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+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __FN_MULTI_FUNCTION_HH__
+#define __FN_MULTI_FUNCTION_HH__
+
+/** \file
+ * \ingroup fn
+ *
+ * A `MultiFunction` encapsulates a function that is optimized for throughput (instead of latency).
+ * The throughput is optimized by always processing many elements at once, instead of each element
+ * separately. This is ideal for functions that are evaluated often (e.g. for every particle).
+ *
+ * By processing a lot of data at once, individual functions become easier to optimize for humans
+ * and for the compiler. Furthermore, performance profiles become easier to understand and show
+ * better where bottlenecks are.
+ *
+ * Every multi-function has a name and an ordered list of parameters. Parameters are used for input
+ * and output. In fact, there are three kinds of parameters: inputs, outputs and mutable (which is
+ * combination of input and output).
+ *
+ * To call a multi-function, one has to provide three things:
+ * - `MFParams`: This references the input and output arrays that the function works with. The
+ *      arrays are not owned by MFParams.
+ * - `IndexMask`: An array of indices indicating which indices in the provided arrays should be
+ *      touched/processed.
+ * - `MFContext`: Further information for the called function.
+ *
+ * A new multi-function is generally implemented as follows:
+ * 1. Create a new subclass of MultiFunction.
+ * 2. Implement a constructor that initialized the signature of the function.
+ * 3. Override the `call` function.
+ */
+
+#include "FN_multi_function_context.hh"
+#include "FN_multi_function_params.hh"
+
+namespace blender {
+namespace fn {
+
+class MultiFunction {
+ private:
+  MFSignature m_signature;
+
+ public:
+  virtual ~MultiFunction()
+  {
+  }
+
+  virtual void call(IndexMask mask, MFParams params, MFContext context) const = 0;
+
+  IndexRange param_indices() const
+  {
+    return m_signature.param_types.index_range();
+  }
+
+  MFParamType param_type(uint param_index) const
+  {
+    return m_signature.param_types[param_index];
+  }
+
+  StringRefNull param_name(uint param_index) const
+  {
+    return m_signature.param_names[param_index];
+  }
+
+  StringRefNull name() const
+  {
+    return m_signature.function_name;
+  }
+
+  const MFSignature &signature() const
+  {
+    return m_signature;
+  }
+
+ protected:
+  MFSignatureBuilder get_builder(std::string function_name)
+  {
+    m_signature.function_name = std::move(function_name);
+    return MFSignatureBuilder(m_signature);
+  }
+};
+
+inline MFParamsBuilder::MFParamsBuilder(const class MultiFunction &fn, uint min_array_size)
+    : MFParamsBuilder(fn.signature(), min_array_size)
+{
+}
+
+extern const MultiFunction &dummy_multi_function;
+
+}  // namespace fn
+}  // namespace blender
+
+#endif /* __FN_MULTI_FUNCTION_HH__ */