001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 */
017package org.apache.bcel.generic;
018
019import java.io.DataOutputStream;
020import java.io.IOException;
021
022import org.apache.bcel.util.ByteSequence;
023
024/**
025 * Select - Abstract super class for LOOKUPSWITCH and TABLESWITCH instructions.
026 *
027 * <p>
028 * We use our super's {@code target} property as the default target.
029 *
030 * @see LOOKUPSWITCH
031 * @see TABLESWITCH
032 * @see InstructionList
033 */
034public abstract class Select extends BranchInstruction implements VariableLengthInstruction, StackConsumer /* @since 6.0 */, StackProducer {
035
036    /**
037     * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
038     */
039    @Deprecated
040    protected int[] match; // matches, i.e., case 1: ... TODO could be package-protected?
041
042    /**
043     * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
044     */
045    @Deprecated
046    protected int[] indices; // target offsets TODO could be package-protected?
047
048    /**
049     * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
050     */
051    @Deprecated
052    protected InstructionHandle[] targets; // target objects in instruction list TODO could be package-protected?
053
054    /**
055     * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
056     */
057    @Deprecated
058    protected int fixed_length; // fixed length defined by subclasses TODO could be package-protected?
059
060    /**
061     * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
062     */
063    @Deprecated
064    protected int match_length; // number of cases TODO could be package-protected?
065
066    /**
067     * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
068     */
069    @Deprecated
070    protected int padding; // number of pad bytes for alignment TODO could be package-protected?
071
072    /**
073     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
074     */
075    Select() {
076    }
077
078    /**
079     * (Match, target) pairs for switch. 'Match' and 'targets' must have the same length of course.
080     *
081     * @param match array of matching values
082     * @param targets instruction targets
083     * @param defaultTarget default instruction target
084     */
085    Select(final short opcode, final int[] match, final InstructionHandle[] targets, final InstructionHandle defaultTarget) {
086        // don't set default target before instuction is built
087        super(opcode, null);
088        this.match = match;
089        this.targets = targets;
090        // now it's safe to set default target
091        setTarget(defaultTarget);
092        for (final InstructionHandle target2 : targets) {
093            notifyTarget(null, target2, this);
094        }
095        if ((match_length = match.length) != targets.length) {
096            throw new ClassGenException("Match and target array have not the same length: Match length: " + match.length + " Target length: " + targets.length);
097        }
098        indices = new int[match_length];
099    }
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}