feat: add address priority queue. will be used in mempool, multiple t…

…xs per account

crates/mempool/src/priority_queue.rs

@@ -56,3 +56,28 @@ impl PartialOrd for PrioritizedTransaction {
         Some(self.cmp(other))
     }
 }
+
+// TODO: remove when is used.
+#[allow(dead_code)]
+// Assumption: there are no gaps, and the transactions are received in order.
+pub struct AddressPriorityQueue(pub Vec<ThinTransaction>);
+
+// TODO: remove when is used.
+#[allow(dead_code)]
+impl AddressPriorityQueue {
+    pub fn push(&mut self, tx: ThinTransaction) {
+        self.0.push(tx);
+    }
+
+    pub fn top(&self) -> Option<ThinTransaction> {
+        self.0.first().cloned()
+    }
+
+    pub fn pop(&mut self) -> Option<ThinTransaction> {
+        Some(self.0.remove(0))
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}