From b4f432f1de2b75647a30911792f727da619a88f8 Mon Sep 17 00:00:00 2001
From: Robin Kertels <robin.kertels@gmail.com>
Date: Wed, 6 Jul 2022 18:10:09 +0200
Subject: [PATCH] [util] Implement LRU list

---
 src/util/util_lru.h | 69 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 src/util/util_lru.h

diff --git a/src/util/util_lru.h b/src/util/util_lru.h
new file mode 100644
index 000000000..96076cc4a
--- /dev/null
+++ b/src/util/util_lru.h
@@ -0,0 +1,69 @@
+#include <cstdint>
+#include <list>
+#include <unordered_map>
+
+namespace dxvk {
+
+  template<typename T>
+  class lru_list {
+
+  public:
+    typedef typename std::list<T>::const_iterator const_iterator;
+
+    void insert(T value) {
+      auto cacheIter = m_cache.find(value);
+      if (cacheIter != m_cache.end())
+        m_list.erase(cacheIter->second);
+
+      m_list.push_back(value);
+      auto iter = m_list.cend();
+      iter--;
+      m_cache[value] = iter;
+    }
+
+    void remove(const T& value) {
+      auto cacheIter = m_cache.find(value);
+      if (cacheIter == m_cache.end())
+        return;
+
+      m_list.erase(cacheIter->second);
+      m_cache.erase(cacheIter);
+    }
+
+    const_iterator remove(const_iterator iter) {
+      auto cacheIter = m_cache.find(*iter);
+      m_cache.erase(cacheIter);
+      return m_list.erase(iter);
+    }
+
+    void touch(const T& value) {
+      auto cacheIter = m_cache.find(value);
+      if (cacheIter == m_cache.end())
+        return;
+
+      m_list.erase(cacheIter->second);
+      m_list.push_back(value);
+      auto iter = m_list.cend();
+      --iter;
+      m_cache[value] = iter;
+    }
+
+    const_iterator leastRecentlyUsedIter() const {
+      return m_list.cbegin();
+    }
+
+    const_iterator leastRecentlyUsedEndIter() const {
+      return m_list.cend();
+    }
+
+    uint32_t size() const noexcept {
+      return m_list.size();
+    }
+
+  private:
+    std::list<T> m_list;
+    std::unordered_map<T, const_iterator> m_cache;
+
+  };
+
+}