www.pudn.com > cryptix-asn1-0.1.11.zip > Choice.java

/* $Id: Choice.java,v 1.7 2001/05/26 07:10:24 raif Exp $ 
 * 
 * Copyright (C) 1997-2001 The Cryptix Foundation Limited. All rights reserved. 
 * 
 * Use, modification, copying and distribution of this software is subject to 
 * the terms and conditions of the Cryptix General Licence. You should have 
 * received a copy of the Cryptix General Licence along with this library; if 
 * not, you can download a copy from http://www.cryptix.org/ 
 */ 
package cryptix.asn1.lang; 
 
import cryptix.asn1.io.ASNReader; 
import cryptix.asn1.io.ASNWriter; 
import cryptix.asn1.io.BlankElementException; 
import cryptix.asn1.io.ElementNotFoundException; 
 
import org.apache.log4j.Category; 
 
import java.io.EOFException; 
import java.io.IOException; 
import java.util.ArrayList; 
import java.util.Iterator; 
import java.util.ListIterator; 
 
/** 
 * The basic implementation of the ASN.1 CHOICE type.
 
 * 
 * The CHOICE alternatives are grouped in a java.util.ArrayList, with 
 * a provided implementation of the cryptix.asn1.lang.IIterativeType 
 * interface to iterate over them. The value of a CHOICE is the first non-blank 
 * type among those contained in its components.
 
 * 
 * @version $Revision: 1.7 $ 
 * @author  Raif S. Naffah 
 */ 
public abstract class Choice extends Set { 
 
	// Constants and vars 
	// ....................................................................... 
 
	static Category cat = Category.getInstance(Choice.class.getName()); 
 
	// Constructor(s) 
	// ....................................................................... 
 
	public Choice(Tag tag) { 
		super("", tag); 
	} 
 
	public Choice(String name, Tag tag) { 
		super(name, tag); 
	} 
 
	/** 
	 * Constructs a new instance of a CHOICE type, given a designated Tag and a 
	 * designated default value. 
	 * 
	 * @param name the name of this instance. 
	 * @param tag the designated Tag value. 
	 * @param value the designated initial value. 
	 * @exception ClassCastException if the designated value is not an IType. 
	 */ 
	public Choice(String name, Tag tag, Object value) { 
		super(name, tag); 
 
		if (value != null) 
			if (value instanceof ArrayList) { 
				value(value); 
			} else 
				throw new ClassCastException(); 
	} 
 
	// Redefinition of methods in superclass Type 
	// ....................................................................... 
 
	/** 
	 * Decodes a CHOICE from an input stream. 
	 * 
	 * @param is the ASN.1 stream to read from. 
	 * @exception IOException if an exception occurs during the operation. 
	 */ 
	public void decode(ASNReader is) throws IOException { 
		String cn = this.getClass().getName(); 
		cat.debug("==> "+cn+".decode()"); 
 
		this.reset(); 
 
		is.mark(Integer.MAX_VALUE); 
		IType t; 
		boolean found = false; 
		cat.info("Looking for a valid ASN.1 alternative for a CHOICE."); 
		try { 
			IType e = is.decodeAny("choice"); 
			Iterator it = this.iterator(); 
			while (it.hasNext()) { 
				t = (Type) it.next(); 
				found = t.tag().equals(e.tag()); 
				if (found) { 
					cat.info("Found a "+t.getClass().getName()); 
					t.value(e.value()); 
					break; 
				} 
			} 
		} catch (IOException x) { 
			cat.warn("Exception ("+String.valueOf(x)+") encountered while decoding a "+cn); 
			if (x instanceof ASNException || x instanceof EOFException) { 
				cat.warn("Resetting stream..."); 
				is.reset(); 
			} 
 
			throw x; 
		} 
 
		if (!found && !isOptional()) 
			throw new ASNException("No valid alternative for "+cn+" (CHOICE) was found..."); 
 
