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ObjectExpressionAbstract
public abstract class ExpressionAbstract
Abstract superclass of these Expression implementations.
Contains additional support for "Expression chaining". This allows Expressions to be constructed as a chain of Java commands similar to the use of the java collections api.
Note: Expression chaining is a simple developer convience, it has no effect on the data model exposed by the GeoAPI interfaces.
Idea: We may also be able to teach this implementation to make use of JXPath to extract "attribute values" from Java Beans, DOM, JDOM in addition to the geotools & geoapi FeatureType models. It is a cunning plan - any implementation will make use of this abstract base class.
Field Summary |
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Fields inherited from interface Expression |
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NIL |
Constructor Summary | |
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ExpressionAbstract()
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Method Summary | |
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Object |
accept(ExpressionVisitor visitor,
Object extraData)
Subclass should override, default implementation just returns extraData |
protected Object |
eval(Expression expression,
SimpleFeature feature)
Helper method for subclasses to reduce null checks |
protected Object |
eval(Expression expression,
SimpleFeature feature)
Helper method for subclasses to reduce null checks |
Object |
evaluate(Object object)
Subclass should overide, default implementation returns null |
Object |
evaluate(Object object,
Class context)
Default implementation delegates handling of context conversion to Value utility class. |
Methods inherited from class Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public ExpressionAbstract()
Method Detail |
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public Object evaluate(Object object)
evaluate
in interface Expression
public Object evaluate(Object object, Class context)
Subclasses are expected to make use of the Value utility class (as the easiest way to provide value morphing in confirmance with the Filter specification).
evaluate
in interface Expression
public Object accept(ExpressionVisitor visitor, Object extraData)
accept
in interface Expression
protected Object eval(Expression expression, SimpleFeature feature)
expression
- feature
-
protected Object eval(Expression expression, SimpleFeature feature)
expression
- feature
-
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