Add handle_pairing

src/process.rs

@@ -99,6 +99,32 @@ impl ProcessState {
         }
     }
 
+    fn handle_pairing(&self, pairing_role: RoleDefinition, previous_addresses: Vec<SilentPaymentAddress>) -> anyhow::Result<()> {
+        // members must be empty
+        if !pairing_role.members.is_empty() { return Err(anyhow::Error::msg("Invalid pairing role: members list must be empty")); }
+        // pairing_role must have one rule that modifies pairedAddresses
+        let paired_addresses_rule = pairing_role.get_applicable_rules(PAIREDADDRESSES);
+        if paired_addresses_rule.len() != 1 { 
+            return Err(anyhow::anyhow!("Invalid pairing role: there must one and only one rule for \"pairedAddresses\""));
+        }
+
+        // We must have a pairedAddresses field in public_data 
+        let updated_addresses = self.public_data.get(PAIREDADDRESSES).ok_or(anyhow::Error::msg("No paired addresses"))?; // This shouldn't happen
+
+        // TODO check that it matches what we have in the commitment here or somewhere else?
+
+        let updated_member = Member::new(serde_json::from_value(updated_addresses.clone())?);
+        let previous_member = Member::new(previous_addresses);
+
+        let members = if previous_member.get_addresses().is_empty() {
+            vec![&updated_member]
+        } else {
+            vec![&previous_member]
+        };
+
+        paired_addresses_rule.iter().next().unwrap().is_satisfied(PAIREDADDRESSES, self.state_id, &self.validation_tokens, members.as_slice())
+    }
+
     pub fn is_valid(&self, previous_state: Option<&ProcessState>, members_list: &OutPointMemberMap) -> anyhow::Result<()> {
         if self.validation_tokens.is_empty() {
             return Err(anyhow::anyhow!(