[Bf-blender-cvs] [ebfeab8fde0] soc-2021-adaptive-cloth: bli: generational_arena: class declaration setup

[ishbosamiya]

Commit: ebfeab8fde0234b55720198f0039446e2ea24965
Author: ishbosamiya
Date:   Mon Jun 14 22:02:01 2021 +0530
Branches: soc-2021-adaptive-cloth
https://developer.blender.org/rBebfeab8fde0234b55720198f0039446e2ea24965

bli: generational_arena: class declaration setup

===================================================================

A	source/blender/blenlib/BLI_generational_arena.hh
M	source/blender/blenlib/CMakeLists.txt

===================================================================

diff --git a/source/blender/blenlib/BLI_generational_arena.hh b/source/blender/blenlib/BLI_generational_arena.hh
new file mode 100644
index 00000000000..418e0669acd
--- /dev/null
+++ b/source/blender/blenlib/BLI_generational_arena.hh
@@ -0,0 +1,118 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup bli
+ *
+ * A `blender::generation_arena<T>` is a dynamically growing
+ * contiguous array for values of type T. It is designed to have
+ * a similar api as `blender::Vector<T>` but with generational
+ * indices. There are benefits to generational arenas.
+ */
+/* TODO(ish): need to complete documentation */
+
+#include <optional>
+#include <tuple>
+#include <variant>
+
+#include "BLI_vector.hh"
+
+namespace blender {
+namespace generational_arena {
+
+template<
+    /**
+     * Type of the values stored in this vector. It has to be movable.
+     */
+    typename T,
+    /**
+     * The number of values that can be stored in this vector, without doing a heap allocation.
+     * Sometimes it makes sense to increase this value a lot. The memory in the inline buffer is
+     * not initialized when it is not needed.
+     *
+     * When T is large, the small buffer optimization is disabled by default to avoid large
+     * unexpected allocations on the stack. It can still be enabled explicitly though.
+     */
+    int64_t InlineBufferCapacity = default_inline_buffer_capacity(sizeof(T)),
+    /**
+     * The allocator used by this vector. Should rarely be changed, except when you don't want that
+     * MEM_* is used internally.
+     */
+    typename Allocator = GuardedAllocator>
+class Arena {
+  /* using declarations */
+  using usize = uint64_t;
+  using isize = int64_t;
+  using Entry = std::variant<EntryNoExist, EntryExist>;
+
+  /* static data members */
+  /* non-static data members */
+  struct EntryNoExist {
+    std::optional<usize> next_free;
+  };
+  struct EntryExist {
+    T value;
+    usize generation;
+  };
+
+ public:
+  /* default constructor */
+  /* other constructors */
+  /* copy constructor */
+  /* move constructor */
+
+  /* destructor */
+
+  /* copy assignment operator */
+  /* move assignment operator */
+  /* other operator overloads */
+
+  /* all public static methods */
+  /* all public non-static methods */
+
+ protected:
+  /* all protected static methods */
+  /* all protected non-static methods */
+
+ private:
+  /* all private static methods */
+  /* all private non-static methods */
+};
+
+class Index {
+  using usize = uint64_t;
+
+  usize index;
+  usize generation;
+
+ public:
+  Index(usize index, usize generation)
+  {
+    this->index = index;
+    this->generation = generation;
+  }
+
+  std::tuple<usize, usize> get_raw() const
+  {
+    return std::make_tuple(this->index, this->generation)
+  }
+};
+
+} /* namespace generational_arena */
+
+} /* namespace blender */
diff --git a/source/blender/blenlib/CMakeLists.txt b/source/blender/blenlib/CMakeLists.txt
index f3dc343ee20..18f207c62be 100644
--- a/source/blender/blenlib/CMakeLists.txt
+++ b/source/blender/blenlib/CMakeLists.txt
@@ -195,6 +195,7 @@ set(SRC
   BLI_float4x4.hh
   BLI_fnmatch.h
   BLI_function_ref.hh
+  BLI_generational_arena.hh
   BLI_ghash.h
   BLI_gsqueue.h
   BLI_hash.h