1 salcianu 1.1.2.1 // GenType.java, created Tue Mar 7 18:32:52 2000 by salcianu
2 cananian 1.1.2.3 // Copyright (C) 2000 Alexandru SALCIANU <salcianu@retezat.lcs.mit.edu>
3 salcianu 1.1.2.1 // Licensed under the terms of the GNU GPL; see COPYING for details.
4 salcianu 1.1.2.1 package harpoon.Analysis.MetaMethods;
5 salcianu 1.1.2.1
6 salcianu 1.1.2.1 import harpoon.ClassFile.HClass;
7 salcianu 1.1.2.1 import harpoon.Analysis.ClassHierarchy;
8 salcianu 1.1.2.1 import harpoon.Analysis.PointerAnalysis.PAWorkList;
9 salcianu 1.1.2.1
10 salcianu 1.1.2.1 import harpoon.Util.Util;
11 salcianu 1.1.2.1
12 salcianu 1.1.2.1 /**
13 salcianu 1.1.2.1 * <code>GenType</code> models a type. Although we can always record
14 salcianu 1.1.2.1 the possible types of a variable as a set of <code>HClass</code>es,
15 salcianu 1.1.2.1 this is inneficient in most of the cases. <code>GenType</code> tries
16 salcianu 1.1.2.1 to cope with this by representing both monomorphic types (which
17 salcianu 1.1.2.1 correspond to a single <code>HCode</code>) and polymorphic types
18 salcianu 1.1.2.1 (which correspond to a set of <code>HClass</code>es, a type cone
19 salcianu 1.1.2.1 rooted in a specific <code>HClass</code>)
20 salcianu 1.1.2.1 *
21 cananian 1.1.2.3 * @author Alexandru SALCIANU <salcianu@retezat.lcs.mit.edu>
22 salcianu 1.5 * @version $Id: GenType.java,v 1.5 2002/05/02 22:11:39 salcianu Exp $
23 salcianu 1.1.2.1 */
24 cananian 1.1.2.2 public class GenType implements java.io.Serializable {
25 salcianu 1.1.2.1
26 salcianu 1.1.2.1 /** Monomorphic type. This is an exact type, just the point
27 salcianu 1.1.2.1 <code>hclass</code> into the type space. */
28 salcianu 1.1.2.1 public static final int MONO = 1;
29 salcianu 1.1.2.1 /** Polymorphic type. This is a cone into the type space, rooted in
30 salcianu 1.1.2.1 <code>hclass</code> and containing <code>hclass</code> and all its
31 salcianu 1.1.2.1 subtypes (subclasses). */
32 salcianu 1.1.2.1 public static final int POLY = 2;
33 salcianu 1.1.2.1
34 salcianu 1.1.2.1 HClass hclass = null;
35 salcianu 1.1.2.1 int kind = POLY;
36 salcianu 1.1.2.1
37 salcianu 1.5 /** Creates a <code>GenType</code>. <code>kind</code> should be
38 salcianu 1.5 <code>MONO</code> or <code>POLY</code>. */
39 salcianu 1.1.2.1 public GenType(HClass hclass, int kind) {
40 salcianu 1.5 assert (kind == MONO) || (kind == POLY) :
41 salcianu 1.5 "kind should be GenType.MONO or GenType.POLY";
42 salcianu 1.1.2.1 this.hclass = hclass;
43 salcianu 1.1.2.1 this.kind = kind;
44 salcianu 1.1.2.1 }
45 salcianu 1.1.2.1
46 salcianu 1.1.2.1 /** Creates a polymorphic type, having <code>hclass</code> as superclass.
47 salcianu 1.1.2.1 */
48 salcianu 1.1.2.1 public GenType(HClass hclass){
49 salcianu 1.1.2.1 this(hclass,POLY);
50 salcianu 1.1.2.1 }
51 salcianu 1.1.2.1
52 salcianu 1.1.2.1 /** Checks whether this is a polymorphic type. */
53 salcianu 1.1.2.1 public boolean isPOLY(){
54 salcianu 1.1.2.1 return kind == POLY;
55 salcianu 1.1.2.1 }
56 salcianu 1.1.2.1
57 salcianu 1.1.2.1 /** Returns the underlying <code>HClass</code>.
