NFA.java

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * This file is part of SableCC.                             *
 * See the file "LICENSE" for copyright information and the  *
 * terms and conditions for copying, distribution and        *
 * modification of SableCC.                                  *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

package org.sablecc.sablecc;


public class NFA implements Cloneable {
    public State[] states;

    private NFA(int size) {
        System.out.print(".");
        states = new State[size];
    }

    public NFA() {
        this(2);
        states[0] = new State();
        states[0].transitions[0] = new Transition(null, 1);
        states[1] = new State();
    }

    public NFA(CharSet chars) {
        this(2);
        states[0] = new State();
        states[0].transitions[0] = new Transition(chars, 1);
        states[1] = new State();
    }

    public NFA(String string) {
        this(string.length() + 1);

        for (int i = 0; i < string.length(); i++) {
            states[i] = new State();
            states[i].transitions[0] = new Transition(new CharSet(string.charAt(i)), i + 1);
        }

        states[string.length()] = new State();
    }

    private NFA(NFA nfa) {
        this(nfa.states.length);

        for (int i = 0; i < nfa.states.length; i++) {
            states[i] = new State(nfa.states[i]);
        }
    }

    public NFA zeroOrMore() {
        NFA nfa = new NFA(states.length + 2);
        nfa.states[0] = new State();
        nfa.states[0].transitions[0] = new Transition(null, 1);
        nfa.states[0].transitions[1] = new Transition(null, states.length + 1);

        for (int i = 0; i < states.length; i++) {
            nfa.states[i + 1] = new State(states[i]);

            if (nfa.states[i + 1].transitions[0] != null) {
                nfa.states[i + 1].transitions[0].destination += 1;
            }

            if (nfa.states[i + 1].transitions[1] != null) {
                nfa.states[i + 1].transitions[1].destination += 1;
            }
        }

        nfa.states[states.length].transitions[0] = new Transition(null, 1);
        nfa.states[states.length].transitions[1] = new Transition(null, states.length + 1);

        nfa.states[states.length + 1] = new State();

        return nfa;
    }

    public NFA zeroOrOne() {
        NFA nfa = new NFA(states.length + 2);
        nfa.states[0] = new State();
        nfa.states[0].transitions[0] = new Transition(null, 1);
        nfa.states[0].transitions[1] = new Transition(null, states.length + 1);

        for (int i = 0; i < states.length; i++) {
            nfa.states[i + 1] = new State(states[i]);

            if (nfa.states[i + 1].transitions[0] != null) {
                nfa.states[i + 1].transitions[0].destination += 1;
            }

            if (nfa.states[i + 1].transitions[1] != null) {
                nfa.states[i + 1].transitions[1].destination += 1;
            }
        }

        nfa.states[states.length].transitions[1] = new Transition(null, states.length + 1);

        nfa.states[states.length + 1] = new State();

        return nfa;
    }

    public NFA oneOrMore() {
        NFA nfa = new NFA(states.length + 2);
        nfa.states[0] = new State();
        nfa.states[0].transitions[0] = new Transition(null, 1);

        for (int i = 0; i < states.length; i++) {
            nfa.states[i + 1] = new State(states[i]);

            if (nfa.states[i + 1].transitions[0] != null) {
                nfa.states[i + 1].transitions[0].destination += 1;
            }

            if (nfa.states[i + 1].transitions[1] != null) {
                nfa.states[i + 1].transitions[1].destination += 1;
            }
        }

        nfa.states[states.length].transitions[0] = new Transition(null, 1);
        nfa.states[states.length].transitions[1] = new Transition(null, states.length + 1);

        nfa.states[states.length + 1] = new State();

        return nfa;
    }

    public NFA concatenate(NFA next) {
        NFA nfa = new NFA(states.length + next.states.length - 1);

        for (int i = 0; i < states.length - 1; i++) {
            nfa.states[i] = new State(states[i]);
        }

        for (int i = 0; i < next.states.length; i++) {
            nfa.states[states.length + i - 1] = new State(next.states[i]);

            if (nfa.states[states.length + i - 1].transitions[0] != null) {
                nfa.states[states.length + i - 1].transitions[0].destination +=
                        states.length - 1;
            }

