BLI: improve various C++ data structures

The changes come from the `functions` branch, where I'm using
these structures a lot.

This also includes a new `BLI::Optional<T>` type, which is similar
to `std::Optional<T>` which can be used when Blender starts using
C++17.

1 files changed, 7 insertions, 2 deletions

diff --git a/source/blender/blenlib/BLI_stack_cxx.h b/source/blender/blenlib/BLI_stack_cxx.h
index 7915acadfac..a26318a3dcb 100644
--- a/source/blender/blenlib/BLI_stack_cxx.h
+++ b/source/blender/blenlib/BLI_stack_cxx.h
@@ -58,7 +58,7 @@ template<typename T, uint N = 4, typename Allocator = GuardedAllocator> class St
   /**
    * Return true when the stack is empty, otherwise false.
    */
-  bool empty() const
+  bool is_empty() const
   {
     return this->size() == 0;
   }
@@ -76,6 +76,11 @@ template<typename T, uint N = 4, typename Allocator = GuardedAllocator> class St
     m_elements.append(std::move(value));
   }
 
+  void push_multiple(ArrayRef<T> values)
+  {
+    m_elements.extend(values);
+  }
+
   /**
    * Remove the element from the top of the stack and return it.
    * This will assert when the stack is empty.
@@ -91,7 +96,7 @@ template<typename T, uint N = 4, typename Allocator = GuardedAllocator> class St
    */
   T &peek()
   {
-    BLI_assert(!this->empty());
+    BLI_assert(!this->is_empty());
     return m_elements[this->size() - 1];
   }