Migration from SVN

eo/contrib/mathsym/gen/NodeSelector.h

@@ -0,0 +1,65 @@
+/*	    
+ *             Copyright (C) 2005 Maarten Keijzer
+ *
+ *          This program is free software; you can redistribute it and/or modify
+ *          it under the terms of version 2 of the GNU General Public License as 
+ *          published by the Free Software Foundation. 
+ *
+ *          This program 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 General Public License for more details.
+ *
+ *          You should have received a copy of the GNU General Public License
+ *          along with this program; if not, write to the Free Software
+ *          Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef NODESELECTOR_H
+#define NODESELECTOR_H
+
+#include <sym/Sym.h>
+
+/** Base class for selecting nodes */
+class NodeSelector {
+    public:
+	
+    class NodeSelection {
+	Sym root_;
+	unsigned subtree_index_;
+	Sym subtree_;
+
+	public :
+	    NodeSelection(Sym r, unsigned idx, Sym s) 
+		: root_(r), subtree_index_(idx), subtree_(s) {}
+
+	    Sym root() const { return root_; }
+	    unsigned idx()  const { return subtree_index_; }
+	    Sym subtree(); 
+	
+    };
+
+    virtual ~NodeSelector() {}
+	
+    virtual NodeSelection select_node(Sym sym) const = 0;  
+};
+
+
+/** Select nodes uniformly */
+class RandomNodeSelector : public NodeSelector {
+    public:
+    NodeSelection select_node(Sym sym) const;
+};
+
+/** A node selector that does a specified number of rounds ignoring terminals */
+class BiasedNodeSelector : public NodeSelector {
+    public:
+    unsigned nRounds;
+
+    BiasedNodeSelector() : nRounds(3) {} // 3: for binary trees 87.5% chance of selecting an internal node
+    BiasedNodeSelector(unsigned n) : nRounds(n) {}
+    
+    NodeSelection select_node(Sym sym) const;
+};
+
+#endif