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 }