Package org.geotools.filter.visitor

Class DefaultExpressionVisitor

Object

DefaultExpressionVisitor

All Implemented Interfaces:

ExpressionVisitor

Direct Known Subclasses:

FeatureChainedAttributeVisitor

public abstract class DefaultExpressionVisitor
extends Object
implements ExpressionVisitor

Abstract implementation of ExpressionVisitor that simply walks the data structure.

This class implements the full ExpressionVisitor interface and will visit every Filter member of an Expression object. This class performs no actions and is not intended to be used directly, instead extend it and overide the methods for the Expression type you are interested in. Remember to call the super method if you want to ensure that the entire expression tree is still visited.

 FilterVisitor allProperties = new DefaultExpressionVisitor(){
     public Object visit( PropertyName expr, Object data ) {
         Set set = (Set) data;
         set.addAll(expr.getPropertyName());
         return set;
     }
 };
 Set set = (Set) allProperties.accept(allFids, new HashSet());
 

Author:

Jody

Constructor Summary

Constructors

Constructor	Description
DefaultExpressionVisitor()

Method Summary

Modifier and Type	Method	Description
Object	visit(Add expression, Object data)
Object	visit(Divide expression, Object data)
Object	visit(Function expression, Object data)
Object	visit(Literal expression, Object data)
Object	visit(Multiply expression, Object data)
Object	visit(NilExpression expression, Object data)	Used to visit a Expression.NIL, also called for null where an expression is expected.
Object	visit(PropertyName expression, Object data)
Object	visit(Subtract expression, Object data)

Methods inherited from class Object

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

Constructor Detail

DefaultExpressionVisitor

public DefaultExpressionVisitor()

Method Detail

visit

public Object visit(NilExpression expression,
                    Object data)

Description copied from interface: ExpressionVisitor

Used to visit a Expression.NIL, also called for 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.

Specified by:

visit in interface ExpressionVisitor

Returns:

implementation specific

visit

public Object visit(Add expression,
                    Object data)

Specified by:

visit in interface ExpressionVisitor

visit

public Object visit(Divide expression,
                    Object data)

Specified by:

visit in interface ExpressionVisitor

visit

public Object visit(Function expression,
                    Object data)

Specified by:

visit in interface ExpressionVisitor

visit

public Object visit(Literal expression,
                    Object data)

Specified by:

visit in interface ExpressionVisitor

visit

public Object visit(Multiply expression,
                    Object data)

Specified by:

visit in interface ExpressionVisitor

visit

public Object visit(PropertyName expression,
                    Object data)

Specified by:

visit in interface ExpressionVisitor

visit

public Object visit(Subtract expression,
                    Object data)

Specified by:

visit in interface ExpressionVisitor