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Supports checking an attribute set satisfies a filter
that is specified as a set of "matching" attributes.
Checking is done by determining whether the given attribute set
is a superset of the matching ones.
Author:
Rosanna Lee/**
  * Supports checking an attribute set satisfies a filter
  * that is specified as a set of "matching" attributes.
  * Checking is done by determining whether the given attribute set
  * is a superset of the matching ones.
  *
  * @author Rosanna Lee
  */

package com.sun.jndi.toolkit.dir;

import javax.naming.*;
import javax.naming.directory.*;

public class ContainmentFilter implements AttrFilter {
    private Attributes matchingAttrs;

    public ContainmentFilter(Attributes match) {
        matchingAttrs = match;
    }

    public boolean check(Attributes attrs) throws NamingException {
        return matchingAttrs == null ||
            matchingAttrs.size() == 0 ||
            contains(attrs, matchingAttrs);
    }

    // returns true if superset contains subset
    public static boolean contains(Attributes superset, Attributes subset)
        throws NamingException {
          if (subset == null)
            return true;  // an empty set is always a subset

            NamingEnumeration m = subset.getAll();
            while (m.hasMore()) {
                if (superset == null) {
                    return false;  // contains nothing
                }
                Attribute target = (Attribute) m.next();
                Attribute fromSuper = superset.get(target.getID());
                if (fromSuper == null) {
                    return false;
                } else {
                    // check whether attribute values match
                    if (target.size() > 0) {
                        NamingEnumeration vals = target.getAll();
                        while (vals.hasMore()) {
                            if (!fromSuper.contains(vals.next())) {
                                return false;
                            }
                        }
                    }
                }
            }
            return true;
        }

}