From eb82661f6b43322f3cd18ff3b7f3aa356508ee1b Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Mon, 18 May 2020 15:38:11 +0300
Subject: [PATCH] compiler/iterator: add missing iterator.Concat function

We have a syscall for it, so it should be exposed.
---
 pkg/compiler/syscall.go          | 1 +
 pkg/interop/iterator/iterator.go | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/pkg/compiler/syscall.go b/pkg/compiler/syscall.go
index 82d49a16e..2c990c87b 100644
--- a/pkg/compiler/syscall.go
+++ b/pkg/compiler/syscall.go
@@ -105,6 +105,7 @@ var syscalls = map[string]map[string]string{
 		"GetExecutingScriptHash": "System.ExecutionEngine.GetExecutingScriptHash",
 	},
 	"iterator": {
+		"Concat": "Neo.Iterator.Concat",
 		"Create": "Neo.Iterator.Create",
 		"Key":    "Neo.Iterator.Key",
 		"Keys":   "Neo.Iterator.Keys",
diff --git a/pkg/interop/iterator/iterator.go b/pkg/interop/iterator/iterator.go
index b4bd281da..5ca5947cc 100644
--- a/pkg/interop/iterator/iterator.go
+++ b/pkg/interop/iterator/iterator.go
@@ -18,6 +18,15 @@ func Create(items []interface{}) Iterator {
 	return Iterator{}
 }
 
+// Concat concatenates two given iterators returning one that will range on
+// a first and then continue with b. Iterator positions are not reset for a
+// and b, so if any of them was already advanced by Next the resulting
+// Iterator will point at this new position and never go back to previous
+// key-value pairs. This function uses `Neo.Iterator.Concat` syscall.
+func Concat(a, b Iterator) Iterator {
+	return Iterator{}
+}
+
 // Key returns iterator's key at current position. It's only valid to call after
 // successful Next call. This function uses `Neo.Iterator.Key` syscall.
 func Key(it Iterator) interface{} {