BLI: Add a reverse method to MutableSpan

Add a method that allows a MutableSpan to reverse itself. This reverses
the data in the original span object. This is a first step in extracting
some functionality from nodes and making it more general.

Differential Revision: https://developer.blender.org/D12485

1 files changed, 10 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_span.hh b/source/blender/blenlib/BLI_span.hh
index e04295b0e51..5adb47ba0b0 100644
--- a/source/blender/blenlib/BLI_span.hh
+++ b/source/blender/blenlib/BLI_span.hh
@@ -644,6 +644,16 @@ template<typename T> class MutableSpan {
   }
 
   /**
+   * Reverse the data in the MutableSpan.
+   */
+  constexpr void reverse()
+  {
+    for (const int i : IndexRange(size_ / 2)) {
+      std::swap(data_[size_ - 1 - i], data_[i]);
+    }
+  }
+
+  /**
    * Returns an (immutable) Span that references the same array. This is usually not needed,
    * due to implicit conversions. However, sometimes automatic type deduction needs some help.
    */