From d3ef96cc052bd83c33cee5d8344bd6a528b9da71 Mon Sep 17 00:00:00 2001
From: Myk Taylor <myk002@yahoo.com>
Date: Thu, 2 Mar 2023 17:49:28 -0800
Subject: [PATCH] allow MaterialInfo structs to be sorted

---
 library/include/modules/Materials.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/library/include/modules/Materials.h b/library/include/modules/Materials.h
index 74acf5a8d..4018fcb2a 100644
--- a/library/include/modules/Materials.h
+++ b/library/include/modules/Materials.h
@@ -169,6 +169,9 @@ namespace DFHack
     inline bool operator!= (const MaterialInfo &a, const MaterialInfo &b) {
         return a.type != b.type || a.index != b.index;
     }
+    inline bool operator< (const MaterialInfo &a, const MaterialInfo &b) {
+        return a.type < b.type || (a.type == b.type && a.index < b.index);
+    }
 
     DFHACK_EXPORT bool isSoilInorganic(int material);
     DFHACK_EXPORT bool isStoneInorganic(int material);