| /* |
| * 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.sparql.engine.binding.Binding ; |
| import org.apache.jena.sparql.function.FunctionEnv ; |
| import org.apache.jena.sparql.sse.Tags ; |
| |
| public class E_Bound extends ExprFunction1 |
| { |
| private static final String symbol = Tags.tagBound ; |
| boolean isBound = false ; |
| |
| public E_Bound(Expr expr) |
| { |
| super(expr, symbol) ; |
| } |
| |
| @Override |
| public NodeValue evalSpecial(Binding binding, FunctionEnv env) { |
| // See also ExprLib.evalOrNull. |
| // This code predates that; it handles exceptions |
| // slightly differently (VariableNotBoundException not |
| // a general ExprEvalException). |
| |
| if ( expr.isConstant() ) |
| // The case of the variable having been substituted for a constant. |
| // Note: this has often been optimized away by constant folding |
| // (ExprTransformConstantFold) which called eval(NodeValue x) -> TRUE. |
| return NodeValue.TRUE ; |
| |
| if ( expr.isVariable() ) |
| // The case of the expr being a single variable. |
| return NodeValue.booleanReturn(binding.contains(expr.asVar())) ; |
| |
| // General expression. This case can't be written in SPARQL |
| // but we keep the code general in case some optimization rewrite |
| // or algebra expression uses the generalized feature. |
| try { |
| expr.eval(binding, env) ; |
| return NodeValue.TRUE ; |
| } catch (VariableNotBoundException ex) { |
| return NodeValue.FALSE ; |
| } |
| } |
| |
| @Override |
| public NodeValue eval(NodeValue x) { return NodeValue.TRUE ; } |
| |
| @Override |
| public Expr copy(Expr expr) { return new E_Bound(expr) ; } |
| } |