001/*
002 * Copyright (c) 2007-2016 Concurrent, Inc. All Rights Reserved.
003 *
004 * Project and contact information: http://www.cascading.org/
005 *
006 * This file is part of the Cascading project.
007 *
008 * Licensed under the Apache License, Version 2.0 (the "License");
009 * you may not use this file except in compliance with the License.
010 * You may obtain a copy of the License at
011 *
012 *     http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing, software
015 * distributed under the License is distributed on an "AS IS" BASIS,
016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017 * See the License for the specific language governing permissions and
018 * limitations under the License.
019 */
020
021package cascading.flow.planner.iso.expression;
022
023import cascading.flow.planner.Scope;
024
025/**
026 * If ScopeExpression is the only edge, the {@link ScopeExpression.Applies} enum will apply,
027 * otherwise the number of edges on the target graph must match the number of edges in the expression.
028 */
029public abstract class ScopeExpression implements Expression<Scope>
030  {
031  /**
032   * Where this expression applies between ANY edge between two nodes.
033   */
034  public static final PathScopeExpression ANY = new PathScopeExpression( Applies.Any );
035  /**
036   * Where this expression applies between ALL edges between two nodes.
037   */
038  public static final PathScopeExpression ALL = new PathScopeExpression( Applies.All );
039  public static final PathScopeExpression EACH = new PathScopeExpression( Applies.Each ); // unsupported
040
041  public enum Applies
042    {
043      Any, All, Each
044    }
045
046  protected Applies applies = Applies.Any;
047
048  protected ScopeExpression()
049    {
050    }
051
052  protected ScopeExpression( Applies applies )
053    {
054    this.applies = applies;
055    }
056
057  public boolean appliesToAllPaths()
058    {
059    return applies == Applies.All;
060    }
061
062  public boolean appliesToAnyPath()
063    {
064    return applies == Applies.Any;
065    }
066
067  public boolean appliesToEachPath()
068    {
069    return applies == Applies.Each;
070    }
071
072  public boolean acceptsAll()
073    {
074    return appliesToAllPaths();
075    }
076
077  public Applies getApplies()
078    {
079    return applies;
080    }
081  }