| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.apache.jena.sparql.expr; |
| |
| import org.apache.jena.atlas.lib.InternalErrorException ; |
| import org.apache.jena.sparql.engine.binding.Binding ; |
| import org.apache.jena.sparql.function.FunctionEnv ; |
| import org.apache.jena.sparql.graph.NodeTransform ; |
| |
| /** Marker, used in place of a null. |
| * This may be tested for using {@code ==} */ |
| |
| //public /*package*/ class ExprNone extends ExprVar { // extends ExprNode { |
| // |
| // /*package*/ static Expr NONE0 = new ExprNone() ; |
| // |
| // private ExprNone() { super("") ; } |
| //} |
| |
| public class ExprNone extends ExprNode { |
| |
| /*package*/ static Expr NONE0 = new ExprNone() ; |
| private ExprNone() {} |
| |
| @Override public void visit(ExprVisitor visitor) { visitor.visit(this); } |
| |
| @Override public NodeValue eval(Binding binding, FunctionEnv env) { |
| throw new InternalErrorException("Attempt to eval ExprNone") ; |
| } |
| |
| @Override |
| public int hashCode() { |
| return -999999 ; |
| } |
| |
| @Override |
| public boolean equals(Expr other, boolean bySyntax) { |
| return other == this ; |
| } |
| |
| @Override |
| public Expr copySubstitute(Binding binding) { |
| return this ; |
| } |
| |
| @Override |
| public Expr applyNodeTransform(NodeTransform transform) { |
| return this ; |
| } |
| } |