/*
* @(#)BagAttribute.java
*
* Copyright 2003-2004 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistribution of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistribution in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
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* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
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* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
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package com.sun.xacml.attr;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* Represents a bag used in the XACML spec as return values from functions
* and designators/selectors that provide more than one value. All values in
* the bag are of the same type, and the bag may be empty. The bag is
* immutable, although its contents may not be.
* <p>
* NOTE: This is the one standard attribute type that can't be created from
* the factory, since you can't have this in an XML block (it is used only
* in return values & dynamic inputs). I think this is right, but we may need
* to add some functionality to let this go into the factory.
*
* @since 1.0
* @author Seth Proctor
* @author Steve Hanna
*/
public class BagAttribute extends AttributeValue
{
// The Collection of AttributeValues that this object encapsulates
private Collection<AttributeValue> bag;
/**
* Creates a new <code>BagAttribute</code> that represents
* the <code>Collection</code> of <code>AttributeValue</code>s supplied.
* If the set is null or empty, then the new bag is empty.
*
* @param type the data type of all the attributes in the set
* @param bag a <code>Collection</code> of <code>AttributeValue</code>s
*/
public BagAttribute(URI type, Collection<AttributeValue> bag) {
super(type);
if (type == null) {
throw new IllegalArgumentException("Bags require a non-null " +
"type be provided");
}
// see if the bag is empty/null
if ((bag == null) || (bag.size() == 0)) {
// empty bag
this.bag = new ArrayList<AttributeValue>();
} else {
// go through the collection to make sure it's a valid bag
Iterator<AttributeValue> it = bag.iterator();
while (it.hasNext()) {
AttributeValue attr = it.next();
// a bag cannot contain other bags, so make sure that each
// value isn't actually another bag
if (attr.isBag()) {
throw new IllegalArgumentException("bags cannot contain " +
"other bags");
}
// make sure that they're all the same type
if (! type.equals(attr.getType())) {
throw new
IllegalArgumentException("Bag items must all be of " +
"the same type");
}
}
// if we get here, then they're all the same type
this.bag = bag;
}
}
/**
* Overrides the default method to always return true.
*
* @return a value of true
*/
public boolean isBag() {
return true;
}
/**
* Convenience function that returns a bag with no elements
*
* @param type the types contained in the bag
*
* @return a new empty bag
*/
public static BagAttribute createEmptyBag(URI type) {
return new BagAttribute(type, null);
}
/**
* A convenience function that returns whether or not the bag is empty
* (ie, whether or not the size of the bag is zero)
*
* @return whether or not the bag is empty
*/
public boolean isEmpty() {
return (this.bag.size() == 0);
}
/**
* Returns the number of elements in this bag
*
* @return the number of elements in this bag
*/
public int size() {
return this.bag.size();
}
/**
* Returns true if this set contains the specified value. More formally,
* returns true if and only if this bag contains a value v such that
* (value==null ? v==null : value.equals(v)). Note that this will only
* work correctly if the <code>AttributeValue</code> has overridden the
* <code>equals</code> method.
*
* @param value the value to look for
*
* @return true if the value is in the bag
*/
public boolean contains(AttributeValue value) {
return this.bag.contains(value);
}
/**
* Returns true if this bag contains all of the values of the specified bag.
* Note that this will only work correctly if the
* <code>AttributeValue</code> type contained in the bag has overridden
* the <code>equals</code> method.
*
* @param bag the bag to compare
*
* @return true if the input is a subset of this bag
*/
public boolean containsAll(BagAttribute bag) {
return this.bag.containsAll(bag.bag);
}
/**
* Returns an iterator over the bag.
*
* @return The iterator.
*/
public Iterator<AttributeValue> iterator() {
return new ImmutableIterator(this.bag.iterator());
}
/**
* Returns an iterator over the bag.
*
* @return The iterator.
*/
public Iterable<AttributeValue> iterable() {
return this.bag;
}
/**
* This is a version of Iterator that overrides the <code>remove</code>
* method so that items can't be taken out of the bag.
*/
private static class ImmutableIterator implements Iterator<AttributeValue> {
// the iterator we're wrapping
private Iterator<AttributeValue> iterator;
/**
* Create a new ImmutableIterator
*
* @param iterator The iterator that shall be made immutable.
*/
public ImmutableIterator(Iterator<AttributeValue> iterator) {
this.iterator = iterator;
}
/**
* Standard hasNext method
*
* @return true of this iterator has a next element, false otherwise.
*/
public boolean hasNext() {
return this.iterator.hasNext();
}
/**
* Standard next method
*
* @return The next Object pointed to by the iterator.
*
* @throws NoSuchElementException
*/
public AttributeValue next() throws NoSuchElementException {
return this.iterator.next();
}
/**
* Makes sure that no one can remove any elements from the bag
*
* @throws UnsupportedOperationException
*/
public void remove() throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
}
/**
* Because a bag cannot be included in a request/response or a
* policy, this will always throw an
* <code>UnsupportedOperationException</code>.
*
* @return The String that would encode this bag.
*/
public String encode() {
throw new UnsupportedOperationException("Bags cannot be encoded");
}
}