Package org.geotools.expr

Provides an Extended Expression/Filter syntax supporting experimentation with DataStore JOIN and FeatureType schema modification.

See:
Description

Interface Summary

Expr	Filter/Expression construction kit - this class forms chains.
GeometryExpr	Expr known to be a Geometry type.
MathExpr	Expr known to be a mathmatical type.
ResolvedExpr	Used to mark expression that have been resolved to a constant.

Class Summary

AbstractGeometryExpr	Default implementation of GeometryExpr.
AbstractMathExpr
AttributeExpr	Retrive attribute from Feature.
AttributeGeometryExpr
AttributeMathExpr	Retrive attribute from Feature.
Exprs	Filter/Expression construction kit - this class starts off chains.
FidsExpr
FunctionExpr
LiteralExpr	Provides a literal for use with Expr.
LiteralGeometryExpr
LiteralMathExpr
MetadataExpr	Retrive attribute from Feature.

Package org.geotools.expr Description

Provides an Extended Expression/Filter syntax supporting experimentation with DataStore JOIN and FeatureType schema modification.

• Expr is backwards compatable with existing Filter/Expression based code.
• Supports chaining of method calls similar to the Collections API

Comparison with FilterFactory

Example Expr:

Exprs.bbox( extent ).and( Exprs.attribute("cost").lt( 50 ) )

Example Filter:

Expression extentExpression =
	factory.createBBoxExpression( bbox );

String geomName = featureType.getDefaultGeometry().getName()
Expression geomExpression =
	factory.createAttributeExpression( featureType, geomName );	    

GeometryFilter disjointExpression =
	factory.createGeometryFilter( GeometryFilter.GEOMETRY_DISJOINT );
disjointExpression.addLeftGeometry( geomExpression );
disjointExpression.addRightGeometry( extentExpression );	    

Filter bboxFilter = disjointExpression.not();	    

AttributeExpression costExpression =
	factory.createAttributeExpression( featureType, "cost" );
	
CompareFilter lessThanFilter =
	factory.createCompareFilter( CompareFilter.COMPARE_LESS_THAN );
lessThanFilter.addLeftValue( costExpression );
lessThanFilter.addRightValue( factory.createLiteralExpression( 50 ) );	    

LogicFilter filter = factory.createLogicFilter( bboxFilter, lessThanFilter, LogicFilter.LOGIC_AND);	    

Package Specification

This package is based on the OGC Filter specification.

Related Documentation

The following classes are used by the java.text classes.

• Filter
• org.geotools.filter.Expresssion
• FeatureType
• Feature

For overviews, tutorials, examples, guides, and tool documentation, please see:

• JDK 1.1.x Internationalization Documentation
• JDK 1.2.x Input Method Framework Documentation