BLI: move generic data structures to blenlib

This is a follow up to rB2252bc6a5527cd7360d1ccfe7a2d1bc640a8dfa6.

1 files changed, 123 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_generic_pointer.hh b/source/blender/blenlib/BLI_generic_pointer.hh
new file mode 100644
index 00000000000..226f76c3d33
--- /dev/null
+++ b/source/blender/blenlib/BLI_generic_pointer.hh
@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#pragma once
+
+#include "BLI_cpp_type.hh"
+
+namespace blender {
+
+/**
+ * A generic non-const pointer whose type is only known at runtime.
+ */
+class GMutablePointer {
+ private:
+  const CPPType *type_ = nullptr;
+  void *data_ = nullptr;
+
+ public:
+  GMutablePointer() = default;
+
+  GMutablePointer(const CPPType *type, void *data = nullptr) : type_(type), data_(data)
+  {
+    /* If there is data, there has to be a type. */
+    BLI_assert(data_ == nullptr || type_ != nullptr);
+  }
+
+  GMutablePointer(const CPPType &type, void *data = nullptr) : GMutablePointer(&type, data)
+  {
+  }
+
+  template<typename T> GMutablePointer(T *data) : GMutablePointer(&CPPType::get<T>(), data)
+  {
+  }
+
+  void *get() const
+  {
+    return data_;
+  }
+
+  const CPPType *type() const
+  {
+    return type_;
+  }
+
+  template<typename T> T *get() const
+  {
+    BLI_assert(this->is_type<T>());
+    return static_cast<T *>(data_);
+  }
+
+  template<typename T> bool is_type() const
+  {
+    return type_ != nullptr && type_->is<T>();
+  }
+
+  template<typename T> T relocate_out()
+  {
+    BLI_assert(this->is_type<T>());
+    T value;
+    type_->relocate_assign(data_, &value);
+    data_ = nullptr;
+    type_ = nullptr;
+    return value;
+  }
+
+  void destruct()
+  {
+    BLI_assert(data_ != nullptr);
+    type_->destruct(data_);
+  }
+};
+
+/**
+ * A generic const pointer whose type is only known at runtime.
+ */
+class GPointer {
+ private:
+  const CPPType *type_ = nullptr;
+  const void *data_ = nullptr;
+
+ public:
+  GPointer() = default;
+
+  GPointer(GMutablePointer ptr) : type_(ptr.type()), data_(ptr.get())
+  {
+  }
+
+  GPointer(const CPPType *type, const void *data = nullptr) : type_(type), data_(data)
+  {
+    /* If there is data, there has to be a type. */
+    BLI_assert(data_ == nullptr || type_ != nullptr);
+  }
+
+  GPointer(const CPPType &type, const void *data = nullptr) : type_(&type), data_(data)
+  {
+  }
+
+  template<typename T> GPointer(T *data) : GPointer(&CPPType::get<T>(), data)
+  {
+  }
+
+  const void *get() const
+  {
+    return data_;
+  }
+
+  const CPPType *type() const
+  {
+    return type_;
+  }
+
+  template<typename T> const T *get() const
+  {
+    BLI_assert(this->is_type<T>());
+    return static_cast<const T *>(data_);
+  }
+
+  template<typename T> bool is_type() const
+  {
+    return type_ != nullptr && type_->is<T>();
+  }
+};
+
+}  // namespace blender