From 6c417830105d27d151284546c6482f0f6eccef26 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 23 Jan 2021 14:01:01 +0000
Subject: Add a basic cache template

---
 lib/cache.h | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 lib/cache.h

diff --git a/lib/cache.h b/lib/cache.h
new file mode 100644
index 0000000..48b9c55
--- /dev/null
+++ b/lib/cache.h
@@ -0,0 +1,29 @@
+#ifndef CACHE_H
+#define CACHE_H
+
+#include <map>
+#include <memory>
+
+template<typename Obj> class Cache {
+public:
+	using Ptr = std::shared_ptr<Obj>;
+	[[nodiscard]] Ptr
+	get(const std::string & key)
+	{
+		if (auto e = cached.find(key); e != cached.end()) {
+			return e->second;
+		}
+		return cached.emplace(key, construct(key)).first->second;
+	}
+
+	[[nodiscard]] virtual Ptr
+	construct(const std::string & key) const
+	{
+		return std::make_shared<Obj>(key);
+	}
+
+private:
+	std::map<std::string, Ptr> cached;
+};
+
+#endif
-- 
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