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include/SafeVector.hpp

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+#pragma once
+
+#include <vector>
+#include <memory>
+#include <functional>
+
+// A vector that can be modified while iterating
+template <typename T>
+class SafeVector {
+public:
+    using PointerType = typename std::pointer_traits<T>::element_type*;
+
+    void push_back(T item) {
+        data.push_back(std::move(item));
+    }
+
+    // Safe to call when vector is empty
+    void pop_back() {
+        if(!data.empty())
+            data.pop_back();
+    }
+
+    // Might not remove the data immediately if inside for_each loop.
+    // In that case the item is remove at the end of the loop.
+    void remove(PointerType item_to_remove) {
+        if(for_each_depth == 0)
+            remove_item(item_to_remove);
+        else
+            remove_queue.push_back(item_to_remove);
+    }
+
+    // Safe to call when vector is empty, in which case it returns nullptr
+    T* back() {
+        if(data.empty())
+            return nullptr;
+        else
+            return &data.back();
+    }
+
+    void clear() {
+        data.clear();
+        remove_queue.clear();
+    }
+
+    // Return true from |callback| to continue. This function returns false if |callback| returned false
+    bool for_each(std::function<bool(T &t)> callback) {
+        bool result = true;
+        ++for_each_depth;
+
+        for(size_t i = 0; i < data.size(); ++i) {
+            result = callback(data[i]);
+            if(!result)
+                break;
+        }
+
+        --for_each_depth;
+        if(for_each_depth == 0) {
+            for(PointerType item_to_remove : remove_queue) {
+                remove_item(item_to_remove);
+            }
+            remove_queue.clear();
+        }
+
+        return result;
+    }
+
+    // Return true from |callback| to continue. This function returns false if |callback| returned false
+    bool for_each_reverse(std::function<bool(T &t)> callback) {
+        bool result = true;
+        ++for_each_depth;
+
+        int i = (int)data.size() - 1;
+        while(true) {
+            // pop_back can be called while iterating so handle that case
+            if(i >= (int)data.size())
+                i = (int)data.size() - 1;
+
+            if(i < 0)
+                break;
+
+            result = callback(data[i]);
+            if(!result)
+                break;
+
+            --i;
+        }
+
+        --for_each_depth;
+        if(for_each_depth == 0) {
+            for(PointerType item_to_remove : remove_queue) {
+                remove_item(item_to_remove);
+            }
+            remove_queue.clear();
+        }
+
+        return result;
+    }
+
+    T& operator[](size_t index) {
+        return data[index];
+    }
+
+    const T& operator[](size_t index) const {
+        return data[index];
+    }
+
+    size_t size() const {
+        return data.size();
+    }
+
+    bool empty() const {
+        return data.empty();
+    }
+private:
+    void remove_item(PointerType item_to_remove) {
+        for(auto it = data.begin(), end = data.end(); it != end; ++it) {
+            if(&*(*it) == item_to_remove) {
+                data.erase(it);
+                return;
+            }
+        }
+    }
+private:
+    std::vector<T> data;
+    std::vector<PointerType> remove_queue;
+    int for_each_depth = 0;
+};