org.geotools.filter
Interface Expression

All Superinterfaces:

ExpressionType

All Known Subinterfaces:

AttributeExpression, BBoxExpression, EnvironmentVariable, FunctionExpression, LiteralExpression, MapScaleDenominator, MathExpression

All Known Implementing Classes:

AreaFunction, AttributeExpressionImpl, AttributeExpressionImpl2, BBoxExpressionImpl, ClassificationFunction, Collection_AverageFunction, Collection_BoundsFunction, Collection_CountFunction, Collection_MaxFunction, Collection_MedianFunction, Collection_MinFunction, Collection_SumFunction, Collection_UniqueFunction, ConstantExpression, DefaultExpression, FilterFunction_area, FilterFunction_between, FilterFunction_boundary, FilterFunction_boundaryDimension, FilterFunction_buffer, FilterFunction_bufferWithSegments, FilterFunction_centroid, FilterFunction_contains, FilterFunction_convexHull, FilterFunction_crosses, FilterFunction_difference, FilterFunction_dimension, FilterFunction_disjoint, FilterFunction_distance, FilterFunction_double2bool, FilterFunction_endPoint, FilterFunction_envelope, FilterFunction_equalsExact, FilterFunction_equalsExactTolerance, FilterFunction_equalTo, FilterFunction_exteriorRing, FilterFunction_geometryType, FilterFunction_geomFromWKT, FilterFunction_geomLength, FilterFunction_getGeometryN, FilterFunction_getX, FilterFunction_getY, FilterFunction_greaterEqualThan, FilterFunction_greaterThan, FilterFunction_if_then_else, FilterFunction_in10, FilterFunction_in2, FilterFunction_in3, FilterFunction_in4, FilterFunction_in5, FilterFunction_in6, FilterFunction_in7, FilterFunction_in8, FilterFunction_in9, FilterFunction_int2bbool, FilterFunction_int2ddouble, FilterFunction_interiorPoint, FilterFunction_interiorRingN, FilterFunction_intersection, FilterFunction_intersects, FilterFunction_isClosed, FilterFunction_isEmpty, FilterFunction_isLike, FilterFunction_isNull, FilterFunction_isRing, FilterFunction_isSimple, FilterFunction_isValid, FilterFunction_isWithinDistance, FilterFunction_lessEqualThan, FilterFunction_lessThan, FilterFunction_not, FilterFunction_notEqualTo, FilterFunction_numGeometries, FilterFunction_numInteriorRing, FilterFunction_numPoints, FilterFunction_overlaps, FilterFunction_parseBoolean, FilterFunction_parseDouble, FilterFunction_parseInt, FilterFunction_pointN, FilterFunction_relate, FilterFunction_relatePattern, FilterFunction_roundDouble, FilterFunction_startPoint, FilterFunction_strConcat, FilterFunction_strEndsWith, FilterFunction_strEqualsIgnoreCase, FilterFunction_strIndexOf, FilterFunction_strLastIndexOf, FilterFunction_strLength, FilterFunction_strMatches, FilterFunction_strStartsWith, FilterFunction_strSubstring, FilterFunction_strSubstringStart, FilterFunction_strTrim, FilterFunction_symDifference, FilterFunction_touches, FilterFunction_toWKT, FilterFunction_union, FilterFunction_within, FunctionExpressionImpl, LiteralExpressionImpl, MapScaleDenominatorImpl, MathExpressionImpl, MaxFunction, MinFunction, PaletteFunction

public interface Expression

extends ExpressionType

Defines an expression, the units that make up Filters. This filter holds one or more filters together and relates them logically in an internally defined manner.

Version:

$Id: Expression.java 17702 2006-01-23 00:08:55Z desruisseaux $

Author:

Rob Hranac, Vision for New York

Field Summary

Fields inherited from interface org.geotools.filter.ExpressionType

ATTRIBUTE, ATTRIBUTE_DOUBLE, ATTRIBUTE_GEOMETRY, ATTRIBUTE_INTEGER, ATTRIBUTE_STRING, ATTRIBUTE_UNDECLARED, FUNCTION, LITERAL_DOUBLE, LITERAL_GEOMETRY, LITERAL_INTEGER, LITERAL_STRING, MATH_ADD, MATH_DIVIDE, MATH_MULTIPLY, MATH_SUBTRACT

Method Summary

void	accept(FilterVisitor visitor) Used by FilterVisitors to perform some action on this filter instance.
short	getType() Gets the type of this expression.
java.lang.Object	getValue(Feature feature) Returns a value for this expression.

Method Detail

getType

public short getType()

Gets the type of this expression.

Returns:

Expression type.

getValue

public java.lang.Object getValue(Feature feature)

Returns a value for this expression. The feature argument is used if a feature is needed to evaluate the expression, as in the case of an AttributeExpression.

Parameters:

feature - Specified feature to use when returning value. Some expressions, such as LiteralExpressions, may ignore this as it does not affect their return value.

Returns:

Value of the expression, evaluated with the feature object if necessary.

accept

public void accept(FilterVisitor visitor)

Used by FilterVisitors to perform some action on this filter instance. Typicaly used by Filter decoders, but may also be used by any thing which needs infomration from filter structure. Implementations should always call: visitor.visit(this); It is importatant that this is not left to a parent class unless the parents API is identical.

Parameters:

visitor - The visitor which requires access to this filter, the method must call visitor.visit(this);