/**
* Returns a new automaton that accepts strings representing decimal non-negative integers in the
* given interval.
*
* @param min minimal value of interval
* @param max maximal value of inverval (both end points are included in the interval)
* @param digits if >0, use fixed number of digits (strings must be prefixed by 0's to obtain the
* right length) - otherwise, the number of digits is not fixed
* @throws IllegalArgumentException if min>max or if numbers in the interval cannot be expressed
* with the given fixed number of digits
*/
public static DefaultAutomaton makeInterval(int min, int max, int digits)
throws IllegalArgumentException {
DefaultAutomaton a = new DefaultAutomaton();
String x = Integer.toString(min);
String y = Integer.toString(max);
if (min > max || (digits > 0 && y.length() > digits)) throw new IllegalArgumentException();
int d;
if (digits > 0) d = digits;
else d = y.length();
StringBuilder bx = new StringBuilder();
for (int i = x.length(); i < d; i++) bx.append('0');
bx.append(x);
x = bx.toString();
StringBuilder by = new StringBuilder();
for (int i = y.length(); i < d; i++) by.append('0');
by.append(y);
y = by.toString();
Collection<State> initials = new ArrayList<State>();
a.initial = between(x, y, 0, initials, digits <= 0);
if (digits <= 0) {
ArrayList<StatePair> pairs = new ArrayList<StatePair>();
for (State p : initials) if (a.initial != p) pairs.add(new StatePair(a.initial, p));
addEpsilons(a, pairs);
a.initial.addTransition(new Transition('0', a.initial));
a.deterministic = false;
} else a.deterministic = true;
a.checkMinimizeAlways();
return a;
}
/** Returns a new (deterministic) automaton with the empty language. */
public static DefaultAutomaton makeEmpty() {
DefaultAutomaton a = new DefaultAutomaton();
State s = new State();
a.initial = s;
a.deterministic = true;
return a;
}
/** Returns a new (deterministic) automaton that accepts all strings. */
public static DefaultAutomaton makeAnyString() {
DefaultAutomaton a = new DefaultAutomaton();
State s = new State();
a.initial = s;
s.accept = true;
s.transitions.add(new Transition(Character.MIN_VALUE, Character.MAX_VALUE, s));
a.deterministic = true;
return a;
}
/**
* Returns a new (deterministic) automaton that accepts a single char whose value is in the given
* interval (including both end points).
*/
public static DefaultAutomaton makeCharRange(char min, char max) {
if (min == max) return makeChar(min);
DefaultAutomaton a = new DefaultAutomaton();
State s1 = new State();
State s2 = new State();
a.initial = s1;
s2.accept = true;
if (min <= max) s1.transitions.add(new Transition(min, max, s2));
a.deterministic = true;
return a;
}
/** Returns a new (deterministic) automaton that accepts a single character in the given set. */
public static DefaultAutomaton makeCharSet(String set) {
if (set.length() == 1) return makeChar(set.charAt(0));
DefaultAutomaton a = new DefaultAutomaton();
State s1 = new State();
State s2 = new State();
a.initial = s1;
s2.accept = true;
for (int i = 0; i < set.length(); i++) s1.transitions.add(new Transition(set.charAt(i), s2));
a.deterministic = true;
a.reduce();
return a;
}
