/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2006-2008, 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.text.cql2;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.List;
import javax.xml.transform.TransformerException;
import org.geotools.filter.FilterTransformer;
import org.geotools.filter.text.commons.CompilerUtil;
import org.opengis.filter.Filter;
import org.opengis.filter.FilterFactory;
import org.opengis.filter.expression.Expression;
/**
* Utility class to parse <b>CQL</b> predicates and expressions to GeoAPI
* {@link Filter}s and {@link Expression}s, respectively.
*
* <p>
* <b>CQL</b> is an acronym for Contextual Query Language, a query predicate
* language whose syntax is similar to a SQL WHERE clause, defined as OGC Common Query Language
* in clause 6.2.2 of the OGC Catalog Service for Web, version 2.0.1 implementation
* specification.
* </p>
* <p>
* This class provides three methods, {@link #toFilter(String)},
* {@link #toExpression(String)} and {@link #toFilterList(String)}; and an
* overloaded version of each one for the user to provide a
* {@link FilterFactory} implementation to use.
* </p>
* <p>
* <h2>Usage</h2>
* Here are some usage examples. Refer to the <a
* href="href="http://docs.geotools.org/latest/userguide/guide/library/cql/internal.html">BNF of
* grammar</a> to see what exactly you can do.
*
*
* <pre>
* <code>
* Filter f = CQL.toFilter("ATTR1 < 10 AND ATTR2 < 2 OR ATTR3 > 10");
*
* Filter f = CQL.toFilter("NAME = 'New York' ");
*
* Filter f = CQL.toFilter("NAME LIKE 'New%' ");
*
* Filter f = CQL.toFilter("NAME IS NULL");
*
* Filter f = CQL.toFilter("DATE BEFORE 2006-11-30T01:30:00Z");
*
* Filter f = CQL.toFilter("NAME DOES-NOT-EXIST");
*
* Filter f = CQL.toFilter("QUANTITY BETWEEN 10 AND 20");
*
* Filter f = CQL.toFilter("CROSSES(SHAPE, LINESTRING(1 2, 10 15))");
*
* Filter f = CQL.toFilter("BBOX(SHAPE, 10,20,30,40)");
*
* Expression e = CQL.toExpression("NAME");
*
* Expression e = CQL.toExpression("QUANTITY * 2");
*
* Expression e = CQL.toExpression("strConcat(NAME, 'suffix')");
*
* List filters = CQL.toFilterList("NAME IS NULL;BBOX(SHAPE, 10,20,30,40);INCLUDE");
* </code>
* </pre>
* <A HREF="http://www.opengis.org/docs/02-059.pdf">Implementation specification 1.0</A>
*
* @since 2.5
* @author Mauricio Pazos (Axios Engineering)
* @author Gabriel Roldan (Axios Engineering)
* @version $Id$
* @source $URL$
*/
public class CQL {
private CQL() {
// do nothing, private constructor
// to indicate it is a pure utility class
}
/**
* Parses the input string in OGC CQL format into a Filter, using the
* systems default FilterFactory implementation.
*
* @param cqlPredicate
* a string containing a query predicate in OGC CQL format.
* @return a {@link Filter} equivalent to the constraint specified in
* <code>cqlPredicate</code>.
*/
public static Filter toFilter(final String cqlPredicate)
throws CQLException {
Filter filter = CQL.toFilter(cqlPredicate, null);
return filter;
}
/**
* Parses the input string in OGC CQL format into a Filter, using the
* provided FilterFactory.
*
* @param cqlPredicate
* a string containing a query predicate in OGC CQL format.
* @param filterFactory
* the {@link FilterFactory} to use for the creation of the
* Filter. If it is null the method finds the default implementation.
* @return a {@link Filter} equivalent to the constraint specified in
* <code>Predicate</code>.
*/
public static Filter toFilter(final String cqlPredicate, final FilterFactory filterFactory)
throws CQLException {
CQLCompilerFactory compilerFactory = new CQLCompilerFactory();
Filter result = CompilerUtil.parseFilter(cqlPredicate, compilerFactory, filterFactory);
return result;
}
/**
* Parses the input string in OGC CQL format into an Expression, using the
* systems default {@link FilterFactory} implementation.
