1 files changed, 34 insertions, 1 deletions
diff --git a/source/blender/blenkernel/BKE_attribute.hh b/source/blender/blenkernel/BKE_attribute.hh
index fbdacee139c..946a7d21580 100644
--- a/source/blender/blenkernel/BKE_attribute.hh
+++ b/source/blender/blenkernel/BKE_attribute.hh
@@ -16,6 +16,10 @@
 
 struct Mesh;
 struct PointCloud;
+namespace blender::fn {
+class MultiFunction;
+class GField;
+}  // namespace blender::fn
 
 namespace blender::bke {
 
@@ -163,6 +167,27 @@ template<typename T> struct AttributeReader {
 };
 
 /**
+ * A utility to make sure attribute values are valid, for attributes like "material_index" which
+ * can only be positive, or attributes that represent enum options. This is usually only necessary
+ * when writing attributes from an untrusted/arbitrary user input.
+ */
+struct AttributeValidator {
+  /**
+   * Single input, single output function that corrects attribute values if necessary.
+   */
+  const fn::MultiFunction *function;
+
+  operator bool() const
+  {
+    return this->function != nullptr;
+  }
+  /**
+   * Return a field that creates corrected attribute values.
+   */
+  fn::GField validate_field_if_necessary(const fn::GField &field) const;
+};
+
+/**
  * Result when looking up an attribute from some geometry with read and write access. After writing
  * to the attribute, the #finish method has to be called. This may invalidate caches based on this
  * attribute.
@@ -343,7 +368,7 @@ struct AttributeAccessorFunctions {
                           eAttrDomain to_domain);
   bool (*for_all)(const void *owner,
                   FunctionRef<bool(const AttributeIDRef &, const AttributeMetaData &)> fn);
-
+  AttributeValidator (*lookup_validator)(const void *owner, const AttributeIDRef &attribute_id);
   GAttributeWriter (*lookup_for_write)(void *owner, const AttributeIDRef &attribute_id);
   bool (*remove)(void *owner, const AttributeIDRef &attribute_id);
   bool (*add)(void *owner,
@@ -498,6 +523,14 @@ class AttributeAccessor {
   }
 
   /**
+   * Same as the generic version above, but should be used when the type is known at compile time.
+   */
+  AttributeValidator lookup_validator(const AttributeIDRef &attribute_id) const
+  {
+    return fn_->lookup_validator(owner_, attribute_id);
+  }
+
+  /**
    * Interpolate data from one domain to another.
    */
   GVArray adapt_domain(const GVArray &varray,