/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.filter.function;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import org.geotools.factory.CommonFactoryFinder;
import org.geotools.filter.FilterAttributeExtractor;
import org.geotools.filter.capability.FunctionNameImpl;
import org.geotools.util.Converters;
import org.opengis.filter.Filter;
import org.opengis.filter.FilterFactory2;
import org.opengis.filter.capability.FunctionName;
import org.opengis.filter.expression.Expression;
import org.opengis.filter.expression.ExpressionVisitor;
import org.opengis.filter.expression.Function;
import org.opengis.filter.expression.Literal;
/**
* Implementation of "Categorize" as a normal function.
* <p>
* This implementation is compatible with the Function
* interface; the parameter list can be used to set the
* threshold values etc...
* <p>
* This function expects:
* <ol>
* <li>PropertyName; use "Rasterdata" to indicate this is a color map
* <li>Literal: lookup value
* <li>Literal: threshold 1
* <li>Literal: value 1
* <li>Literal: threshold 2
* <li>Literal: value 2
* <li>Literal: (Optional) succeeding or preceding
* </ol>
* In reality any expression will do.
* @author Jody Garnett
* @author Johann Sorel (Geomatys)
*
*
*
* @source $URL$
*/
public class CategorizeFunction implements Function {
/** Use as a literal value to indicate behaviour of threshold boundary */
public static final String SUCCEEDING = "succeeding";
/** Use as a literal value to indicate behaviour of threshold boundary */
public static final String PRECEDING = "preceding";
/**
* Use as a PropertyName when defining a color map.
* The "Raterdata" is expected to apply to only a single band; if multiple
* bands are provided it is probably a mistake; but we will use the maximum
* value (since we are working against a threshold).
*/
public static final String RASTER_DATA = "Rasterdata";
private final List<Expression> parameters;
private final Literal fallback;
/**
* True if all expressions in the param set are static values
*/
private boolean staticTable = true;
double[] thresholds;
Expression[] values;
volatile Object[] convertedValues;
private Class convertedValuesContext;
private String belongsTo;
/**
* Make the instance of FunctionName available in
* a consistent spot.
*/
public static final FunctionName NAME = new FunctionNameImpl("Categorize", "LookupValue",
"Value", "Threshold 1", "Value 1", "Threshold 2", "Value 2", "succeeding or preceding");
public CategorizeFunction() {
this( new ArrayList<Expression>(), null);
}
public CategorizeFunction(List<Expression> parameters, Literal fallback) {
this.parameters = parameters;
this.fallback = fallback;
// check for valid structure, we need lookup, value, [threshold, value]*, [thresholdInclusion]
if(parameters.size() % 2 != 0) {
// in this case the last value must be either succeeding or preceding, as a literal
Expression lastParameter = parameters.get(parameters.size() - 1);
String lastValue = lastParameter.evaluate(null, String.class);
if (PRECEDING.equalsIgnoreCase(lastValue)) {
belongsTo = PRECEDING;
} else if (SUCCEEDING.equalsIgnoreCase(lastValue)) {
belongsTo = SUCCEEDING;
} else {
throw new IllegalArgumentException("The valid structure of a categorize function call is " +
"\"lookup, value, [threshold, value]*, [succeeding|preceding]\", " +
"yet there is a odd number of parameters and the last value is not succeeding nor preceeding");
}
}
// see if the table is full of attribute independent expressions
FilterAttributeExtractor extractor = new FilterAttributeExtractor();
thresholds = new double[(parameters.size() - 1) / 2];
values = new Expression[thresholds.length + 1];
for (int i = 1; i < parameters.size(); i++) {
Expression expression = parameters.get(i);
if(expression != null) {
extractor.clear();
expression.accept(extractor, null);
if(!extractor.isConstantExpression()) {
staticTable = false;
thresholds = null;
break;
} else {
if(i % 2 == 0) {
Double threshold = expression.evaluate(null, Double.class);
if(threshold == null) {
staticTable = false;
thresholds = null;
break;
} else {
thresholds[i / 2 - 1] = threshold;
}
} else {
values[i / 2] = expression;
}
}
}
}
// allow for binary search
if(thresholds != null) {
Arrays.sort(thresholds);
}
}
public String getName() {
return NAME.getName();
}
public FunctionName getFunctionName() {
return NAME;
}
public List<Expression> getParameters() {
return Collections.unmodifiableList(parameters);
}
public Object accept(ExpressionVisitor visitor, Object extraData) {
return visitor.visit(this, extraData);
}
public Object evaluate(Object object) {
return evaluate(object, Object.class);
}
public <T> T evaluate(Object object, Class<T> context) {
final Expression lookupExp = parameters.get(0);
// check the value we're looking for
Double value = lookupExp.evaluate(object, Double.class);
if(value == null) {
value = Converters.convert(object, Double.class);
}
if(value != null && staticTable) {
int expIdx = Arrays.binarySearch(thresholds, value);
int valIdx;
if(expIdx >= 0) {
// right at the threshold
if (PRECEDING.equals(belongsTo)) {
valIdx = expIdx;
} else {
valIdx = expIdx + 1;
}
} else {
// between threshold values, get the next value
valIdx = -expIdx - 1;
}
// do we have a pre-converted set of values as well?
if(convertedValues == null) {
synchronized (this) {
if(convertedValues == null) {
convertedValues = new Object[values.length];
for (int i = 0; i < convertedValues.length; i++) {
convertedValues[i] = values[i].evaluate(object, context);
}
convertedValuesContext = context;
}
}
}
// if we can use the pre-converted go for it, otherwise dynamic eval
if(convertedValuesContext == context) {
return (T) convertedValues[valIdx];
} else {
return values[valIdx].evaluate(object, context);
}
}
// generic evaluation path, slow
Expression currentExp = parameters.get(1);
final List<Expression> splits;
if (parameters.size() == 2) {
return currentExp.evaluate(object, context);
} else if (parameters.size() % 2 == 0) {
splits = parameters.subList(2, parameters.size());
} else {
splits = parameters.subList(2, parameters.size() - 1);
}
FilterFactory2 ff = CommonFactoryFinder.getFilterFactory2(null);
for (int i = 0; i < splits.size(); i += 2) {
Expression threshholdExp = splits.get(i);
Expression rangedExp = splits.get(i + 1);
Filter isIncludedInThreshold;
if (PRECEDING.equals(belongsTo)) {
isIncludedInThreshold = ff.greater(lookupExp, threshholdExp);
} else {
isIncludedInThreshold = ff.greaterOrEqual(lookupExp, threshholdExp);
}
if (isIncludedInThreshold.evaluate(object)) {
currentExp = rangedExp;
} else {
break;
}
}
return currentExp.evaluate(object, context);
}
public Literal getFallbackValue() {
return fallback;
}
}