		cat.debug("<== "+cn+".decode()"); 
	} 
 
	/** 
	 * Encodes a CHOICE to an output stream. 
	 * 
	 * @param os the ASN.1 stream to write to. 
	 * @exception RuntimeException always. 
	 */ 
	public void encode(ASNWriter os) throws IOException { 
		String cn = this.getClass().getName(); 
		cat.debug("==> "+cn+".encode()"); 
 
		boolean found = false; 
		for (Iterator it = this.iterator(); it.hasNext(); ) { 
			IType t = (Type) it.next(); 
			found = !t.isBlank(); 
			if (found) { 
				cat.info("Encoding "+t.getClass().getName()+"..."); 
				t.encode(os); 
				break; 
			} 
		} 
 
		if (!found && !isOptional()) 
			throw new BlankElementException(cn); 
 
		cat.debug("<== "+cn+".encode()"); 
	} 
 
	/** 
	 * Sets the current value of this instance to the designated one. For a 
	 * CHOICE, this operation consists of iterating through the elements of 
	 * the designated value, and assigning the first non-blank element (with 
	 * the same tag) in this instance's corresponding component, the value of 
	 * the element from value. 
	 * 
	 * @param value the new value to assign to this instance. 
	 */ 
	public void value(Object value) { 
		String cn = this.getClass().getName(); 
		cat.debug("==> "+cn+".value("+String.valueOf(value)+")"); 
      cat.debug("value is a "+String.valueOf(value.getClass().getName())); 
      if (value instanceof IType) 
         cat.debug("Tag="+String.valueOf( ((IType) value).tag() )); 
 
		this.reset(); 
 
      if (value instanceof Any) { 
         Any src = (Any) value; 
   		for (Iterator dst = this.iterator(); dst.hasNext(); ) { 
   			IType td = (IType) dst.next(); 
   		   if (td.tag().equals(src.tag())) { 
   		      td.value(src.value()); 
      			cat.info("Assigned value to "+td.getClass().getName()); 
   		      break; 
   		   } 
   		} 
      } else { 
         if (value instanceof IType) 
            value = ((IType) value).value(); 
 
   		Iterator src; 
   		if (value instanceof ArrayList) 
   		   src = ((ArrayList) value).iterator(); 
   		else 
   		   src = ((ArrayList) ((Any) value).value()).iterator(); 
 
   		Iterator dst = this.iterator(); 
   		while (src.hasNext() && dst.hasNext()) { 
   			IType ts = (IType) src.next(); 
   			IType td = (IType) dst.next(); 
   			// what checks should we make? remember that any term may be an ANY 
   			// (with a null tag)? 
   			cat.info("Assigning value from "+ts.getClass().getName()+" to "+td.getClass().getName()); 
   			td.value(ts.value()); 
   		} 
		} 
 
		cat.debug("<== "+cn+".value()"); 
	} 
 
   // java.lang.Object overloaded methods 
   // ....................................................................... 
 
	/** 
	 * Returns a string representation of this instance. 
	 * 
	 * @return a string representation of this instance. 
	 */ 
	public String toString() { 
		String cn = this.getClass().getName(); 
		String ls = System.getProperty("line.separator"); 
		StringBuffer sb = new StringBuffer(ls); 
		sb.append("-- Begin ").append(cn).append(" (CHOICE)").append(ls); 
		int i = 1; 
		boolean found = false; 
		for (Iterator it = this.iterator(); it.hasNext(); i++) { 
			IType t = (Type) it.next(); 
			found = !t.isBlank(); 
			if (found) { 
				sb.append("--   alternative #").append(i) 
					.append(" (").append(t.getClass().getName()).append("): ") 
					.append(String.valueOf(t)).append(ls); 
				break; 
			} 
		} 
 
		if (!found) 
			sb.append("--   N/A").append(ls); 
 
		sb.append("-- End ").append(cn).append(" (CHOICE)"); 
		return sb.toString(); 
	} 
}