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package com.sun.tools.xjc.model;
import java.math.BigInteger;
/**
* represents a possible number of occurence.
*
* Usually, denoted by a pair of integers like (1,1) or (5,10).
* A special value "unbounded" is allowed as the upper bound.
*
* <p>
* For example, (0,unbounded) corresponds to the '*' occurence of DTD.
* (0,1) corresponds to the '?' occurence of DTD.
*
* @author
* <a href="mailto:kohsuke.kawaguchi@sun.com">Kohsuke KAWAGUCHI</a>
*/
public final class Multiplicity {
public final BigInteger min;
public final BigInteger max; // null is used to represent "unbounded".
public static Multiplicity create(BigInteger min, BigInteger max ) {
if (BigInteger.ZERO.equals(min) && max==null) return STAR;
if (BigInteger.ONE.equals(min) && max==null) return PLUS;
if (max!=null) {
if(BigInteger.ZERO.equals(min) && BigInteger.ZERO.equals(max)) return ZERO;
if(BigInteger.ZERO.equals(min) && BigInteger.ONE.equals(max)) return OPTIONAL;
if(BigInteger.ONE.equals(min) && BigInteger.ONE.equals(max)) return ONE;
}
return new Multiplicity(min, max);
}
public static Multiplicity create(int min, Integer max ) {
return Multiplicity.create(BigInteger.valueOf(min), BigInteger.valueOf(max.intValue()));
}
private Multiplicity(BigInteger min, BigInteger max) {
this.min = min;
this.max = max;
}
private Multiplicity(int min, int max) {
this(BigInteger.valueOf(min), BigInteger.valueOf(max));
}
private Multiplicity(int min, Integer max) {
this(BigInteger.valueOf(min), (max == null) ? null : BigInteger.valueOf(max));
}
@Override
public boolean equals(Object o) {
if (!(o instanceof Multiplicity)) return false;
Multiplicity that = (Multiplicity) o;
if (!this.min.equals(that.min)) return false;
if (this.max != null ? !this.max.equals(that.max) : that.max != null) return false;
return true;
}
@Override
public int hashCode() {
return min.add(max).intValue();
}
/** returns true if the multiplicity is (1,1). */
public boolean isUnique() {
if(max==null) return false;
return BigInteger.ONE.equals(min) && BigInteger.ONE.equals(max);
}
/** returns true if the multiplicity is (0,1) */
public boolean isOptional() {
if(max==null) return false;
return BigInteger.ZERO.equals(min) && BigInteger.ONE.equals(max);
}
/** returns true if the multiplicity is (0,1) or (1,1). */
public boolean isAtMostOnce() {
if(max==null) return false;
return max.compareTo(BigInteger.ONE)<=0;
}
/** returns true if the multiplicity is (0,0). */
public boolean isZero() {
if(max==null) return false;
return BigInteger.ZERO.equals(max);
}
/**
* Returns true if the multiplicity represented by this object
* completely includes the multiplicity represented by the
* other object. For example, we say [1,3] includes [1,2] but
* [2,4] doesn't include [1,3].
*/
public boolean includes( Multiplicity rhs ) {
if (rhs.min.compareTo(min) == -1) return false;
if (max==null) return true;
if (rhs.max==null) return false;
return rhs.max.compareTo(max) <= 0;
}
/**
* Returns the string representation of the 'max' property.
* Either a number or a token "unbounded".
*/
public String getMaxString() {
if(max==null) return "unbounded";
else return max.toString();
}
/** gets the string representation.
* mainly debug purpose.
*/
@Override
public String toString() {
return "("+min+','+getMaxString()+')';
}
/** the constant representing the (0,0) multiplicity. */
public static final Multiplicity ZERO = new Multiplicity(0,0);
/** the constant representing the (1,1) multiplicity. */
public static final Multiplicity ONE = new Multiplicity(1,1);
/** the constant representing the (0,1) multiplicity. */
public static final Multiplicity OPTIONAL = new Multiplicity(0,1);
/** the constant representing the (0,unbounded) multiplicity. */
public static final Multiplicity STAR = new Multiplicity(0,null);
/** the constant representing the (1,unbounded) multiplicity. */
public static final Multiplicity PLUS = new Multiplicity(1,null);
// arithmetic methods
public static Multiplicity choice( Multiplicity lhs, Multiplicity rhs ) {
return create(
lhs.min.min(rhs.min),
(lhs.max==null || rhs.max==null) ? null : lhs.max.max(rhs.max) );
}
public static Multiplicity group( Multiplicity lhs, Multiplicity rhs ) {
return create(
lhs.min.add(rhs.min),
(lhs.max==null || rhs.max==null) ? null : lhs.max.add(rhs.max) );
}
public static Multiplicity multiply( Multiplicity lhs, Multiplicity rhs ) {
BigInteger min = lhs.min.multiply(rhs.min);
BigInteger max;
if (isZero(lhs.max) || isZero(rhs.max))
max = BigInteger.ZERO;
else
if (lhs.max==null || rhs.max==null)
max = null;
else
max = lhs.max.multiply(rhs.max);
return create(min,max);
}
private static boolean isZero(BigInteger i) {
return (i != null && BigInteger.ZERO.equals(i));
}
public static Multiplicity oneOrMore( Multiplicity c ) {
if(c.max==null) return c; // (x,*) => (x,*)
if(BigInteger.ZERO.equals(c.max)) return c; // (0,0) => (0,0)
else return create( c.min, null ); // (x,y) => (x,*)
}
public Multiplicity makeOptional() {
if (BigInteger.ZERO.equals(min)) return this;
return create(BigInteger.ZERO, max);
}
public Multiplicity makeRepeated() {
if (max==null || BigInteger.ZERO.equals(max)) return this; // (0,0)* = (0,0) and (n,unbounded)* = (n,unbounded)
return create(min,null);
}
}