001/*
002 * Copyright (c) 2016-2017 Chris K Wensel. 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.nested.core;
022
023import java.util.function.Predicate;
024
025import heretical.pointer.path.NestedPointerCompiler;
026import heretical.pointer.path.Pointer;
027
028/**
029 *
030 */
031public abstract class BasePointerFilter<Node, Result> implements Predicate<Node>
032  {
033  final NestedPointerCompiler<Node, Result> nestedPointerCompiler;
034  final String stringPointer;
035
036  transient Pointer<Node> pointer;
037
038  public BasePointerFilter( NestedPointerCompiler<Node, Result> nestedPointerCompiler, String pointer )
039    {
040    this.nestedPointerCompiler = nestedPointerCompiler;
041    this.stringPointer = pointer;
042
043    // verify the pointer is valid
044    nodePointer();
045    }
046
047  protected Pointer<Node> nodePointer()
048    {
049    if( pointer == null )
050      pointer = nestedPointerCompiler.compile( stringPointer );
051
052    return pointer;
053    }
054
055  @Override
056  public boolean test( Node node )
057    {
058    return compares( nodePointer().at( node ) );
059    }
060
061  protected abstract boolean compares( Node at );
062  }