Frames | No Frames |
1: /* TypeSignature.java -- Class used to compute type signatures 2: Copyright (C) 1998, 2000, 2002 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package gnu.java.lang.reflect; 40: 41: import java.lang.reflect.Constructor; 42: import java.lang.reflect.Field; 43: import java.lang.reflect.Member; 44: import java.lang.reflect.Method; 45: 46: /** 47: * This class provides static methods that can be used to compute 48: * type-signatures of <code>Class</code>s or <code>Member</code>s. 49: * More specific methods are also provided for computing the 50: * type-signature of <code>Constructor</code>s and 51: * <code>Method</code>s. Methods are also provided to go in the 52: * reverse direction. 53: * 54: * @author Eric Blake (ebb9@email.byu.edu) 55: */ 56: public class TypeSignature 57: { 58: /** 59: * Returns a <code>String</code> representing the type-encoding of a class. 60: * The .class file format has different encodings for classes, depending 61: * on whether it must be disambiguated from primitive types or not; hence 62: * the descriptor parameter to choose between them. If you are planning 63: * on decoding primitive types along with classes, then descriptor should 64: * be true for correct results. Type-encodings are computed as follows: 65: * 66: * <pre> 67: * boolean -> "Z" 68: * byte -> "B" 69: * char -> "C" 70: * double -> "D" 71: * float -> "F" 72: * int -> "I" 73: * long -> "J" 74: * short -> "S" 75: * void -> "V" 76: * arrays -> "[" + descriptor format of component type 77: * object -> class format: fully qualified name with '.' replaced by '/' 78: * descriptor format: "L" + class format + ";" 79: * </pre> 80: * 81: * @param type the class name to encode 82: * @param descriptor true to return objects in descriptor format 83: * @return the class name, as it appears in bytecode constant pools 84: * @see #getClassForEncoding(String) 85: */ 86: public static String getEncodingOfClass(String type, boolean descriptor) 87: { 88: if (! descriptor || type.charAt(0) == '[') 89: return type.replace('.', '/'); 90: if (type.equals("boolean")) 91: return "Z"; 92: if (type.equals("byte")) 93: return "B"; 94: if (type.equals("short")) 95: return "S"; 96: if (type.equals("char")) 97: return "C"; 98: if (type.equals("int")) 99: return "I"; 100: if (type.equals("long")) 101: return "J"; 102: if (type.equals("float")) 103: return "F"; 104: if (type.equals("double")) 105: return "D"; 106: if (type.equals("void")) 107: return "V"; 108: return 'L' + type.replace('.', '/') + ';'; 109: } 110: 111: /** 112: * Gets the descriptor encoding for a class. 113: * 114: * @param clazz the class to encode 115: * @param descriptor true to return objects in descriptor format 116: * @return the class name, as it appears in bytecode constant pools 117: * @see #getEncodingOfClass(String, boolean) 118: */ 119: public static String getEncodingOfClass(Class clazz, boolean descriptor) 120: { 121: return getEncodingOfClass(clazz.getName(), descriptor); 122: } 123: 124: /** 125: * Gets the descriptor encoding for a class. 126: * 127: * @param clazz the class to encode 128: * @return the class name, as it appears in bytecode constant pools 129: * @see #getEncodingOfClass(String, boolean) 130: */ 131: public static String getEncodingOfClass(Class clazz) 132: { 133: return getEncodingOfClass(clazz.getName(), true); 134: } 135: 136: 137: /** 138: * This function is the inverse of <code>getEncodingOfClass</code>. This 139: * accepts both object and descriptor formats, but must know which style 140: * of string is being passed in (usually, descriptor should be true). In 141: * descriptor format, "I" is treated as int.class, in object format, it 142: * is treated as a class named I in the unnamed package. This method is 143: * strictly equivalent to {@link #getClassForEncoding(java.lang.String, boolean, java.lang.ClassLoader)} 144: * with a class loader equal to <code>null</code>. In that case, it 145: * uses the default class loader on the calling stack. 