[Bf-blender-cvs] [805e2ccb07e] soc-2021-adaptive-cloth: bli: generational_arena: get(), get_no_gen(), get_no_gen_index()

[ishbosamiya]

Commit: 805e2ccb07ec19cb62d98dc88cfb5532a3356bb2
Author: ishbosamiya
Date:   Tue Jun 15 22:18:33 2021 +0530
Branches: soc-2021-adaptive-cloth
https://developer.blender.org/rB805e2ccb07ec19cb62d98dc88cfb5532a3356bb2

bli: generational_arena: get(), get_no_gen(), get_no_gen_index()

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

M	source/blender/blenlib/BLI_generational_arena.hh

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

diff --git a/source/blender/blenlib/BLI_generational_arena.hh b/source/blender/blenlib/BLI_generational_arena.hh
index 30a147ba157..8cec19ca76e 100644
--- a/source/blender/blenlib/BLI_generational_arena.hh
+++ b/source/blender/blenlib/BLI_generational_arena.hh
@@ -52,6 +52,7 @@
  */
 /* TODO(ish): need to complete documentation */
 
+#include <functional>
 #include <limits>
 #include <optional>
 #include <tuple>
@@ -235,6 +236,70 @@ class Arena {
     }
   }
 
+  std::optional<std::reference_wrapper<const T>> get(Index index) const
+  {
+    /* if index exceeds size of the container, return std::nullopt */
+    if (index.index >= this->data.size()) {
+      return std::nullopt;
+    }
+
+    if (index.generation != this->data[index.index]) {
+      return std::nullopt;
+    }
+
+    return std::cref(this->data[index.index]);
+  }
+
+  std::optional<std::reference_wrapper<T>> get(Index index)
+  {
+    /* if index exceeds size of the container, return std::nullopt */
+    if (index.index >= this->data.size()) {
+      return std::nullopt;
+    }
+
+    if (index.generation != this->data[index.index]) {
+      return std::nullopt;
+    }
+
+    return std::ref(this->data[index.index]);
+  }
+
+  std::optional<std::reference_wrapper<const T>> get_no_gen(usize index) const
+  {
+    /* if index exceeds size of the container, return std::nullopt */
+    if (index >= this->data.size()) {
+      return std::nullopt;
+    }
+
+    return std::cref(this->data[index]);
+  }
+
+  std::optional<std::reference_wrapper<T>> get_no_gen(usize index)
+  {
+    /* if index exceeds size of the container, return std::nullopt */
+    if (index >= this->data.size()) {
+      return std::nullopt;
+    }
+
+    return std::ref(this->data[index]);
+  }
+
+  std::optional<Index> get_no_gen_index(usize index) const
+  {
+    /* if index exceeds size of the container, return std::nullopt */
+    if (index >= this->data.size()) {
+      return std::nullopt;
+    }
+
+    std::optional<Index> res;
+    std::visit(extra::overloaded{
+                   [&res](EntryNoExist &entry) { res = std::nullopt; },
+                   [&res, index](EntryExist &entry) { res = Index(index, entry.generation); }},
+               this->data[index]);
+
+    return res;
+  }
+
  protected:
   /* all protected static methods */
   /* all protected non-static methods */