001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.bcel.generic;
020
021import org.apache.bcel.classfile.CodeException;
022
023/**
024 * This class represents an exception handler, i.e., specifies the region where a handler is active and an instruction
025 * where the actual handling is done. pool as parameters. Opposed to the JVM specification the end of the handled region
026 * is set to be inclusive, i.e. all instructions between start and end are protected including the start and end
027 * instructions (handles) themselves. The end of the region is automatically mapped to be exclusive when calling
028 * getCodeException(), i.e., there is no difference semantically.
029 *
030 * @see MethodGen
031 * @see CodeException
032 * @see InstructionHandle
033 */
034public final class CodeExceptionGen implements InstructionTargeter, Cloneable {
035
036    static final CodeExceptionGen[] EMPTY_ARRAY = {};
037
038    private InstructionHandle startPc;
039    private InstructionHandle endPc;
040    private InstructionHandle handlerPc;
041    private ObjectType catchType;
042
043    /**
044     * Add an exception handler, i.e., specify region where a handler is active and an instruction where the actual handling
045     * is done.
046     *
047     * @param startPc Start of handled region (inclusive)
048     * @param endPc End of handled region (inclusive)
049     * @param handlerPc Where handling is done
050     * @param catchType which exception is handled, null for ANY
051     */
052    public CodeExceptionGen(final InstructionHandle startPc, final InstructionHandle endPc, final InstructionHandle handlerPc, final ObjectType catchType) {
053        setStartPC(startPc);
054        setEndPC(endPc);
055        setHandlerPC(handlerPc);
056        this.catchType = catchType;
057    }
058
059    @Override
060    public Object clone() {
061        try {
062            return super.clone();
063        } catch (final CloneNotSupportedException e) {
064            throw new UnsupportedOperationException("Clone Not Supported", e); // never happens
065        }
066    }
067
068    /**
069     * @return true, if ih is target of this handler
070     */
071    @Override
072    public boolean containsTarget(final InstructionHandle ih) {
073        return startPc == ih || endPc == ih || handlerPc == ih;
074    }
075
076    /** Gets the type of the Exception to catch, 'null' for ANY. */
077    public ObjectType getCatchType() {
078        return catchType;
079    }
080
081    /**
082     * Gets CodeException object.<BR>
083     *
084     * This relies on that the instruction list has already been dumped to byte code or that the 'setPositions' methods
085     * has been called for the instruction list.
086     *
087     * @param cp constant pool
088     */
089    public CodeException getCodeException(final ConstantPoolGen cp) {
090        return new CodeException(startPc.getPosition(), endPc.getPosition() + endPc.getInstruction().getLength(), handlerPc.getPosition(),
091            catchType == null ? 0 : cp.addClass(catchType));
092    }
093
094    /**
095     * @return end of handled region (inclusive)
096     */
097    public InstructionHandle getEndPC() {
098        return endPc;
099    }
100
101    /**
102     * @return start of handler
103     */
104    public InstructionHandle getHandlerPC() {
105        return handlerPc;
106    }
107
108    /**
109     * @return start of handled region (inclusive)
110     */
111    public InstructionHandle getStartPC() {
112        return startPc;
113    }
114
115    /** Sets the type of the Exception to catch. Set 'null' for ANY. */
116    public void setCatchType(final ObjectType catchType) {
117        this.catchType = catchType;
118    }
119
120    /*
121     * Sets end of handler
122     *
123     * @param endPc End of handled region (inclusive)
124     */
125    public void setEndPC(final InstructionHandle endPc) { // TODO could be package-protected?
126        BranchInstruction.notifyTarget(this.endPc, endPc, this);
127        this.endPc = endPc;
128    }
129
130    /*
131     * Sets handler code
132     *
133     * @param handlerPc Start of handler
134     */
135    public void setHandlerPC(final InstructionHandle handlerPc) { // TODO could be package-protected?
136        BranchInstruction.notifyTarget(this.handlerPc, handlerPc, this);
137        this.handlerPc = handlerPc;
138    }
139
140    /*
141     * Sets start of handler
142     *
143     * @param startPc Start of handled region (inclusive)
144     */
145    public void setStartPC(final InstructionHandle startPc) { // TODO could be package-protected?
146        BranchInstruction.notifyTarget(this.startPc, startPc, this);
147        this.startPc = startPc;
148    }
149
150    @Override
151    public String toString() {
152        return "CodeExceptionGen(" + startPc + ", " + endPc + ", " + handlerPc + ")";
153    }
154
155    /**
156     * @param oldIh old target, either start or end
157     * @param newIh new target
158     */
159    @Override
160    public void updateTarget(final InstructionHandle oldIh, final InstructionHandle newIh) {
161        boolean targeted = false;
162        if (startPc == oldIh) {
163            targeted = true;
164            setStartPC(newIh);
165        }
166        if (endPc == oldIh) {
167            targeted = true;
168            setEndPC(newIh);
169        }
170        if (handlerPc == oldIh) {
171            targeted = true;
172            setHandlerPC(newIh);
173        }
174        if (!targeted) {
175            throw new ClassGenException("Not targeting " + oldIh + ", but {" + startPc + ", " + endPc + ", " + handlerPc + "}");
176        }
177    }
178}