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  package org.apache.cayenne.dba.sybase;
  
  import org.apache.cayenne.access.sqlbuilder.sqltree.EmptyNode;
  import org.apache.cayenne.access.sqlbuilder.sqltree.FunctionNode;
  import org.apache.cayenne.access.sqlbuilder.sqltree.LimitOffsetNode;
  import org.apache.cayenne.access.sqlbuilder.sqltree.Node;
  import org.apache.cayenne.access.sqlbuilder.sqltree.NodeType;
  import org.apache.cayenne.access.sqlbuilder.sqltree.OpExpressionNode;
  import org.apache.cayenne.access.sqlbuilder.sqltree.TextNode;
  import org.apache.cayenne.access.sqlbuilder.sqltree.TopNode;
  import org.apache.cayenne.access.translator.select.BaseSQLTreeProcessor;
  
  /**
   * @since 4.2
   */
  public class SybaseSQLTreeProcessor extends BaseSQLTreeProcessor {
  
      @Override
      protected void onLimitOffsetNode(Node parent, LimitOffsetNode child, int index) {
          // SQLServer uses "SELECT DISTINCT TOP N" or "SELECT TOP N" instead of LIMIT
          // Offset will be calculated in-memory
          replaceChild(parent, index, new EmptyNode(), false);
          if(child.getLimit() > 0) {
              int limit = child.getLimit() + child.getOffset();
              // we have root actually as input for processor, but it's better to keep processor stateless
              // root shouldn't be far from limit's parent (likely it will be parent itself)
              Node root = getRoot(parent);
              int idx = 0;
              if(root.getChild(0).getType() == NodeType.DISTINCT) {
                  idx = 1;
              }
              root.addChild(idx, new TopNode(limit));
          }
      }
  
      private Node getRoot(Node node) {
          while(node.getParent() != null) {
              node = node.getParent();
          }
          return node;
      }
  
      @Override
      protected void onFunctionNode(Node parent, FunctionNode child, int index) {
          String functionName = child.getFunctionName();
          Node replacement = null;
          switch (functionName) {
              case "LENGTH":
                  replacement = new FunctionNode("LEN", child.getAlias(), true);
                  break;
              case "LOCATE":
                  replacement = new FunctionNode("CHARINDEX", child.getAlias(), true);
                  break;
              case "MOD":
                  replacement = new OpExpressionNode("%");
                  break;
              case "TRIM":
                  Node rtrim = new FunctionNode("RTRIM", null, true);
                  replacement = new FunctionNode("LTRIM", child.getAlias(), true);
                  for(int i=0; i<child.getChildrenCount(); i++) {
                      rtrim.addChild(child.getChild(i));
                  }
                  replacement.addChild(rtrim);
                  parent.replaceChild(index, replacement);
                  return;
              case "CURRENT_DATE":
                  replacement = new FunctionNode("{fn CURDATE()}", child.getAlias(), false);
                  break;
              case "CURRENT_TIME":
                  replacement = new FunctionNode("{fn CURTIME()}", child.getAlias(), false);
                  break;
              case "CURRENT_TIMESTAMP":
                  replacement = new FunctionNode("CURRENT_TIMESTAMP", child.getAlias(), false);
                  break;
  
              case "YEAR":
              case "MONTH":
              case "WEEK":
              case "DAY_OF_YEAR":
              case "DAY":
              case "DAY_OF_MONTH":
              case "DAY_OF_WEEK":
              case "HOUR":
              case "MINUTE":
              case "SECOND":
                  replacement = new FunctionNode("DATEPART", child.getAlias(), true);
                  switch (functionName) {
                      case "DAY_OF_MONTH":
                          functionName = "DAY";
                          break;
                      case "DAY_OF_WEEK":
                          functionName = "WEEKDAY";
                          break;
                      case "DAY_OF_YEAR":
                          functionName = "DAYOFYEAR";
                          break;
                  }
                  replacement.addChild(new TextNode(functionName));
                  break;
          }
  
          if(replacement != null) {
              replaceChild(parent, index, replacement);
          }
      }
  
  }
  