Class IsEmptyExpression

  extended by org.apache.openjpa.jdbc.kernel.exps.IsEmptyExpression
All Implemented Interfaces:
Serializable, Exp, Expression

 class IsEmptyExpression
extends Object
implements Exp

Tests whether the given value is empty.

Abe White

Constructor Summary
IsEmptyExpression(Val val)
Method Summary
 void acceptVisit(ExpressionVisitor visitor)
          Accept a visit from a tree visitor.
 void appendTo(Select sel, ExpContext ctx, ExpState state, SQLBuffer buf)
          Append the SQL for this expression to the given buffer.
 ExpState initialize(Select sel, ExpContext ctx, Map contains)
          Initialize the expression.
 void selectColumns(Select sel, ExpContext ctx, ExpState state, boolean pks)
          Select just the columns for this expression.
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public IsEmptyExpression(Val val)
Constructor. Supply value to test.

Method Detail


public ExpState initialize(Select sel,
                           ExpContext ctx,
                           Map contains)
Description copied from interface: Exp
Initialize the expression. This method should recursively initialize any sub-expressions or values.

Specified by:
initialize in interface Exp
contains - map of relation paths to the number of times the paths appear in a contains() expression; used to ensure paths used for contains() within the same AND expression used different aliases


public void appendTo(Select sel,
                     ExpContext ctx,
                     ExpState state,
                     SQLBuffer buf)
Description copied from interface: Exp
Append the SQL for this expression to the given buffer. The SQL should optionally include any joins this expression needs.

Specified by:
appendTo in interface Exp


public void selectColumns(Select sel,
                          ExpContext ctx,
                          ExpState state,
                          boolean pks)
Description copied from interface: Exp
Select just the columns for this expression.

Specified by:
selectColumns in interface Exp


public void acceptVisit(ExpressionVisitor visitor)
Description copied from interface: Expression
Accept a visit from a tree visitor.

Specified by:
acceptVisit in interface Expression

Copyright © 2006-2010 Apache Software Foundation. All Rights Reserved.