1/*
2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package com.sun.tools.internal.xjc.model;
27
28import java.math.BigInteger;
29
30
31
32/**
33 * represents a possible number of occurence.
34 *
35 * Usually, denoted by a pair of integers like (1,1) or (5,10).
36 * A special value "unbounded" is allowed as the upper bound.
37 *
38 * <p>
39 * For example, (0,unbounded) corresponds to the '*' occurence of DTD.
40 * (0,1) corresponds to the '?' occurence of DTD.
41 *
42 * @author
43 *    <a href="mailto:kohsuke.kawaguchi@sun.com">Kohsuke KAWAGUCHI</a>
44 */
45public final class Multiplicity {
46    public final BigInteger min;
47    public final BigInteger max;    // null is used to represent "unbounded".
48
49    public static Multiplicity create(BigInteger min, BigInteger max ) {
50        if (BigInteger.ZERO.equals(min) && max==null) return STAR;
51        if (BigInteger.ONE.equals(min) && max==null) return PLUS;
52        if (max!=null) {
53            if(BigInteger.ZERO.equals(min) && BigInteger.ZERO.equals(max))    return ZERO;
54            if(BigInteger.ZERO.equals(min) && BigInteger.ONE.equals(max))    return OPTIONAL;
55            if(BigInteger.ONE.equals(min) && BigInteger.ONE.equals(max))    return ONE;
56        }
57        return new Multiplicity(min, max);
58    }
59
60    public static Multiplicity create(int min, Integer max ) {
61        return Multiplicity.create(BigInteger.valueOf(min), BigInteger.valueOf(max.intValue()));
62    }
63
64    private Multiplicity(BigInteger min, BigInteger max) {
65        this.min = min;
66        this.max = max;
67    }
68
69    private Multiplicity(int min, int max) {
70        this(BigInteger.valueOf(min), BigInteger.valueOf(max));
71    }
72
73    private Multiplicity(int min, Integer max) {
74        this(BigInteger.valueOf(min), (max == null) ? null : BigInteger.valueOf(max));
75    }
76
77    @Override
78    public boolean equals(Object o) {
79        if (!(o instanceof Multiplicity)) return false;
80
81        Multiplicity that = (Multiplicity) o;
82
83        if (!this.min.equals(that.min)) return false;
84        if (this.max != null ? !this.max.equals(that.max) : that.max != null) return false;
85
86        return true;
87    }
88
89    @Override
90    public int hashCode() {
91        return min.add(max).intValue();
92    }
93
94    /** returns true if the multiplicity is (1,1). */
95    public boolean isUnique() {
96        if(max==null)    return false;
97        return BigInteger.ONE.equals(min) && BigInteger.ONE.equals(max);
98    }
99
100    /** returns true if the multiplicity is (0,1) */
101    public boolean isOptional() {
102        if(max==null) return false;
103        return BigInteger.ZERO.equals(min) && BigInteger.ONE.equals(max);
104    }
105
106    /** returns true if the multiplicity is (0,1) or (1,1). */
107    public boolean isAtMostOnce() {
108        if(max==null)    return false;
109        return max.compareTo(BigInteger.ONE)<=0;
110    }
111
112    /** returns true if the multiplicity is (0,0). */
113    public boolean isZero() {
114        if(max==null)    return false;
115        return BigInteger.ZERO.equals(max);
116    }
117
118    /**
119     * Returns true if the multiplicity represented by this object
120     * completely includes the multiplicity represented by the
121     * other object. For example, we say [1,3] includes [1,2] but
122     * [2,4] doesn't include [1,3].
123     */
124    public boolean includes( Multiplicity rhs ) {
125        if (rhs.min.compareTo(min) == -1)   return false;
126        if (max==null) return true;
127        if (rhs.max==null) return false;
128        return rhs.max.compareTo(max) <= 0;
129    }
130
131    /**
132     * Returns the string representation of the 'max' property.
133     * Either a number or a token "unbounded".
134     */
135    public String getMaxString() {
136        if(max==null)       return "unbounded";
137        else                return max.toString();
138    }
139
140    /** gets the string representation.
141     * mainly debug purpose.
142     */
143    @Override
144    public String toString() {
145        return "("+min+','+getMaxString()+')';
146    }
147
148    /** the constant representing the (0,0) multiplicity. */
149    public static final Multiplicity ZERO = new Multiplicity(0,0);
150
151    /** the constant representing the (1,1) multiplicity. */
152    public static final Multiplicity ONE = new Multiplicity(1,1);
153
154    /** the constant representing the (0,1) multiplicity. */
155    public static final Multiplicity OPTIONAL = new Multiplicity(0,1);
156
157    /** the constant representing the (0,unbounded) multiplicity. */
158    public static final Multiplicity STAR = new Multiplicity(0,null);
159
160    /** the constant representing the (1,unbounded) multiplicity. */
161    public static final Multiplicity PLUS = new Multiplicity(1,null);
162
163// arithmetic methods
164    public static Multiplicity choice( Multiplicity lhs, Multiplicity rhs ) {
165        return create(
166            lhs.min.min(rhs.min),
167            (lhs.max==null || rhs.max==null) ? null : lhs.max.max(rhs.max) );
168    }
169    public static Multiplicity group( Multiplicity lhs, Multiplicity rhs ) {
170        return create(
171            lhs.min.add(rhs.min),
172            (lhs.max==null || rhs.max==null) ? null : lhs.max.add(rhs.max) );
173    }
174    public static Multiplicity multiply( Multiplicity lhs, Multiplicity rhs ) {
175        BigInteger min = lhs.min.multiply(rhs.min);
176        BigInteger max;
177        if (isZero(lhs.max) || isZero(rhs.max))
178            max = BigInteger.ZERO;
179        else
180        if (lhs.max==null || rhs.max==null)
181            max = null;
182        else
183            max = lhs.max.multiply(rhs.max);
184        return create(min,max);
185    }
186
187    private static boolean isZero(BigInteger i) {
188        return (i != null && BigInteger.ZERO.equals(i));
189    }
190
191    public static Multiplicity oneOrMore( Multiplicity c ) {
192        if(c.max==null)  return c; // (x,*) => (x,*)
193        if(BigInteger.ZERO.equals(c.max)) return c; // (0,0) => (0,0)
194        else        return create( c.min, null );    // (x,y) => (x,*)
195    }
196
197    public Multiplicity makeOptional() {
198        if (BigInteger.ZERO.equals(min)) return this;
199        return create(BigInteger.ZERO, max);
200    }
201
202    public Multiplicity makeRepeated() {
203        if (max==null || BigInteger.ZERO.equals(max))  return this;   // (0,0)* = (0,0)  and (n,unbounded)* = (n,unbounded)
204        return create(min,null);
205    }
206}
207