From 6aed2c58e85f16f3b26a7d4238c810ac8520873b Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Tue, 23 May 2023 20:21:20 +0200
Subject: [PATCH] auxiliary function atmod

---
 hyper.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/hyper.h b/hyper.h
index a120a713..1c4df2a5 100644
--- a/hyper.h
+++ b/hyper.h
@@ -884,6 +884,18 @@ const typename Map::mapped_type *at_or_null(const Map& map, const Key& key) {
   return (it == map.end()) ? nullptr : &it->second;
   }
 
+int gmod(int i, int j);
+
+// vector::at(i) modulo its size (const version)
+template<class T> const T& atmod(const vector<T>& container, int index) {
+  return container[gmod(index, isize(container))];
+  }
+
+// vector::at(i) modulo its size (non-const version)
+template<class T> T& atmod(vector<T>& container, int index) {
+  return container[gmod(index, isize(container))];
+  }
+
 namespace daily {
   extern bool on;
   extern int daily_id;