1 // ASM: a very small and fast Java bytecode manipulation framework 2 // Copyright (c) 2000-2011 INRIA, France Telecom 3 // All rights reserved. 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions 7 // are met: 8 // 1. Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // 2. Redistributions in binary form must reproduce the above copyright 11 // notice, this list of conditions and the following disclaimer in the 12 // documentation and/or other materials provided with the distribution. 13 // 3. Neither the name of the copyright holders nor the names of its 14 // contributors may be used to endorse or promote products derived from 15 // this software without specific prior written permission. 16 // 17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 18 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 21 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 22 // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 23 // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 24 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 25 // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 26 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 27 // THE POSSIBILITY OF SUCH DAMAGE. 28 29 package org.objectweb.asm; 30 31 /** 32 * The path to a type argument, wildcard bound, array element type, or static inner type within an 33 * enclosing type. 34 * 35 * @author Eric Bruneton 36 */ 37 public final class TypePath { 38 39 /** A type path step that steps into the element type of an array type. See {@link #getStep}. */ 40 public static final int ARRAY_ELEMENT = 0; 41 42 /** A type path step that steps into the nested type of a class type. See {@link #getStep}. */ 43 public static final int INNER_TYPE = 1; 44 45 /** A type path step that steps into the bound of a wildcard type. See {@link #getStep}. */ 46 public static final int WILDCARD_BOUND = 2; 47 48 /** A type path step that steps into a type argument of a generic type. See {@link #getStep}. */ 49 public static final int TYPE_ARGUMENT = 3; 50 51 /** 52 * The byte array where the 'type_path' structure - as defined in the Java Virtual Machine 53 * Specification (JVMS) - corresponding to this TypePath is stored. The first byte of the 54 * structure in this array is given by {@link #typePathOffset}. 55 * 56 * @see <a 57 * href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.20.2">JVMS 58 * 4.7.20.2</a> 59 */ 60 private final byte[] typePathContainer; 61 62 /** The offset of the first byte of the type_path JVMS structure in {@link #typePathContainer}. */ 63 private final int typePathOffset; 64 65 /** 66 * Constructs a new TypePath. 67 * 68 * @param typePathContainer a byte array containing a type_path JVMS structure. 69 * @param typePathOffset the offset of the first byte of the type_path structure in 70 * typePathContainer. 71 */ TypePath(final byte[] typePathContainer, final int typePathOffset)72 TypePath(final byte[] typePathContainer, final int typePathOffset) { 73 this.typePathContainer = typePathContainer; 74 this.typePathOffset = typePathOffset; 75 } 76 77 /** 78 * Returns the length of this path, i.e. its number of steps. 79 * 80 * @return the length of this path. 81 */ getLength()82 public int getLength() { 83 // path_length is stored in the first byte of a type_path. 84 return typePathContainer[typePathOffset]; 85 } 86 87 /** 88 * Returns the value of the given step of this path. 89 * 90 * @param index an index between 0 and {@link #getLength()}, exclusive. 91 * @return one of {@link #ARRAY_ELEMENT}, {@link #INNER_TYPE}, {@link #WILDCARD_BOUND}, or {@link 92 * #TYPE_ARGUMENT}. 93 */ getStep(final int index)94 public int getStep(final int index) { 95 // Returns the type_path_kind of the path element of the given index. 96 return typePathContainer[typePathOffset + 2 * index + 1]; 97 } 98 99 /** 100 * Returns the index of the type argument that the given step is stepping into. This method should 101 * only be used for steps whose value is {@link #TYPE_ARGUMENT}. 102 * 103 * @param index an index between 0 and {@link #getLength()}, exclusive. 104 * @return the index of the type argument that the given step is stepping into. 105 */ getStepArgument(final int index)106 public int getStepArgument(final int index) { 107 // Returns the type_argument_index of the path element of the given index. 108 return typePathContainer[typePathOffset + 2 * index + 2]; 109 } 110 111 /** 112 * Converts a type path in string form, in the format used by {@link #toString()}, into a TypePath 113 * object. 114 * 115 * @param typePath a type path in string form, in the format used by {@link #toString()}. May be 116 * {@literal null} or empty. 117 * @return the corresponding TypePath object, or {@literal null} if the path is empty. 118 */ fromString(final String typePath)119 public static TypePath fromString(final String typePath) { 120 if (typePath == null || typePath.length() == 0) { 121 return null; 122 } 123 int typePathLength = typePath.length(); 124 ByteVector output = new ByteVector(typePathLength); 125 output.putByte(0); 126 int typePathIndex = 0; 127 while (typePathIndex < typePathLength) { 128 char c = typePath.charAt(typePathIndex++); 129 if (c == '[') { 130 output.put11(ARRAY_ELEMENT, 0); 131 } else if (c == '.') { 132 output.put11(INNER_TYPE, 0); 133 } else if (c == '*') { 134 output.put11(WILDCARD_BOUND, 0); 135 } else if (c >= '0' && c <= '9') { 136 int typeArg = c - '0'; 137 while (typePathIndex < typePathLength) { 138 c = typePath.charAt(typePathIndex++); 139 if (c >= '0' && c <= '9') { 140 typeArg = typeArg * 10 + c - '0'; 141 } else if (c == ';') { 142 break; 143 } else { 144 throw new IllegalArgumentException(); 145 } 146 } 147 output.put11(TYPE_ARGUMENT, typeArg); 148 } else { 149 throw new IllegalArgumentException(); 150 } 151 } 152 output.data[0] = (byte) (output.length / 2); 153 return new TypePath(output.data, 0); 154 } 155 156 /** 157 * Returns a string representation of this type path. {@link #ARRAY_ELEMENT} steps are represented 158 * with '[', {@link #INNER_TYPE} steps with '.', {@link #WILDCARD_BOUND} steps with '*' and {@link 159 * #TYPE_ARGUMENT} steps with their type argument index in decimal form followed by ';'. 160 */ 161 @Override toString()162 public String toString() { 163 int length = getLength(); 164 StringBuilder result = new StringBuilder(length * 2); 165 for (int i = 0; i < length; ++i) { 166 switch (getStep(i)) { 167 case ARRAY_ELEMENT: 168 result.append('['); 169 break; 170 case INNER_TYPE: 171 result.append('.'); 172 break; 173 case WILDCARD_BOUND: 174 result.append('*'); 175 break; 176 case TYPE_ARGUMENT: 177 result.append(getStepArgument(i)).append(';'); 178 break; 179 default: 180 throw new AssertionError(); 181 } 182 } 183 return result.toString(); 184 } 185 186 /** 187 * Puts the type_path JVMS structure corresponding to the given TypePath into the given 188 * ByteVector. 189 * 190 * @param typePath a TypePath instance, or {@literal null} for empty paths. 191 * @param output where the type path must be put. 192 */ put(final TypePath typePath, final ByteVector output)193 static void put(final TypePath typePath, final ByteVector output) { 194 if (typePath == null) { 195 output.putByte(0); 196 } else { 197 int length = typePath.typePathContainer[typePath.typePathOffset] * 2 + 1; 198 output.putByteArray(typePath.typePathContainer, typePath.typePathOffset, length); 199 } 200 } 201 } 202