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/*
 * Copyright 2011 Revelytix Inc.
 *
 * Licensed 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 spark.spi;

import java.util.Iterator;
import java.util.List;
import java.util.Map;

import spark.api.Command;
import spark.api.Solutions;
import spark.api.exception.SparqlException;
import spark.api.rdf.RDFNode;

public class SolutionSet extends BaseSolutions implements Solutions {
  
  private final List> data;
  
  private static final int BEFORE_FIRST = -1;
  private static final int FIRST = 0;
  private volatile int cursor = BEFORE_FIRST;
  
  public SolutionSet(Command command, List vars, List> data) {
    super(command, vars);
    this.data = data;
  }
  
  @Override
  public Map getResult() {
    return data.get(cursor);
  }

  @Override
  public boolean isAfterLast() {
    return cursor >= data.size();
  }

  @Override
  public boolean isBeforeFirst() {
    return cursor == BEFORE_FIRST;
  }

  @Override
  public boolean isFirst() {
    return cursor == FIRST;
  }

  @Override
  public boolean isLast() {
    return data.size() > 0 && cursor == (data.size() - 1);
  }

  @Override
  public boolean next() {
    cursor++;
    return cursor < data.size();
  }

  @Override
  public int getRow() {
    return cursor+1;
  }

  @Override
  public Iterator> iterator() {
    return new SolutionIterator();
  }

  
  private class SolutionIterator implements Iterator> {
    int iterCursor = -1;
    
    @Override
    public boolean hasNext() {
      return (iterCursor + 1) < data.size();
    }

    @Override
    public Map next() {
      iterCursor++;
      if (data.size() > 0 && iterCursor < data.size()) {
        return data.get(iterCursor);
      } else {
        return null;
      }
    }

    @Override
    public void remove() {
      throw new SparqlException("remove not supported on Solutions");
    }
    
  }

}