org.apache.openjpa.jdbc.kernel.exps
Class Null

java.lang.Object
  extended by org.apache.openjpa.jdbc.kernel.exps.AbstractVal
      extended by org.apache.openjpa.jdbc.kernel.exps.Const
          extended by org.apache.openjpa.jdbc.kernel.exps.Null
All Implemented Interfaces:
Serializable, Val, Constant, Value

public class Null
extends Const

A literal null value in a filter.

Author:
Abe White
See Also:
Serialized Form

Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.openjpa.jdbc.kernel.exps.Const
Const.ConstExpState
 
Field Summary
 
Fields inherited from class org.apache.openjpa.jdbc.kernel.exps.AbstractVal
FALSE, TRUE
 
Fields inherited from interface org.apache.openjpa.jdbc.kernel.exps.Val
ABS_VAL, ARGS_VAL, CMP_EQUAL, COALESCE_VAL, CONCAT_VAL, FORCE_OUTER, GENERALCASE_VAL, INDEXOF_VAL, JOIN_REL, LENGTH_VAL, LOCATE_VAL, LOWER_VAL, MATH_VAL, NULL_CMP, NULLIF_VAL, SIMPLECASE_VAL, SQRT_VAL, SUBSTRING_VAL, TRIM_VAL, UPPER_VAL, VAL, WHENCONDITION_VAL, WHENSCALAR_VAL
 
Constructor Summary
Null()
           
 
Method Summary
 void appendTo(Select sel, ExpContext ctx, ExpState state, SQLBuffer sql, int index)
          Append the indexth SQL element to the given buffer.
 void calculateValue(Select sel, ExpContext ctx, ExpState state, Val other, ExpState otherState)
          Calculate and cache the SQL for this value.
 Class getType()
          Return the expected type for this value, or Object if the type is unknown.
 Object getValue(Object[] params)
          Return the value for this constant given the specified parameters.
 void setImplicitType(Class type)
          Set the implicit type of the value, based on how it is used in the filter.
 
Methods inherited from class org.apache.openjpa.jdbc.kernel.exps.Const
appendIsEmpty, appendIsNotEmpty, appendIsNotNull, appendIsNull, appendSize, getMetaData, getSQLValue, getValue, groupBy, initialize, isSQLValueNull, length, load, orderBy, select, selectColumns, setMetaData
 
Methods inherited from class org.apache.openjpa.jdbc.kernel.exps.AbstractVal
acceptVisit, appendIndex, appendType, getAlias, getId, getName, getPath, getSelectAs, isAggregate, isVariable, isXPath, setAlias, toDataStoreValue
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Null

public Null()
Method Detail

getType

public Class getType()
Description copied from interface: Value
Return the expected type for this value, or Object if the type is unknown.


setImplicitType

public void setImplicitType(Class type)
Description copied from interface: Value
Set the implicit type of the value, based on how it is used in the filter. This method is only called on values who return Object from Value.getType().


getValue

public Object getValue(Object[] params)
Description copied from interface: Constant
Return the value for this constant given the specified parameters.


calculateValue

public void calculateValue(Select sel,
                           ExpContext ctx,
                           ExpState state,
                           Val other,
                           ExpState otherState)
Description copied from interface: Val
Calculate and cache the SQL for this value. This method is called before length or any append methods.

Specified by:
calculateValue in interface Val
Overrides:
calculateValue in class Const
other - the value being compared to, or null if not a comparison

appendTo

public void appendTo(Select sel,
                     ExpContext ctx,
                     ExpState state,
                     SQLBuffer sql,
                     int index)
Description copied from interface: Val
Append the indexth SQL element to the given buffer.



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