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 * @see Constant
39 * @see com.sun.org.apache.bcel.internal.generic.ConstantPoolGen
40 */
41 public class ConstantPool implements Cloneable, Node {
42
43 private Constant[] constant_pool;
44
45 /**
46 * @param constant_pool Array of constants
47 */
48 public ConstantPool(final Constant[] constant_pool) {
49 this.constant_pool = constant_pool;
50 }
51
52 /**
53 * Reads constants from given input stream.
54 *
55 * @param input Input stream
56 * @throws IOException
57 * @throws ClassFormatException
58 */
59 public ConstantPool(final DataInput input) throws IOException, ClassFormatException {
60 byte tag;
61 final int constant_pool_count = input.readUnsignedShort();
62 constant_pool = new Constant[constant_pool_count];
63 /* constant_pool[0] is unused by the compiler and may be used freely
64 * by the implementation.
65 */
66 for (int i = 1; i < constant_pool_count; i++) {
67 constant_pool[i] = Constant.readConstant(input);
68 /* Quote from the JVM specification:
69 * "All eight byte constants take up two spots in the constant pool.
70 * If this is the n'th byte in the constant pool, then the next item
71 * will be numbered n+2"
72 *
73 * Thus we have to increment the index counter.
74 */
75 tag = constant_pool[i].getTag();
76 if ((tag == Const.CONSTANT_Double) || (tag == Const.CONSTANT_Long)) {
77 i++;
78 }
79 }
80 }
81
82 /**
83 * Called by objects that are traversing the nodes of the tree implicitely
84 * defined by the contents of a Java class. I.e., the hierarchy of methods,
85 * fields, attributes, etc. spawns a tree of objects.
86 *
87 * @param v Visitor object
88 */
89 @Override
90 public void accept( final Visitor v ) {
91 v.visitConstantPool(this);
92 }
93
94 /**
95 * Resolves constant to a string representation.
96 *
97 * @param c Constant to be printed
98 * @return String representation
99 */
100 public String constantToString( Constant c ) throws ClassFormatException {
101 String str;
102 int i;
103 final byte tag = c.getTag();
104 switch (tag) {
105 case Const.CONSTANT_Class:
106 i = ((ConstantClass) c).getNameIndex();
107 c = getConstant(i, Const.CONSTANT_Utf8);
108 str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
109 break;
110 case Const.CONSTANT_String:
111 i = ((ConstantString) c).getStringIndex();
112 c = getConstant(i, Const.CONSTANT_Utf8);
113 str = "\"" + escape(((ConstantUtf8) c).getBytes()) + "\"";
114 break;
115 case Const.CONSTANT_Utf8:
116 str = ((ConstantUtf8) c).getBytes();
117 break;
118 case Const.CONSTANT_Double:
119 str = String.valueOf(((ConstantDouble) c).getBytes());
120 break;
121 case Const.CONSTANT_Float:
122 str = String.valueOf(((ConstantFloat) c).getBytes());
123 break;
124 case Const.CONSTANT_Long:
125 str = String.valueOf(((ConstantLong) c).getBytes());
126 break;
127 case Const.CONSTANT_Integer:
128 str = String.valueOf(((ConstantInteger) c).getBytes());
129 break;
130 case Const.CONSTANT_NameAndType:
131 str = constantToString(((ConstantNameAndType) c).getNameIndex(),
132 Const.CONSTANT_Utf8)
133 + " " + constantToString(((ConstantNameAndType) c).getSignatureIndex(),
134 Const.CONSTANT_Utf8);
135 break;
136 case Const.CONSTANT_InterfaceMethodref:
137 case Const.CONSTANT_Methodref:
138 case Const.CONSTANT_Fieldref:
139 str = constantToString(((ConstantCP) c).getClassIndex(), Const.CONSTANT_Class)
140 + "." + constantToString(((ConstantCP) c).getNameAndTypeIndex(),
141 Const.CONSTANT_NameAndType);
142 break;
143 case Const.CONSTANT_MethodHandle:
144 // Note that the ReferenceIndex may point to a Fieldref, Methodref or
145 // InterfaceMethodref - so we need to peek ahead to get the actual type.
146 final ConstantMethodHandle cmh = (ConstantMethodHandle) c;
147 str = Const.getMethodHandleName(cmh.getReferenceKind())
148 + " " + constantToString(cmh.getReferenceIndex(),
149 getConstant(cmh.getReferenceIndex()).getTag());
150 break;
151 case Const.CONSTANT_MethodType:
152 final ConstantMethodType cmt = (ConstantMethodType) c;
153 str = constantToString(cmt.getDescriptorIndex(), Const.CONSTANT_Utf8);
154 break;
155 case Const.CONSTANT_InvokeDynamic:
156 final ConstantInvokeDynamic cid = (ConstantInvokeDynamic) c;
157 str = cid.getBootstrapMethodAttrIndex()
158 + ":" + constantToString(cid.getNameAndTypeIndex(),
159 Const.CONSTANT_NameAndType);
160 break;
161 case Const.CONSTANT_Module:
162 i = ((ConstantModule) c).getNameIndex();
163 c = getConstant(i, Const.CONSTANT_Utf8);
164 str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
165 break;
166 case Const.CONSTANT_Package:
167 i = ((ConstantPackage) c).getNameIndex();
168 c = getConstant(i, Const.CONSTANT_Utf8);
169 str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
170 break;
171 default: // Never reached
172 throw new RuntimeException("Unknown constant type " + tag);
173 }
174 return str;
175 }
176
177 private static String escape( final String str ) {
178 final int len = str.length();
179 final StringBuilder buf = new StringBuilder(len + 5);
180 final char[] ch = str.toCharArray();
181 for (int i = 0; i < len; i++) {
182 switch (ch[i]) {
183 case '\n':
184 buf.append("\\n");
185 break;
186 case '\r':
187 buf.append("\\r");
188 break;
189 case '\t':
190 buf.append("\\t");
191 break;
192 case '\b':
193 buf.append("\\b");
194 break;
195 case '"':
196 buf.append("\\\"");
197 break;
198 default:
199 buf.append(ch[i]);
200 }
201 }
202 return buf.toString();
203 }
204
205 /**
206 * Retrieves constant at `index' from constant pool and resolve it to
207 * a string representation.
