From c039a77d218d1653c5c0ffd9e8107b2a138d105f Mon Sep 17 00:00:00 2001
From: omar <omarcornut@gmail.com>
Date: Thu, 6 Sep 2018 15:34:03 +0200
Subject: [PATCH] Internals: Added ImPool helper structure. Moved ImVec1f.

---
 imgui_internal.h | 41 +++++++++++++++++++++++++++++++++--------
 1 file changed, 33 insertions(+), 8 deletions(-)

diff --git a/imgui_internal.h b/imgui_internal.h
index 9384b1a4..530653d0 100644
--- a/imgui_internal.h
+++ b/imgui_internal.h
@@ -211,18 +211,32 @@ 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
+// Creation/Erasure invalidate all pointers, but indexes are valid as long as the object lifetime.
+template<typename T>
+struct IMGUI_API ImPool
+{
+    ImVector<T>     Data;       // Contiguous data
+    ImGuiStorage    Map;        // ID->Index
+    int             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(int n)                   { return &Data[n]; }
+    int         GetIndex(const T* p) const          { IM_ASSERT(p >= Data.Data && p < Data.Data + Data.Size); return (int)(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, int idx)        { Data[idx].~T(); *(int*)&Data[idx] = FreeIdx; FreeIdx = idx; Map.SetInt(key, -1); }
+};
+typedef int ImPoolIdx;
+
 //-----------------------------------------------------------------------------
 // Types
 //-----------------------------------------------------------------------------
 
-// 1D vector (this odd construct is used to facilitate the transition between 1D and 2D and maintenance of some patches)
-struct ImVec1
-{
-    float     x;
-    ImVec1() { x = 0.0f; }
-    ImVec1(float _x) { x = _x; }
-};
-
 enum ImGuiButtonFlags_
 {
     ImGuiButtonFlags_None                   = 0,
@@ -366,6 +380,14 @@ enum ImGuiPopupPositionPolicy
     ImGuiPopupPositionPolicy_ComboBox
 };
 
+// 1D vector (this odd construct is used to facilitate the transition between 1D and 2D and maintenance of some patches)
+struct ImVec1
+{
+    float   x;
+    ImVec1()         { x = 0.0f; }
+    ImVec1(float _x) { x = _x; }
+};
+
 // 2D axis aligned bounding-box
 // NB: we can't rely on ImVec2 math operators being available here
 struct IMGUI_API ImRect
@@ -632,7 +654,10 @@ struct ImGuiNextWindowData
     }
 };
 
+//-----------------------------------------------------------------------------
 // Main imgui context
+//-----------------------------------------------------------------------------
+
 struct ImGuiContext
 {
     bool                    Initialized;