ExceptionHandler.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.utility.classfile;

import java.io.IOException;
import java.io.StringWriter;

import org.eclipse.persistence.tools.workbench.utility.ClassTools;
import org.eclipse.persistence.tools.workbench.utility.classfile.tools.ClassFileDataInputStream;
import org.eclipse.persistence.tools.workbench.utility.io.IndentingPrintWriter;


/**
 * This class models an exception handler:
 *     u2 start_pc;
 *     u2 end_pc;
 *     u2 handler_pc;
 *     u2 catch_type;
 *
 * See "The Java Virtual Machine Specification" Chapter 4.
 */
public class ExceptionHandler {
    private ConstantPool constantPool;
    private short startPC;
    private short endPC;
    private short handlerPC;
    private short catchType;

    /**
     * Construct a local variable from the specified stream
     * of byte codes.
     */
    ExceptionHandler(ClassFileDataInputStream stream, ConstantPool constantPool) throws IOException {
        super();
        this.constantPool = constantPool;
        this.initialize(stream);
    }

    void initialize(ClassFileDataInputStream stream) throws IOException {
        this.startPC = stream.readU2();
        this.endPC = stream.readU2();
        this.handlerPC = stream.readU2();
        this.catchType = stream.readU2();
    }

    public String displayString() {
        StringWriter sw = new StringWriter(1000);
        IndentingPrintWriter writer = new IndentingPrintWriter(sw);
        this.displayStringOn(writer);
        return sw.toString();
    }

    public void displayStringOn(IndentingPrintWriter writer) {
        writer.println(this.description());
        writer.indent();
        writer.print("PC start: ");
        writer.print(this.startPC);
        writer.print(" end: ");
        writer.print(this.endPC);
        writer.print(" handler: ");
        writer.println(this.handlerPC);
        writer.undent();
    }

    public String description() {
        short type = this.catchType;
        if (type == 0) {
            return "finally";
        }
        return "catch (" + this.className(type) + ")";
    }

    public String exceptionClassName() {
        return this.className(this.catchType);
    }

    private String className(short index) {
        return this.constantPool.getClassConstant(index).name();
    }

    public void accept(Visitor visitor) {
        visitor.visit(this);
    }

    public ConstantPool getConstantPool() {
        return this.constantPool;
    }

    public short getStartPC() {
        return this.startPC;
    }

    public short getEndPC() {
        return this.endPC;
    }

    public short getHandlerPC() {
        return this.handlerPC;
    }

    public short getCatchType() {
        return this.catchType;
    }

    public String toString() {
        return ClassTools.shortClassNameForObject(this) + '(' + this.description() + ')';
    }

}