[#48] Add commonclient package

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

commonclient/iterator.go

@@ -0,0 +1,35 @@
+package commonclient
+
+import (
+	"fmt"
+
+	"github.com/nspcc-dev/neo-go/pkg/rpcclient/unwrap"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+// ReadIteratorItems calls method that returns iterator and traverses the iterator until all items are read into array.
+func ReadIteratorItems(inv Invoker, batchSize int, contract util.Uint160, method string, params ...any) ([]stackitem.Item, error) {
+	if batchSize <= 0 {
+		panic("batch size must be positive")
+	}
+
+	sessionID, iter, err := unwrap.SessionIterator(inv.Call(contract, method, params...))
+	if err != nil {
+		return nil, fmt.Errorf("unwrap session iterator: %w", err)
+	}
+
+	var shouldStop bool
+	res := make([]stackitem.Item, 0, len(iter.Values))
+	for !shouldStop {
+		items, err := inv.TraverseIterator(sessionID, &iter, batchSize)
+		if err != nil {
+			return nil, err
+		}
+
+		res = append(res, items...)
+		shouldStop = len(items) < batchSize
+	}
+
+	return res, nil
+}