org.apache.openjpa.kernel.exps
Class Val

java.lang.Object
  org.apache.openjpa.kernel.exps.Val

All Implemented Interfaces:

Serializable, Value

Direct Known Subclasses:

CandidatePath, Coalesce, NullIf, SimpleCase

public abstract class Val
extends Object
implements Value

An in-memory representation of a Value.

Author:

Abe White

See Also:

Serialized Form

Constructor Summary

Val()

Method Summary

void	acceptVisit(ExpressionVisitor visitor) Accept a visit from a tree visitor.
protected Collection	eval(Collection candidates, Object orig, StoreContext ctx, Object[] params) Return a list of values resulting from evaluating each given candidate.
protected abstract Object	eval(Object candidate, Object orig, StoreContext ctx, Object[] params) Return this value for the given candidate.
Object	evaluate(Collection candidates, Object orig, StoreContext ctx, Object[] params) Return this value as an aggregate projection on the given group of candidates.
Object	evaluate(Object candidate, Object orig, StoreContext ctx, Object[] params) Return this value as a projection on the given candidate.
String	getAlias() Return select item alias
ClassMetaData	getMetaData() Return any associated persistent type.
String	getName()
Path	getPath()
Value	getSelectAs() Return 'this' concrete class if alias is set, otherwise null
boolean	isAggregate() Return true if this value is an aggregate.
boolean	isVariable() Return true if this value is a variable.
boolean	isXPath() Return true if this value is an XML Path.
void	setAlias(String alias) Set select item alias
void	setMetaData(ClassMetaData meta) Associate a persistent type with this value.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.openjpa.kernel.exps.Value

getType, setImplicitType

Constructor Detail

Val

public Val()

Method Detail

evaluate

public final Object evaluate(Object candidate,
                             Object orig,
                             StoreContext ctx,
                             Object[] params)

Return this value as a projection on the given candidate.

evaluate

public final Object evaluate(Collection candidates,
                             Object orig,
                             StoreContext ctx,
                             Object[] params)

Return this value as an aggregate projection on the given group of candidates.

eval

protected abstract Object eval(Object candidate,
                               Object orig,
                               StoreContext ctx,
                               Object[] params)

Return this value for the given candidate.

eval

protected Collection eval(Collection candidates,
                          Object orig,
                          StoreContext ctx,
                          Object[] params)

Return a list of values resulting from evaluating each given candidate. By default, this implementation invokes #eval(Object,Object,StoreContext,Map) for each instance and packs the return value into a new list. Aggregates should override.

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

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

acceptVisit

public void acceptVisit(ExpressionVisitor visitor)

Description copied from interface: Value

Accept a visit from a tree visitor.

Specified by:

acceptVisit in interface Value

getAlias

public String getAlias()

Description copied from interface: Value

Return select item alias

Specified by:

getAlias in interface Value

setAlias

public void setAlias(String alias)

Description copied from interface: Value

Set select item alias

Specified by:

setAlias in interface Value

getSelectAs

public Value getSelectAs()

Description copied from interface: Value

Return 'this' concrete class if alias is set, otherwise null

Specified by:

getSelectAs in interface Value

getPath

public Path getPath()

Specified by:

getPath in interface Value

getName

public String getName()

Specified by:

getName in interface Value