Implement pointer spec (#2499)

src/envelope.rs

@@ -10,6 +10,7 @@ pub(crate) const PROTOCOL_ID: [u8; 3] = *b"ord";
 
 pub(crate) const BODY_TAG: [u8; 0] = [];
 pub(crate) const CONTENT_TYPE_TAG: [u8; 1] = [1];
+pub(crate) const POINTER_TAG: [u8; 1] = [2];
 pub(crate) const PARENT_TAG: [u8; 1] = [3];
 pub(crate) const METADATA_TAG: [u8; 1] = [5];
 pub(crate) const METAPROTOCOL_TAG: [u8; 1] = [7];
@@ -27,12 +28,18 @@ pub(crate) struct Envelope<T> {
 }
 
 fn remove_field(fields: &mut BTreeMap<&[u8], Vec<&[u8]>>, field: &[u8]) -> Option<Vec<u8>> {
- let value = fields.get_mut(field)?;
+ let values = fields.get_mut(field)?;
 
- if value.is_empty() {
+ if values.is_empty() {
  None
  } else {
- Some(value.remove(0).to_vec())
+ let value = values.remove(0).to_vec();
+
+ if values.is_empty() {
+ fields.remove(field);
+ }
+
+ Some(value)
  }
 }
 
@@ -72,6 +79,7 @@ impl From<RawEnvelope> for ParsedEnvelope {
 
  let content_type = remove_field(&mut fields, &CONTENT_TYPE_TAG);
  let parent = remove_field(&mut fields, &PARENT_TAG);
+ let pointer = remove_field(&mut fields, &POINTER_TAG);
  let metaprotocol = remove_field(&mut fields, &METAPROTOCOL_TAG);
  let metadata = remove_and_concatenate_field(&mut fields, &METADATA_TAG);
 
@@ -90,6 +98,7 @@ impl From<RawEnvelope> for ParsedEnvelope {
  }),
  content_type,
  parent,
+ pointer,
  unrecognized_even_field,
  duplicate_field,
  incomplete_field,
@@ -743,6 +752,36 @@ mod tests {
  );
  }
 
+ #[test]
+ fn pointer_field_is_recognized() {
+ assert_eq!(
+ parse(&[envelope(&[b"ord", &[2], &[1]])]),
+ vec![ParsedEnvelope {
+ payload: Inscription {
+ pointer: Some(vec![1]),
+ ..Default::default()
+ },
+ ..Default::default()
+ }],
+ );
+ }
+
+ #[test]
+ fn duplicate_pointer_field_makes_inscription_unbound() {
+ assert_eq!(
+ parse(&[envelope(&[b"ord", &[2], &[1], &[2], &[0]])]),
+ vec![ParsedEnvelope {
+ payload: Inscription {
+ pointer: Some(vec![1]),
+ duplicate_field: true,
+ unrecognized_even_field: true,
+ ..Default::default()
+ },
+ ..Default::default()
+ }],
+ );
+ }
+
  #[test]
  fn incomplete_field() {
  assert_eq!(