logic: improved codeview performance

* reduced database queries necessary for creating code snippets in the codeview.

src/lib/utility/Cache.h

@@ -0,0 +1,38 @@
+#ifndef CACHE_H
+#define CACHE_H
+
+#include <functional>
+#include <map>
+
+template <typename KeyType, typename ValType>
+class Cache
+{
+public:
+	Cache(std::function<ValType(KeyType)> calculator);
+	ValType getValue(KeyType key);
+
+private:
+	std::function<ValType(KeyType)> m_calculator;
+	std::map<KeyType, ValType> m_map;
+};
+
+template <typename KeyType, typename ValType>
+Cache<KeyType, ValType>::Cache(std::function<ValType(KeyType)> calculator)
+	: m_calculator(calculator)
+{
+}
+
+template <typename KeyType, typename ValType>
+ValType Cache<KeyType, ValType>::getValue(KeyType key)
+{
+	std::map<KeyType, ValType>::const_iterator it = m_map.find(key);
+	if (it != m_map.end())
+	{
+		return it->second;
+	}
+	ValType val = m_calculator(key);
+	m_map[key] = val;
+	return val;
+}
+
+#endif // CACHE_H