add SurroundMap class header

src/world/generator/SurroundMap.hpp

@@ -0,0 +1,38 @@
+#pragma once
+
+#include <unordered_map>
+
+#define GLM_ENABLE_EXPERIMENTAL
+#include <glm/gtx/hash.hpp>
+
+class SurroundMap {
+    struct Entry {
+        /// @brief Level is increased when all surrounding (8) entries having
+        // greather or equal confirmed level
+        int level = 0;
+        /// @brief number of surrounding entries having greather or equal
+        /// confirmed level
+        int surrounding = 0;
+        /// @brief level confirmed status (entry is ready to expand)
+        bool confirmed = true;
+        /// @brief mark used on sweep event (extra isles garbage collection)
+        bool marked = false;
+    };
+    std::unordered_map<glm::ivec2, Entry> entries;
+public:
+    /// @brief Reset all isles marks
+    void resetMarks();
+
+    /// @brief Mark all connected entries
+    /// @param point origin point
+    void markIsle(const glm::ivec2& point);
+
+    /// @brief Erase all non-marked isles
+    /// @return erased entries positions
+    std::vector<glm::ivec2> sweep();
+
+    /// @brief Expand all confirmed entries with specified level
+    /// @param level target entries level
+    /// @return All upgraded entries positions 
+    std::vector<glm::ivec2> expand(int level);
+};

test/world/generator/SurroundMap.cpp

@@ -0,0 +1,7 @@
+#include <gtest/gtest.h>
+
+#include "world/generator/SurroundMap.hpp"
+
+TEST(SurroundMap, InitTest) {
+    SurroundMap map;
+}