1 /*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5 /*
6 * Licensed to the Apache Software Foundation (ASF) under one or more
7 * contributor license agreements. See the NOTICE file distributed with
8 * this work for additional information regarding copyright ownership.
9 * The ASF licenses this file to You under the Apache License, Version 2.0
10 * (the "License"); you may not use this file except in compliance with
11 * the License. You may obtain a copy of the License at
12 *
13 * http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing, software
16 * distributed under the License is distributed on an "AS IS" BASIS,
17 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18 * See the License for the specific language governing permissions and
19 * limitations under the License.
20 */
21
22 package com.sun.org.apache.bcel.internal.classfile;
23
24 import java.io.DataInput;
25 import java.io.DataOutputStream;
26 import java.io.IOException;
27
28 import com.sun.org.apache.bcel.internal.Const;
29
30 /**
31 * This class represents the constant pool, i.e., a table of constants, of
32 * a parsed classfile. It may contain null references, due to the JVM
33 * specification that skips an entry after an 8-byte constant (double,
34 * long) entry. Those interested in generating constant pools
35 * programatically should see <a href="../generic/ConstantPoolGen.html">
36 * ConstantPoolGen</a>.
37
38 * @version $Id: ConstantPool.java 1749603 2016-06-21 20:50:19Z ggregory $
39 * @see Constant
40 * @see com.sun.org.apache.bcel.internal.generic.ConstantPoolGen
41 */
42 public class ConstantPool implements Cloneable, Node {
43
44 private Constant[] constant_pool;
45
46
47 /**
48 * @param constant_pool Array of constants
49 */
50 public ConstantPool(final Constant[] constant_pool) {
51 this.constant_pool = constant_pool;
52 }
53
54
55 /**
56 * Read constants from given input stream.
57 *
58 * @param input Input stream
59 * @throws IOException
60 * @throws ClassFormatException
61 */
62 public ConstantPool(final DataInput input) throws IOException, ClassFormatException {
63 byte tag;
64 final int constant_pool_count = input.readUnsignedShort();
65 constant_pool = new Constant[constant_pool_count];
66 /* constant_pool[0] is unused by the compiler and may be used freely
67 * by the implementation.
68 */
69 for (int i = 1; i < constant_pool_count; i++) {
70 constant_pool[i] = Constant.readConstant(input);
71 /* Quote from the JVM specification:
72 * "All eight byte constants take up two spots in the constant pool.
73 * If this is the n'th byte in the constant pool, then the next item
74 * will be numbered n+2"
75 *
76 * Thus we have to increment the index counter.
77 */
78 tag = constant_pool[i].getTag();
79 if ((tag == Const.CONSTANT_Double) || (tag == Const.CONSTANT_Long)) {
80 i++;
81 }
82 }
83 }
84
85
86 /**
87 * Called by objects that are traversing the nodes of the tree implicitely
88 * defined by the contents of a Java class. I.e., the hierarchy of methods,
89 * fields, attributes, etc. spawns a tree of objects.
90 *
91 * @param v Visitor object
92 */
93 @Override
94 public void accept( final Visitor v ) {
95 v.visitConstantPool(this);
96 }
97
98
99 /**
100 * Resolve constant to a string representation.
