/*
* 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 com.hp.hpl.jena.sparql.function.library;
//import org.apache.commons.logging.*;
import com.hp.hpl.jena.query.QueryBuildException ;
import com.hp.hpl.jena.sparql.ARQInternalErrorException ;
import com.hp.hpl.jena.sparql.engine.binding.Binding ;
import com.hp.hpl.jena.sparql.expr.Expr ;
import com.hp.hpl.jena.sparql.expr.ExprEvalException ;
import com.hp.hpl.jena.sparql.expr.ExprList ;
import com.hp.hpl.jena.sparql.expr.NodeValue ;
import com.hp.hpl.jena.sparql.function.Function ;
import com.hp.hpl.jena.sparql.function.FunctionEnv ;
/** Function that evaluates an expression - catches evaluation failures
* and returns false.
* Mainly used in extensions.
* Would be better if that were eval and this were "safe" or somesuch */
public class eval implements Function
{
@Override
public void build(String uri, ExprList args)
{
if ( args.size() != 1 )
throw new QueryBuildException("'eval' takes one argument") ;
}
/** Processes unevaluated arguments */
@Override
public NodeValue exec(Binding binding, ExprList args, String uri, FunctionEnv env)
{
if ( args == null )
// The contract on the function interface is that this should not happen.
throw new ARQInternalErrorException("function eval: Null args list") ;
if ( args.size() != 1 )
throw new ARQInternalErrorException("function eval: Arg list not of size 1") ;
Expr ex = args.get(0) ;
try {
NodeValue v = ex.eval(binding, env) ;
return v ;
} catch (ExprEvalException evalEx)
{
return NodeValue.FALSE ;
}
}
}