From d569fe01e670a8d05050ecc039f84c5db43754b6 Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Wed, 9 Nov 2022 10:20:44 +0300
Subject: [PATCH] rpcbinding: initial support for iterators, see #2768

Already better than stackitem.Item.
---
 cli/smartcontract/testdata/nameservice/nns.go | 11 ++++++-----
 docs/compiler.md                              |  5 ++++-
 pkg/smartcontract/rpcbinding/binding.go       | 14 +++++++++++---
 3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/cli/smartcontract/testdata/nameservice/nns.go b/cli/smartcontract/testdata/nameservice/nns.go
index 5c849b8e7..daf1e6842 100644
--- a/cli/smartcontract/testdata/nameservice/nns.go
+++ b/cli/smartcontract/testdata/nameservice/nns.go
@@ -2,12 +2,13 @@
 package nameservice
 
 import (
+	"github.com/google/uuid"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
+	"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/nep11"
 	"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"
 	"math/big"
 )
 
@@ -59,8 +60,8 @@ func New(actor Actor) *Contract {
 
 
 // Roots invokes `roots` method of contract.
-func (c *ContractReader) Roots() (stackitem.Item, error) {
-	return unwrap.Item(c.invoker.Call(Hash, "roots"))
+func (c *ContractReader) Roots() (uuid.UUID, result.Iterator, error) {
+	return unwrap.SessionIterator(c.invoker.Call(Hash, "roots"))
 }
 
 // GetPrice invokes `getPrice` method of contract.
@@ -79,8 +80,8 @@ func (c *ContractReader) GetRecord(name string, typev *big.Int) (string, error)
 }
 
 // GetAllRecords invokes `getAllRecords` method of contract.
-func (c *ContractReader) GetAllRecords(name string) (stackitem.Item, error) {
-	return unwrap.Item(c.invoker.Call(Hash, "getAllRecords", name))
+func (c *ContractReader) GetAllRecords(name string) (uuid.UUID, result.Iterator, error) {
+	return unwrap.SessionIterator(c.invoker.Call(Hash, "getAllRecords", name))
 }
 
 // Resolve invokes `resolve` method of contract.
diff --git a/docs/compiler.md b/docs/compiler.md
index ab1358b7e..78e6d0416 100644
--- a/docs/compiler.md
+++ b/docs/compiler.md
@@ -449,7 +449,10 @@ returns false.
 If your contract is NEP-11 or NEP-17 that's autodetected and an appropriate
 package is included as well. Notice that the type data available in the
 manifest is limited, so in some cases the interface generated may use generic
-stackitem types. Iterators are not supported yet.
+stackitem types. Any InteropInterface returned from a method is treated as
+iterator and an appropriate unwrapper is used with UUID and iterator structure
+result. This pair can then be used in Invoker `TraverseIterator` method to
+retrieve actual resulting items.
 
 ```
 $ ./bin/neo-go contract generate-rpcwrapper --manifest manifest.json --out rpcwrapper.go --hash 0x1b4357bff5a01bdf2a6581247cf9ed1e24629176
diff --git a/pkg/smartcontract/rpcbinding/binding.go b/pkg/smartcontract/rpcbinding/binding.go
index d3e9bb507..8fdc4d26a 100644
--- a/pkg/smartcontract/rpcbinding/binding.go
+++ b/pkg/smartcontract/rpcbinding/binding.go
@@ -334,9 +334,17 @@ func scTemplateToRPC(cfg binding.Config, ctr ContractTmpl, imports map[string]st
 	for i := range ctr.SafeMethods {
 		switch ctr.SafeMethods[i].ReturnType {
 		case "interface{}":
-			imports["github.com/nspcc-dev/neo-go/pkg/vm/stackitem"] = struct{}{}
-			ctr.SafeMethods[i].ReturnType = "stackitem.Item"
-			ctr.SafeMethods[i].CallFlag = "Item"
+			abim := cfg.Manifest.ABI.GetMethod(ctr.SafeMethods[i].NameABI, len(ctr.SafeMethods[i].Arguments))
+			if abim.ReturnType == smartcontract.InteropInterfaceType {
+				imports["github.com/google/uuid"] = struct{}{}
+				imports["github.com/nspcc-dev/neo-go/pkg/neorpc/result"] = struct{}{}
+				ctr.SafeMethods[i].ReturnType = "uuid.UUID, result.Iterator"
+				ctr.SafeMethods[i].CallFlag = "SessionIterator"
+			} else {
+				imports["github.com/nspcc-dev/neo-go/pkg/vm/stackitem"] = struct{}{}
+				ctr.SafeMethods[i].ReturnType = "stackitem.Item"
+				ctr.SafeMethods[i].CallFlag = "Item"
+			}
 		case "bool":
 			ctr.SafeMethods[i].CallFlag = "Bool"
 		case "*big.Int":