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org/hibernate/hql/HolderInstantiator.java
//$Id: HolderInstantiator.java 9636 2006-03-16 14:14:48Z [email protected] $
package org.hibernate.hql;

import java.lang.reflect.Constructor;

import org.hibernate.transform.AliasToBeanConstructorResultTransformer;
import org.hibernate.transform.ResultTransformer;
import org.hibernate.transform.Transformers;

/**
 @author Gavin King
 */
public final class HolderInstantiator {
    
  public static final HolderInstantiator NOOP_INSTANTIATOR = new HolderInstantiator(null,null);
  
  private final ResultTransformer transformer;
  private final String[] queryReturnAliases;
  
  public static HolderInstantiator getHolderInstantiator(ResultTransformer selectNewTransformer, ResultTransformer customTransformer, String[] queryReturnAliases) {
    if(selectNewTransformer!=null) {
      return new HolderInstantiator(selectNewTransformer, queryReturnAliases);
    else {
      return new HolderInstantiator(customTransformer, queryReturnAliases);
    }
  }
  
  public static ResultTransformer createSelectNewTransformer(Constructor constructor, boolean returnMaps, boolean returnLists) {
    if constructor != null ) {
      return new AliasToBeanConstructorResultTransformer(constructor);
    }
    else if returnMaps ) {
      return Transformers.ALIAS_TO_ENTITY_MAP;      
    }
    else if returnLists ) {
      return Transformers.TO_LIST;
    }    
    else {
      return null;
    }
  }
  
  static public HolderInstantiator createClassicHolderInstantiator(Constructor constructor, 
      ResultTransformer transformer) {
    if constructor != null ) {
      return new HolderInstantiator(new AliasToBeanConstructorResultTransformer(constructor)null);
    }
    else {
      return new HolderInstantiator(transformer, null);
    }
  }
  
  public HolderInstantiator
      ResultTransformer transformer,
      String[] queryReturnAliases
  ) {
    this.transformer = transformer;    
    this.queryReturnAliases = queryReturnAliases;
  }
  
  public boolean isRequired() {
    return transformer!=null;
  }
  
  public Object instantiate(Object[] row) {
    if(transformer==null) {
      return row;
    else {
      return transformer.transformTuple(row, queryReturnAliases);
    }
  }  
  
  public String[] getQueryReturnAliases() {
    return queryReturnAliases;
  }

  public ResultTransformer getResultTransformer() {
    return transformer;
  }

}