Add IndexSet::pop_front, pop_back, and is_empty

diff --git a/include/deal.II/base/index_set.h b/include/deal.II/base/index_set.h
index 34400387a1057d6478e73fb3686ef703889efe8d..20261c4cb2d54701d804d31039dabf7e7e0f3681 100644 (file)
--- a/include/deal.II/base/index_set.h
+++ b/include/deal.II/base/index_set.h
@@ -217,6 +217,12 @@ public:
    */
   bool is_contiguous () const;
 
+  /**
+   * Return whether the index set stored by this object contains no elements.
+   * This is similar, but faster than checking <code>n_elements() == 0</code>.
+   */
+  bool is_empty () const;
+
   /**
    * Return whether the IndexSets are ascending with respect to MPI process
    * number and 1:1, i.e., each index is contained in exactly one IndexSet
@@ -315,6 +321,18 @@ public:
    */
   void subtract_set (const IndexSet &other);
 
+  /**
+   * Removes and returns the last element of the last range.
+   * Throws an exception if the IndexSet is empty.
+   */
+  size_type pop_back ();
+
+  /**
+   * Removes and returns the first element of the first range.
+   * Throws an exception if the IndexSet is empty.
+   */
+  size_type pop_front ();
+
   /**
    * Fills the given vector with all indices contained in this IndexSet.
    */
@@ -1519,6 +1537,14 @@ IndexSet::is_contiguous () const
 }
 
 
+inline
+bool
+IndexSet::is_empty () const
+{
+  return ranges.empty();
+}
+
+
 
 inline
 IndexSet::size_type

diff --git a/source/base/index_set.cc b/source/base/index_set.cc
index 6126766db58fd0ea8ccfeb519a1639d69944ed8d..9af19f060ded53ed5af23337b04c5b624187afe6 100644 (file)
--- a/source/base/index_set.cc
+++ b/source/base/index_set.cc
@@ -341,6 +341,44 @@ IndexSet::subtract_set (const IndexSet &other)
 
 
 
+IndexSet::size_type
+IndexSet::pop_back ()
+{
+  Assert(ranges.size() != 0,
+         ExcMessage("pop_back() failed, because this IndexSet contains no entries."));
+
+  const size_type index = ranges.back().end-1;
+  --ranges.back().end;
+
+  if (ranges.back().begin == ranges.back().end)
+    ranges.pop_back();
+
+  return index;
+}
+
+
+
+IndexSet::size_type
+IndexSet::pop_front ()
+{
+  Assert(ranges.size() != 0,
+         ExcMessage("pop_front() failed, because this IndexSet contains no entries."));
+
+  const size_type index = ranges.front().begin;
+  ++ranges.front().begin;
+
+  if (ranges.front().begin == ranges.front().end)
+    ranges.erase(ranges.begin());
+
+  // We have to set this in any case, because nth_index_in_set is not longer
+  // up to date for all but the first range
+  is_compressed = false;
+
+  return index;
+}
+
+
+
 void
 IndexSet::add_indices(const IndexSet &other,
                       const unsigned int offset)

diff --git a/tests/base/index_set_25.cc b/tests/base/index_set_25.cc
new file mode 100644 (file)
index 0000000..6f507a2
--- /dev/null
+++ b/tests/base/index_set_25.cc
@@ -0,0 +1,41 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2010 - 2015 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE at
+// the top level of the deal.II distribution.
+//
+// ---------------------------------------------------------------------
+
+// Check that pop_front() for `IndexSet` works properly
+
+#include "../tests.h"
+#include <fstream>
+
+#include <deal.II/base/logstream.h>
+#include <deal.II/base/index_set.h>
+
+int main()
+{
+  std::ofstream logfile("output");
+  deallog.attach(logfile);
+
+  IndexSet is1(10);
+  is1.add_range(0, 2);
+  is1.add_range(5,8);
+
+  deallog << is1.n_elements() << ", " << is1.pop_front() << std::endl;
+  deallog << is1.n_elements() << ", " << is1.pop_front() << std::endl;
+  deallog << is1.n_elements() << ", " << is1.pop_front() << std::endl;
+
+  is1.add_index(1);
+
+  deallog << is1.n_elements() << ", " << is1.pop_front() << std::endl;
+  deallog << is1.n_elements() << ", " << is1.pop_front() << std::endl;
+}

diff --git a/tests/base/index_set_25.output b/tests/base/index_set_25.output
new file mode 100644 (file)
index 0000000..850d440
--- /dev/null
+++ b/tests/base/index_set_25.output
@@ -0,0 +1,6 @@
+
+DEAL::4, 0
+DEAL::3, 1
+DEAL::2, 5
+DEAL::2, 1
+DEAL::1, 6

diff --git a/tests/base/index_set_26.cc b/tests/base/index_set_26.cc
new file mode 100644 (file)
index 0000000..528a4f3
--- /dev/null
+++ b/tests/base/index_set_26.cc
@@ -0,0 +1,41 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2010 - 2015 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE at
+// the top level of the deal.II distribution.
+//
+// ---------------------------------------------------------------------
+
+// Check that pop_back() for `IndexSet` works properly
+
+#include "../tests.h"
+#include <fstream>
+
+#include <deal.II/base/logstream.h>
+#include <deal.II/base/index_set.h>
+
+int main()
+{
+  std::ofstream logfile("output");
+  deallog.attach(logfile);
+
+  IndexSet is1(10);
+  is1.add_range(0, 2);
+  is1.add_range(5,8);
+
+  deallog << is1.n_elements() << ", " << is1.pop_back() << std::endl;
+  deallog << is1.n_elements() << ", " << is1.pop_back() << std::endl;
+  deallog << is1.n_elements() << ", " << is1.pop_back() << std::endl;
+
+  is1.add_index(9);
+
+  deallog << is1.n_elements() << ", " << is1.pop_back() << std::endl;
+  deallog << is1.n_elements() << ", " << is1.pop_back() << std::endl;
+}

diff --git a/tests/base/index_set_26.output b/tests/base/index_set_26.output
new file mode 100644 (file)
index 0000000..1da8192
--- /dev/null
+++ b/tests/base/index_set_26.output
@@ -0,0 +1,6 @@
+
+DEAL::4, 7
+DEAL::3, 6
+DEAL::2, 5
+DEAL::2, 9
+DEAL::1, 1