| /* |
| * 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.Lib ; |
| import org.apache.jena.graph.Node ; |
| import org.apache.jena.sparql.function.FunctionEnv ; |
| import org.apache.jena.sparql.util.Symbol ; |
| |
| public abstract class ExprSystem extends ExprFunction0 |
| { |
| protected final Symbol systemSymbol ; |
| |
| protected ExprSystem(String fName, Symbol systemSymbol) |
| { |
| super(fName) ; |
| this.systemSymbol = systemSymbol ; |
| } |
| |
| @Override |
| public NodeValue eval(FunctionEnv env) |
| { |
| Object obj = env.getContext().get(systemSymbol) ; |
| |
| if ( obj == null ) |
| throw new ExprEvalException("null for system symbol: "+systemSymbol) ; |
| if ( ! ( obj instanceof Node ) ) |
| throw new ExprEvalException("ExprSystem: Not a Node: "+Lib.className(obj)) ; |
| |
| Node n = (Node)obj ; |
| if ( n == null ) |
| throw new ExprEvalException("No value for system variable: "+systemSymbol) ; |
| NodeValue nv = NodeValue.makeNode(n) ; |
| return nv ; |
| } |
| } |