1 package org.apache.bcel.generic;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache BCEL" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache BCEL", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56 import java.io.*;
57 import org.apache.bcel.util.ByteSequence;
58
59 /***
60 * Select - Abstract super class for LOOKUPSWITCH and TABLESWITCH instructions.
61 *
62 * @version $Id: Select.java,v 1.2 2002/04/26 09:30:11 mdahm Exp $
63 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
64 * @see LOOKUPSWITCH
65 * @see TABLESWITCH
66 * @see InstructionList
67 */
68 public abstract class Select extends BranchInstruction
69 implements VariableLengthInstruction, StackProducer
70 {
71 protected int[] match; // matches, i.e., case 1: ...
72 protected int[] indices; // target offsets
73 protected InstructionHandle[] targets; // target objects in instruction list
74 protected int fixed_length; // fixed length defined by subclasses
75 protected int match_length; // number of cases
76 protected int padding = 0; // number of pad bytes for alignment
77
78 /***
79 * Empty constructor needed for the Class.newInstance() statement in
80 * Instruction.readInstruction(). Not to be used otherwise.
81 */
82 Select() {}
83
84 /***
85 * (Match, target) pairs for switch.
86 * `Match' and `targets' must have the same length of course.
87 *
88 * @param match array of matching values
89 * @param targets instruction targets
90 * @param target default instruction target
91 */
92 Select(short opcode, int[] match, InstructionHandle[] targets,
93 InstructionHandle target) {
94 super(opcode, target);
95
96 this.targets = targets;
97 for(int i=0; i < targets.length; i++)
98 notifyTarget(null, targets[i], this);
99
100 this.match = match;
101
102 if((match_length = match.length) != targets.length)
103 throw new ClassGenException("Match and target array have not the same length");
104
105 indices = new int[match_length];
106 }
107
108 /***
109 * Since this is a variable length instruction, it may shift the following
110 * instructions which then need to update their position.
111 *
112 * Called by InstructionList.setPositions when setting the position for every
113 * instruction. In the presence of variable length instructions `setPositions'
114 * performs multiple passes over the instruction list to calculate the
115 * correct (byte) positions and offsets by calling this function.
116 *
117 * @param offset additional offset caused by preceding (variable length) instructions
118 * @param max_offset the maximum offset that may be caused by these instructions
119 * @return additional offset caused by possible change of this instruction's length
120 */
121 protected int updatePosition(int offset, int max_offset) {
122 position += offset; // Additional offset caused by preceding SWITCHs, GOTOs, etc.
123
124 short old_length = length;
125
126 /* Alignment on 4-byte-boundary, + 1, because of tag byte.
127 */
128 padding = (4 - ((position + 1) % 4)) % 4;
129 length = (short)(fixed_length + padding); // Update length
130
131 return length - old_length;
132 }
133
134 /***
135 * Dump instruction as byte code to stream out.
136 * @param out Output stream
137 */
138 public void dump(DataOutputStream out) throws IOException {
139 out.writeByte(opcode);
140
141 for(int i=0; i < padding; i++) // Padding bytes
142 out.writeByte(0);
143
144 index = getTargetOffset(); // Write default target offset
145 out.writeInt(index);
146 }
147
148 /***
149 * Read needed data (e.g. index) from file.
150 */
151 protected void initFromFile(ByteSequence bytes, boolean wide) throws IOException
152 {
153 padding = (4 - (bytes.getIndex() % 4)) % 4; // Compute number of pad bytes
154
155 for(int i=0; i < padding; i++) {
156 bytes.readByte();
157 }
158
159 // Default branch target common for both cases (TABLESWITCH, LOOKUPSWITCH)
160 index = bytes.readInt();
161 }
162
163 /***
164 * @return mnemonic for instruction
165 */
166 public String toString(boolean verbose) {
167 StringBuffer buf = new StringBuffer(super.toString(verbose));
168
169 if(verbose) {
170 for(int i=0; i < match_length; i++) {
171 String s = "null";
172
173 if(targets[i] != null)
174 s = targets[i].getInstruction().toString();
175
176 buf.append("(" + match[i] + ", " + s + " = {" + indices[i] + "})");
177 }
178 }
179 else
180 buf.append(" ...");
181
182 return buf.toString();
183 }
184
185 /***
186 * Set branch target for `i'th case
187 */
188 public void setTarget(int i, InstructionHandle target) {
189 notifyTarget(targets[i], target, this);
190 targets[i] = target;
191 }
192
193 /***
194 * @param old_ih old target
195 * @param new_ih new target
196 */
197 public void updateTarget(InstructionHandle old_ih, InstructionHandle new_ih) {
198 boolean targeted = false;
199
200 if(target == old_ih) {
201 targeted = true;
202 setTarget(new_ih);
203 }
204
205 for(int i=0; i < targets.length; i++) {
206 if(targets[i] == old_ih) {
207 targeted = true;
208 setTarget(i, new_ih);
209 }
210 }
211
212 if(!targeted)
213 throw new ClassGenException("Not targeting " + old_ih);
214 }
215
216 /***
217 * @return true, if ih is target of this instruction
218 */
219 public boolean containsTarget(InstructionHandle ih) {
220 if(target == ih)
221 return true;
222
223 for(int i=0; i < targets.length; i++)
224 if(targets[i] == ih)
225 return true;
226
227 return false;
228 }
229
230 /***
231 * Inform targets that they're not targeted anymore.
232 */
233 void dispose() {
234 super.dispose();
235
236 for(int i=0; i < targets.length; i++)
237 targets[i].removeTargeter(this);
238 }
239
240 /***
241 * @return array of match indices
242 */
243 public int[] getMatchs() { return match; }
244
245 /***
246 * @return array of match target offsets
247 */
248 public int[] getIndices() { return indices; }
249
250 /***
251 * @return array of match targets
252 */
253 public InstructionHandle[] getTargets() { return targets; }
254 }
This page was automatically generated by Maven