1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.bcel.generic;
18
19 import java.io.DataOutputStream;
20 import java.io.IOException;
21
22 import org.apache.bcel.util.ByteSequence;
23
24 /**
25 * Select - Abstract super class for LOOKUPSWITCH and TABLESWITCH instructions.
26 *
27 * <p>
28 * We use our super's {@code target} property as the default target.
29 *
30 * @see LOOKUPSWITCH
31 * @see TABLESWITCH
32 * @see InstructionList
33 */
34 public abstract class Select extends BranchInstruction implements VariableLengthInstruction, StackConsumer /* @since 6.0 */, StackProducer {
35
36 /**
37 * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
38 */
39 @Deprecated
40 protected int[] match; // matches, i.e., case 1: ... TODO could be package-protected?
41
42 /**
43 * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
44 */
45 @Deprecated
46 protected int[] indices; // target offsets TODO could be package-protected?
47
48 /**
49 * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
50 */
51 @Deprecated
52 protected InstructionHandle[] targets; // target objects in instruction list TODO could be package-protected?
53
54 /**
55 * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
56 */
57 @Deprecated
58 protected int fixed_length; // fixed length defined by subclasses TODO could be package-protected?
59
60 /**
61 * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
62 */
63 @Deprecated
64 protected int match_length; // number of cases TODO could be package-protected?
65
66 /**
67 * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
68 */
69 @Deprecated
70 protected int padding; // number of pad bytes for alignment TODO could be package-protected?
71
72 /**
73 * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
74 */
75 Select() {
76 }
77
78 /**
79 * (Match, target) pairs for switch. 'Match' and 'targets' must have the same length of course.
80 *
81 * @param match array of matching values
82 * @param targets instruction targets
83 * @param defaultTarget default instruction target
84 */
85 Select(final short opcode, final int[] match, final InstructionHandle[] targets, final InstructionHandle defaultTarget) {
86 // don't set default target before instruction is built
87 super(opcode, null);
88 this.match = match;
89 this.targets = targets;
90 // now it's safe to set default target
91 setTarget(defaultTarget);
92 for (final InstructionHandle target2 : targets) {
93 notifyTarget(null, target2, this);
94 }
95 if ((match_length = match.length) != targets.length) {
96 throw new ClassGenException("Match and target array have not the same length: Match length: " + match.length + " Target length: " + targets.length);
97 }
98 indices = new int[match_length];
99 }
100
101 @Override
102 protected Object clone() throws CloneNotSupportedException {
103 final Select copy = (Select) super.clone();
104 copy.match = match.clone();
105 copy.indices = indices.clone();
106 copy.targets = targets.clone();
107 return copy;
108 }
109
110 /**
111 * @return true, if ih is target of this instruction
112 */
113 @Override
114 public boolean containsTarget(final InstructionHandle ih) {
115 if (super.getTarget() == ih) {
116 return true;
117 }
118 for (final InstructionHandle target2 : targets) {
119 if (target2 == ih) {
120 return true;
121 }
122 }
123 return false;
124 }
125
126 /**
127 * Inform targets that they're not targeted anymore.
128 */
129 @Override
130 void dispose() {
131 super.dispose();
132 for (final InstructionHandle target2 : targets) {
133 target2.removeTargeter(this);
134 }
135 }
136
137 /**
138 * Dump instruction as byte code to stream out.
139 *
140 * @param out Output stream
141 */
142 @Override
143 public void dump(final DataOutputStream out) throws IOException {
144 out.writeByte(super.getOpcode());
145 for (int i = 0; i < padding; i++) {
146 out.writeByte(0);
147 }
148 super.setIndex(getTargetOffset()); // Write default target offset
149 out.writeInt(super.getIndex());
150 }
151
152 /**
153 * @return the fixed_length
154 * @since 6.0
155 */
156 final int getFixedLength() {
157 return fixed_length;
158 }
159
160 /**
161 * @return array of match target offsets
162 */
163 public int[] getIndices() {
164 return indices;
165 }
166
167 /**
168 * @return index entry from indices
169 * @since 6.0
170 */
171 final int getIndices(final int index) {
172 return indices[index];
173 }
174
175 /**
176 * @return match entry
177 * @since 6.0
178 */
179 final int getMatch(final int index) {
180 return match[index];
181 }
182
183 /**
184 * @return the match_length
185 * @since 6.0
186 */
187 final int getMatchLength() {
188 return match_length;
189 }
190
191 /**
192 * @return array of match indices
193 */
194 public int[] getMatchs() {
195 return match;
196 }
197
198 /**
199 *
200 * @return the padding
201 * @since 6.0
202 */
203 final int getPadding() {
204 return padding;
205 }
206
207 /**
208 * @return target entry
209 * @since 6.0
210 */
211 final InstructionHandle getTarget(final int index) {
212 return targets[index];
213 }
214
215 /**
216 * @return array of match targets
217 */
218 public InstructionHandle[] getTargets() {
219 return targets;
220 }
221
222 /**
223 * Read needed data (e.g. index) from file.
