plugins/org.eclipse.wst.common.project.facet.core/src/org/eclipse/wst/common/project/facet/core/IConstraint.java

/******************************************************************************
 * Copyright (c) 2005 BEA Systems, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Konstantin Komissarchik - initial API and implementation
 ******************************************************************************/

package org.eclipse.wst.common.project.facet.core;

import java.util.Collection;
import java.util.List;

import org.eclipse.core.runtime.IStatus;

/**
 * Models a single constraint in the constraint expression. 
 *  
 * @author <a href="mailto:kosta@bea.com">Konstantin Komissarchik</a>
 */

public interface IConstraint 
{
    /**
     * The enumeration of operator types.
     *  
     * @author <a href="mailto:kosta@bea.com">Konstantin Komissarchik</a>
     */
    
    static final class Type
    {
        public static final Type AND = new Type();
        public static final Type OR = new Type();
        public static final Type REQUIRES = new Type();
        public static final Type CONFLICTS = new Type();

        public static Type get( final String str )
        {
            if( str.equals( "and" ) )
            {
                return AND;
            }
            else if( str.equals( "or" ) )
            {
                return OR;
            }
            else if( str.equals( "requires" ) )
            {
                return REQUIRES;
            }
            else if( str.equals( "conflicts" ) )
            {
                return CONFLICTS;
            }
            else
            {
                throw new IllegalArgumentException();
            }
        }
        
        private Type() {};
    }
    
    /**
     * Returns the operator type
     * 
     * @return the operator type
     */
    
    Type getType();
    
    /**
     * Returns the list operands.
     * 
     * @return the list of operands (element type: {@link Object})
     */
    
    List getOperands();
    
    /**
     * Returns the operand at the specified position.
     * 
     * @param index the position of the operand in the list of operands
     * @return the operand
     */
    
    Object getOperand( int index );
    
    /**
     * Checks this constraint against the given set of project facets.
     * 
     * @param facets a set of project facets (element type:
     *   {@link IProjectFacetVersion})
     * @return a status object with severity of {@see IStatus#OK} if the
     *   constraint was satisfied or otherwise a {@see MultiStatus} composed of
     *   {@see ValidationProblem} status objects
     */
    
    IStatus check( Collection facets );
    
    /**
     * Checks this constraint against the given set of project facets.
     * 
     * @param facets a set of project facets (element type:
     *   {@link IProjectFacetVersion})
     * @param validateSoftDependencies if <code>true</code> soft dependencies
     *   will be treated as required
     * @return a status object with severity of {@see IStatus#OK} if the
     *   constraint was satisfied or otherwise a {@see MultiStatus} composed of
     *   {@see ValidationProblem} status objects
     */

    IStatus check( Collection facets,
                   boolean validateSoftDependencies );
}