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  package org.apache.cayenne.access.translator.select;
  
  import java.util.List;
  
  import org.apache.cayenne.access.sqlbuilder.ExpressionNodeBuilder;
  import org.apache.cayenne.access.sqlbuilder.JoinNodeBuilder;
  import org.apache.cayenne.access.sqlbuilder.NodeBuilder;
  import org.apache.cayenne.map.DbAttribute;
  import org.apache.cayenne.map.DbJoin;
  
  import static org.apache.cayenne.access.sqlbuilder.SQLBuilder.*;
  
  /**
   * @since 4.2
   */
  class TableTreeStage implements TranslationStage {
  
      @Override
      public void perform(TranslatorContext context) {
          context.getTableTree().visit(node -> {
              NodeBuilder tableNode = table(node.getEntity()).as(node.getTableAlias());
              if(node.getRelationship() != null) {
                  tableNode = getJoin(node, tableNode).on(getJoinExpression(context, node));
              }
              context.getSelectBuilder().from(tableNode);
          });
      }
  
      private JoinNodeBuilder getJoin(TableTreeNode node, NodeBuilder table) {
          switch (node.getJoinType()) {
              case INNER:
                  return join(table);
              case LEFT_OUTER:
                  return leftJoin(table);
              default:
                  throw new IllegalArgumentException("Unsupported join type: " + node.getJoinType());
          }
      }
  
      private NodeBuilder getJoinExpression(TranslatorContext context, TableTreeNode node) {
          List<DbJoin> joins = node.getRelationship().getJoins();
  
          ExpressionNodeBuilder expressionNodeBuilder = null;
          String sourceAlias = context.getTableTree().aliasForPath(node.getAttributePath().parent());
          for (DbJoin dbJoin : joins) {
              DbAttribute src = dbJoin.getSource();
              DbAttribute dst = dbJoin.getTarget();
              ExpressionNodeBuilder joinExp = table(sourceAlias).column(src)
                      .eq(table(node.getTableAlias()).column(dst));
  
              if (expressionNodeBuilder != null) {
                  expressionNodeBuilder = expressionNodeBuilder.and(joinExp);
              } else {
                  expressionNodeBuilder = joinExp;
              }
          }
  
          return expressionNodeBuilder;
      }
  }
  