/usr/include/dolfin/mesh/MeshEntityIterator.h is in libdolfin-dev 2017.2.0.post0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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//
// This file is part of DOLFIN.
//
// DOLFIN is free software: you can 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 3 of the License, or
// (at your option) any later version.
//
// DOLFIN is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with DOLFIN. If not, see <http://www.gnu.org/licenses/>.
//
// Modified by Andre Massing 2009
//
// First added: 2006-05-09
// Last changed: 2014-07-02
#ifndef __MESH_ENTITY_ITERATOR_H
#define __MESH_ENTITY_ITERATOR_H
#include "Mesh.h"
#include "MeshEntity.h"
namespace dolfin
{
/// MeshEntityIterator provides a common iterator for mesh entities
/// over meshes, boundaries and incidence relations. The basic use
/// is illustrated below.
///
///
/// The following example shows how to iterate over all mesh entities
/// of a mesh of topological dimension dim:
///
/// @code{.cpp}
///
/// for (MeshEntityIterator e(mesh, dim); !e.end(); ++e)
/// {
/// e->foo();
/// }
/// @endcode
///
/// The following example shows how to iterate over mesh entities of
/// topological dimension dim connected (incident) to some mesh entity f:
///
/// @code{.cpp}
///
/// for (MeshEntityIterator e(f, dim); !e.end(); ++e)
/// {
/// e->foo();
/// }
/// @endcode
///
/// In addition to the general iterator, a set of specific named iterators
/// are provided for entities of type _Vertex_, _Edge_, _Face_, _Facet_
/// and _Cell_. These iterators are defined along with their respective
/// classes.
class MeshEntityIterator
{
public:
/// Default constructor
MeshEntityIterator() : _pos(0), pos_end(0), index(0) {}
/// Create iterator for mesh entities over given topological dimension
MeshEntityIterator(const Mesh& mesh, std::size_t dim)
: _entity(), _pos(0), pos_end(0), index(0)
{
// Check if mesh is empty
if (mesh.num_vertices() == 0)
return;
// Initialize mesh entity
_entity.init(mesh, dim, 0);
mesh.init(dim);
// End at ghost cells for normal iterator
pos_end = mesh.topology().ghost_offset(dim);
}
/// Iterator over MeshEntity of dimension dim on mesh, with string option
/// to iterate over "regular", "ghost" or "all" entities
MeshEntityIterator(const Mesh& mesh, std::size_t dim, std::string opt)
: _entity(), _pos(0), pos_end(0), index(0)
{
// Check if mesh is empty
if (mesh.num_vertices() == 0)
return;
// Initialize mesh entity
_entity.init(mesh, dim, 0);
mesh.init(dim);
pos_end = mesh.topology().size(dim);
if (opt == "regular")
pos_end = mesh.topology().ghost_offset(dim);
else if (opt == "ghost")
_pos = mesh.topology().ghost_offset(dim);
else if (opt != "all")
dolfin_error("MeshEntityIterator.h",
"initialize MeshEntityIterator",
"unknown opt=\"%s\", choose from "
"opt=[\"regular\", \"ghost\", \"all\"]", opt.c_str());
}
/// Create iterator for entities of given dimension connected to
/// given entity
MeshEntityIterator(const MeshEntity& entity, std::size_t dim)
: _entity(entity.mesh(), dim, 0), _pos(0), index(0)
{
// Get connectivity
const MeshConnectivity& c = entity.mesh().topology()(entity.dim(), dim);
// Compute connectivity if empty
if (c.empty())
entity.mesh().init(entity.dim(), dim);
// Get size and index map
if (c.empty())
{
pos_end = 0;
index = 0;
}
else
{
pos_end = c.size(entity.index());
index = c(entity.index());
}
}
/// Copy constructor
MeshEntityIterator(const MeshEntityIterator& it)
: _entity(it._entity), _pos(it._pos), pos_end(it.pos_end),
index(it.index) {}
/// Destructor
virtual ~MeshEntityIterator() {}
/// Step to next mesh entity (prefix increment)
MeshEntityIterator& operator++()
{
++_pos;
return *this;
}
/// Step to the previous mesh entity (prefix decrease)
MeshEntityIterator& operator--()
{
--_pos;
return *this;
}
/// Return current position
std::size_t pos() const
{ return _pos; }
/// Comparison operator
bool operator==(const MeshEntityIterator& it) const
{
// Use const_cast to use operator* inside comparison, which
// automatically updates the entity index corresponding to pos
// *before* comparison (since update of entity delays until
// request for entity)
return ((const_cast<MeshEntityIterator *>(this))->operator*()
== (const_cast<MeshEntityIterator *>(&it))->operator*()
&& _pos == it._pos && index == it.index);
}
/// Comparison operator
bool operator!=(const MeshEntityIterator & it) const
{ return !operator==(it); }
/// Dereference operator
MeshEntity& operator*()
{ return *operator->(); }
/// Member access operator
MeshEntity* operator->()
{ _entity._local_index = (index ? index[_pos] : _pos); return &_entity; }
/// Check if iterator has reached the end
bool end() const
{ return _pos >= pos_end; }
/// Provide a safeguard iterator pointing beyond the end of an
/// iteration process, either iterating over the mesh /or incident
/// entities. Added to be bit more like STL iterators, since many
/// algorithms rely on a kind of beyond iterator.
MeshEntityIterator end_iterator()
{
MeshEntityIterator
sg(*this);
sg.set_end();
return sg;
}
// Note: Not a subclass of Variable for efficiency!
// Commented out to avoid warning about shadowing str() for MeshEntity
// Return informal string representation (pretty-print)
// std::string str(bool verbose) const;
private:
// Set pos to end position. To create a kind of mesh.end() iterator.
void set_end()
{ _pos = pos_end; }
// Mesh entity
MeshEntity _entity;
// Current position
std::size_t _pos;
// End position
std::size_t pos_end;
// Mapping from pos to index (if any)
const unsigned int* index;
};
}
#endif
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