Package edu.caltech.nanodb.expressions

Class OrderByExpression

  • public class OrderByExpression
extends java.lang.Object
    This class represents an expression that results are ordered by, as well as whether the order is ascending or descending. Lists of this object specify ordering of results from a query, as well as the ordering of tuples in a sequential file, or attributes in an ordered index.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private boolean ascending
      A flag indicating whether the results should be in ascending or descending order.
      private Expression expression
      The expression that the results should be ordered by.

    • Constructor Summary

      Constructors 
      Constructor Description
      OrderByExpression​(Expression expression)
      Initialize a new order-by object with the specified expression.
      OrderByExpression​(Expression expression, boolean ascending)
      Initialize a new order-by object with the specified expression and order.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      Expression getExpression()
      Returns the expression that results will be sorted on
      boolean isAscending()
      Returns the flag indicating whether the results should be in ascending or descending order.
      java.lang.String toString()  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Field Detail

      • expression

        private Expression expression
        The expression that the results should be ordered by.

      • ascending

        private boolean ascending
        A flag indicating whether the results should be in ascending or descending order. A value of true means ascending order.

    • Constructor Detail

      • OrderByExpression

        public OrderByExpression​(Expression expression)
        Initialize a new order-by object with the specified expression. Results will be in ascending order.
        Parameters:
        expression - The expression to order results by.

      • OrderByExpression

        public OrderByExpression​(Expression expression,
                         boolean ascending)
        Initialize a new order-by object with the specified expression and order.
        Parameters:
        expression - The expression to order results by.
        ascending - a value of true will cause the results to be in ascending order; a value of false will cause them to be in descending order

    • Method Detail

      • getExpression

        public Expression getExpression()
        Returns the expression that results will be sorted on
        Returns:
        the expression that results will be sorted on

      • isAscending

        public boolean isAscending()
        Returns the flag indicating whether the results should be in ascending or descending order.
        Returns:
        true if the results should be in ascending order, false otherwise.

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object