added limited queue

messages/limitedqueuesnapshot.h

@@ -0,0 +1,48 @@
+#ifndef LIMITEDQUEUESNAPSHOT_H
+#define LIMITEDQUEUESNAPSHOT_H
+
+#include <cassert>
+#include <memory>
+#include <vector>
+
+namespace chatterino {
+namespace messages {
+
+template <typename T>
+class LimitedQueueSnapshot
+{
+public:
+    LimitedQueueSnapshot(std::shared_ptr<std::vector<T>> ptr, int offset,
+                         int length)
+        : vectorPtr(ptr)
+        , vector(ptr.get())
+        , offset(offset)
+        , length(length)
+    {
+    }
+
+    int
+    getLength()
+    {
+        return length;
+    }
+
+    T const &operator[](int index) const
+    {
+        assert(index >= 0);
+        assert(index < length);
+
+        return vector->at(index + offset);
+    }
+
+private:
+    std::shared_ptr<std::vector<T>> vectorPtr;
+    std::vector<T> *vector;
+
+    int offset;
+    int length;
+};
+}
+}
+
+#endif  // LIMITEDQUEUESNAPSHOT_H