/Users/green/Documents/workspace/DavisDB_public/ProjectOperator.h

/*
 *  ProjectOperator.h
 *  DavisDB
 *
 *  Created by Mingmin Chen on 5/6/10.
 *  Copyright 2010 UCD. All rights reserved.
 *
 */


#ifndef PROJECTION_H_
#define PROJECTION_H_

#include "IQueryOperator.h"

class RelationAttribute;

class ProjectOperator : public IQueryOperator {
public:
        ProjectOperator();
        ReturnCode initialize(IQueryOperator* child, int nAttributes,
                                        const RelationAttribute attributes[]);
        ~ProjectOperator();
        ReturnCode openExecution();
        ReturnCode closeExecution();
        ReturnCode getNextRecord(Record* record);
        int getArity();
        void getSchema(RelationAttributeInfo attributes[]) ;
        void printSubtree(int indent) ;
private:
        RelationAttributeInfo* attributes_;
        int nAttributes_;
        int childRecordSize_;   
        struct ProjectionSlot {
                int offset;
                int length;
        };
        ProjectionSlot* slots_;
        IQueryOperator* child_;
        Record* childRecord_;
};

#endif

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