Internals: Added ImPool helper data structure (used by testing system, and already in docking branch)

imgui_internal.h

@@ -213,6 +213,30 @@ static inline ImVec2 ImRotate(const ImVec2& v, float cos_a, float sin_a)
 static inline float  ImLinearSweep(float current, float target, float speed)    { if (current < target) return ImMin(current + speed, target); if (current > target) return ImMax(current - speed, target); return current; }
 static inline ImVec2 ImMul(const ImVec2& lhs, const ImVec2& rhs)                { return ImVec2(lhs.x * rhs.x, lhs.y * rhs.y); }
 
+// Helper: ImPool<>. Basic keyed storage for contiguous instances, slow/amortized insertion, O(1) indexable, O(Log N) queries by ID over a dense/hot buffer,
+// Honor constructor/destructor. Add/remove invalidate all pointers. Indexes have the same lifetime as the associated object.
+typedef int ImPoolIdx;
+template<typename T>
+struct IMGUI_API ImPool
+{
+    ImVector<T>     Data;       // Contiguous data
+    ImGuiStorage    Map;        // ID->Index
+    ImPoolIdx       FreeIdx;    // Next free idx to use
+
+    ImPool()    { FreeIdx = 0; }
+    ~ImPool()   { Clear(); }
+    T*          GetByKey(ImGuiID key)               { int idx = Map.GetInt(key, -1); return (idx != -1) ? &Data[idx] : NULL; }
+    T*          GetByIndex(ImPoolIdx n)             { return &Data[n]; }
+    ImPoolIdx   GetIndex(const T* p) const          { IM_ASSERT(p >= Data.Data && p < Data.Data + Data.Size); return (ImPoolIdx)(p - Data.Data); }
+    T*          GetOrAddByKey(ImGuiID key)          { int* p_idx = Map.GetIntRef(key, -1); if (*p_idx != -1) return &Data[*p_idx]; *p_idx = FreeIdx; return Add(); }
+    void        Clear()                             { for (int n = 0; n < Map.Data.Size; n++) { int idx = Map.Data[n].val_i; if (idx != -1) Data[idx].~T(); }  Map.Clear(); Data.clear(); FreeIdx = 0; }
+    T*          Add()                               { int idx = FreeIdx; if (idx == Data.Size) { Data.resize(Data.Size + 1); FreeIdx++; } else { FreeIdx = *(int*)&Data[idx]; } IM_PLACEMENT_NEW(&Data[idx]) T(); return &Data[idx]; }
+    void        Remove(ImGuiID key, const T* p)     { Remove(key, GetIndex(p)); }
+    void        Remove(ImGuiID key, ImPoolIdx idx)  { Data[idx].~T(); *(int*)&Data[idx] = FreeIdx; FreeIdx = idx; Map.SetInt(key, -1); }
+    void        Reserve(int capacity)               { Data.reserve(capacity); Map.Data.reserve(capacity); }
+    int         GetSize() const                     { return Data.Size; }
+};
+
 //-----------------------------------------------------------------------------
 // Types
 //-----------------------------------------------------------------------------