@Extension public interface ExpressionVisitor
visit
methods to be called by Expression.accept(...)
.
Please note that a generic visit( Expression ) entry point has not been provided, although Expression forms a heirarchy for your convience it is not an open heirarchy. If you need to extend this system please make use of {code Function}, this will allow extention while remaining standards complient.
It is very common for a single instnace to implement both ExpressionVisitor and FilterVisitor.
Modifier and Type | Method and Description |
---|---|
Object |
visit(Add expression,
Object extraData) |
Object |
visit(Divide expression,
Object extraData) |
Object |
visit(Function expression,
Object extraData) |
Object |
visit(Literal expression,
Object extraData) |
Object |
visit(Multiply expression,
Object extraData) |
Object |
visit(NilExpression expression,
Object extraData)
Used to visit a Expression.NIL, also called for
null where an expression is
expected. |
Object |
visit(PropertyName expression,
Object extraData) |
Object |
visit(Subtract expression,
Object extraData) |
Object visit(NilExpression expression, Object extraData)
null
where an expression is
expected.
This is particularly useful when doing data transformations, as an example when using a StyleSymbolizer Expression.NIL can be used to represent the default stroke color.
Object visit(PropertyName expression, Object extraData)
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