*
* @param cqlExpression
* a string containing an OGC CQL expression.
* @return a {@link Expression} equivalent to the one specified in
* <code>cqlExpression</code>.
*/
public static Expression toExpression(String cqlExpression)
throws CQLException {
return toExpression(cqlExpression, null);
}
/**
* Parses the input string in OGC CQL format into an {@link Expression}, using the
* provided {@link FilterFactory}.
*
* @param cqlExpression
* a string containing a OGC CQL expression.
*
* @param filterFactory
* the {@link FilterFactory} to use for the creation of the
* Expression. If it is null the method finds the default implementation.
* @return a {@link Filter} equivalent to the constraint specified in
* <code>cqlExpression</code>.
*/
public static Expression toExpression(final String cqlExpression,
final FilterFactory filterFactory) throws CQLException {
CQLCompilerFactory compilerFactory = new CQLCompilerFactory();
Expression expression = CompilerUtil.parseExpression(cqlExpression, compilerFactory, filterFactory);
return expression;
}
/**
* Parses the input string, which has to be a list of OGC CQL predicates
* separated by <code>;</code> into a <code>List</code> of
* <code>Filter</code>s, using the provided FilterFactory.
*
* @param cqlFilterList
* a list of OGC CQL predicates separated by "<code>;</code>"
*
* @return a {@link List} of {@link Filter}, one for each input CQL statement
*/
public static List<Filter> toFilterList(final String cqlFilterList)
throws CQLException {
List<Filter> filters = CQL.toFilterList(cqlFilterList, null);
return filters;
}
/**
* WARNING THIS IS A WORK IN PROGRESS.
*
* @param filterList
* @return
*/
public static String toCQL( List<Filter> filterList ){
FilterToCQL toCQL = new FilterToCQL();
StringBuffer output = new StringBuffer();
for( Filter filter : filterList ){
filter.accept( toCQL, output );
output.append("; ");
}
return output.toString();
}
/**
* WARNING THIS IS A WORK IN PROGRESS.
*
* @param filter
* @return
*/
public static String toCQL( Filter filter ){
FilterToCQL toCQL = new FilterToCQL();
StringBuffer output = (StringBuffer) filter.accept( toCQL, new StringBuffer() );
return output.toString();
}
/**
* WARNING THIS IS A WORK IN PROGRESS.
*
* @param filter
* @return
*/
public static String toCQL( Expression expression ){
FilterToCQL toCQL = new FilterToCQL();
StringBuffer output = (StringBuffer) expression.accept( toCQL, new StringBuffer() );
return output.toString();
}
/**
* Parses the input string which has to be a list of OGC CQL predicates
* separated by "<code>;</code>" into a <code>List</code> of
* <code>Filter</code>s, using the provided FilterFactory.
*
* @param cqlSequencePredicate
* a list of OGC CQL predicates separated by "<code>;</code>"
*
* @param filterFactory
* the {@link FilterFactory} to use for the creation of the
* Expression. If it is null the method finds the default implementation.
* @return a List of {@link Filter}, one for each input CQL statement
*/
public static List<Filter> toFilterList(final String cqlSequencePredicate, final FilterFactory filterFactory)
throws CQLException {
CQLCompilerFactory compilerFactory = new CQLCompilerFactory();
List<Filter> filters = CompilerUtil.parseFilterList(cqlSequencePredicate, compilerFactory, filterFactory);
return filters;
}
/**
* Command line expression tester used to try out filters and expressions.
* @param args
*/
public static final void main(String[] args) {
System.out.println("CQL Filter Tester");
System.out.println("(\"quit\" to finish)");
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
FilterTransformer filterTransformer = new FilterTransformer();
filterTransformer.setIndentation(4);
while (true) {
System.out.print(">");
String line = null;
try {
line = reader.readLine();
if (line.equals("quit")) {
System.out.println("Bye!");
break;
}
List<Filter> filters = CQL.toFilterList(line);
for( Filter filter : filters ){
System.out.println();
filterTransformer.transform( filter, System.out);
}
} catch (IOException e1) {
e1.printStackTrace();
} catch (CQLException cqlex) {
System.out.println(cqlex.getSyntaxError());
} catch (TransformerException e) {
e.printStackTrace();
}
}
}
}