package edu.stanford.peer.rbtm.engine;

import java.util.*;

import edu.stanford.peer.rbtm.credential.*;
import edu.stanford.peer.rbtm.util.*;

/**
 * The class AbstractProofGraph represents a proof graph.  It <OL>
 * <LI> makes sure that the same node is not added more than once
 * <LI> makes sure that the same edge is not added more than once </OL>
 * If one wants to implement priority queue, one should extend this
 * class.
 */
public interface ProofGraph extends SolutionFilter
{
    /** Add a node into the worklist for forward processing */
    ProofNode addForwardNode(EntityExpression roleExp);
	
    /** Add a node into the worklist for backward processing */
    ProofNode addBackwardNode (EntityExpression roleExp);

    /** Search graph for credentials based on their right hand side (RHS) */
    Iterator findCredentialsBySubject(EntityExpression re);

    /** Search graph for credentials w/subject intersection matching part */
    Iterator findCredentialsByPartialSubject(EntityExpression part);

    /** Search graph for credentials based on their left hand side (LHS) */
    Iterator findCredentialsDefiningRole(Role r);

    /** Find all the members of a role expression */
    ResultEvidenceMap backwardSearch(EntityExpression roleExp);

    /** Find all the roles to which a role expression belongs */
    ResultEvidenceMap forwardSearch(EntityExpression roleExp);

    /** Public accessor method for the predicate if any for this graph. */
    Predicate getPredicate();

    /** Utility function for composing a credential chain */
    public HashSet getChain(EntityExpression source, EntityExpression target); 

}