Simple Reader for KeyValues

KeyValueReader

class KeyValueReader {

    private final String line;
    private int idx;
    private int mark;

    public KeyValueReader(String l) {
        this.line = l;
    }

    public void mark() {
        this.mark = this.idx;
    }

    public String getMarkedSegment() {
        correctState(this.mark <= this.idx, "mark is greater than this.idx");
        return this.line.substring(this.mark, this.idx);
    }

    public int getc() {
        correctState(this.idx + 1 < this.line.length(), "Attempt to read past end");
        return this.line.charAt(this.idx++);
    }

    public boolean available() {
        return idx < (line.length() - 1);
    }


    public boolean is(char c) {
        return idx < line.length() && this.line.charAt(this.idx) == c;
    }

    private boolean was(char c) {
        correctState(this.idx >= 1, "Reading before beginning of data");
        return this.line.charAt(this.idx - 1) == c;
    }
}