/*
* 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;
import java.util.ArrayList ;
import java.util.Iterator ;
import java.util.List ;
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.ExprList ;
import com.hp.hpl.jena.sparql.expr.NodeValue ;
import com.hp.hpl.jena.sparql.util.Context ;
/** Interface to value-testing extensions to the expression evaluator. */
public abstract class FunctionBase implements Function
{
String uri = null ;
protected ExprList arguments = null ;
private FunctionEnv env ;
@Override
public final void build(String uri, ExprList args)
{
this.uri = uri ;
arguments = args ;
checkBuild(uri, args) ;
}
@Override
public NodeValue exec(Binding binding, ExprList args, String uri, FunctionEnv env)
{
// This is merely to allow functions to be
// It duplicates code in E_Function/ExprFunctionN.
this.env = env ;
if ( args == null )
// The contract on the function interface is that this should not happen.
throw new ARQInternalErrorException("FunctionBase: Null args list") ;
List<NodeValue> evalArgs = new ArrayList<NodeValue>() ;
for ( Iterator<Expr> iter = args.iterator() ; iter.hasNext() ; )
{
Expr e = iter.next() ;
NodeValue x = e.eval(binding, env) ;
evalArgs.add(x) ;
}
NodeValue nv = exec(evalArgs) ;
arguments = null ;
return nv ;
}
/** Return the Context object for this execution */
public Context getContext() { return env.getContext() ; }
/** Function call to a list of evaluated argument values */
public abstract NodeValue exec(List<NodeValue> args) ;
public abstract void checkBuild(String uri, ExprList args) ;
// /** Get argument, indexing from 1 **/
// public NodeValue getArg(int i)
// {
// i = i-1 ;
// if ( i < 0 || i >= arguments.size() )
// return null ;
// return (NodeValue)arguments.get(i) ;
// }
}