core: implement System.Json.* interops

pkg/core/interop/json/json.go

@@ -0,0 +1,29 @@
+package json
+
+import (
+	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/vm"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+// Serialize handles System.JSON.Serialize syscall.
+func Serialize(_ *interop.Context, v *vm.VM) error {
+	item := v.Estack().Pop().Item()
+	data, err := stackitem.ToJSON(item)
+	if err != nil {
+		return err
+	}
+	v.Estack().PushVal(data)
+	return nil
+}
+
+// Deserialize handles System.JSON.Deserialize syscall.
+func Deserialize(_ *interop.Context, v *vm.VM) error {
+	data := v.Estack().Pop().Bytes()
+	item, err := stackitem.FromJSON(data)
+	if err != nil {
+		return err
+	}
+	v.Estack().PushVal(item)
+	return nil
+}