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 org.apache.bcel.classfile.CodeException;
020
021/**
022 * This class represents an exception handler, i.e., specifies the region where a handler is active and an instruction
023 * where the actual handling is done. pool as parameters. Opposed to the JVM specification the end of the handled region
024 * is set to be inclusive, i.e. all instructions between start and end are protected including the start and end
025 * instructions (handles) themselves. The end of the region is automatically mapped to be exclusive when calling
026 * getCodeException(), i.e., there is no difference semantically.
027 *
028 * @see MethodGen
029 * @see CodeException
030 * @see InstructionHandle
031 */
032public final class CodeExceptionGen implements InstructionTargeter, Cloneable {
033
034    static final CodeExceptionGen[] EMPTY_ARRAY = {};
035
036    private InstructionHandle startPc;
037    private InstructionHandle endPc;
038    private InstructionHandle handlerPc;
039    private ObjectType catchType;
040
041    /**
042     * Add an exception handler, i.e., specify region where a handler is active and an instruction where the actual handling
043     * is done.
044     *
045     * @param startPc Start of handled region (inclusive)
046     * @param endPc End of handled region (inclusive)
047     * @param handlerPc Where handling is done
048     * @param catchType which exception is handled, null for ANY
049     */
050    public CodeExceptionGen(final InstructionHandle startPc, final InstructionHandle endPc, final InstructionHandle handlerPc, final ObjectType catchType) {
051        setStartPC(startPc);
052        setEndPC(endPc);
053        setHandlerPC(handlerPc);
054        this.catchType = catchType;
055    }
056
057    @Override
058    public Object clone() {
059        try {
060            return super.clone();
061        } catch (final CloneNotSupportedException e) {
062            throw new UnsupportedOperationException("Clone Not Supported", e); // never happens
063        }
064    }
065
066    /**
067     * @return true, if ih is target of this handler
068     */
069    @Override
070    public boolean containsTarget(final InstructionHandle ih) {
071        return startPc == ih || endPc == ih || handlerPc == ih;
072    }
073
074    /** Gets the type of the Exception to catch, 'null' for ANY. */
075    public ObjectType getCatchType() {
076        return catchType;
077    }
078
079    /**
080     * Gets CodeException object.<BR>
081     *
082     * This relies on that the instruction list has already been dumped to byte code or that the 'setPositions' methods
083     * has been called for the instruction list.
084     *
085     * @param cp constant pool
086     */
087    public CodeException getCodeException(final ConstantPoolGen cp) {
088        return new CodeException(startPc.getPosition(), endPc.getPosition() + endPc.getInstruction().getLength(), handlerPc.getPosition(),
089            catchType == null ? 0 : cp.addClass(catchType));
090    }
091
092    /**
093     * @return end of handled region (inclusive)
094     */
095    public InstructionHandle getEndPC() {
096        return endPc;
097    }
098
099    /**
100     * @return start of handler
101     */
102    public InstructionHandle getHandlerPC() {
103        return handlerPc;
104    }
105
106    /**
107     * @return start of handled region (inclusive)
108     */
109    public InstructionHandle getStartPC() {
110        return startPc;
111    }
112
113    /** Sets the type of the Exception to catch. Set 'null' for ANY. */
114    public void setCatchType(final ObjectType catchType) {
115        this.catchType = catchType;
116    }
117
118    /*
119     * Sets end of handler
120     *
121     * @param endPc End of handled region (inclusive)
122     */
123    public void setEndPC(final InstructionHandle endPc) { // TODO could be package-protected?
124        BranchInstruction.notifyTarget(this.endPc, endPc, this);
125        this.endPc = endPc;
126    }
127
128    /*
129     * Sets handler code
130     *
131     * @param handlerPc Start of handler
132     */
133    public void setHandlerPC(final InstructionHandle handlerPc) { // TODO could be package-protected?
134        BranchInstruction.notifyTarget(this.handlerPc, handlerPc, this);
135        this.handlerPc = handlerPc;
136    }
137
138    /*
139     * Sets start of handler
140     *
141     * @param startPc Start of handled region (inclusive)
142     */
143    public void setStartPC(final InstructionHandle startPc) { // TODO could be package-protected?
144        BranchInstruction.notifyTarget(this.startPc, startPc, this);
145        this.startPc = startPc;
146    }
147
148    @Override
149    public String toString() {
150        return "CodeExceptionGen(" + startPc + ", " + endPc + ", " + handlerPc + ")";
151    }
152
153    /**
154     * @param oldIh old target, either start or end
155     * @param newIh new target
156     */
157    @Override
158    public void updateTarget(final InstructionHandle oldIh, final InstructionHandle newIh) {
159        boolean targeted = false;
160        if (startPc == oldIh) {
161            targeted = true;
162            setStartPC(newIh);
163        }
164        if (endPc == oldIh) {
165            targeted = true;
166            setEndPC(newIh);
167        }
168        if (handlerPc == oldIh) {
169            targeted = true;
170            setHandlerPC(newIh);
171        }
172        if (!targeted) {
173            throw new ClassGenException("Not targeting " + oldIh + ", but {" + startPc + ", " + endPc + ", " + handlerPc + "}");
174        }
175    }
176}