101 *
102 * @param c Constant to be printed
103 * @return String representation
104 */
105 public String constantToString( Constant c ) throws ClassFormatException {
106 String str;
107 int i;
108 final byte tag = c.getTag();
109 switch (tag) {
110 case Const.CONSTANT_Class:
111 i = ((ConstantClass) c).getNameIndex();
112 c = getConstant(i, Const.CONSTANT_Utf8);
113 str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
114 break;
115 case Const.CONSTANT_String:
116 i = ((ConstantString) c).getStringIndex();
117 c = getConstant(i, Const.CONSTANT_Utf8);
118 str = "\"" + escape(((ConstantUtf8) c).getBytes()) + "\"";
119 break;
120 case Const.CONSTANT_Utf8:
121 str = ((ConstantUtf8) c).getBytes();
122 break;
123 case Const.CONSTANT_Double:
124 str = String.valueOf(((ConstantDouble) c).getBytes());
125 break;
126 case Const.CONSTANT_Float:
127 str = String.valueOf(((ConstantFloat) c).getBytes());
128 break;
129 case Const.CONSTANT_Long:
130 str = String.valueOf(((ConstantLong) c).getBytes());
131 break;
132 case Const.CONSTANT_Integer:
133 str = String.valueOf(((ConstantInteger) c).getBytes());
134 break;
135 case Const.CONSTANT_NameAndType:
136 str = constantToString(((ConstantNameAndType) c).getNameIndex(),
137 Const.CONSTANT_Utf8)
138 + ":" + constantToString(((ConstantNameAndType) c).getSignatureIndex(),
139 Const.CONSTANT_Utf8);
140 break;
141 case Const.CONSTANT_InterfaceMethodref:
142 case Const.CONSTANT_Methodref:
143 case Const.CONSTANT_Fieldref:
144 str = constantToString(((ConstantCP) c).getClassIndex(), Const.CONSTANT_Class)
145 + "." + constantToString(((ConstantCP) c).getNameAndTypeIndex(),
146 Const.CONSTANT_NameAndType);
147 break;
148 case Const.CONSTANT_MethodHandle:
149 // Note that the ReferenceIndex may point to a Fieldref, Methodref or
150 // InterfaceMethodref - so we need to peek ahead to get the actual type.
151 final ConstantMethodHandle cmh = (ConstantMethodHandle) c;
152 str = Const.getMethodHandleName(cmh.getReferenceKind())
153 + " " + constantToString(cmh.getReferenceIndex(),
154 getConstant(cmh.getReferenceIndex()).getTag());
155 break;
156 case Const.CONSTANT_MethodType:
157 final ConstantMethodType cmt = (ConstantMethodType) c;
158 str = constantToString(cmt.getDescriptorIndex(), Const.CONSTANT_Utf8);
159 break;
160 case Const.CONSTANT_InvokeDynamic:
161 final ConstantInvokeDynamic cid = (ConstantInvokeDynamic) c;
162 str = cid.getBootstrapMethodAttrIndex()
163 + ":" + constantToString(cid.getNameAndTypeIndex(),
164 Const.CONSTANT_NameAndType);
165 break;
166 default: // Never reached
167 throw new RuntimeException("Unknown constant type " + tag);
168 }
169 return str;
170 }
171
172
173 private static String escape( final String str ) {
174 final int len = str.length();
175 final StringBuilder buf = new StringBuilder(len + 5);
176 final char[] ch = str.toCharArray();
177 for (int i = 0; i < len; i++) {
178 switch (ch[i]) {
179 case '\n':
180 buf.append("\\n");
181 break;
182 case '\r':
183 buf.append("\\r");
184 break;
185 case '\t':
186 buf.append("\\t");
187 break;
188 case '\b':
189 buf.append("\\b");
190 break;
191 case '"':
192 buf.append("\\\"");
193 break;
194 default:
195 buf.append(ch[i]);
196 }
197 }
198 return buf.toString();
199 }
200
201
202 /**
203 * Retrieve constant at `index' from constant pool and resolve it to
204 * a string representation.
205 *
206 * @param index of constant in constant pool
207 * @param tag expected type
208 * @return String representation
209 */
210 public String constantToString( final int index, final byte tag ) throws ClassFormatException {
211 final Constant c = getConstant(index, tag);
212 return constantToString(c);
213 }
214
215
216 /**
217 * Dump constant pool to file stream in binary format.
218 *
219 * @param file Output file stream
220 * @throws IOException
221 */
222 public void dump( final DataOutputStream file ) throws IOException {
223 file.writeShort(constant_pool.length);
224 for (int i = 1; i < constant_pool.length; i++) {
225 if (constant_pool[i] != null) {
226 constant_pool[i].dump(file);
227 }
228 }
229 }
230
231
232 /**
233 * Get constant from constant pool.