            if (nfa.states[states.length + i - 1].transitions[1] != null) {
                nfa.states[states.length + i - 1].transitions[1].destination +=
                        states.length - 1;
            }
        }

        return nfa;
    }

    public NFA alternate(NFA next) {
        NFA nfa = new NFA(states.length + next.states.length + 2);

        nfa.states[0] = new State();
        nfa.states[0].transitions[0] = new Transition(null, 1);
        nfa.states[0].transitions[1] = new Transition(null, states.length + 1);

        for (int i = 0; i < states.length; i++) {
            nfa.states[i + 1] = new State(states[i]);

            if (nfa.states[i + 1].transitions[0] != null) {
                nfa.states[i + 1].transitions[0].destination += 1;
            }

            if (nfa.states[i + 1].transitions[1] != null) {
                nfa.states[i + 1].transitions[1].destination += 1;
            }
        }

        nfa.states[states.length].transitions[0] =
                new Transition(null, states.length + next.states.length + 1);

        for (int i = 0; i < next.states.length; i++) {
            nfa.states[states.length + i + 1] = new State(next.states[i]);

            if (nfa.states[states.length + i + 1].transitions[0] != null) {
                nfa.states[states.length + i + 1].transitions[0].destination +=
                        states.length + 1;
            }

            if (nfa.states[states.length + i + 1].transitions[1] != null) {
                nfa.states[states.length + i + 1].transitions[1].destination +=
                        states.length + 1;
            }
        }

        nfa.states[states.length + next.states.length].transitions[0] =
                new Transition(null, states.length + next.states.length + 1);

        nfa.states[states.length + next.states.length + 1] = new State();

        return nfa;
    }

    public NFA merge(NFA next) {
        NFA nfa = new NFA(states.length + next.states.length + 1);

        nfa.states[0] = new State();
        nfa.states[0].transitions[0] = new Transition(null, 1);
        nfa.states[0].transitions[1] = new Transition(null, states.length + 1);

        for (int i = 0; i < states.length; i++) {
            nfa.states[i + 1] = new State(states[i]);

            if (nfa.states[i + 1].transitions[0] != null) {
                nfa.states[i + 1].transitions[0].destination += 1;
            }

            if (nfa.states[i + 1].transitions[1] != null) {
                nfa.states[i + 1].transitions[1].destination += 1;
            }
        }

        for (int i = 0; i < next.states.length; i++) {
            nfa.states[states.length + i + 1] = new State(next.states[i]);

            if (nfa.states[states.length + i + 1].transitions[0] != null) {
                nfa.states[states.length + i + 1].transitions[0].destination +=
                        states.length + 1;
            }

            if (nfa.states[states.length + i + 1].transitions[1] != null) {
                nfa.states[states.length + i + 1].transitions[1].destination +=
                        states.length + 1;
            }
        }

        return nfa;
    }

    @Override
    public Object clone() {
        return new NFA(this);
    }

    @Override
    public String toString() {
        StringBuffer result = new StringBuffer();
        for (int i = 0; i < states.length; i++) {
            result.append(i + ":" + states[i] + System.getProperty("line.separator"));
        }
        return result.toString();
    }

    public static class State {
        public String accept;

        public Transition[] transitions = new Transition[2];

        public State() {
        }

        public State(State state) {
            if (state.accept != null) {
                accept = state.accept;
            }

            if (state.transitions[0] != null) {
                transitions[0] = new Transition(state.transitions[0]);
            }

            if (state.transitions[1] != null) {
                transitions[1] = new Transition(state.transitions[1]);
            }
        }

        @Override
        public String toString() {
            StringBuffer result = new StringBuffer();
            if (accept != null) {
                result.append("(" + accept + ") ");
            }
            if (transitions[0] != null) {
                result.append(" " + transitions[0]);
            }
            if (transitions[1] != null) {
                result.append(" " + transitions[1]);
            }
            return result.toString();
        }
    }

    public static class Transition {
        public CharSet chars;
        public int destination;

        public Transition(CharSet chars, int destination) {
            this.chars = chars;
            this.destination = destination;
        }

        public Transition(Transition transition) {
            chars = transition.chars;
            destination = transition.destination;
        }

        @Override
        public String toString() {
            return destination + ":{" + chars + "}";
        }
    }
}