58 salcianu 1.1.2.1 If <code>this</code> general type represents a monomorphic type,
59 salcianu 1.1.2.1 the result is exactly that type. Otherwise, for polymorphic types,
60 salcianu 1.1.2.1 the result is the root of the type cone. */
61 salcianu 1.1.2.1 public HClass getHClass(){
62 salcianu 1.1.2.1 return hclass;
63 salcianu 1.1.2.1 }
64 salcianu 1.1.2.1
65 salcianu 1.1.2.1 /** Checks the equality of <code>this</code> object with object
66 salcianu 1.1.2.1 <code>o</code>. */
67 salcianu 1.1.2.1 public boolean equals(Object o){
68 salcianu 1.1.2.1 GenType gt2 = (GenType) o;
69 salcianu 1.1.2.1 return (kind == gt2.kind) && hclass.equals(gt2.hclass);
70 salcianu 1.1.2.1 }
71 salcianu 1.1.2.1
72 cananian 1.1.2.2 private transient int hash = 0;
73 salcianu 1.1.2.1 /** Computes the hash code of <code>this</code> object. */
74 salcianu 1.1.2.1 public int hashCode(){
75 cananian 1.1.2.2 if(hash == 0)
76 cananian 1.1.2.2 hash = hclass.hashCode() + kind;
77 salcianu 1.1.2.1 return hash;
78 salcianu 1.1.2.1 }
79 salcianu 1.1.2.1
80 salcianu 1.1.2.1 /** Checks whether <code>this</code> general type is included into the
81 salcianu 1.1.2.1 set of types abstracted by the general type <code>gt2</code>. */
82 salcianu 1.1.2.1 public boolean included(GenType gt2, ClassHierarchy ch){
83 salcianu 1.1.2.1 if(gt2 == null) return false;
84 salcianu 1.1.2.1 if(equals(gt2)) return true;
85 salcianu 1.1.2.1
86 salcianu 1.1.2.1 // if the other type is monomorphic then either this type is
87 salcianu 1.1.2.1 // monomorphic and different (equals returned false) and so this type
88 salcianu 1.1.2.1 // is not included in it, or this is polymorphic and again gt2 cannot
89 salcianu 1.1.2.1 // include this.
90 salcianu 1.1.2.1 if(!gt2.isPOLY()) return false;
91 salcianu 1.1.2.1
92 salcianu 1.1.2.1 // now, gt2 is known to be polymorphic, we have to check if hclass is
93 salcianu 1.1.2.1 // included in the gt2 type cone <=> hclass is a subclass of gt2.hclass
94 salcianu 1.1.2.1 // generate all the ancestors of hclass and see if gt2.hclass is among
95 salcianu 1.1.2.1 // them.
96 salcianu 1.1.2.1
97 salcianu 1.1.2.1 PAWorkList W = new PAWorkList();
98 salcianu 1.1.2.1 W.add(hclass);
99 salcianu 1.1.2.1 while(!W.isEmpty()){
100 salcianu 1.1.2.1 HClass c = (HClass) W.remove();
101 salcianu 1.1.2.1
102 salcianu 1.1.2.1 HClass parent = c.getSuperclass();
103 salcianu 1.1.2.1 if(parent != null){
104 salcianu 1.1.2.1 if(parent.equals(gt2.hclass)) return true;
105 salcianu 1.1.2.1 W.add(parent);
106 salcianu 1.1.2.1 }
107 salcianu 1.1.2.1
108 salcianu 1.1.2.1 HClass[] interfs = c.getInterfaces();
109 salcianu 1.1.2.1 for(int i = 0; i < interfs.length ; i++){
110 salcianu 1.1.2.1 if(interfs[i].equals(gt2.hclass)) return true;
111 salcianu 1.1.2.1 W.add(interfs[i]);
112 salcianu 1.1.2.1 }
113 salcianu 1.1.2.1 }
114 salcianu 1.1.2.1 return false;
115 salcianu 1.1.2.1 }
116 salcianu 1.1.2.1
117 salcianu 1.1.2.1 /** Pretty printer for debug purposes. */
118 salcianu 1.1.2.1 public String toString(){
119 salcianu 1.1.2.1 return "<" + hclass.toString() + "," + (isPOLY()?"P":"M") + ">";
120 salcianu 1.1.2.1 }
121 salcianu 1.1.2.1
122 cananian 1.2 }