1 cananian 1.1 // HClassUtil.java, created Fri Sep 11 09:14:23 1998 by cananian
2 cananian 1.6 // Copyright (C) 1998 C. Scott Ananian <cananian@alumni.princeton.edu>
3 cananian 1.6 // Licensed under the terms of the GNU GPL; see COPYING for details.
4 cananian 1.1 package harpoon.Util;
5 cananian 1.1
6 cananian 1.6.2.2 import harpoon.ClassFile.HClass;
7 cananian 1.6.2.10 import harpoon.ClassFile.Linker;
8 cananian 1.6.2.2
9 cananian 1.11 import net.cscott.jutil.Util;
10 cananian 1.1 /**
11 cananian 1.1 * <code>HClassUtil</code> contains various useful methods for dealing with
12 cananian 1.1 * HClasses that do not seem to belong with the standard HClass methods.
13 cananian 1.1 *
14 cananian 1.1 * @author C. Scott Ananian <cananian@alumni.princeton.edu>
15 cananian 1.11 * @version $Id: HClassUtil.java,v 1.11 2004/02/08 01:56:15 cananian Exp $
16 cananian 1.1 */
17 cananian 1.5 public abstract class HClassUtil {
18 cananian 1.5 // Only static methods.
19 cananian 1.1
20 cananian 1.1 /** Count the number of dimensions of an array type.
21 cananian 1.1 * @return 0 for a non-array, n for an n-dimensional array type.
22 cananian 1.1 */
23 cananian 1.1 public static final int dims(HClass hc) {
24 cananian 1.1 int i;
25 cananian 1.1 for (i=0; hc.isArray(); i++)
26 cananian 1.1 hc = hc.getComponentType();
27 cananian 1.1 return i;
28 cananian 1.1 }
29 cananian 1.1 /** Return the ultimate component type of an array (that is, after
30 cananian 1.4 * all array dimensions have been stripped off).
31 cananian 1.1 * @return input class <code>hc</code> if <code>hc</code> is not an
32 cananian 1.1 * array, otherwise a component class <code>c</code> where
33 cananian 1.1 * <code>c</code> is not an array. */
34 cananian 1.1 public static final HClass baseClass(HClass hc) {
35 cananian 1.1 while (hc.isArray())
36 cananian 1.1 hc = hc.getComponentType();
37 cananian 1.1 return hc;
38 cananian 1.1 }
39 cananian 1.1 /** Make an n-dimensional array class from the given component class.
40 cananian 1.1 * The parameter <code>dims</code> is the number of array dimensions
41 cananian 1.1 * to add. */
42 cananian 1.6.2.10 public static final HClass arrayClass(Linker linker, HClass hc, int dims) {
43 cananian 1.10 assert dims>=0;
44 cananian 1.1 StringBuffer sb = new StringBuffer();
45 cananian 1.6.2.10 return linker.forDescriptor(Util.repeatString("[",dims)+
46 cananian 1.6.2.8 hc.getDescriptor());
47 cananian 1.2 }
48 cananian 1.2 /** Create an array describing the inheritance of class hc.
49 cananian 1.2 * @return an array, where element 0 is the HClass for java.lang.Object,
50 cananian 1.2 * an the last element is hc.
51 cananian 1.2 */
52 cananian 1.2 public static final HClass[] parents(HClass hc) {
53 cananian 1.2 int len=0;
54 cananian 1.2 for (HClass h=hc; h!=null; h=h.getSuperclass())
55 cananian 1.2 len++;
56 cananian 1.2 HClass[] r = new HClass[len];
57 cananian 1.2 for (len--; len>=0 && hc!=null; hc=hc.getSuperclass(), len--)
58 cananian 1.2 r[len] = hc;
59 cananian 1.2 return r;
60 cananian 1.2 }
61 cananian 1.6.2.9 /** Find and return the first common superclass of a pair of classes.
62 cananian 1.6.2.9 * Not valid for interface or array types --- both <code>a</code>
63 cananian 1.6.2.9 * and <code>b</code> must be primitive or simple object types.
64 cananian 1.6.2.9 */
65 cananian 1.2 public static final HClass commonSuper(HClass a, HClass b) {
66 cananian 1.8.2.1 assert !a.isInterface() && !b.isInterface();
67 cananian 1.8.2.1 assert !a.isArray() && !b.isArray();
68 cananian 1.6.2.4 if (a.isPrimitive() || b.isPrimitive()) {
69 cananian 1.8.2.1 assert a==b : "Can't merge differing primitive types. "+
70 cananian 1.8.2.1 "("+a+" and "+b+")";
71 cananian 1.6.2.4 return a;
72 duncan 1.6.2.3 }
73 duncan 1.6.2.3
74 cananian 1.2 HClass[] A = parents(a);
75 cananian 1.2 HClass[] B = parents(b);
76 cananian 1.6.2.6 // both A[0] and B[0] should be java.lang.Object.
