65 lines
1.8 KiB
C++
65 lines
1.8 KiB
C++
/*
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* Copyright (C) 2005 Maarten Keijzer
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef NODESELECTOR_H
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#define NODESELECTOR_H
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#include <sym/Sym.h>
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/** Base class for selecting nodes */
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class NodeSelector {
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public:
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class NodeSelection {
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Sym root_;
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unsigned subtree_index_;
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Sym subtree_;
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public :
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NodeSelection(Sym r, unsigned idx, Sym s)
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: root_(r), subtree_index_(idx), subtree_(s) {}
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Sym root() const { return root_; }
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unsigned idx() const { return subtree_index_; }
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Sym subtree();
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};
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virtual ~NodeSelector() {}
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virtual NodeSelection select_node(Sym sym) const = 0;
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};
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/** Select nodes uniformly */
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class RandomNodeSelector : public NodeSelector {
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public:
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NodeSelection select_node(Sym sym) const;
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};
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/** A node selector that does a specified number of rounds ignoring terminals */
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class BiasedNodeSelector : public NodeSelector {
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public:
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unsigned nRounds;
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BiasedNodeSelector() : nRounds(3) {} // 3: for binary trees 87.5% chance of selecting an internal node
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BiasedNodeSelector(unsigned n) : nRounds(n) {}
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NodeSelection select_node(Sym sym) const;
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};
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#endif
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