224 */
225 @Override
226 protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
227 padding = (4 - bytes.getIndex() % 4) % 4; // Compute number of pad bytes
228 for (int i = 0; i < padding; i++) {
229 bytes.readByte();
230 }
231 // Default branch target common for both cases (TABLESWITCH, LOOKUPSWITCH)
232 super.setIndex(bytes.readInt());
233 }
234
235 /**
236 * @param fixedLength the fixed_length to set
237 * @since 6.0
238 */
239 final void setFixedLength(final int fixedLength) {
240 this.fixed_length = fixedLength;
241 }
242
243 /** @since 6.0 */
244 final int setIndices(final int i, final int value) {
245 indices[i] = value;
246 return value; // Allow use in nested calls
247 }
248
249 /**
250 *
251 * @param array
252 * @since 6.0
253 */
254 final void setIndices(final int[] array) {
255 indices = array;
256 }
257
258 /**
259 *
260 * @param index
261 * @param value
262 * @since 6.0
263 */
264 final void setMatch(final int index, final int value) {
265 match[index] = value;
266 }
267
268 /**
269 *
270 * @param array
271 * @since 6.0
272 */
273 final void setMatches(final int[] array) {
274 match = array;
275 }
276
277 /**
278 * @param matchLength the match_length to set
279 * @since 6.0
280 */
281 final int setMatchLength(final int matchLength) {
282 this.match_length = matchLength;
283 return matchLength;
284 }
285
286 /**
287 * Sets branch target for 'i'th case
288 */
289 public void setTarget(final int i, final InstructionHandle target) { // TODO could be package-protected?
290 notifyTarget(targets[i], target, this);
291 targets[i] = target;
292 }
293
294 /**
295 *
296 * @param array
297 * @since 6.0
298 */
299 final void setTargets(final InstructionHandle[] array) {
300 targets = array;
301 }
302
303 /**
304 * @return mnemonic for instruction
305 */
306 @Override
307 public String toString(final boolean verbose) {
308 final StringBuilder buf = new StringBuilder(super.toString(verbose));
309 if (verbose) {
310 for (int i = 0; i < match_length; i++) {
311 String s = "null";
312 if (targets[i] != null) {
313 if (targets[i].getInstruction() == this) {
314 s = "<points to itself>";
315 } else {
316 s = targets[i].getInstruction().toString();
317 }
318 }
319 buf.append("(").append(match[i]).append(", ").append(s).append(" = {").append(indices[i]).append("})");
320 }
321 } else {
322 buf.append(" ...");
323 }
324 return buf.toString();
325 }
326
327 /**
328 * Since this is a variable length instruction, it may shift the following instructions which then need to update their
329 * position.
330 *
331 * Called by InstructionList.setPositions when setting the position for every instruction. In the presence of variable
332 * length instructions 'setPositions' performs multiple passes over the instruction list to calculate the correct (byte)
333 * positions and offsets by calling this function.
334 *
335 * @param offset additional offset caused by preceding (variable length) instructions
336 * @param maxOffset the maximum offset that may be caused by these instructions
337 * @return additional offset caused by possible change of this instruction's length
338 */
339 @Override
340 protected int updatePosition(final int offset, final int maxOffset) {
341 setPosition(getPosition() + offset); // Additional offset caused by preceding SWITCHs, GOTOs, etc.
342 final short oldLength = (short) super.getLength();
343 /*
344 * Alignment on 4-byte-boundary, + 1, because of tag byte.
345 */
346 padding = (4 - (getPosition() + 1) % 4) % 4;
347 super.setLength((short) (fixed_length + padding)); // Update length
348 return super.getLength() - oldLength;
349 }
350
351 /**
352 * @param oldIh old target
353 * @param newIh new target
354 */
355 @Override
356 public void updateTarget(final InstructionHandle oldIh, final InstructionHandle newIh) {
357 boolean targeted = false;
358 if (super.getTarget() == oldIh) {
359 targeted = true;
360 setTarget(newIh);
361 }
362 for (int i = 0; i < targets.length; i++) {
363 if (targets[i] == oldIh) {
364 targeted = true;
365 setTarget(i, newIh);
366 }
367 }
368 if (!targeted) {
369 throw new ClassGenException("Not targeting " + oldIh);
370 }
371 }
372 }