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package java.security.cert;
import java.util.Iterator;
import java.util.Set;
/**
* An immutable valid policy tree node as defined by the PKIX certification
* path validation algorithm.
*
* <p>One of the outputs of the PKIX certification path validation
* algorithm is a valid policy tree, which includes the policies that
* were determined to be valid, how this determination was reached,
* and any policy qualifiers encountered. This tree is of depth
* <i>n</i>, where <i>n</i> is the length of the certification
* path that has been validated.
*
* <p>Most applications will not need to examine the valid policy tree.
* They can achieve their policy processing goals by setting the
* policy-related parameters in <code>PKIXParameters</code>. However,
* the valid policy tree is available for more sophisticated applications,
* especially those that process policy qualifiers.
*
* <p>{@link PKIXCertPathValidatorResult#getPolicyTree()
* PKIXCertPathValidatorResult.getPolicyTree} returns the root node of the
* valid policy tree. The tree can be traversed using the
* {@link #getChildren getChildren} and {@link #getParent getParent} methods.
* Data about a particular node can be retrieved using other methods of
* <code>PolicyNode</code>.
*
* <p><b>Concurrent Access</b>
* <p>All <code>PolicyNode</code> objects must be immutable and
* thread-safe. Multiple threads may concurrently invoke the methods defined
* in this class on a single <code>PolicyNode</code> object (or more than one)
* with no ill effects. This stipulation applies to all public fields and
* methods of this class and any added or overridden by subclasses.
*
* @since 1.4
* @author Sean Mullan
*/
public interface PolicyNode {
/**
* Returns the parent of this node, or <code>null</code> if this is the
* root node.
*
* @return the parent of this node, or <code>null</code> if this is the
* root node
*/
PolicyNode getParent();
/**
* Returns an iterator over the children of this node. Any attempts to
* modify the children of this node through the
* <code>Iterator</code>'s remove method must throw an
* <code>UnsupportedOperationException</code>.
*
* @return an iterator over the children of this node
*/
Iterator<? extends PolicyNode> getChildren();
/**
* Returns the depth of this node in the valid policy tree.
*
* @return the depth of this node (0 for the root node, 1 for its
* children, and so on)
*/
int getDepth();
/**
* Returns the valid policy represented by this node.
*
* @return the <code>String</code> OID of the valid policy
* represented by this node, or the special value "any-policy". For
* the root node, this method always returns the special value "any-policy".
*/
String getValidPolicy();
/**
* Returns the set of policy qualifiers associated with the
* valid policy represented by this node.
*
* @return an immutable <code>Set</code> of
* <code>PolicyQualifierInfo</code>s. For the root node, this
* is always an empty <code>Set</code>.
*/
Set<? extends PolicyQualifierInfo> getPolicyQualifiers();
/**
* Returns the set of expected policies that would satisfy this
* node's valid policy in the next certificate to be processed.
*
* @return an immutable <code>Set</code> of expected policy
* <code>String</code> OIDs, or an immutable <code>Set</code> with
* the single special value "any-policy". For the root node, this method
* always returns a <code>Set</code> with the single value "any-policy".
*/
Set<String> getExpectedPolicies();
/**
* Returns the criticality indicator of the certificate policy extension
* in the most recently processed certificate.
*
* @return <code>true</code> if extension marked critical,
* <code>false</code> otherwise. For the root node, <code>false</code>
* is always returned.
*/
boolean isCritical();
}