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 * @version $Id: CodeExceptionGen.java 1806200 2017-08-25 16:33:06Z ggregory $
032 * @see     MethodGen
033 * @see     CodeException
034 * @see     InstructionHandle
035 */
036public final class CodeExceptionGen implements InstructionTargeter, Cloneable {
037
038    private InstructionHandle start_pc;
039    private InstructionHandle end_pc;
040    private InstructionHandle handler_pc;
041    private ObjectType catch_type;
042
043
044    /**
045     * Add an exception handler, i.e., specify region where a handler is active and an
046     * instruction where the actual handling is done.
047     *
048     * @param start_pc Start of handled region (inclusive)
049     * @param end_pc End of handled region (inclusive)
050     * @param handler_pc Where handling is done
051     * @param catch_type which exception is handled, null for ANY
052     */
053    public CodeExceptionGen(final InstructionHandle start_pc, final InstructionHandle end_pc,
054            final InstructionHandle handler_pc, final ObjectType catch_type) {
055        setStartPC(start_pc);
056        setEndPC(end_pc);
057        setHandlerPC(handler_pc);
058        this.catch_type = catch_type;
059    }
060
061
062    /**
063     * Get CodeException object.<BR>
064     *
065     * This relies on that the instruction list has already been dumped
066     * to byte code or or that the `setPositions' methods has been
067     * called for the instruction list.
068     *
069     * @param cp constant pool
070     */
071    public CodeException getCodeException( final ConstantPoolGen cp ) {
072        return new CodeException(start_pc.getPosition(), end_pc.getPosition()
073                + end_pc.getInstruction().getLength(), handler_pc.getPosition(),
074                (catch_type == null) ? 0 : cp.addClass(catch_type));
075    }
076
077
078    /* Set start of handler
079     * @param start_pc Start of handled region (inclusive)
080     */
081    public void setStartPC( final InstructionHandle start_pc ) { // TODO could be package-protected?
082        BranchInstruction.notifyTarget(this.start_pc, start_pc, this);
083        this.start_pc = start_pc;
084    }
085
086
087    /* Set end of handler
088     * @param end_pc End of handled region (inclusive)
089     */
090    public void setEndPC( final InstructionHandle end_pc ) { // TODO could be package-protected?
091        BranchInstruction.notifyTarget(this.end_pc, end_pc, this);
092        this.end_pc = end_pc;
093    }
094
095
096    /* Set handler code
097     * @param handler_pc Start of handler
098     */
099    public void setHandlerPC( final InstructionHandle handler_pc ) { // TODO could be package-protected?
100        BranchInstruction.notifyTarget(this.handler_pc, handler_pc, this);
101        this.handler_pc = handler_pc;
102    }
103
104
105    /**
106     * @param old_ih old target, either start or end
107     * @param new_ih new target
108     */
109    @Override
110    public void updateTarget( final InstructionHandle old_ih, final InstructionHandle new_ih ) {
111        boolean targeted = false;
112        if (start_pc == old_ih) {
113            targeted = true;
114            setStartPC(new_ih);
115        }
116        if (end_pc == old_ih) {
117            targeted = true;
118            setEndPC(new_ih);
119        }
120        if (handler_pc == old_ih) {
121            targeted = true;
122            setHandlerPC(new_ih);
123        }
124        if (!targeted) {
125            throw new ClassGenException("Not targeting " + old_ih + ", but {" + start_pc + ", "
126                    + end_pc + ", " + handler_pc + "}");
127        }
128    }
129
130
131    /**
132     * @return true, if ih is target of this handler
133     */
134    @Override
135    public boolean containsTarget( final InstructionHandle ih ) {
136        return (start_pc == ih) || (end_pc == ih) || (handler_pc == ih);
137    }
138
139
140    /** Sets the type of the Exception to catch. Set 'null' for ANY. */
141    public void setCatchType( final ObjectType catch_type ) {
142        this.catch_type = catch_type;
143    }
144
145
146    /** Gets the type of the Exception to catch, 'null' for ANY. */
147    public ObjectType getCatchType() {
148        return catch_type;
149    }
150
151
152    /** @return start of handled region (inclusive)
153     */
154    public InstructionHandle getStartPC() {
155        return start_pc;
156    }
157
158
159    /** @return end of handled region (inclusive)
160     */
161    public InstructionHandle getEndPC() {
162        return end_pc;
163    }
164
165
166    /** @return start of handler
167     */
168    public InstructionHandle getHandlerPC() {
169        return handler_pc;
170    }
171
172
173    @Override
174    public String toString() {
175        return "CodeExceptionGen(" + start_pc + ", " + end_pc + ", " + handler_pc + ")";
176    }
177
178
179    @Override
180    public Object clone() {
181        try {
182            return super.clone();
183        } catch (final CloneNotSupportedException e) {
184            throw new Error("Clone Not Supported"); // never happens
185        }
186    }
187}