core, compiler: return struct from GetScriptContainer interop

Closes #1173

examples/engine/engine.go

@@ -7,7 +7,7 @@ import (
 // Main is that famous Main() function, you know.
 func Main() bool {
 	tx := runtime.GetScriptContainer()
-	runtime.Notify(tx)
+	runtime.Notify(tx.Hash)
 
 	callingScriptHash := runtime.GetCallingScriptHash()
 	runtime.Notify(callingScriptHash)

pkg/compiler/codegen.go

@@ -1146,7 +1146,7 @@ func (c *codegen) convertSyscall(expr *ast.CallExpr, api, name string) {
 	}
 	emit.Syscall(c.prog.BinWriter, api)
 	switch name {
-	case "GetTransaction", "GetBlock":
+	case "GetTransaction", "GetBlock", "GetScriptContainer":
 		c.emitConvert(stackitem.StructT)
 	}
 

pkg/core/interop_system.go

@@ -179,10 +179,19 @@ func bcGetTransactionHeight(ic *interop.Context, v *vm.VM) error {
 	return nil
 }
 
-// engineGetScriptContainer returns transaction that contains the script being
-// run.
+// engineGetScriptContainer returns transaction or block that contains the script
+// being run.
 func engineGetScriptContainer(ic *interop.Context, v *vm.VM) error {
-	v.Estack().PushVal(stackitem.NewInterop(ic.Container))
+	var item stackitem.Item
+	switch t := ic.Container.(type) {
+	case *transaction.Transaction:
+		item = transactionToStackItem(t)
+	case *block.Block:
+		item = blockToStackItem(t)
+	default:
+		return errors.New("unknown script container")
+	}
+	v.Estack().PushVal(item)
 	return nil
 }