/* Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.security.acls.domain;

import org.springframework.security.acls.AclFormattingUtils;
import org.springframework.security.acls.Permission;


/**
 * Represents a <code>Permission</code> that is constructed at runtime from other permissions.
 * 
 * <p>Methods return <code>this</code>, in order to facilitate method chaining.</p>
 *
 * @author Ben Alex
 * @version $Id$
 */
public class CumulativePermission extends AbstractPermission {

    private String pattern = THIRTY_TWO_RESERVED_OFF;

    public CumulativePermission() {
    	super(0, ' ');
    }
    
    public CumulativePermission clear(Permission permission) {
        this.mask &= ~permission.getMask();
        this.pattern = AclFormattingUtils.demergePatterns(this.pattern, permission.getPattern());

        return this;
    }

    public CumulativePermission clear() {
        this.mask = 0;
        this.pattern = THIRTY_TWO_RESERVED_OFF;

        return this;
    }
    
    public CumulativePermission set(Permission permission) {
        this.mask |= permission.getMask();
        this.pattern = AclFormattingUtils.mergePatterns(this.pattern, permission.getPattern());

        return this;
    }
    
    public String getPattern() {
        return this.pattern;
    }

}
