msv.tahiti.src.com.sun.tahiti.grammar.util.Multiplicity Maven / Gradle / Ivy
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/*
* @(#)$Id: Multiplicity.java 1081 2001-08-17 01:36:51Z Bear $
*
* Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
*
* This software is the proprietary information of Sun Microsystems, Inc.
* Use is subject to license terms.
*
*/
package com.sun.tahiti.grammar.util;
import com.sun.msv.grammar.Expression;
/**
* 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.
*
*
* For example, (0,unbounded) corresponds to the '*' occurence of DTD.
* (0,1) corresponds to the '?' occurence of DTD.
*
* @author
* Kohsuke KAWAGUCHI
*/
public class Multiplicity {
public final int min;
public final Integer max; // null is used to represent "unbounded".
public Multiplicity( int min, Integer max ) {
this.min = min; this.max = max;
}
public Multiplicity( int min, int max ) {
this.min = min; this.max = new Integer(max);
}
/** returns true if the multiplicity is (1,1). */
public boolean isUnique() {
if(max==null) return false;
return min==1 && max.intValue()==1;
}
/** returns true if the multiplicity is (0,1) or (1,1). */
public boolean isAtMostOnce() {
if(max==null) return false;
return max.intValue()<=1;
}
/** returns true if the multiplicity is (0,0). */
public boolean isZero() {
if(max==null) return false;
return max.intValue()==0;
}
/** gets the string representation.
* mainly debug purpose.
*/
public String toString() {
return "("+(max==null?"unbounded":max.toString())+","+min+")";
}
/** the constant representing the (0,0) multiplicity. */
public static Multiplicity zero = new Multiplicity(0,0);
/** the constante representing the (1,1) multiplicity. */
public static Multiplicity one = new Multiplicity(1,1);
public static Multiplicity calc( Expression exp, MultiplicityCounter calc ) {
return (Multiplicity)exp.visit(calc);
}
// arithmetic methods
//============================
public static Multiplicity choice( Multiplicity lhs, Multiplicity rhs ) {
return new Multiplicity(
Math.min(lhs.min,rhs.min),
(lhs.max==null||rhs.max==null)?
null:
new Integer(Math.max(lhs.max.intValue(),rhs.max.intValue())) );
}
public static Multiplicity group( Multiplicity lhs, Multiplicity rhs ) {
return new Multiplicity( lhs.min+rhs.min,
(lhs.max==null||rhs.max==null)?
null:
new Integer(lhs.max.intValue()+rhs.max.intValue()) );
}
public static Multiplicity oneOrMore( Multiplicity c ) {
if(c.max==null) return c; // (x,*) => (x,*)
if(c.max.intValue()==0 ) return c; // (0,0) => (0,0)
else return new Multiplicity( c.min, null ); // (x,y) => (x,*)
}
}