104 lines
4.0 KiB
C++
104 lines
4.0 KiB
C++
/**
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* @file lldependencies.cpp
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* @author Nat Goodspeed
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* @date 2008-09-17
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* @brief Implementation for lldependencies.
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*
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* $LicenseInfo:firstyear=2008&license=viewerlgpl$
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* Second Life Viewer Source Code
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* Copyright (C) 2010, Linden Research, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License only.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
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* $/LicenseInfo$
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*/
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// Precompiled header
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#include "linden_common.h"
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// associated header
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#include "lldependencies.h"
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// STL headers
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#include <map>
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#include <sstream>
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// std headers
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// external library headers
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#include <boost/graph/graph_traits.hpp> // for boost::graph_traits
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#include <boost/graph/adjacency_list.hpp>
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#include <boost/graph/topological_sort.hpp>
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#include <boost/graph/exception.hpp>
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// other Linden headers
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LLDependenciesBase::VertexList LLDependenciesBase::topo_sort(std::size_t vertices, const EdgeList& edges) const
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{
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// Construct a Boost Graph Library graph according to the constraints
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// we've collected. It seems as though we ought to be able to capture
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// the uniqueness of vertex keys using a setS of vertices with a
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// string property -- but I don't yet understand adjacency_list well
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// enough to get there. All the examples I've seen so far use integers
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// for vertices.
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// Define the Graph type. Use a vector for vertices so we can use the
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// default topological_sort vertex lookup by int index. Use a set for
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// edges because the same dependency may be stated twice: Node "a" may
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// specify that it must precede "b", while "b" may also state that it
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// must follow "a".
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typedef boost::adjacency_list<boost::setS, boost::vecS, boost::directedS,
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boost::no_property> Graph;
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// Instantiate the graph. Without vertex properties, we need say no
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// more about vertices than the total number.
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Graph g(edges.begin(), edges.end(), vertices);
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// topo sort
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typedef boost::graph_traits<Graph>::vertex_descriptor VertexDesc;
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typedef std::vector<VertexDesc> SortedList;
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SortedList sorted;
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// note that it throws not_a_dag if it finds a cycle
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try
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{
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boost::topological_sort(g, std::back_inserter(sorted));
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}
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catch (const boost::not_a_dag& e)
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{
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// translate to the exception we define
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std::ostringstream out;
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out << "LLDependencies cycle: " << e.what() << '\n';
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// Omit independent nodes: display only those that might contribute to
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// the cycle.
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describe(out, false);
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throw Cycle(out.str());
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}
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// A peculiarity of boost::topological_sort() is that it emits results in
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// REVERSE topological order: to get the result you want, you must
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// traverse the SortedList using reverse iterators.
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return VertexList(sorted.rbegin(), sorted.rend());
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}
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std::ostream& LLDependenciesBase::describe(std::ostream& out, bool full) const
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{
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// Should never encounter this base-class implementation; may mean that
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// the KEY type doesn't have a suitable ostream operator<<().
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out << "<no description available>";
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return out;
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}
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std::string LLDependenciesBase::describe(bool full) const
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{
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// Just use the ostream-based describe() on a std::ostringstream. The
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// implementation is here mostly so that we can avoid #include <sstream>
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// in the header file.
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std::ostringstream out;
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describe(out, full);
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return out.str();
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}
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