add Backbone length computation from dfa

alib2algo/src/stringology/properties/BackboneLength.cpp

+/*
+ * BackboneLength.cpp
+ *
+ *  Created on: 17. 5. 2017
+ *      Author: Jan Travnicek
+ */
+
+#include "BackboneLength.h"
+
+namespace stringology {
+
+namespace properties {
+
+unsigned BackboneLength::length ( const automaton::Automaton & automaton ) {
+	return dispatch ( automaton.getData ( ) );
+}
+
+auto backboneLengthDFA = BackboneLength::RegistratorWrapper < unsigned, automaton::DFA < > > ( BackboneLength::length );
+
+} /* namespace properties */
+
+} /* namespace stringology */

alib2algo/src/stringology/properties/BackboneLength.h

+/*
+ * BackboneLength.h
+ *
+ *  Created on: 17. 5. 2017
+ *      Author: Jan Travnicek
+ */
+
+#ifndef BACKBONE_LENGTH_H
+#define BACKBONE_LENGTH_H
+
+#include <automaton/Automaton.h>
+#include <automaton/FSM/DFA.h>
+#include <core/multipleDispatch.hpp>
+#include <set>
+#include <queue>
+#include <algorithm>
+#include <utility>
+
+namespace stringology {
+
+namespace properties {
+
+class BackboneLength : public std::SingleDispatch < BackboneLength, unsigned, const automaton::AutomatonBase & > {
+public:
+	/**
+	 * Computes length of backbone for a suffix/factor/oracle automaton
+	 * @param automaton the suffix/factor/oracle automaton
+	 * @return backbone length
+	 */
+	static unsigned length ( const automaton::Automaton & automaton );
+
+	template < class SymbolType, class StateType >
+	static unsigned length ( const automaton::DFA < SymbolType, StateType > & automaton );
+
+	template < class StateType >
+	class BackboneLengthLess {
+	public:
+		bool operator ( ) ( const std::pair < StateType, unsigned > & first, const std::pair < StateType, unsigned > & second ) {
+			return first.second < second.second;
+		}
+	};
+
+};
+
+template < class SymbolType, class StateType >
+unsigned BackboneLength::length ( const automaton::DFA < SymbolType, StateType > & automaton ) {
+	std::priority_queue < std::pair < StateType, unsigned >, std::vector < std::pair < StateType, unsigned > >, BackboneLengthLess < StateType > > open;
+	std::map < StateType, unsigned > closed;
+
+	unsigned max = 0;
+	open.push ( std::make_pair ( automaton.getInitialState ( ), max ) );
+
+	while ( ! open.empty ( ) ) {
+		std::pair < StateType, unsigned > current = std::move ( open.top ( ) );
+		open.pop ( );
+		unsigned & dist = closed [ current.first ];
+
+		if ( dist > current.second )
+			continue;
+
+		dist = current.second;
+		max = std::max ( max, current.second );
+
+		for ( const std::pair < const std::pair < StateType, SymbolType >, StateType > & target : automaton.getTransitionsFromState ( current.first ) )
+			open.push ( std::make_pair ( target.second, current.second + 1 ) );
+	}
+
+	return max;
+}
+
+} /* namespace properties */
+
+} /* namespace stringology */
+
+#endif /* BACKBONE_LENGTH_H */