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  package org.apache.cayenne.access.translator.ejbql;
  
  import org.apache.cayenne.CayenneRuntimeException;
  import org.apache.cayenne.dba.TypesMapping;
  import org.apache.cayenne.ejbql.EJBQLBaseVisitor;
  import org.apache.cayenne.ejbql.EJBQLException;
  import org.apache.cayenne.ejbql.EJBQLExpression;
  import org.apache.cayenne.map.DbAttribute;
  import org.apache.cayenne.map.DbEntity;
  import org.apache.cayenne.map.DbRelationship;
  import org.apache.cayenne.map.ObjAttribute;
  import org.apache.cayenne.map.ObjEntity;
  import org.apache.cayenne.map.ObjRelationship;
  
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.Map;
  
  /**
   * Translator of the EJBQL select clause.
   * 
   * @since 3.0
   */
  public class EJBQLSelectColumnsTranslator extends EJBQLBaseVisitor {
  
      protected EJBQLTranslationContext context;
      private int expressionsCount;
  
      protected EJBQLSelectColumnsTranslator(EJBQLTranslationContext context) {
          this.context = context;
      }
  
      @Override
      public boolean visitSelectExpression(EJBQLExpression expression) {
          if (expressionsCount++ > 0) {
              context.append(",");
          }
  
          return true;
      }
  
      @Override
      public boolean visitAggregate(EJBQLExpression expression) {
          expression.visit(context.getTranslatorFactory().getAggregateColumnTranslator(context));
          return false;
      }
  
      @Override
      public boolean visitDbPath(EJBQLExpression expression, int finishedChildIndex) {
  
          EJBQLDbPathTranslator pathTranslator = new EJBQLDbPathTranslator(context) {
              @Override
              protected void appendMultiColumnPath(EJBQLMultiColumnOperand operand) {
                  throw new EJBQLException("Can't use multi-column paths in column clause");
              }
  
              @Override
              protected void processTerminatingRelationship(DbRelationship relationship) {
                  Map<String, String> xfields = null;
                  if (context.isAppendingResultColumns()) {
                      xfields = context.nextEntityResult().getFields();
                  }
  
                  final Map<String, String> fields = xfields;
  
                  DbEntity table = relationship.getTargetEntity();
                  Collection<DbAttribute> dbAttr = table.getAttributes();
  
                  if (dbAttr.size() > 0) {
                      resolveJoin();
                  }
  
                  String alias = this.lastAlias != null
                          ? lastAlias
                          : context.getTableAlias(idPath, context.getQuotingStrategy().quotedFullyQualifiedName(table));
  
                  boolean first = true;
                  for (DbAttribute dbAttribute : dbAttr) {
                      context.append(!first ? ", " : " ");
                      appendColumn(TypesMapping.getJavaBySqlType(dbAttribute), alias, dbAttribute,
                              fields != null ? fields.get(dbAttribute.getName()) : "");
                      first = false;
                  }
              }
  
              @Override
              protected void processTerminatingAttribute(DbAttribute attribute) {
                  String alias = this.lastAlias != null
                          ? lastAlias
                          : context.getTableAlias(idPath, context.getQuotingStrategy().quotedFullyQualifiedName(currentEntity));
  
                  appendColumn(TypesMapping.getJavaBySqlType(attribute), alias, attribute,
                          context.isAppendingResultColumns() ? context.nextColumnAlias() : "");
              }
          };
  
          expression.visit(pathTranslator);
          return false;
      }
  
      @Override
      public boolean visitPath(EJBQLExpression expression, int finishedChildIndex) {
  
          EJBQLPathTranslator pathTranslator = new EJBQLPathTranslator(context) {
  
              @Override
              protected void appendMultiColumnPath(EJBQLMultiColumnOperand operand) {
                  throw new EJBQLException("Can't use multi-column paths in column clause");
              }
  
