From d0a3ce25ffbc1bf144ebdb7181c49aaa1d14ca73 Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Mon, 18 May 2020 18:13:45 +0300
Subject: [PATCH] compiler/storage: add read-only related interops

---
 pkg/compiler/syscall.go        | 12 +++++++-----
 pkg/interop/storage/storage.go | 15 ++++++++++++++-
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/pkg/compiler/syscall.go b/pkg/compiler/syscall.go
index 2c990c87b..a470f34fb 100644
--- a/pkg/compiler/syscall.go
+++ b/pkg/compiler/syscall.go
@@ -18,11 +18,13 @@ var syscalls = map[string]map[string]string{
 		"Value":  "Neo.Enumerator.Value",
 	},
 	"storage": {
-		"GetContext": "Neo.Storage.GetContext",
-		"Put":        "Neo.Storage.Put",
-		"Get":        "Neo.Storage.Get",
-		"Delete":     "Neo.Storage.Delete",
-		"Find":       "Neo.Storage.Find",
+		"ConvertContextToReadOnly": "Neo.StorageContext.AsReadOnly",
+		"Delete":                   "Neo.Storage.Delete",
+		"Find":                     "Neo.Storage.Find",
+		"Get":                      "Neo.Storage.Get",
+		"GetContext":               "Neo.Storage.GetContext",
+		"GetReadOnlyContext":       "Neo.Storage.GetReadOnlyContext",
+		"Put":                      "Neo.Storage.Put",
 	},
 	"runtime": {
 		"GetTrigger":   "Neo.Runtime.GetTrigger",
diff --git a/pkg/interop/storage/storage.go b/pkg/interop/storage/storage.go
index aade7e1e3..a047eebb1 100644
--- a/pkg/interop/storage/storage.go
+++ b/pkg/interop/storage/storage.go
@@ -10,13 +10,26 @@ import "github.com/nspcc-dev/neo-go/pkg/interop/iterator"
 
 // Context represents storage context that is mandatory for Put/Get/Delete
 // operations. It's an opaque type that can only be created properly by
-// GetContext. It's similar to Neo .net framework's StorageContext class.
+// GetContext, GetReadOnlyContext or ConvertContextToReadOnly. It's similar
+// to Neo .net framework's StorageContext class.
 type Context struct{}
 
+// ConvertContextToReadOnly returns new context from the given one, but with
+// writing capability turned off, so that you could only invoke Get and Find
+// using this new Context. If Context is already read-only this function is a
+// no-op. It uses `Neo.StorageContext.AsReadOnly` syscall.
+func ConvertContextToReadOnly(ctx Context) Context { return Context{} }
+
 // GetContext returns current contract's (that invokes this function) storage
 // context. It uses `Neo.Storage.GetContext` syscall.
 func GetContext() Context { return Context{} }
 
+// GetReadOnlyContext returns current contract's (that invokes this function)
+// storage context in read-only mode, you can use this context for Get and Find
+// functions, but using it for Put and Delete will fail. It uses
+// `Neo.Storage.GetReadOnlyContext` syscall.
+func GetReadOnlyContext() Context { return Context{} }
+
 // Put saves given value with given key in the storage using given Context.
 // Even though it accepts interface{} for both, you can only pass simple types
 // there like string, []byte, int or bool (not structures or slices of more