Range.java

import java.util.LinkedList;

class BasicRange { // Abschnitte von Buchstaben ohne Lücken
    char start, end;
    public BasicRange(char a, char b) {
        start = a;
        end = b;
    }
    public int compare(char a, char b) { // -2 means b<start-1, -1 means b==start-1, 0 means [a,b] and [start,end] have common elements,
                                         // 1 means a==end+1, 2 means a>end+1
        if (a==end+1) return 1;
        else if (a>end+1) return 2;
        else if (b==start-1) return -1;
        else if (b<start-1) return -2;
        else return 0;
    }
    public boolean isSingle() { return start==end; }
    public String toString() {
        if (isSingle()) return "'"+start+"'";
        else return "['"+start+"' - '"+end+"']";
    }
}

public class Range {
    private LinkedList<BasicRange> element = new LinkedList<>();

    public Range() { }
    public Range(char a) { this(a,a); }
    public Range(char a, char b) { element.add(new BasicRange(a,b)); }
    public Range add(char a) { return add(a,a); }
    public Range add(char a, char b) { // füge den Bereich [a - b] hinzu
         loop:for (int i=0; i<element.size(); i++) {
             BasicRange currentElement = element.get(i);
             switch (currentElement.compare(a, b)) {
                 case -2: element.add(i, new BasicRange(a,b)); break loop;
                 case -1: currentElement.start = a; break loop;
                 case 1: currentElement.end = b; break loop;
                 case 2: if (i==element.size()-1) { element.add(new BasicRange(a,b)); break loop; }
                         break;
                 default:
                     if (a<currentElement.start) currentElement.start=a;
                     if (b>currentElement.end) currentElement.end = b;
                     break loop;
             }
         }
         return this;
    }

    public boolean isEmpty() { return element.size()==0; }

    public String toString() {
        String erg = "{ ";
        boolean first = true;
        for (BasicRange cr:element) {
            if (!first) erg += ", ";
            else first=false;
            erg += cr.toString();
        }
        erg += " }";
        return erg;
    }

    public static Range getUniversalRange() { return new Range((char) 0, (char) 0xffff); }
    public static Range getEmptyRange() { return new Range(); }
}