultiEraBlock<'b> {
@@ -46,7 +55,7 @@ pub enum MultiEraBlock<'b> {
 #[derive(Debug)]
 #[non_exhaustive]
 pub enum MultiEraTx<'b> {
-    AlonzoCompatible(Box<Cow<'b, alonzo::MintedTx<'b>>>),
+    AlonzoCompatible(Box<Cow<'b, alonzo::MintedTx<'b>>>, Era),
     Byron(Box<Cow<'b, byron::MintedTxPayload<'b>>>),
 }
 
@@ -78,6 +87,9 @@ pub enum Error {
 
     #[error("Unknown CBOR structure: {0}")]
     UnknownCbor(String),
+
+    #[error("Unknown era tag: {0}")]
+    UnkownEra(u16),
 }
 
 impl Error {

pallas-traverse/src/tx.rs

@@ -3,34 +3,56 @@ use pallas_crypto::hash::Hash;
 use pallas_primitives::{alonzo, byron, ToHash};
 use std::borrow::Cow;
 
-use crate::{MultiEraCert, MultiEraInput, MultiEraOutput, MultiEraTx};
+use crate::{Era, MultiEraCert, MultiEraInput, MultiEraOutput, MultiEraTx};
 
 impl<'b> MultiEraTx<'b> {
     pub fn from_byron(tx: &'b byron::MintedTxPayload<'b>) -> Self {
         Self::Byron(Box::new(Cow::Borrowed(tx)))
     }
 
-    pub fn from_alonzo_compatible(tx: &'b alonzo::MintedTx<'b>) -> Self {
-        Self::AlonzoCompatible(Box::new(Cow::Borrowed(tx)))
+    pub fn from_alonzo_compatible(tx: &'b alonzo::MintedTx<'b>, era: Era) -> Self {
+        Self::AlonzoCompatible(Box::new(Cow::Borrowed(tx)), era)
     }
 
     pub fn encode(&self) -> Result<Vec<u8>, minicbor::encode::Error<std::io::Error>> {
         match self {
-            MultiEraTx::AlonzoCompatible(x) => minicbor::to_vec(x),
+            MultiEraTx::AlonzoCompatible(x, _) => minicbor::to_vec(x),
             MultiEraTx::Byron(x) => minicbor::to_vec(x),
         }
     }
 
+    pub fn decode(era: Era, cbor: &'b [u8]) -> Result<Self, minicbor::decode::Error> {
+        match era {
+            Era::Byron => {
+                let tx = minicbor::decode(cbor)?;
+                let tx = Box::new(Cow::Owned(tx));
+                Ok(MultiEraTx::Byron(tx))
+            }
+            Era::Shelley | Era::Allegra | Era::Mary | Era::Alonzo => {
+                let tx = minicbor::decode(cbor)?;
+                let tx = Box::new(Cow::Owned(tx));
+                Ok(MultiEraTx::AlonzoCompatible(tx, era))
+            }
+        }
+    }
+
+    pub fn era(&self) -> Era {
+        match self {
+            MultiEraTx::AlonzoCompatible(_, era) => *era,
+            MultiEraTx::Byron(_) => Era::Byron,
+        }
+    }
+
     pub fn hash(&self) -> Hash<32> {
         match self {
-            MultiEraTx::AlonzoCompatible(x) => x.transaction_body.to_hash(),
+            MultiEraTx::AlonzoCompatible(x, _) => x.transaction_body.to_hash(),
             MultiEraTx::Byron(x) => x.transaction.to_hash(),
         }
     }
 
     pub fn outputs(&self) -> Vec<MultiEraOutput> {
         match self {
-            MultiEraTx::AlonzoCompatible(x) => x
+            MultiEraTx::AlonzoCompatible(x, _) => x
                 .transaction_body
                 .outputs
                 .iter()
@@ -47,7 +69,7 @@ impl<'b> MultiEraTx<'b> {
 
     pub fn inputs(&self) -> Vec<MultiEraInput> {
         match self {
-            MultiEraTx::AlonzoCompatible(x) => x
+            MultiEraTx::AlonzoCompatible(x, _) => x
                 .transaction_body
                 .inputs
                 .iter()
@@ -65,7 +87,7 @@ impl<'b> MultiEraTx<'b> {
 
     pub fn certs(&self) -> Vec<MultiEraCert> {
         match self {
-            MultiEraTx::AlonzoCompatible(x) => x
+            MultiEraTx::AlonzoCompatible(x, _) => x
                 .transaction_body
                 .certificates
                 .iter()
@@ -78,14 +100,14 @@ impl<'b> MultiEraTx<'b> {
 
     pub fn as_alonzo(&self) -> Option<&alonzo::MintedTx> {
         match self {
-            MultiEraTx::AlonzoCompatible(x) => Some(x),
+            MultiEraTx::AlonzoCompatible(x, _) => Some(x),
             MultiEraTx::Byron(_) => None,
         }
     }
 
     pub fn as_byron(&self) -> Option<&byron::MintedTxPayload> {
         match self {
-            MultiEraTx::AlonzoCompatible(_) => None,
+            MultiEraTx::AlonzoCompatible(_, _) => None,
             MultiEraTx::Byron(x) => Some(x),
         }
     }