From 51cb41667da60aa044a9999dbb660946aa959ac3 Mon Sep 17 00:00:00 2001
From: Matthias Maier <tamiko@43-1.org>
Date: Tue, 8 Aug 2017 11:58:50 -0500
Subject: [PATCH] Add ConstraintMatrix::get_lines() that returns a range of
 line iterators

---
 include/deal.II/lac/constraint_matrix.h | 24 ++++++++++++++++++++++++
 source/lac/constraint_matrix.cc         |  7 +++++++
 2 files changed, 31 insertions(+)

diff --git a/include/deal.II/lac/constraint_matrix.h b/include/deal.II/lac/constraint_matrix.h
index 233fd53b91..4a8cda20e0 100644
--- a/include/deal.II/lac/constraint_matrix.h
+++ b/include/deal.II/lac/constraint_matrix.h
@@ -26,6 +26,8 @@
 #include <deal.II/lac/vector.h>
 #include <deal.II/lac/vector_element_access.h>
 
+#include <boost/range/iterator_range.hpp>
+
 #include <vector>
 #include <set>
 #include <utility>
@@ -1178,6 +1180,28 @@ public:
   };
 
 
+  /**
+   * Typedef for the iterator type that is used in the LineRange container.
+   */
+  typedef std::vector<ConstraintLine>::const_iterator const_iterator;
+
+
+  /**
+   * Typedef for the return type used by get_lines().
+   */
+  typedef boost::iterator_range<const_iterator> LineRange;
+
+
+  /**
+   * Return a range object containing (const) iterators to all line entries
+   * stored in the ConstraintMatrix. Such a range is useful to initialize
+   * range-based for loops as supported by C++11.
+   *
+   * @return A range object for the half open range <code>[this->begin(),
+   * this->end())</code> of line entries.
+   */
+  const LineRange get_lines() const;
+
 
   /**
    * Exception
diff --git a/source/lac/constraint_matrix.cc b/source/lac/constraint_matrix.cc
index f9aa08942c..b00e08cee6 100644
--- a/source/lac/constraint_matrix.cc
+++ b/source/lac/constraint_matrix.cc
@@ -97,6 +97,13 @@ ConstraintMatrix::ConstraintLine::memory_consumption () const
 
 
 
+const ConstraintMatrix::LineRange ConstraintMatrix::get_lines() const
+{
+  return boost::make_iterator_range(lines.begin(), lines.end());
+}
+
+
+
 void
 ConstraintMatrix::add_lines (const std::set<size_type> &lines)
 {
-- 
2.39.5