/*
* @(#)AttributeValue.java
*
* Copyright 2003-2005 Sun Microsystems, Inc. All Rights Reserved.
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package org.jboss.security.xacml.sunxacml.attr;
import java.io.OutputStream;
import java.io.PrintStream;
import java.net.URI;
import java.util.Collections;
import java.util.List;
import org.jboss.security.xacml.sunxacml.EvaluationCtx;
import org.jboss.security.xacml.sunxacml.Indenter;
import org.jboss.security.xacml.sunxacml.cond.Evaluatable;
import org.jboss.security.xacml.sunxacml.cond.EvaluationResult;
/**
* The base type for all datatypes used in a policy or request/response,
* this abstract class represents a value for a given attribute type.
* All the required types defined in the XACML specification are
* provided as instances of <code>AttributeValue<code>s. If you want to
* provide a new type, extend this class and implement the
* <code>equals(Object)</code> and <code>hashCode</code> methods from
* <code>Object</code>, which are used for equality checking.
*
* @since 1.0
* @author Seth Proctor
*/
@SuppressWarnings( "rawtypes" )
public abstract class AttributeValue implements Evaluatable
{
// the type of this attribute
private URI type;
/**
* Constructor that takes the specific attribute type.
*
* @param type the attribute's type
*/
protected AttributeValue(URI type) {
this.type = type;
}
/**
* Returns the type of this attribute value. By default this always
* returns the type passed to the constructor.
*
* @return the attribute's type
*/
public URI getType() {
return type;
}
/**
* Get the value represented
* @return
*/
public abstract Object getValue();
/**
* Returns whether or not this value is actually a bag of values. This
* is a required interface from <code>Expression</code>, but the
* more meaningful <code>isBag</code> method is used by
* <code>AttributeValue</code>s, so this method is declared as final
* and calls the <code>isBag</code> method for this value.
*
* @return true if this is a bag of values, false otherwise
*/
public final boolean returnsBag() {
return isBag();
}
/**
* Returns whether or not this value is actually a bag of values. This
* is a required interface from <code>Evaluatable</code>, but the
* more meaningful <code>isBag</code> method is used by
* <code>AttributeValue</code>s, so this method is declared as final
* and calls the <code>isBag</code> method for this value.
*
*
* @deprecated As of 2.0, you should use the <code>returnsBag</code>
* method from the super-interface <code>Expression</code>.
*
* @return true if this is a bag of values, false otherwise
*/
public final boolean evaluatesToBag() {
return isBag();
}
/**
* Always returns an empty list since values never have children.
*
* @return an empty <code>List</code>
*/
public List getChildren() {
return Collections.EMPTY_LIST;
}
/**
* Returns whether or not this value is actually a bag of values. By
* default this returns <code>false</code>. Typically, only the
* <code>BagAttribute</code> should ever override this to return
* <code>true</code>.
*
* @return true if this is a bag of values, false otherwise
*/
public boolean isBag() {
return false;
}
/**
* Implements the required interface from <code>Evaluatable</code>.
* Since there is nothing to evaluate in an attribute value, the default
* result is just this instance. Override this method if you want
* special behavior, like a dynamic value.
*
* @param context the representation of the request
*
* @return a successful evaluation containing this value
*/
public EvaluationResult evaluate(EvaluationCtx context) {
return new EvaluationResult(this);
}
/**
* Encodes the value in a form suitable for including in XML data like
* a request or an obligation. This must return a value that could in
* turn be used by the factory to create a new instance with the same
* value.
*
* @return a <code>String</code> form of the value
*/
public abstract String encode();
/**
* Encodes this <code>AttributeValue</code> into its XML representation
* and writes this encoding to the given <code>OutputStream</code> with
* no indentation. This will always produce the version used in a
* policy rather than that used in a request, so this is equivalent
* to calling <code>encodeWithTags(true)</code> and then stuffing that
* into a stream.
*
* @param output a stream into which the XML-encoded data is written
*/
public void encode(OutputStream output) {
encode(output, new Indenter(0));
}
/**
* Encodes this <code>AttributeValue</code> into its XML representation
* and writes this encoding to the given <code>OutputStream</code> with
* indentation. This will always produce the version used in a
* policy rather than that used in a request, so this is equivalent
* to calling <code>encodeWithTags(true)</code> and then stuffing that
* into a stream.
*
* @param output a stream into which the XML-encoded data is written
* @param indenter an object that creates indentation strings
*/
public void encode(OutputStream output, Indenter indenter) {
PrintStream out = new PrintStream(output);
out.println(indenter.makeString() + encodeWithTags(true));
}
/**
* Encodes the value and includes the AttributeValue XML tags so that
* the resulting string can be included in a valid XACML policy or
* Request/Response. The <code>boolean</code> parameter lets you include
* the DataType attribute, which is required in a policy but not allowed
* in a Request or Response.
*
* @param includeType include the DataType XML attribute if
* <code>true</code>, exclude if <code>false</code>
*
* @return a <code>String</code> encoding including the XML tags
*/
public String encodeWithTags(boolean includeType) {
if (includeType)
return "<AttributeValue DataType=\"" + type.toString() + "\">" +
encode() + "</AttributeValue>";
else
return "<AttributeValue>" + encode() + "</AttributeValue>";
}
}