[#64] commonclient: Use partial unwrap in ReadIteratorItems()

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

commonclient/invoker.go

@@ -11,6 +11,7 @@ import (
 // Invoker is a subset of methods provided by struct invoker.Invoker. The subset contains only those
 // methods that are used by ActorWrapper and clients of the contracts.
 type Invoker interface {
+	Run([]byte) (*result.Invoke, error)
 	Call(contract util.Uint160, method string, params ...any) (*result.Invoke, error)
 	TraverseIterator(sessionID uuid.UUID, iterator *result.Iterator, num int) ([]stackitem.Item, error)
 	TerminateSession(sessionID uuid.UUID) error

commonclient/iterator.go

@@ -3,7 +3,9 @@ package commonclient
 import (
 	"fmt"
 
+	"github.com/google/uuid"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/unwrap"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 )
@@ -14,13 +16,21 @@ func ReadIteratorItems(inv Invoker, batchSize int, contract util.Uint160, method
 		panic("batch size must be positive")
 	}
 
-	sessionID, iter, err := unwrap.SessionIterator(inv.Call(contract, method, params...))
+	script, err := smartcontract.CreateCallAndPrefetchIteratorScript(contract, method, batchSize, params...)
+	if err != nil {
+		return nil, fmt.Errorf("couldn't create unwrap script: %w", err)
+	}
+
+	arr, sessionID, iter, err := unwrap.ArrayAndSessionIterator(inv.Run(script))
 	if err != nil {
 		return nil, fmt.Errorf("unwrap session iterator: %w", err)
 	}
+	if (sessionID == uuid.UUID{}) {
+		return arr, nil
+	}
 
 	var shouldStop bool
-	res := make([]stackitem.Item, 0, len(iter.Values))
+	res := arr
 	for !shouldStop {
 		items, err := inv.TraverseIterator(sessionID, &iter, batchSize)
 		if err != nil {