208 *
209 * @param index of constant in constant pool
210 * @param tag expected type
211 * @return String representation
212 */
213 public String constantToString( final int index, final byte tag ) throws ClassFormatException {
214 final Constant c = getConstant(index, tag);
215 return constantToString(c);
216 }
217
218 /**
219 * Dump constant pool to file stream in binary format.
220 *
221 * @param file Output file stream
222 * @throws IOException
223 */
224 public void dump( final DataOutputStream file ) throws IOException {
225 file.writeShort(constant_pool.length);
226 for (int i = 1; i < constant_pool.length; i++) {
227 if (constant_pool[i] != null) {
228 constant_pool[i].dump(file);
229 }
230 }
231 }
232
233 /**
234 * Gets constant from constant pool.
235 *
236 * @param index Index in constant pool
237 * @return Constant value
238 * @see Constant
239 */
240 public Constant getConstant( final int index ) {
241 if (index >= constant_pool.length || index < 0) {
242 throw new ClassFormatException("Invalid constant pool reference: " + index
243 + ". Constant pool size is: " + constant_pool.length);
244 }
245 return constant_pool[index];
246 }
247
248 /**
249 * Gets 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 * @return Array of constants.
273 * @see Constant
274 */
275 public Constant[] getConstantPool() {
276 return constant_pool;
277 }
278
279 /**
280 * Gets string from constant pool and bypass the indirection of
281 * `ConstantClass' and `ConstantString' objects. I.e. these classes have
282 * an index field that points to another entry of the constant pool of
283 * type `ConstantUtf8' which contains the real data.
284 *
285 * @param index Index in constant pool
286 * @param tag Tag of expected constant, either ConstantClass or ConstantString
287 * @return Contents of string reference
288 * @see ConstantClass
289 * @see ConstantString
290 * @throws ClassFormatException
291 */
292 public String getConstantString( final int index, final byte tag ) throws ClassFormatException {
293 Constant c;
294 int i;
295 c = getConstant(index, tag);
296 /* This switch() is not that elegant, since the four classes have the
297 * same contents, they just differ in the name of the index
298 * field variable.
299 * But we want to stick to the JVM naming conventions closely though
300 * we could have solved these more elegantly by using the same
301 * variable name or by subclassing.
302 */
303 switch (tag) {
304 case Const.CONSTANT_Class:
305 i = ((ConstantClass) c).getNameIndex();
306 break;
307 case Const.CONSTANT_String:
308 i = ((ConstantString) c).getStringIndex();
309 break;
310 case Const.CONSTANT_Module:
311 i = ((ConstantModule) c).getNameIndex();
312 break;
313 case Const.CONSTANT_Package:
314 i = ((ConstantPackage) c).getNameIndex();
315 break;
316 default:
317 throw new RuntimeException("getConstantString called with illegal tag " + tag);
318 }
319 // Finally get the string from the constant pool
320 c = getConstant(i, Const.CONSTANT_Utf8);
321 return ((ConstantUtf8) c).getBytes();
322 }
323
324
325 /**
326 * @return Length of constant pool.
327 */
328 public int getLength() {
329 return constant_pool == null ? 0 : constant_pool.length;
330 }
331
332
333 /**
334 * @param constant Constant to set
335 */
336 public void setConstant( final int index, final Constant constant ) {
337 constant_pool[index] = constant;
338 }
339
340
341 /**
342 * @param constant_pool
343 */
344 public void setConstantPool( final Constant[] constant_pool ) {
345 this.constant_pool = constant_pool;
346 }
347
348
349 /**
350 * @return String representation.
351 */
352 @Override
353 public String toString() {
354 final StringBuilder buf = new StringBuilder();
355 for (int i = 1; i < constant_pool.length; i++) {
356 buf.append(i).append(")").append(constant_pool[i]).append("\n");
357 }
358 return buf.toString();
359 }
360
361
362 /**
363 * @return deep copy of this constant pool
364 */
365 public ConstantPool copy() {
366 ConstantPool c = null;
367 try {
368 c = (ConstantPool) clone();
369 c.constant_pool = new Constant[constant_pool.length];
370 for (int i = 1; i < constant_pool.length; i++) {
371 if (constant_pool[i] != null) {
372 c.constant_pool[i] = constant_pool[i].copy();
373 }
374 }
375 } catch (final CloneNotSupportedException e) {
376 // TODO should this throw?
377 }
378 return c;
379 }
380 }