feat(traverse): Expose multi-era metadata (#151)

pallas-traverse/src/lib.rs

@@ -14,6 +14,7 @@ pub mod cert;
 pub mod era;
 pub mod header;
 pub mod input;
+pub mod meta;
 pub mod output;
 pub mod probe;
 mod support;
@@ -87,6 +88,8 @@ pub enum MultiEraCert<'b> {
     AlonzoCompatible(Box<Cow<'b, alonzo::Certificate>>),
 }
 
+pub struct MultiEraMeta<'b>(Cow<'b, alonzo::Metadata>);
+
 #[derive(Debug, Clone)]
 pub struct OutputRef(Hash<32>, u64);
 

pallas-traverse/src/meta.rs

@@ -0,0 +1,15 @@
+use pallas_primitives::alonzo;
+
+use crate::MultiEraMeta;
+
+impl<'b> MultiEraMeta<'b> {
+    pub fn entries(&self) -> &alonzo::Metadata {
+        &self.0
+    }
+
+    pub fn find(&self, label: alonzo::MetadatumLabel) -> Option<&alonzo::Metadatum> {
+        self.entries()
+            .iter()
+            .find_map(|(key, value)| if key.eq(&label) { Some(value) } else { None })
+    }
+}

pallas-traverse/src/tx.rs

@@ -1,9 +1,12 @@
-use pallas_codec::minicbor;
+use pallas_codec::{minicbor, utils::KeepRaw};
 use pallas_crypto::hash::Hash;
-use pallas_primitives::{alonzo, babbage, byron, ToHash};
-use std::borrow::Cow;
+use pallas_primitives::{
+    alonzo::{self, AuxiliaryData},
+    babbage, byron, ToHash,
+};
+use std::{borrow::Cow, ops::Deref};
 
-use crate::{Era, MultiEraCert, MultiEraInput, MultiEraOutput, MultiEraTx};
+use crate::{Era, MultiEraCert, MultiEraInput, MultiEraMeta, MultiEraOutput, MultiEraTx};
 
 impl<'b> MultiEraTx<'b> {
     pub fn from_byron(tx: &'b byron::MintedTxPayload<'b>) -> Self {
@@ -148,6 +151,26 @@ impl<'b> MultiEraTx<'b> {
         }
     }
 
+    fn aux_data(&self) -> Option<&KeepRaw<'_, AuxiliaryData>> {
+        match self {
+            MultiEraTx::AlonzoCompatible(x, _) => x.auxiliary_data.as_ref(),
+            MultiEraTx::Babbage(x) => x.auxiliary_data.as_ref(),
+            MultiEraTx::Byron(_) => None,
+        }
+    }
+
+    pub fn metadata(&self) -> Option<MultiEraMeta> {
+        match self.aux_data()?.deref() {
+            AuxiliaryData::Shelley(x) => MultiEraMeta(Cow::Borrowed(x)).into(),
+            AuxiliaryData::ShelleyMa(x) => {
+                MultiEraMeta(Cow::Borrowed(&x.transaction_metadata)).into()
+            }
+            AuxiliaryData::PostAlonzo(x) => {
+                x.metadata.as_ref().map(|x| MultiEraMeta(Cow::Borrowed(x)))
+            }
+        }
+    }
+
     pub fn as_babbage(&self) -> Option<&babbage::MintedTx> {
         match self {
             MultiEraTx::AlonzoCompatible(_, _) => None,