fr.univnantes.lina.uima.tkregex.AutomatonFactory.java Source code

Introduction

Here is the source code for fr.univnantes.lina.uima.tkregex.AutomatonFactory.java

Source

/*******************************************************************************
 * Copyright 2015 - CNRS (Centre National de Recherche Scientifique)
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 *******************************************************************************/
package fr.univnantes.lina.uima.tkregex;

import java.util.List;
import java.util.Set;
import java.util.TreeSet;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;

public class AutomatonFactory {

    public static Automaton createMNAutomaton(Automaton automaton, int m, int n) {
        List<Automaton> toConcat = Lists.newLinkedList();
        toConcat.add(createNAutomaton(automaton, m));
        for (int i = 0; i < (n - m); i++)
            toConcat.add(createZeroOneAutomaton(automaton));
        return createConcatenation(toConcat);
    }

    public static Automaton createNAutomaton(Automaton automaton, int n) {
        List<Automaton> clones = Lists.newArrayListWithCapacity(n);
        for (int i = 0; i < n; i++)
            clones.add(automaton.deepClone());
        return createConcatenation(clones);
    }

    public static Automaton createZeroOneAutomaton(Automaton automaton) {
        Automaton a = automaton.deepClone();
        Set<State> states = new TreeSet<State>(a.getStates());
        State acceptingState = new State();
        states.add(acceptingState);
        for (State s : a.getAcceptingStates())
            addEpsilon(s, acceptingState);
        addEpsilon(a.getInitState(), acceptingState);
        Automaton zeroOneAutomaton = new Automaton(a.getInitState(), ImmutableSet.of(acceptingState), states);
        return zeroOneAutomaton;
    }

    public static Automaton createPlusAutomaton(Automaton a) {
        return createConcatenation(ImmutableList.of(a.deepClone(), createStarAutomaton(a)));
    }

    public static Automaton createStarAutomaton(Automaton automaton) {
        Automaton a = automaton.deepClone();
        State initState = a.getInitState();
        a.addAcceptingState(initState);
        for (State s : a.getAcceptingStates()) {
            if (!s.equals(initState))
                addEpsilon(s, initState);
        }
        return a;
    }

    private static void addEpsilon(State from, State to) {
        EpsilonTransition e = new EpsilonTransition();
        e.setFromState(from);
        e.setToState(to);
        if (from.equals(to))
            throw new IllegalArgumentException("Epsilon transition from and to the same stae is useless");
        from.addTransition(e);
    }

    public static Automaton createOrAutomaton(List<Automaton> automata) {
        if (automata.size() == 0)
            return createEmptyAutomaton();
        else if (automata.size() == 1)
            return automata.get(1).deepClone();
        else {
            List<Automaton> clonedAutomata = getClonedAutomataList(automata);
            Set<State> states = new TreeSet<State>();
            Set<State> acceptingStates = new TreeSet<State>();
            for (Automaton a : clonedAutomata) {
                states.addAll(a.getStates());
                acceptingStates.addAll(a.getAcceptingStates());
            }

            Automaton a1 = clonedAutomata.get(0);
            for (int i = 1; i < clonedAutomata.size(); i++) {
                Automaton ai = clonedAutomata.get(i);
                addEpsilon(a1.getInitState(), ai.getInitState());
            }

            Automaton or = new Automaton(a1.getInitState(), acceptingStates, states);
            return or;
        }
    }

    public static Automaton createConcatenation(List<Automaton> automata) {
        if (automata.size() == 0)
            return createEmptyAutomaton();
        else if (automata.size() == 1)
            return automata.get(0).deepClone();
        else {
            List<Automaton> clonedAutomata = getClonedAutomataList(automata);
            Set<State> states = new TreeSet<State>();
            for (Automaton a : clonedAutomata)
                states.addAll(a.getStates());

            for (int i = 0; i < (clonedAutomata.size() - 1); i++) {
                Automaton a1 = clonedAutomata.get(i);
                Automaton a2 = clonedAutomata.get(i + 1);
                for (State accepting : a1.getAcceptingStates())
                    addEpsilon(accepting, a2.getInitState());
            }
            Automaton concat = new Automaton(clonedAutomata.get(0).getInitState(),
                    clonedAutomata.get(clonedAutomata.size() - 1).getAcceptingStates(), states);
            return concat;
        }
    }

    private static Automaton createEmptyAutomaton() {
        return new Automaton();
    }

    private static List<Automaton> getClonedAutomataList(List<Automaton> automata) {
        List<Automaton> clones = Lists.newArrayListWithCapacity(automata.size());
        for (Automaton a : automata)
            clones.add(a.deepClone());
        return clones;
    }

    public static Automaton createSimpleAutomaton(AnnotationMatcher annoMatcher) {
        AutomatonBuilder builder = new AutomatonBuilder();
        builder.addTransition(builder.addInitState(), annoMatcher, builder.addAcceptingState());
        return builder.getAutomaton();
    }

    public static Automaton createQuantifiedAutomaton(Automaton automaton, AutomatonQuantifier quantifier) {
        switch (quantifier.getQuantifierType()) {
        case AutomatonQuantifier.ZERO_ONE:
            return createZeroOneAutomaton(automaton);
        case AutomatonQuantifier.ZERO_N:
            return createStarAutomaton(automaton);
        case AutomatonQuantifier.ONE_N:
            return createPlusAutomaton(automaton);
        case AutomatonQuantifier.N:
            return createNAutomaton(automaton, quantifier.getLowerBound());
        case AutomatonQuantifier.M_N:
            return createMNAutomaton(automaton, quantifier.getLowerBound(), quantifier.getUpperBound());
        case AutomatonQuantifier.ONE:
        default:
            return automaton;
        }
    }
}