| /* |
| * reserved comment block |
| * DO NOT REMOVE OR ALTER! |
| */ |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.sun.org.apache.bcel.internal.generic; |
| |
| import java.io.*; |
| import com.sun.org.apache.bcel.internal.util.ByteSequence; |
| |
| /** |
| * Select - Abstract super class for LOOKUPSWITCH and TABLESWITCH instructions. |
| * |
| * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A> |
| * @see LOOKUPSWITCH |
| * @see TABLESWITCH |
| * @see InstructionList |
| */ |
| public abstract class Select extends BranchInstruction |
| implements VariableLengthInstruction, StackProducer |
| { |
| protected int[] match; // matches, i.e., case 1: ... |
| protected int[] indices; // target offsets |
| protected InstructionHandle[] targets; // target objects in instruction list |
| protected int fixed_length; // fixed length defined by subclasses |
| protected int match_length; // number of cases |
| protected int padding = 0; // number of pad bytes for alignment |
| |
| /** |
| * Empty constructor needed for the Class.newInstance() statement in |
| * Instruction.readInstruction(). Not to be used otherwise. |
| */ |
| Select() {} |
| |
| /** |
| * (Match, target) pairs for switch. |
| * `Match' and `targets' must have the same length of course. |
| * |
| * @param match array of matching values |
| * @param targets instruction targets |
| * @param target default instruction target |
| */ |
| Select(short opcode, int[] match, InstructionHandle[] targets, |
| InstructionHandle target) { |
| super(opcode, target); |
| |
| this.targets = targets; |
| for(int i=0; i < targets.length; i++) { |
| BranchInstruction.notifyTargetChanged(targets[i], this); |
| } |
| |
| this.match = match; |
| |
| if((match_length = match.length) != targets.length) |
| throw new ClassGenException("Match and target array have not the same length"); |
| |
| indices = new int[match_length]; |
| } |
| |
| /** |
| * Since this is a variable length instruction, it may shift the following |
| * instructions which then need to update their position. |
| * |
| * Called by InstructionList.setPositions when setting the position for every |
| * instruction. In the presence of variable length instructions `setPositions' |
| * performs multiple passes over the instruction list to calculate the |
| * correct (byte) positions and offsets by calling this function. |
| * |
| * @param offset additional offset caused by preceding (variable length) instructions |
| * @param max_offset the maximum offset that may be caused by these instructions |
| * @return additional offset caused by possible change of this instruction's length |
| */ |
| @Override |
| protected int updatePosition(int offset, int max_offset) { |
| position += offset; // Additional offset caused by preceding SWITCHs, GOTOs, etc. |
| |
| short old_length = length; |
| |
| /* Alignment on 4-byte-boundary, + 1, because of tag byte. |
| */ |
| padding = (4 - ((position + 1) % 4)) % 4; |
| length = (short)(fixed_length + padding); // Update length |
| |
| return length - old_length; |
| } |
| |
| /** |
| * Dump instruction as byte code to stream out. |
| * @param out Output stream |
| */ |
| @Override |
| public void dump(DataOutputStream out) throws IOException { |
| out.writeByte(opcode); |
| |
| for(int i=0; i < padding; i++) // Padding bytes |
| out.writeByte(0); |
| |
| index = getTargetOffset(); // Write default target offset |
| out.writeInt(index); |
| } |
| |
| /** |
| * Read needed data (e.g. index) from file. |
| */ |
| @Override |
| protected void initFromFile(ByteSequence bytes, boolean wide) throws IOException |
| { |
| padding = (4 - (bytes.getIndex() % 4)) % 4; // Compute number of pad bytes |
| |
| for(int i=0; i < padding; i++) { |
| bytes.readByte(); |
| } |
| |
| // Default branch target common for both cases (TABLESWITCH, LOOKUPSWITCH) |
| index = bytes.readInt(); |
| } |
| |
| /** |
| * @return mnemonic for instruction |
| */ |
| @Override |
| public String toString(boolean verbose) { |
| final StringBuilder buf = new StringBuilder(super.toString(verbose)); |
| |
| if(verbose) { |
| for(int i=0; i < match_length; i++) { |
| String s = "null"; |
| |
| if(targets[i] != null) |
| s = targets[i].getInstruction().toString(); |
| |
| buf.append("(").append(match[i]).append(", ") |
| .append(s).append(" = {").append(indices[i]).append("})"); |
| } |
| } |
| else |
| buf.append(" ..."); |
| |
| return buf.toString(); |
| } |
| |
| /** |
| * Set branch target for `i'th case |
| */ |
| public final void setTarget(int i, InstructionHandle target) { |
| notifyTargetChanging(targets[i], this); |
| targets[i] = target; |
| notifyTargetChanged(targets[i], this); |
| } |
| |
| /** |
| * @param old_ih old target |
| * @param new_ih new target |
| */ |
| @Override |
| public void updateTarget(InstructionHandle old_ih, InstructionHandle new_ih) { |
| boolean targeted = false; |
| |
| if(target == old_ih) { |
| targeted = true; |
| setTarget(new_ih); |
| } |
| |
| for(int i=0; i < targets.length; i++) { |
| if(targets[i] == old_ih) { |
| targeted = true; |
| setTarget(i, new_ih); |
| } |
| } |
| |
| if(!targeted) |
| throw new ClassGenException("Not targeting " + old_ih); |
| } |
| |
| /** |
| * @return true, if ih is target of this instruction |
| */ |
| @Override |
| public boolean containsTarget(InstructionHandle ih) { |
| if(target == ih) |
| return true; |
| |
| for(int i=0; i < targets.length; i++) |
| if(targets[i] == ih) |
| return true; |
| |
| return false; |
| } |
| |
| /** |
| * Inform targets that they're not targeted anymore. |
| */ |
| @Override |
| void dispose() { |
| super.dispose(); |
| |
| for(int i=0; i < targets.length; i++) |
| targets[i].removeTargeter(this); |
| } |
| |
| /** |
| * @return array of match indices |
| */ |
| public int[] getMatchs() { return match; } |
| |
| /** |
| * @return array of match target offsets |
| */ |
| public int[] getIndices() { return indices; } |
| |
| /** |
| * @return array of match targets |
| */ |
| public InstructionHandle[] getTargets() { return targets; } |
| } |