              @Override
              protected void processTerminatingRelationship(ObjRelationship relationship) {
  
                  Map<String, String> xfields = null;
                  if (context.isAppendingResultColumns()) {
                      xfields = context.nextEntityResult().getFields();
                  }
  
                  final Map<String, String> fields = xfields;
  
                  Collection<DbAttribute> dbAttr = relationship.getTargetEntity().getDbEntity().getAttributes();
  
                  DbRelationship dbRelationship = relationship.getDbRelationships().get(0);
                  DbEntity table = dbRelationship.getTargetEntity();
  
                  Iterator<DbAttribute> it = dbAttr.iterator();
                  if (dbAttr.size() > 0) {
                      resolveJoin();
                  }
  
                  String alias = this.lastAlias != null
                          ? lastAlias
                          : context.getTableAlias(idPath, context.getQuotingStrategy().quotedFullyQualifiedName(table));
  
                  boolean first = true;
                  while (it.hasNext()) {
  
                      context.append(!first ? ", " : " ");
  
                      DbAttribute dbAttribute = it.next();
                      appendColumn(TypesMapping.getJavaBySqlType(dbAttribute), alias, dbAttribute,
                              fields != null ? fields.get(dbAttribute.getName()) : "");
  
                      first = false;
                  }
  
              }
  
              @Override
              protected void processTerminatingAttribute(ObjAttribute attribute) {
                  DbEntity table = currentEntity.getDbEntity();
                  String alias = this.lastAlias != null
                          ? lastAlias
                          : context.getTableAlias(idPath, context.getQuotingStrategy().quotedFullyQualifiedName(table));
                  if (attribute.isFlattened()) {
                      Iterator<?> dbPathIterator = attribute.getDbPathIterator();
                      EJBQLTableId lhsId = new EJBQLTableId(idPath);
  
                      while (dbPathIterator.hasNext()) {
                          Object pathPart = dbPathIterator.next();
                          // DbRelationships not processed, because they will be processed later when appending table
                          if (pathPart == null) {
                              throw new CayenneRuntimeException("ObjAttribute has no component: %s", attribute.getName());
                          } else if (pathPart instanceof DbAttribute) {
                              DbAttribute dbAttribute = (DbAttribute) pathPart;
                              appendColumn(attribute.getType(),
                                      context.getTableAlias(lhsId.getEntityId(), context.getQuotingStrategy()
                                              .quotedFullyQualifiedName(dbAttribute.getEntity())),
                                      dbAttribute, context.isAppendingResultColumns() ? context.nextColumnAlias() : "");
  
                          }
  
                      }
  
                  } else {
  
                      DbAttribute dbAttribute = attribute.getDbAttribute();
  
                      appendColumn(attribute.getType(), alias, dbAttribute,
                              context.isAppendingResultColumns() ? context.nextColumnAlias() : "");
                  }
              }
  
          };
          expression.visit(pathTranslator);
          return false;
      }
  
      @Override
      public boolean visitIdentifier(EJBQLExpression expression) {
          expression.visit(context.getTranslatorFactory().getIdentifierColumnsTranslator(context));
          return false;
      }
  
      public void appendColumn(String javaType, String alias, DbAttribute dbAttribute, String columnAlias) {
          if (context.isAppendingResultColumns()) {
              context.append(" #result('");
          } else {
              context.append(' ');
          }
  
          context.append(alias).append('.').append(context.getQuotingStrategy().quotedName(dbAttribute));
  
          if (context.isAppendingResultColumns()) {
              // String columnAlias = context.nextColumnAlias();
  
              // TODO: andrus 6/27/2007 - the last parameter is an unofficial
              //       "jdbcType" pending CAY-813 implementation, switch to #column directive
              context.append("' '").append(javaType).append("' '").append(columnAlias).append("' '").append(columnAlias)
                      .append("' " + dbAttribute.getType()).append(")");
          }
  
      }
  
  }
  