146: * 147: * @param type_code the class name to decode 148: * @param descriptor if the string is in descriptor format 149: * @return the corresponding Class object 150: * @throws ClassNotFoundException if the class cannot be located 151: * @see #getEncodingOfClass(Class, boolean) 152: */ 153: public static Class getClassForEncoding(String type_code, boolean descriptor) 154: throws ClassNotFoundException 155: { 156: return getClassForEncoding(type_code, descriptor, null); 157: } 158: 159: /** 160: * This function is the inverse of <code>getEncodingOfClass</code>. This 161: * accepts both object and descriptor formats, but must know which style 162: * of string is being passed in (usually, descriptor should be true). In 163: * descriptor format, "I" is treated as int.class, in object format, it 164: * is treated as a class named I in the unnamed package. 165: * 166: * @param type_code The class name to decode. 167: * @param descriptor If the string is in descriptor format. 168: * @param loader The class loader when resolving generic object name. If 169: * <code>loader</code> is null then it uses the default class loader on the 170: * calling stack. 171: * @return the corresponding Class object. 172: * @throws ClassNotFoundException if the class cannot be located. 173: * @see #getEncodingOfClass(Class, boolean) 174: * @see #getClassForEncoding(String, boolean) 175: */ 176: public static Class getClassForEncoding(String type_code, boolean descriptor, 177: ClassLoader loader) 178: throws ClassNotFoundException 179: { 180: if (descriptor) 181: { 182: switch (type_code.charAt(0)) 183: { 184: case 'B': 185: return byte.class; 186: case 'C': 187: return char.class; 188: case 'D': 189: return double.class; 190: case 'F': 191: return float.class; 192: case 'I': 193: return int.class; 194: case 'J': 195: return long.class; 196: case 'S': 197: return short.class; 198: case 'V': 199: return void.class; 200: case 'Z': 201: return boolean.class; 202: default: 203: throw new ClassNotFoundException("Invalid class name: " 204: + type_code); 205: case 'L': 206: type_code = type_code.substring(1, type_code.length() - 1); 207: // Fallthrough. 208: case '[': 209: } 210: } 211: return Class.forName(type_code.replace('/', '.'), true, loader); 212: } 213: 214: /** 215: * Gets the Class object for a type name. 216: * 217: * @param type_code the class name to decode 218: * @return the corresponding Class object 219: * @throws ClassNotFoundException if the class cannot be located 220: * @see #getClassForEncoding(String, boolean) 221: */ 222: public static Class getClassForEncoding(String type_code) 223: throws ClassNotFoundException 224: { 225: return getClassForEncoding(type_code, true); 226: } 227: 228: /** 229: * Returns a <code>String</code> representing the type-encoding of a 230: * method. The type-encoding of a method is: 231: * 232: * "(" + parameter type descriptors + ")" + return type descriptor 233: * 234: * XXX This could be faster if it were implemented natively. 235: * 236: * @param m the method to encode 237: * @return the encoding 238: */ 239: public static String getEncodingOfMethod(Method m) 240: { 241: Class[] paramTypes = m.getParameterTypes(); 242: StringBuffer buf = new StringBuffer().append('('); 243: for (int i = 0; i < paramTypes.length; i++) 244: buf.append(getEncodingOfClass(paramTypes[i].getName(), true)); 245: buf.append(')').append(getEncodingOfClass(m.getReturnType().getName(), 246: true)); 247: return buf.toString(); 248: } 249: 250: /** 251: * Returns a <code>String</code> representing the type-encoding of a 252: * constructor. The type-encoding of a method is: 253: * 254: * "(" + parameter type descriptors + ")V" 255: * 256: * XXX This could be faster if it were implemented natively. 257: * 258: * @param c the constructor to encode 259: * @return the encoding 260: */ 261: public static String getEncodingOfConstructor(Constructor c) 262: { 263: Class[] paramTypes = c.getParameterTypes(); 264: StringBuffer buf = new StringBuffer().append('('); 265: for (int i = 0; i < paramTypes.length; i++) 266: buf.append(getEncodingOfClass(paramTypes[i].getName(), true)); 267: buf.append(")V"); 268: return buf.toString(); 269: } 270: 271: /** 272: * Returns a <code>String</code> representing the type-encoding of a 273: * class member. This appropriately handles Constructors, Methods, and 274: * Fields. 275: * 276: * @param mem the member to encode 277: * @return the encoding 278: */ 279: public static String getEncodingOfMember(Member mem) 280: { 281: if (mem instanceof Constructor) 282: return getEncodingOfConstructor((Constructor) mem); 283: if (mem instanceof Method) 284: return getEncodingOfMethod((Method) mem); 285: else // Field 286: return getEncodingOfClass(((Field) mem).getType().getName(), true); 287: } 288: } // class TypeSignature