1 files changed, 72 insertions, 0 deletions
diff --git a/matching/include/spdlog/details/circular_q.h b/matching/include/spdlog/details/circular_q.h
new file mode 100644
index 0000000..b01325b
--- /dev/null
+++ b/matching/include/spdlog/details/circular_q.h
@@ -0,0 +1,72 @@
+//
+// Copyright(c) 2018 Gabi Melman.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+//
+
+// cirucal q view of std::vector.
+#pragma once
+
+#include <vector>
+
+namespace spdlog {
+namespace details {
+template<typename T>
+class circular_q
+{
+public:
+    using item_type = T;
+
+    explicit circular_q(size_t max_items)
+        : max_items_(max_items + 1) // one item is reserved as marker for full q
+        , v_(max_items_)
+    {
+    }
+
+    // push back, overrun (oldest) item if no room left
+    void push_back(T &&item)
+    {
+        v_[tail_] = std::move(item);
+        tail_ = (tail_ + 1) % max_items_;
+
+        if (tail_ == head_) // overrun last item if full
+        {
+            head_ = (head_ + 1) % max_items_;
+            ++overrun_counter_;
+        }
+    }
+
+    // Pop item from front.
+    // If there are no elements in the container, the behavior is undefined.
+    void pop_front(T &popped_item)
+    {
+        popped_item = std::move(v_[head_]);
+        head_ = (head_ + 1) % max_items_;
+    }
+
+    bool empty()
+    {
+        return tail_ == head_;
+    }
+
+    bool full()
+    {
+        // head is ahead of the tail by 1
+        return ((tail_ + 1) % max_items_) == head_;
+    }
+
+    size_t overrun_counter() const
+    {
+        return overrun_counter_;
+    }
+
+private:
+    size_t max_items_;
+    typename std::vector<T>::size_type head_ = 0;
+    typename std::vector<T>::size_type tail_ = 0;
+
+    std::vector<T> v_;
+
+    size_t overrun_counter_ = 0;
+};
+} // namespace details
+} // namespace spdlog