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Scala example source code file (JCodeAttribute.java)

This example Scala source code file (JCodeAttribute.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Scala tags/keywords

code, io, ioexception, iterator, iterator, jattribute, jattribute, jcodeattribute, jcodeattribute, jmethod, jmethod, list/*, string, stringbuffer, unknown_stack_size, util

The Scala JCodeAttribute.java source code

/* FJBG -- Fast Java Bytecode Generator
 * Copyright 2002-2011 LAMP/EPFL
 * @author  Michel Schinz
 */

package ch.epfl.lamp.fjbg;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;

/**
 * Code attribute, containing code of methods.
 *
 * A Code attribute contains the JVM instructions and auxiliary information
 * for a single method, instance initialization method, or class or interface
 * initialization method. See section 4.8.3 of the JVM specification.
 *
 * @author Michel Schinz, Stephane Micheloud
 * @version 1.1
 */

public class JCodeAttribute extends JAttribute {
    protected final JCode code;
    protected final JMethod owner;
    protected static int UNKNOWN_STACK_SIZE = Integer.MIN_VALUE;
    protected final int maxStackSize;
    protected final int maxLocals;

    public JCodeAttribute(FJBGContext context, JClass clazz, JMethod owner) {
        super(context, clazz);
        this.owner = owner;

        this.maxStackSize = UNKNOWN_STACK_SIZE;
        this.maxLocals = 0; // unknown
        this.code = owner.getCode();

        assert clazz == owner.getOwner();
    }

    public JCodeAttribute(FJBGContext context,
                          JClass clazz,
                          Object owner,
                          String name,
                          int size,
                          DataInputStream stream)
        throws IOException {
        super(context, clazz, name);
        this.owner = (JMethod)owner;

        this.maxStackSize = stream.readShort();
        this.maxLocals = stream.readShort();
        this.code = context.JCode(clazz, (JMethod)owner, stream);

        int handlersCount = stream.readShort();
        for (int i = 0; i < handlersCount; ++i)
            code.addExceptionHandler(code.new ExceptionHandler(stream));
        List/*<JAttribute>*/ attributes =
            JAttribute.readFrom(context, clazz, code, stream);
        Iterator attrIt = attributes.iterator();
        while (attrIt.hasNext())
            code.addAttribute((JAttribute)attrIt.next());

        assert name.equals(getName());
    }

    public String getName() { return "Code"; }

    // Follows javap output format for Code attribute.
    /*@Override*/ public String toString() {
        StringBuffer buf = new StringBuffer("  Code:");
        buf.append("\n   Stack=");
        buf.append(maxStackSize);
        buf.append(", Locals=");
        buf.append(maxLocals);
        buf.append(", Args_size=");
        buf.append(owner.getArgsSize());
        buf.append(code);
        buf.append("\n");
        Iterator it = code.getAttributes().iterator();
        while (it.hasNext()) {
            JAttribute attr = (JAttribute)it.next();
            buf.append(attr);
            buf.append("\n");
        }
        return buf.toString();
    }

    protected int getSize() {
        int handlersNum = code.getExceptionHandlers().size();

        int attrsSize = 0;
        Iterator attrsIt = code.getAttributes().iterator();
        while (attrsIt.hasNext()) {
            JAttribute attr = (JAttribute)attrsIt.next();
            attrsSize += attr.getSize() + 6;
        }

        return 2                // max stack
            + 2                 // max locals
            + 4                 // code size
            + code.getSize()    // code
            + 2                 // exception table size
            + 8 * handlersNum   // exception table
            + 2                 // attributes count
            + attrsSize;        // attributes
    }

    protected void writeContentsTo(DataOutputStream stream) throws IOException {
        List/*<ExceptionHandler>*/ handlers = code.getExceptionHandlers();

        stream.writeShort(code.getMaxStackSize());
        stream.writeShort(owner.getMaxLocals());

        code.writeTo(stream);

        stream.writeShort(handlers.size());
        Iterator handlerIt = handlers.iterator();
        while (handlerIt.hasNext())
            ((JCode.ExceptionHandler)handlerIt.next()).writeTo(stream);
        JAttribute.writeTo(code.getAttributes(), stream);
    }
}

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