Add a workaround class for std::unique_ptr that can also be used in the non-C++11...

diff --git a/doc/news/changes.h b/doc/news/changes.h
index dc72729f46d8c1b6f4f2b612a0dea4aa708ec3a2..4b616855f03065be86be5bf7b01edc27c35fd6cc 100644 (file)
--- a/doc/news/changes.h
+++ b/doc/news/changes.h
@@ -350,6 +350,13 @@ inconvenience this causes.
 <h3>Specific improvements</h3>
 
 <ol>
+  <li> New: There is now a class std_cxx11::unique_ptr that provides
+  the functionality of std::unique_ptr in C++11 mode, and that
+  provides an emulation for older compilers.
+  <br>
+  (Wolfgang Bangerth, 2015/02/22)
+  </li>
+
   <li> New: IndexSet now has a local typedef IndexSet::value_type.
   <br>
   (Wolfgang Bangerth, 2015/02/22)

diff --git a/include/deal.II/base/std_cxx11/unique_ptr.h b/include/deal.II/base/std_cxx11/unique_ptr.h
new file mode 100644 (file)
index 0000000..9e4f931
--- /dev/null
+++ b/include/deal.II/base/std_cxx11/unique_ptr.h
@@ -0,0 +1,83 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 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.
+//
+// ---------------------------------------------------------------------
+
+#ifndef __deal2__std_cxx11_unique_ptr_h
+#define __deal2__std_cxx11_unique_ptr_h
+
+
+#include <deal.II/base/config.h>
+
+#ifdef DEAL_II_WITH_CXX11
+
+#  include <memory>
+DEAL_II_NAMESPACE_OPEN
+namespace std_cxx11
+{
+  using std::unique_ptr;
+}
+DEAL_II_NAMESPACE_CLOSE
+
+#else
+
+#include <boost/shared_ptr.hpp>
+DEAL_II_NAMESPACE_OPEN
+namespace std_cxx11
+{
+  /**
+   * Implementation of a basic replacement for C++11's std::unique_ptr
+   * class.
+   *
+   * BOOST does not have a replacement for std::unique_ptr (because
+   * unique_ptr requires move semantics that aren't available unless
+   * you have a C++11 compiler -- in which case you also have
+   * std::unique_ptr; see for example
+   * http://stackoverflow.com/questions/2953530/unique-ptr-boost-equivalent)
+   *
+   * Consequently, we emulate the class by just wrapping a
+   * boost::shared_ptr in the cheapest possible way -- by just
+   * deriving from it and repeating the basic constructors. Everything
+   * else is inherited from the shared_ptr class.
+   *
+   * This replacement comes with a certain overhead: doing reference
+   * counting instead of just passing ownership of pointers has a
+   * cost. But we don't use unique_ptrs in expensive places, and it is
+   * also a cost that will disappear once we require C++11 (and the
+   * cost of course does not apply if your compiler already supports
+   * C++11 and deal.II uses it).
+   */
+  template <typename T>
+  class unique_ptr : public boost::shared_ptr<T>
+  {
+  public:
+    unique_ptr () {}
+
+    template<class Y>
+    explicit unique_ptr (Y *p)
+      :
+      boost::shared_ptr<T>(p)
+    {}
+  };
+
+}
+DEAL_II_NAMESPACE_CLOSE
+
+#endif
+
+// then allow using the old namespace name instead of the new one
+DEAL_II_NAMESPACE_OPEN
+namespace std_cxx1x = std_cxx11;
+DEAL_II_NAMESPACE_CLOSE
+
+#endif

diff --git a/tests/base/unique_ptr_01.cc b/tests/base/unique_ptr_01.cc
new file mode 100644 (file)
index 0000000..b0d430e
--- /dev/null
+++ b/tests/base/unique_ptr_01.cc
@@ -0,0 +1,92 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 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.
+//
+// ---------------------------------------------------------------------
+
+
+
+#include "../tests.h"
+#include <deal.II/base/std_cxx11/unique_ptr.h>
+#include <fstream>
+#include <iomanip>
+
+// counter for how many objects of type X there are
+int counter = 0;
+
+struct X
+{
+  X () 
+    {
+      ++counter;
+    }
+
+  X (const X &)
+    {
+      ++counter;
+    }
+
+  ~X ()
+    {
+      --counter;
+    }
+};
+
+
+
+int main ()
+{
+  std::ofstream logfile("output");
+  deallog.attach(logfile);
+  deallog.depth_console(0);
+  deallog.threshold_double(1.e-10);
+
+  // test with plain new/delete
+  {
+    Assert (counter == 0, ExcInternalError());
+    {
+      X *p = new X;
+      Assert (counter == 1, ExcInternalError());
+      delete p;
+    }
+    Assert (counter == 0, ExcInternalError());
+  }
+  
+  // test with plain unique_ptr
+  {
+    Assert (counter == 0, ExcInternalError());
+    {
+      std_cxx11::unique_ptr<X> p (new X);
+      Assert (counter == 1, ExcInternalError());
+    }
+    Assert (counter == 0, ExcInternalError());
+  }
+
+  // test with plain unique_ptr, but also copy stuff. this only works
+  // with move constructors, so test only in C++11 mode
+#ifdef DEAL_II_WITH_CXX11
+  {
+    Assert (counter == 0, ExcInternalError());
+    {
+      std_cxx11::unique_ptr<X> p (new X);
+      Assert (counter == 1, ExcInternalError());
+
+      std_cxx11::unique_ptr<X> q = std::move(p);
+      Assert (counter == 1, ExcInternalError());
+    }
+    Assert (counter == 0, ExcInternalError());
+  }
+#endif
+
+  deallog << "OK" << std::endl;
+}
+

diff --git a/tests/base/unique_ptr_01.output b/tests/base/unique_ptr_01.output
new file mode 100644 (file)
index 0000000..0fd8fc1
--- /dev/null
+++ b/tests/base/unique_ptr_01.output
@@ -0,0 +1,2 @@
+
+DEAL::OK