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


/**
 * This class models a code attribute:
 *     u2 attribute_name_index;
 *     u4 attribute_length;
 *     u2 max_stack;
 *     u2 max_locals;
 *     u4 code_length;
 *     u1[code_length] code;
 *     u2 exception_table_length;
 *     {
 *         u2 start_pc;
 *         u2 end_pc;
 *         u2 handler_pc;
 *         u2 catch_type;
 *     }[exception_table_length] exception_table;
 *     u2 attributes_count;
 *     attribute_info[attributes_count] attributes;
 *
 * See "The Java Virtual Machine Specification" Chapter 4.
 */
public class CodeAttribute extends Attribute {
    private short maxStack;
    private short maxLocals;
    private int codeLength;
    private byte[] code;
    private short exceptionHandlerCount;
    private ExceptionHandler[] exceptionHandlers;
    private AttributePool attributePool;


    /**
     * Construct a code attribute from the specified stream
     * of byte codes.
     */
    CodeAttribute(ClassFileDataInputStream stream, short nameIndex, AttributePool pool) throws IOException {
        super(stream, nameIndex, pool);
    }

    void initializeInfo(ClassFileDataInputStream stream) throws IOException {
        this.maxStack = stream.readU2();
        this.maxLocals = stream.readU2();

        this.codeLength = stream.readU4();
        int len = this.codeLength;
        this.code = new byte[len];
        stream.read(this.code);

        this.exceptionHandlerCount = stream.readU2();
        short cnt = this.exceptionHandlerCount;
        this.exceptionHandlers = new ExceptionHandler[cnt];
        ExceptionHandler[] handlers = this.exceptionHandlers;
        for (short i = 0; i < cnt; i++) {
            handlers[i] = new ExceptionHandler(stream, this.constantPool());
        }

        this.attributePool = new AttributePool(stream, this.classFile());
    }

    void displayInfoStringOn(IndentingPrintWriter writer) {
        writer.print("max stack: ");
        writer.println(this.maxStack);
        writer.print("max locals: ");
        writer.println(this.maxLocals);
        writer.print("code: ");
        this.writeHexStringOn(this.code, writer);
        writer.println();
        short count = this.exceptionHandlerCount;
        writer.print("Exception Handlers (count: ");
        writer.print(count);
        writer.println(")");
        writer.indent();
            ExceptionHandler[] handlers = this.exceptionHandlers;
            for (short i = 0; i < count; i++) {
                writer.print(i);
                writer.print(": ");
                handlers[i].displayStringOn(writer);
            }
        writer.undent();
        this.attributePool.displayStringOn(writer);
    }

    public void accept(Visitor visitor) {
        visitor.visit(this);
        short count = this.exceptionHandlerCount;
        ExceptionHandler[] handlers = this.exceptionHandlers;
        for (short i = 0; i < count; i++) {
            handlers[i].accept(visitor);
        }
        this.attributePool.accept(visitor);
    }

    public short getMaxStack() {
        return this.maxStack;
    }

    public short getMaxLocals() {
        return this.maxLocals;
    }

    public int getCodeLength() {
        return this.codeLength;
    }

    public byte[] getCode() {
        return this.code;
    }

    public short getExceptionHandlerCount() {
        return this.exceptionHandlerCount;
    }

    public ExceptionHandler getExceptionHandler(short index) {
        return this.exceptionHandlers[index];
    }

    public ExceptionHandler[] getExceptionHandlers() {
        return this.exceptionHandlers;
    }

    public AttributePool getAttributePool() {
        return this.attributePool;
    }

    void toString(StringBuffer sb) {
        sb.append("code length: ");
        sb.append(this.codeLength);
    }

}