From c15cd74361e0b068544611417ee05b414f164f05 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Mon, 19 Apr 2021 15:16:14 -0600
Subject: [PATCH] Provide a move constructor for
 Functions::InterpolatedUniformGridData.

---
 include/deal.II/base/function_lib.h | 14 ++++++++++++++
 source/base/function_lib.cc         | 26 ++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/deal.II/base/function_lib.h b/include/deal.II/base/function_lib.h
index f181ea44f3..a48ec6dcbb 100644
--- a/include/deal.II/base/function_lib.h
+++ b/include/deal.II/base/function_lib.h
@@ -1555,6 +1555,20 @@ namespace Functions
       const std::array<unsigned int, dim> &             n_subintervals,
       const Table<dim, double> &                        data_values);
 
+    /**
+     * Like the previous constructor, but take the arguments as rvalue
+     * references and *move*, instead of *copy* the data. This is often useful
+     * in cases where the data stored in these tables is large and the
+     * information used to initialize the current object is no longer needed
+     * separately. In other words, there is no need to keep the original object
+     * from which this object could copy its information, but it might as well
+     * take over ("move") the data.
+     */
+    InterpolatedUniformGridData(
+      std::array<std::pair<double, double>, dim> &&interval_endpoints,
+      std::array<unsigned int, dim> &&             n_subintervals,
+      Table<dim, double> &&                        data_values);
+
     /**
      * Compute the value of the function set by bilinear interpolation of the
      * given data set.
diff --git a/source/base/function_lib.cc b/source/base/function_lib.cc
index 1a7b8f7674..1ef60b8eed 100644
--- a/source/base/function_lib.cc
+++ b/source/base/function_lib.cc
@@ -2683,6 +2683,32 @@ namespace Functions
   }
 
 
+
+  template <int dim>
+  InterpolatedUniformGridData<dim>::InterpolatedUniformGridData(
+    std::array<std::pair<double, double>, dim> &&interval_endpoints,
+    std::array<unsigned int, dim> &&             n_subintervals,
+    Table<dim, double> &&                        data_values)
+    : interval_endpoints(std::move(interval_endpoints))
+    , n_subintervals(std::move(n_subintervals))
+    , data_values(std::move(data_values))
+  {
+    for (unsigned int d = 0; d < dim; ++d)
+      {
+        Assert(this->n_subintervals[d] >= 1,
+               ExcMessage("There needs to be at least one subinterval in each "
+                          "coordinate direction."));
+        Assert(this->interval_endpoints[d].first <
+                 this->interval_endpoints[d].second,
+               ExcMessage("The interval in each coordinate direction needs "
+                          "to have positive size"));
+        Assert(this->data_values.size()[d] == this->n_subintervals[d] + 1,
+               ExcMessage("The data table does not have the correct size."));
+      }
+  }
+
+
+
   template <int dim>
   double
   InterpolatedUniformGridData<dim>::value(const Point<dim> & p,
-- 
2.39.5