Source code

    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 *
    017 */
    018package org.apache.bcel.generic;
    019
    020import org.apache.bcel.classfile.CodeException;
    021
    022/**
    023 * This class represents an exception handler, i.e., specifies the  region where
    024 * a handler is active and an instruction where the actual handling is done.
    025 * pool as parameters. Opposed to the JVM specification the end of the handled
    026 * region is set to be inclusive, i.e. all instructions between start and end
    027 * are protected including the start and end instructions (handles) themselves.
    028 * The end of the region is automatically mapped to be exclusive when calling
    029 * getCodeException(), i.e., there is no difference semantically.
    030 *
    031 * @see     MethodGen
    032 * @see     CodeException
    033 * @see     InstructionHandle
    034 */
    035public final class CodeExceptionGen implements InstructionTargeter, Cloneable {
    036
    037    private InstructionHandle start_pc;
    038    private InstructionHandle end_pc;
    039    private InstructionHandle handler_pc;
    040    private ObjectType catch_type;
    041
    042
    043    /**
    044     * Add an exception handler, i.e., specify region where a handler is active and an
    045     * instruction where the actual handling is done.
    046     *
    047     * @param start_pc Start of handled region (inclusive)
    048     * @param end_pc End of handled region (inclusive)
    049     * @param handler_pc Where handling is done
    050     * @param catch_type which exception is handled, null for ANY
    051     */
    052    public CodeExceptionGen(final InstructionHandle start_pc, final InstructionHandle end_pc,
    053            final InstructionHandle handler_pc, final ObjectType catch_type) {
    054        setStartPC(start_pc);
    055        setEndPC(end_pc);
    056        setHandlerPC(handler_pc);
    057        this.catch_type = catch_type;
    058    }
    059
    060
    061    /**
    062     * Get CodeException object.<BR>
    063     *
    064     * This relies on that the instruction list has already been dumped
    065     * to byte code or or that the `setPositions' methods has been
    066     * called for the instruction list.
    067     *
    068     * @param cp constant pool
    069     */
    070    public CodeException getCodeException( final ConstantPoolGen cp ) {
    071        return new CodeException(start_pc.getPosition(), end_pc.getPosition()
    072                + end_pc.getInstruction().getLength(), handler_pc.getPosition(),
    073                (catch_type == null) ? 0 : cp.addClass(catch_type));
    074    }
    075
    076
    077    /* Set start of handler
    078     * @param start_pc Start of handled region (inclusive)
    079     */
    080    public void setStartPC( final InstructionHandle start_pc ) { // TODO could be package-protected?
    081        BranchInstruction.notifyTarget(this.start_pc, start_pc, this);
    082        this.start_pc = start_pc;
    083    }
    084
    085
    086    /* Set end of handler
    087     * @param end_pc End of handled region (inclusive)
    088     */
    089    public void setEndPC( final InstructionHandle end_pc ) { // TODO could be package-protected?
    090        BranchInstruction.notifyTarget(this.end_pc, end_pc, this);
    091        this.end_pc = end_pc;
    092    }
    093
    094
    095    /* Set handler code
    096     * @param handler_pc Start of handler
    097     */
    098    public void setHandlerPC( final InstructionHandle handler_pc ) { // TODO could be package-protected?
    099        BranchInstruction.notifyTarget(this.handler_pc, handler_pc, this);
    100        this.handler_pc = handler_pc;
    101    }
    102
    103
    104    /**
    105     * @param old_ih old target, either start or end
    106     * @param new_ih new target
    107     */
    108    @Override
    109    public void updateTarget( final InstructionHandle old_ih, final InstructionHandle new_ih ) {
    110        boolean targeted = false;
    111        if (start_pc == old_ih) {
    112            targeted = true;
    113            setStartPC(new_ih);
    114        }
    115        if (end_pc == old_ih) {
    116            targeted = true;
    117            setEndPC(new_ih);
    118        }
    119        if (handler_pc == old_ih) {
    120            targeted = true;
    121            setHandlerPC(new_ih);
    122        }
    123        if (!targeted) {
    124            throw new ClassGenException("Not targeting " + old_ih + ", but {" + start_pc + ", "
    125                    + end_pc + ", " + handler_pc + "}");
    126        }
    127    }
    128
    129
    130    /**
    131     * @return true, if ih is target of this handler
    132     */
    133    @Override
    134    public boolean containsTarget( final InstructionHandle ih ) {
    135        return (start_pc == ih) || (end_pc == ih) || (handler_pc == ih);
    136    }
    137
    138
    139    /** Sets the type of the Exception to catch. Set 'null' for ANY. */
    140    public void setCatchType( final ObjectType catch_type ) {
    141        this.catch_type = catch_type;
    142    }
    143
    144
    145    /** Gets the type of the Exception to catch, 'null' for ANY. */
    146    public ObjectType getCatchType() {
    147        return catch_type;
    148    }
    149
    150
    151    /** @return start of handled region (inclusive)
    152     */
    153    public InstructionHandle getStartPC() {
    154        return start_pc;
    155    }
    156
    157
    158    /** @return end of handled region (inclusive)
    159     */
    160    public InstructionHandle getEndPC() {
    161        return end_pc;
    162    }
    163
    164
    165    /** @return start of handler
    166     */
    167    public InstructionHandle getHandlerPC() {
    168        return handler_pc;
    169    }
    170
    171
    172    @Override
    173    public String toString() {
    174        return "CodeExceptionGen(" + start_pc + ", " + end_pc + ", " + handler_pc + ")";
    175    }
    176
    177
    178    @Override
    179    public Object clone() {
    180        try {
    181            return super.clone();
    182        } catch (final CloneNotSupportedException e) {
    183            throw new Error("Clone Not Supported"); // never happens
    184        }
    185    }
    186}