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

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

public class Null
extends Object

A literal null value in a filter.

Author:
Abe White
See Also:
Serialized Form

Nested Class Summary
protected static class Const.ConstExpState
          Constant expression state.
 
Field Summary
protected static String FALSE
           
protected static String TRUE
           
 
Fields inherited from interface org.apache.openjpa.jdbc.kernel.exps.Val
ABS_VAL, ARGS_VAL, CONCAT_VAL, FORCE_OUTER, INDEXOF_VAL, JOIN_REL, LENGTH_VAL, LOCATE_VAL, LOWER_VAL, MATH_VAL, NULL_CMP, SQRT_VAL, SUBSTRING_VAL, TRIM_VAL, UPPER_VAL, VAL
 
Constructor Summary
Null()
           
 
Method Summary
 void acceptVisit(ExpressionVisitor visitor)
          Accept a visit from a tree visitor.
 void appendIsEmpty(Select sel, ExpContext ctx, ExpState state, SQLBuffer sql)
          Append the SQL testing whether this value is empty to the given buffer.
 void appendIsNotEmpty(Select sel, ExpContext ctx, ExpState state, SQLBuffer sql)
          Append the SQL testing whether this value is not empty to the given buffer.
 void appendIsNotNull(Select sel, ExpContext ctx, ExpState state, SQLBuffer sql)
          Append the SQL testing whether this value is not null to the given buffer.
 void appendIsNull(Select sel, ExpContext ctx, ExpState state, SQLBuffer sql)
          Append the SQL testing whether this value is null to the given buffer.
 void appendSize(Select sel, ExpContext ctx, ExpState state, SQLBuffer sql)
          Append the SQL checking the size of this value.
 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.
 int getId()
           
 ClassMetaData getMetaData()
          Return any associated persistent type.
 Object getSQLValue(Select sel, ExpContext ctx, ExpState state)
          Return the SQL value of this constant.
 Class getType()
          Return the expected type for this value, or Object if the type is unknown.
 Object getValue(ExpContext ctx, ExpState state)
          Return the value of this constant.
 Object getValue(Object[] params)
          Return the value for this constant given the specified parameters.
 void groupBy(Select sel, ExpContext ctx, ExpState state)
          Group by this value.
 ExpState initialize(Select sel, ExpContext ctx, int flags)
          Initialize the value.
 boolean isAggregate()
          Return true if this value is an aggregate.
 boolean isSQLValueNull(Select sel, ExpContext ctx, ExpState state)
          Return true if this constant's SQL value is equivalent to NULL.
 boolean isVariable()
          Return true if this value is a variable.
 boolean isXPath()
          Return true if this value is an XML Path.
 int length(Select sel, ExpContext ctx, ExpState state)
          Return the number of SQL elements in this value.
 Object load(ExpContext ctx, ExpState state, Result res)
          Load the data for this value.
 void orderBy(Select sel, ExpContext ctx, ExpState state, boolean asc)
          Order by this value.
 void select(Select sel, ExpContext ctx, ExpState state, boolean pks)
          Select the data for this value.
 void selectColumns(Select sel, ExpContext ctx, ExpState state, boolean pks)
          Select just the columns for this value.
 void setImplicitType(Class type)
          Set the implicit type of the value, based on how it is used in the filter.
 void setMetaData(ClassMetaData meta)
          Associate a persistent type with this value.
 Object toDataStoreValue(Select sel, ExpContext ctx, ExpState state, Object val)
          Return the datastore value of the given object in the context of this value.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

TRUE

protected static final String TRUE
See Also:
Constant Field Values

FALSE

protected static final String FALSE
See Also:
Constant Field Values
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
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.


getMetaData

public ClassMetaData getMetaData()
Description copied from interface: Value
Return any associated persistent type.

Specified by:
getMetaData in interface Value

setMetaData

public void setMetaData(ClassMetaData meta)
Description copied from interface: Value
Associate a persistent type with this value.