234 *
235 * @param index Index in constant pool
236 * @return Constant value
237 * @see Constant
238 */
239 public Constant getConstant( final int index ) {
240 if (index >= constant_pool.length || index < 0) {
241 throw new ClassFormatException("Invalid constant pool reference: " + index
242 + ". Constant pool size is: " + constant_pool.length);
243 }
244 return constant_pool[index];
245 }
246
247
248 /**
249 * Get constant from constant pool and check whether it has the
250 * expected type.
251 *
252 * @param index Index in constant pool
253 * @param tag Tag of expected constant, i.e., its type
254 * @return Constant value
255 * @see Constant
256 * @throws ClassFormatException
257 */
258 public Constant getConstant( final int index, final byte tag ) throws ClassFormatException {
259 Constant c;
260 c = getConstant(index);
261 if (c == null) {
262 throw new ClassFormatException("Constant pool at index " + index + " is null.");
263 }
264 if (c.getTag() != tag) {
265 throw new ClassFormatException("Expected class `" + Const.getConstantName(tag)
266 + "' at index " + index + " and got " + c);
267 }
268 return c;
269 }
270
271
272 /**
273 * @return Array of constants.
274 * @see Constant
275 */
276 public Constant[] getConstantPool() {
277 return constant_pool;
278 }
279
280
281 /**
282 * Get string from constant pool and bypass the indirection of
283 * `ConstantClass' and `ConstantString' objects. I.e. these classes have
284 * an index field that points to another entry of the constant pool of
285 * type `ConstantUtf8' which contains the real data.
286 *
287 * @param index Index in constant pool
288 * @param tag Tag of expected constant, either ConstantClass or ConstantString
289 * @return Contents of string reference
290 * @see ConstantClass
291 * @see ConstantString
292 * @throws ClassFormatException
293 */
294 public String getConstantString( final int index, final byte tag ) throws ClassFormatException {
295 Constant c;
296 int i;
297 c = getConstant(index, tag);
298 /* This switch() is not that elegant, since the two classes have the
299 * same contents, they just differ in the name of the index
300 * field variable.
301 * But we want to stick to the JVM naming conventions closely though
302 * we could have solved these more elegantly by using the same
303 * variable name or by subclassing.
304 */
305 switch (tag) {
306 case Const.CONSTANT_Class:
307 i = ((ConstantClass) c).getNameIndex();
308 break;
309 case Const.CONSTANT_String:
310 i = ((ConstantString) c).getStringIndex();
311 break;
312 default:
313 throw new RuntimeException("getConstantString called with illegal tag " + tag);
314 }
315 // Finally get the string from the constant pool
316 c = getConstant(i, Const.CONSTANT_Utf8);
317 return ((ConstantUtf8) c).getBytes();
318 }
319
320
321 /**
322 * @return Length of constant pool.
323 */
324 public int getLength() {
325 return constant_pool == null ? 0 : constant_pool.length;
326 }
327
328
329 /**
330 * @param constant Constant to set
331 */
332 public void setConstant( final int index, final Constant constant ) {
333 constant_pool[index] = constant;
334 }
335
336
337 /**
338 * @param constant_pool
339 */
340 public void setConstantPool( final Constant[] constant_pool ) {
341 this.constant_pool = constant_pool;
342 }
343
344
345 /**
346 * @return String representation.
347 */
348 @Override
349 public String toString() {
350 final StringBuilder buf = new StringBuilder();
351 for (int i = 1; i < constant_pool.length; i++) {
352 buf.append(i).append(")").append(constant_pool[i]).append("\n");
353 }
354 return buf.toString();
355 }
356
357
358 /**
359 * @return deep copy of this constant pool
360 */
361 public ConstantPool copy() {
362 ConstantPool c = null;
363 try {
364 c = (ConstantPool) clone();
365 c.constant_pool = new Constant[constant_pool.length];
366 for (int i = 1; i < constant_pool.length; i++) {
367 if (constant_pool[i] != null) {
368 c.constant_pool[i] = constant_pool[i].copy();
369 }
370 }
371 } catch (final CloneNotSupportedException e) {
372 // TODO should this throw?
373 }
374 return c;
375 }
376 }