/*
 * 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.engine.iterator;

import java.util.List ;

import org.apache.jena.atlas.io.IndentedWriter ;
import org.apache.jena.atlas.lib.Lib ;
import org.apache.jena.atlas.lib.ListUtils ;
import org.apache.jena.sparql.core.Var ;
import org.apache.jena.sparql.engine.ExecutionContext ;
import org.apache.jena.sparql.engine.QueryIterator ;
import org.apache.jena.sparql.engine.binding.Binding ;
import org.apache.jena.sparql.engine.binding.BindingProject ;
import org.apache.jena.sparql.serializer.SerializationContext ;


public class QueryIterProject extends QueryIterConvert
{
    List<Var> projectionVars ;

    public QueryIterProject(QueryIterator input, List<Var> vars, ExecutionContext qCxt)
    {
        super(input, project(vars, qCxt), qCxt) ;
        projectionVars = vars ;
    }

    static QueryIterConvert.Converter project(List<Var> vars, ExecutionContext qCxt)
    {
        return new Projection(vars, qCxt) ;
    }
    
    public List<Var> getProjectionVars()   { return projectionVars ; }

    @Override
    protected void details(IndentedWriter out, SerializationContext sCxt)
    {
        out.print(Lib.className(this)) ;
        out.print(" ") ;
        ListUtils.print(out, projectionVars) ;
    }
    
    static
    class Projection implements QueryIterConvert.Converter
    {
        List<Var> projectionVars ;

        Projection(List<Var> vars, ExecutionContext qCxt)
        { 
            this.projectionVars = vars ;
        }

        @Override
        public Binding convert(Binding bind)
        {
            return new BindingProject(projectionVars, bind) ;
        }
    }
}