/*
* @(#)AttributeValue.java
*
* Copyright 2003-2005 Sun Microsystems, Inc. All Rights Reserved.
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package com.sun.xacml.attr;
import java.io.OutputStream;
import java.io.PrintStream;
import java.net.URI;
import java.util.Collections;
import java.util.List;
import com.sun.xacml.EvaluationCtx;
import com.sun.xacml.Indenter;
import com.sun.xacml.cond.Evaluatable;
import com.sun.xacml.cond.EvaluationResult;
import com.sun.xacml.cond.Expression;
/**
* 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
*/
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;
}
/**
* 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<Expression> getChildren() {
return Collections.emptyList();
}
/**
* 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>";
}
}