77 cananian 1.8.2.1 assert A[0]==B[0] : ("Hierarchy roots differ: "+A[0]+"/"+B[0]);
78 cananian 1.2 int i;
79 cananian 1.2 for(i=1; i<A.length && i<B.length; i++)
80 cananian 1.2 if (A[i] != B[i]) break;
81 cananian 1.2 // A[i] and B[i] now point to the first *different* parent.
82 cananian 1.2 return A[i-1];
83 cananian 1.6.2.7 }
84 cananian 1.6.2.9 /** Find and return the first common superinterface of a pair of
85 cananian 1.6.2.9 * interfaces. */
86 cananian 1.6.2.7 public static final HClass commonInterface(HClass a, HClass b) {
87 cananian 1.8.2.1 assert a.isInterface() && b.isInterface();
88 cananian 1.8.2.1 assert !a.isArray() && !b.isArray();
89 cananian 1.6.2.7 // this is a quick hack.
90 cananian 1.6.2.7 if (a.isSuperinterfaceOf(b)) return a;
91 cananian 1.6.2.7 if (b.isSuperinterfaceOf(a)) return b;
92 cananian 1.8.2.1 assert !a.isPrimitive(); // getLinker() won't work in this case
93 cananian 1.6.2.8 return a.getLinker().forName("java.lang.Object");
94 cananian 1.6.2.7 }
95 cananian 1.10 /** Find a class which is a common parent of both supplied classes.
96 cananian 1.6.2.9 * Valid for array, interface, and primitive types.
97 cananian 1.6.2.9 */
98 cananian 1.6.2.7 public static final HClass commonParent(HClass a, HClass b) {
99 cananian 1.6.2.8 if (a.isPrimitive() || b.isPrimitive()) return commonSuper(a, b);
100 cananian 1.6.2.10 // note that using getLinker() is safe because neither a nor b
101 cananian 1.6.2.10 // is primitive by this point.
102 cananian 1.8.2.1 assert a.getLinker()==b.getLinker();
103 cananian 1.6.2.7 if (a.isArray() && b.isArray()) {
104 cananian 1.6.2.11 Linker linker = a.getLinker();
105 cananian 1.6.2.7 int ad = dims(a), bd = dims(b), d = (ad<bd)?ad:bd;
106 cananian 1.6.2.7 for (int i=0; i<d; i++)
107 cananian 1.6.2.7 { a=a.getComponentType(); b=b.getComponentType(); }
108 cananian 1.10 // merging two differing primitive arrays should result in
109 cananian 1.10 // type 'Object'; e.g. float[][] merge int[][] = Object[]
110 cananian 1.10 if (a.isPrimitive() && b.isPrimitive() && a!=b)
111 cananian 1.10 return arrayClass(linker,
112 cananian 1.10 linker.forName("java.lang.Object"), d-1);
113 cananian 1.10 // otherwise, find the commonParent of the components
114 cananian 1.10 // (at least one is not an array now) and rebuild into array
115 cananian 1.10 assert (!a.isArray()) || (!b.isArray());
116 cananian 1.6.2.11 return arrayClass(linker, commonParent(a, b), d);
117 cananian 1.6.2.7 }
118 cananian 1.6.2.7 if (a.isInterface() && b.isInterface())
119 cananian 1.6.2.7 return commonInterface(a, b);
120 cananian 1.6.2.7 if (b.isArray()) return commonParent(b,a);
121 cananian 1.6.2.7 if (a.isArray()) // b is interface or object, not array.
122 cananian 1.6.2.8 if (b==b.getLinker().forName("java.lang.Cloneable") ||
123 cananian 1.6.2.8 b==b.getLinker().forName("java.io.Serializable"))
124 cananian 1.6.2.7 return b;
125 cananian 1.6.2.8 else return b.getLinker().forName("java.lang.Object");
126 cananian 1.6.2.7 if (b.isInterface()) return commonParent(b,a);
127 cananian 1.6.2.7 if (a.isInterface()) // b is object
128 cananian 1.6.2.7 if (a.isSuperinterfaceOf(b)) return a;
129 cananian 1.6.2.8 else return a.getLinker().forName("java.lang.Object");
130 cananian 1.6.2.7 // both a and b are object.
131 cananian 1.6.2.7 return commonSuper(a,b);
132 cananian 1.1 }
133 cananian 1.1 }