|
||||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||
ObjectNilExpression
public final class NilExpression
Placeholder class used to represent a NIL expression, evaultates to null.
This placeholder class is allows data structures to avoid
the use of null. Please note that Expression.NIL is
not considered a Literal with value null (since the literal may have its
value changed).
| Field Summary |
|---|
| Fields inherited from interface Expression |
|---|
NIL |
| Method Summary | ||
|---|---|---|
Object |
accept(ExpressionVisitor visitor,
Object extraData)
Accepts a visitor. |
|
boolean |
equals(Object other)
Equals is defined only against Expression.NIL. |
|
Object |
evaluate(Object object)
Returns null |
|
|
evaluate(Object object,
Class<T> context)
Returns null |
|
int |
hashCode()
Returns 0 in order to agree with hashcode of null. |
|
String |
toString()
|
|
| Methods inherited from class Object |
|---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
| Method Detail |
|---|
public Object accept(ExpressionVisitor visitor,
Object extraData)
Expressionreturn visitor.visit(this, extraData);
accept in interface Expressionpublic Object evaluate(Object object)
null
evaluate in interface Expression
public <T> T evaluate(Object object,
Class<T> context)
null
evaluate in interface ExpressionT - The type of the returned object.object - The object to evaluate the expression against.context - The type of the resulting value of the expression.
context.public boolean equals(Object other)
Expression.NIL.
equals in class Objectother -
true for Expression.NILpublic int hashCode()
0 in order to agree with hashcode of null.
hashCode in class Objectpublic String toString()
toString in class Object
|
||||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||