--- /dev/null
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2014 - 2017 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.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+
+/**
+ * @defgroup CPP11 deal.II and the C++11 standard
+ *
+ * Since version 9.0, deal.II requires a compiler that supports at
+ * least <a href="http://en.wikipedia.org/wiki/C%2B%2B11">C++11</a>.
+ * As part of this, many places in the internal implementation of
+ * deal.II are now using features that were only introduced in C++11.
+ * That said, deal.II also has functions and classes that make using
+ * it with C++11 features easier.
+ *
+ * One example is support for C++11
+ * <a href="http://en.wikipedia.org/wiki/C++11#Range-based_for_loop">range-based
+ * for loops</a>. deal.II-based codes often have many loops of the kind
+ * @code
+ * Triangulation<dim> triangulation;
+ * ...
+ * typename Triangulation<dim>::active_cell_iterator
+ * cell = triangulation.begin_active(),
+ * endc = triangulation.end();
+ * for (; cell!=endc; ++cell)
+ * cell->set_refine_flag();
+ * @endcode
+ * Using C++11's range-based for loops, you can now write this as follows:
+ * @code
+ * Triangulation<dim> triangulation;
+ * ...
+ * for (auto &cell : triangulation.active_cell_iterators())
+ * cell->set_refine_flag();
+ * @endcode
+ * This relies on functions such as Triangulation::active_cell_iterators(),
+ * and equivalents in the DoF handler classes,
+ * DoFHandler::active_cell_iterators(), hp::DoFHandler::active_cell_iterators().
+ * There are variants of these functions that provide iterator ranges
+ * for all cells (not just the active ones) and for cells on individual
+ * levels.
+ *
+ * There are numerous other functions in the library that allow for
+ * the idiomatic use of range-based for loops. Examples are
+ * GeometryInfo::face_indices(), GeometryInfo::vertex_indices(),
+ * FEValuesBase::quadrature_point_indices(), among many others.
+ */
+
+
+
+/**
+ * deal.II currently only requires a C++11-conforming compiler, but there are a
+ * number of functions and classes from the C++14 standard that are easy to
+ * provide also in case the compiler only supports C++11. These are collected
+ * in the current namespace.
+ *
+ * The most notable example is the <a
+ * href="https://en.cppreference.com/w/cpp/memory/unique_ptr/make_unique">`std::make_unique`</a>
+ * function which is arguably an oversight for not having been
+ * included in C++11 (given that there is <a
+ * href="https://en.cppreference.com/w/cpp/memory/shared_ptr/make_shared">`std::make_shared`</a>
+ * in C++11).
+ *
+ * There are other small additions in this namespace that allow us to
+ * use C++14 features at this point already, even though we don't
+ * require a C++14-compliant compiler.
+ *
+ * @note If the compiler in use actually does support C++14, then the
+ * contents of this namespace are simply imported classes and
+ * functions from namespace `std`. That is, we fall back to what the
+ * compiler provides, rather than our own implementations.
+ */
+namespace std_cxx14
+{}
+
+
+
+/**
+ * deal.II currently only requires a C++11-conforming compiler, but there are a
+ * number of functions and classes from the C++17 standard that are easy to
+ * provide also in case the compiler only supports C++11. These are collected
+ * in the current namespace.
+ *
+ * The most notable example is the <a
+ * href="https://en.cppreference.com/w/cpp/utility/optional">`std::optional`</a> class
+ * that was introduced to C++ starting with the C++17 standard.
+ *
+ * There are other small additions in this namespace that allow us to
+ * use C++17 features at this point already, even though we don't
+ * require a C++17-compliant compiler.
+ *
+ * @note If the compiler in use actually does support C++17, then the
+ * contents of this namespace are simply imported classes and
+ * functions from namespace `std`. That is, we fall back to what the
+ * compiler provides, rather than our own implementations.
+ */
+namespace std_cxx17
+{}
+
+
+
+/**
+ * deal.II currently only requires a C++11-conforming compiler, but there are a
+ * number of functions and classes from the C++20 standard that are easy to
+ * provide also in case the compiler only supports C++11. These are collected
+ * in the current namespace.
+ *
+ * One example is the <a
+ * href="https://en.cppreference.com/w/cpp/ranges/iota_view">`std::ranges::iota_view`</a>
+ * class that was introduced to C++ starting with the C++20
+ * standard. It is used as the return type for the
+ * GeometryInfo::face_indices(), GeometryInfo::vertex_indices(), and
+ * FEValuesBase::quadrature_point_indices() functions, among others,
+ * to support range-based for loops (see @ref CPP11 for examples of
+ * range-based for loops, as well as the documentation of the
+ * functions mentioned above).
+ *
+ * There are other small additions in this namespace that allow us to
+ * use C++20 features at this point already, even though we don't
+ * require a C++20-compliant compiler.
+ *
+ * @note If the compiler in use actually does support C++20, then the
+ * contents of this namespace are simply imported classes and
+ * functions from namespace `std`. That is, we fall back to what the
+ * compiler provides, rather than our own implementations.
+ */
+namespace std_cxx20
+{}
+++ /dev/null
-// ---------------------------------------------------------------------
-//
-// Copyright (C) 2014 - 2017 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.md at
-// the top level directory of deal.II.
-//
-// ---------------------------------------------------------------------
-
-
-/**
- * @defgroup CPP11 deal.II and the C++11 standard
- *
- * Since version 9.0, deal.II requires a compiler that supports at
- * least <a href="http://en.wikipedia.org/wiki/C%2B%2B11">C++11</a>.
- * As part of this, many places in the internal implementation of
- * deal.II are now using features that were only introduced in C++11.
- * That said, deal.II also has functions and classes that make using
- * it with C++11 features easier.
- *
- * One example is support for C++11
- * <a href="http://en.wikipedia.org/wiki/C++11#Range-based_for_loop">range-based
- * for loops</a>. deal.II-based codes often have many loops of the kind
- * @code
- * Triangulation<dim> triangulation;
- * ...
- * typename Triangulation<dim>::active_cell_iterator
- * cell = triangulation.begin_active(),
- * endc = triangulation.end();
- * for (; cell!=endc; ++cell)
- * cell->set_refine_flag();
- * @endcode
- * Using C++11's range-based for loops, you can now write this as follows:
- * @code
- * Triangulation<dim> triangulation;
- * ...
- * for (auto &cell : triangulation.active_cell_iterators())
- * cell->set_refine_flag();
- * @endcode
- * This relies on functions such as Triangulation::active_cell_iterators(),
- * and equivalents in the DoF handler classes,
- * DoFHandler::active_cell_iterators(), hp::DoFHandler::active_cell_iterators().
- * There are variants of these functions that provide iterator ranges
- * for all cells (not just the active ones) and for cells on individual
- * levels.
- */
projects / dealii.git / commitdiff