feat: add remove to account tx index (#317)

Subsequent PRs will integrate this remove into the tx_pool

commit-id:ef407f33

Co-authored-by: Gilad Chase <[email protected]>

crates/mempool/src/transaction_pool.rs

@@ -86,4 +86,17 @@ impl AccountTransactionIndex {
     pub fn insert(&mut self, tx: TransactionReference) -> Option<TransactionReference> {
         self.0.entry(tx.sender_address).or_default().insert(tx.nonce, tx)
     }
+
+    pub fn remove(&mut self, tx: TransactionReference) -> Option<TransactionReference> {
+        let ThinTransaction { sender_address, nonce, .. } = tx.0;
+        let account_txs = self.0.get_mut(&sender_address)?;
+
+        let removed_tx = account_txs.remove(&nonce);
+
+        if removed_tx.is_some() && account_txs.is_empty() {
+            self.0.remove(&sender_address);
+        }
+
+        removed_tx
+    }
 }