Redesign audio to support multiple audio tracks explicitly

include/SafeVector.hpp

@@ -1,8 +1,15 @@
 #pragma once
 
 #include <vector>
-#include <memory>
 #include <functional>
+#include <assert.h>
+#include "gui/Widget.hpp"
+
+template <typename T>
+struct SafeVectorItem {
+    T item;
+    bool alive = false;
+};
 
 // A vector that can be modified while iterating
 template <typename T>
@@ -10,64 +17,84 @@ class SafeVector {
 public:
     using PointerType = typename std::pointer_traits<T>::element_type*;
 
+    SafeVector() = default;
+    SafeVector(const SafeVector&) = delete;
+    SafeVector& operator=(const SafeVector&) = delete;
+    ~SafeVector() {
+        clear();
+    }
+
     void push_back(T item) {
-        data.push_back(std::move(item));
+        data.push_back({std::move(item), true});
+        ++num_items_alive;
     }
 
     // Safe to call when vector is empty
     // TODO: Make this iterator safe
     void pop_back() {
-        if(!data.empty())
+        if(!data.empty()) {
+            gsr::add_widget_to_remove(std::move(data.back().item));
             data.pop_back();
+            --num_items_alive;
+        }
     }
 
     // Might not remove the data immediately if inside for_each loop.
     // In that case the item is removed at the end of the loop.
     void remove(PointerType item_to_remove) {
-        if(for_each_depth == 0)
+        if(for_each_depth == 0) {
             remove_item(item_to_remove);
-        else
-            remove_queue.push_back(item_to_remove);
+            return;
+        }
+
+        SafeVectorItem<T> *item = get_item(item_to_remove);
+        if(item && item->alive) {
+            item->alive = false;
+            --num_items_alive;
+            has_items_to_remove = true;
+        }
     }
 
     // Safe to call when vector is empty, in which case it returns nullptr
     T* back() {
-        if(data.empty())
-            return nullptr;
-        else
-            return &data.back();
+        for(auto it = data.rbegin(), end = data.rend(); it != end; ++it) {
+            if(it->alive)
+                return &it->item;
+        }
+        return nullptr;
     }
 
     // TODO: Make this iterator safe
     void clear() {
+        for(auto &item : data) {
+            gsr::add_widget_to_remove(std::move(item.item));
+        }
         data.clear();
-        remove_queue.clear();
+        num_items_alive = 0;
     }
 
     // Return true from |callback| to continue. This function returns false if |callback| returned false
-    bool for_each(std::function<bool(T &t)> callback) {
+    bool for_each(std::function<bool(T &t)> callback, bool include_dead = false) {
         bool result = true;
         ++for_each_depth;
 
         for(size_t i = 0; i < data.size(); ++i) {
-            result = callback(data[i]);
-            if(!result)
-                break;
+            if(data[i].alive || include_dead) {
+                result = callback(data[i].item);
+                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();
-        }
+        if(for_each_depth == 0)
+            remove_dead_items();
 
         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 for_each_reverse(std::function<bool(T &t)> callback, bool include_dead = false) {
         bool result = true;
         ++for_each_depth;
 
@@ -80,50 +107,84 @@ public:
             if(i < 0)
                 break;
 
-            result = callback(data[i]);
-            if(!result)
-                break;
+            if(data[i].alive || include_dead) {
+                result = callback(data[i].item);
+                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();
-        }
+        if(for_each_depth == 0)
+            remove_dead_items();
 
         return result;
     }
 
     T& operator[](size_t index) {
-        return data[index];
+        assert(index < data.size());
+        return data[index].item;
     }
 
     const T& operator[](size_t index) const {
-        return data[index];
+        assert(index < data.size());
+        return data[index].item;
     }
 
     size_t size() const {
-        return data.size();
+        return (size_t)num_items_alive;
     }
 
     bool empty() const {
-        return data.empty();
+        return num_items_alive == 0;
+    }
+
+    void replace_item(PointerType item_to_replace, T new_item) {
+        SafeVectorItem<T> *item = get_item(item_to_replace);
+        if(item->alive) {
+            gsr::add_widget_to_remove(std::move(item->item));
+            item->item = std::move(new_item);
+        }
     }
 private:
     void remove_item(PointerType item_to_remove) {
         for(auto it = data.begin(), end = data.end(); it != end; ++it) {
-            if(&*(*it) == item_to_remove) {
+            if(&*(it->item) == item_to_remove) {
+                gsr::add_widget_to_remove(std::move(it->item));
                 data.erase(it);
+                --num_items_alive;
                 return;
             }
         }
     }
+
+    SafeVectorItem<T>* get_item(PointerType item_to_remove) {
+        for(auto &item : data) {
+            if(&*(item.item) == item_to_remove)
+                return &item;
+        }
+        return nullptr;
+    }
+
+    void remove_dead_items() {
+        if(!has_items_to_remove)
+            return;
+
+        for(auto it = data.begin(); it != data.end();) {
+            if(it->alive) {
+                ++it;
+            } else {
+                gsr::add_widget_to_remove(std::move(it->item));
+                it = data.erase(it);
+            }
+        }
+        has_items_to_remove = false;
+    }
 private:
-    std::vector<T> data;
-    std::vector<PointerType> remove_queue;
+    std::vector<SafeVectorItem<T>> data;
     int for_each_depth = 0;
+    int num_items_alive = 0;
+    bool has_items_to_remove = false;
 };