/*
 *    StackMapAttribute.java    1.2    00/08/23
 *
 * Copyright © 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package components;
import java.io.DataOutput;
import java.io.DataInput;
import java.io.IOException;
import util.DataFormatException;
import vm.Const;

/*
 * A class to represent the StackMap attribute of a method's code.
 */

public
class StackMapAttribute extends Attribute
{
    public StackMapFrame    data[];

    public
    StackMapAttribute( UnicodeConstant name, int l, StackMapFrame d[] ){
    super( name, l );
    this.data = d;
    }

    public void
    externalize( ConstantPool p ){
    super.externalize( p );
     for (int i = 0; i < data.length; i++) {
        data[i].externalize(p);
    }
    }

    protected int
    writeData( DataOutput o ) throws IOException{
    int length = 2;
    o.writeShort(data.length);
    for ( int i = 0; i < data.length; i++ ){
        length += data[i].writeData(o);
    }
    return length;
    }

    public void
    countConstantReferences( boolean isRelocatable ){
    super.countConstantReferences( isRelocatable );
    for (int i = 0; i < data.length; i++) {
        data[i].countConstantReferences(isRelocatable);
    }
    }

    public static Attribute
    readAttribute( DataInput i, ConstantObject globals[] ) throws IOException{
    UnicodeConstant name;
    name = (UnicodeConstant)globals[i.readUnsignedShort()];
    return finishReadAttribute(i, name, globals );
    }

    //
    // for those cases where we already read the name index
    // and know that its not something requiring special handling.
    //
    public static Attribute
    finishReadAttribute(DataInput in, 
            UnicodeConstant name, 
            ConstantObject globals[] ) throws IOException {
    int length = in.readInt();
    // Read the number of frames
    int n = in.readUnsignedShort();
    StackMapFrame d[] = new StackMapFrame[n];
    // Read each frame
    for (int i = 0; i < n; i++) { 
        d[i] = new StackMapFrame(in, globals);
    }
    return new StackMapAttribute(name, length, d);
    }

}