Specified by:
setMetaData in interface Value

getSQLValue

public Object getSQLValue(Select sel,
                          ExpContext ctx,
                          ExpState state)
Return the SQL value of this constant.


isSQLValueNull

public boolean isSQLValueNull(Select sel,
                              ExpContext ctx,
                              ExpState state)
Return true if this constant's SQL value is equivalent to NULL.


getValue

public Object getValue(ExpContext ctx,
                       ExpState state)
Return the value of this constant. May be more robust than the parameters-only form.


initialize

public ExpState initialize(Select sel,
                           ExpContext ctx,
                           int flags)
Description copied from interface: Val
Initialize the value. This method should recursively initialize any sub-values.

Specified by:
initialize in interface Val

select

public void select(Select sel,
                   ExpContext ctx,
                   ExpState state,
                   boolean pks)
Description copied from interface: Val
Select the data for this value.

Specified by:
select in interface Val

selectColumns

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

Specified by:
selectColumns in interface Val

groupBy

public void groupBy(Select sel,
                    ExpContext ctx,
                    ExpState state)
Description copied from interface: Val
Group by this value.

Specified by:
groupBy in interface Val

orderBy

public void orderBy(Select sel,
                    ExpContext ctx,
                    ExpState state,
                    boolean asc)
Description copied from interface: Val
Order by this value.

Specified by:
orderBy in interface Val

load

public Object load(ExpContext ctx,
                   ExpState state,
                   Result res)
            throws SQLException
Description copied from interface: Val
Load the data for this value.

Specified by:
load in interface Val
Throws:
SQLException

length

public int length(Select sel,
                  ExpContext ctx,
                  ExpState state)
Description copied from interface: Val
Return the number of SQL elements in this value.

Specified by:
length in interface Val

appendIsEmpty

public void appendIsEmpty(Select sel,
                          ExpContext ctx,
                          ExpState state,
                          SQLBuffer sql)
Description copied from interface: Val
Append the SQL testing whether this value is empty to the given buffer.

Specified by:
appendIsEmpty in interface Val

appendIsNotEmpty

public void appendIsNotEmpty(Select sel,
                             ExpContext ctx,
                             ExpState state,
                             SQLBuffer sql)
Description copied from interface: Val
Append the SQL testing whether this value is not empty to the given buffer.

Specified by:
appendIsNotEmpty in interface Val

appendSize

public void appendSize(Select sel,
                       ExpContext ctx,
                       ExpState state,
                       SQLBuffer sql)
Description copied from interface: Val
Append the SQL checking the size of this value.

Specified by:
appendSize in interface Val

appendIsNull

public void appendIsNull(Select sel,
                         ExpContext ctx,
                         ExpState state,
                         SQLBuffer sql)
Description copied from interface: Val
Append the SQL testing whether this value is null to the given buffer.

Specified by:
appendIsNull in interface Val

appendIsNotNull

public void appendIsNotNull(Select sel,
                            ExpContext ctx,
                            ExpState state,
                            SQLBuffer sql)
Description copied from interface: Val
Append the SQL testing whether this value is not null to the given buffer.

Specified by:
appendIsNotNull in interface Val

isVariable

public boolean isVariable()
Description copied from interface: Value
Return true if this value is a variable.

Specified by:
isVariable in interface Value

isAggregate

public boolean isAggregate()
Description copied from interface: Value
Return true if this value is an aggregate.

Specified by:
isAggregate in interface Value

isXPath

public boolean isXPath()
Description copied from interface: Value
Return true if this value is an XML Path.

Specified by:
isXPath in interface Value

toDataStoreValue

public Object toDataStoreValue(Select sel,
                               ExpContext ctx,
                               ExpState state,
                               Object val)
Description copied from interface: Val
Return the datastore value of the given object in the context of this value.

Specified by:
toDataStoreValue in interface Val

acceptVisit

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

Specified by:
acceptVisit in interface Value

getId

public int getId()
Specified by:
getId in interface Val


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