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SparqlQueryParser.java
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SparqlQueryParser.java
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/**
* Copyright (C) 2016 Czech Technical University in Prague
*
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* This program 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 General Public License for more
* details. You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package cz.cvut.kbss.jopa.query.sparql;
import cz.cvut.kbss.jopa.exception.QueryParserException;
import cz.cvut.kbss.jopa.query.QueryParameter;
import cz.cvut.kbss.jopa.query.QueryParser;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class SparqlQueryParser implements QueryParser {
private String query;
private Map<Object, QueryParameter<?>> uniqueParams;
private Integer positionalCounter;
List<String> queryParts;
List<QueryParameter<?>> parameters;
private boolean inParam;
private boolean inSQString; // In apostrophe string (')
private boolean inDQString; // In double-quoted string (")
private int lastParamEndIndex;
private int paramStartIndex;
ParamType currentParamType;
private enum ParamType {
POSITIONAL, NAMED
}
@Override
public SparqlQueryHolder parseQuery(String query) {
this.query = query;
this.queryParts = new ArrayList<>();
this.uniqueParams = new HashMap<>();
this.positionalCounter = 1;
this.parameters = new ArrayList<>();
this.inSQString = false;
// In double-quoted string
this.inDQString = false;
this.inParam = false;
this.lastParamEndIndex = 0;
this.paramStartIndex = 0;
this.currentParamType = null;
int i;
for (i = 0; i < query.length(); i++) {
final char c = query.charAt(i);
switch (c) {
case '\'':
inSQString = !inSQString;
break;
case '"':
inDQString = !inDQString;
break;
case '$':
parameterStart(i, ParamType.POSITIONAL);
break;
case '?':
parameterStart(i, ParamType.NAMED);
break;
// TODO Take a look at some existing SPARQL parsers and maybe use them instead of this simplified version
case '<':
case '>':
case ',':
case '\n':
case ')':
case ' ':
case '.':
case ';':
if (inParam) {
parameterEnd(i);
}
break;
default:
break;
}
}
if (inParam) {
parameterEnd(i);
} else {
queryParts.add(query.substring(lastParamEndIndex));
}
return new SparqlQueryHolder(query, queryParts, parameters);
}
private void parameterStart(int index, ParamType paramType) {
if (!inSQString && !inDQString) {
queryParts.add(query.substring(lastParamEndIndex, index));
paramStartIndex = index + 1;
inParam = true;
this.currentParamType = paramType;
}
}
private void parameterEnd(int index) {
this.lastParamEndIndex = index;
this.inParam = false;
final String param = query.substring(paramStartIndex, index);
parameters.add(resolveParamIdentification(param));
}
private QueryParameter<?> resolveParamIdentification(String identification) {
final QueryParameter<?> queryParameter;
if (identification.isEmpty()) {
if (currentParamType == ParamType.POSITIONAL) {
queryParameter = getQueryParameter(positionalCounter++);
} else {
throw new QueryParserException("Missing parameter name in query " + query);
}
} else {
if (currentParamType == ParamType.POSITIONAL) {
try {
Integer position = Integer.parseInt(identification);
positionalCounter++;
queryParameter = getQueryParameter(position);
} catch (NumberFormatException e) {
throw new QueryParserException(identification + " is not a valid parameter position.", e);
}
} else {
queryParameter = getQueryParameter(identification);
}
}
return queryParameter;
}
private QueryParameter<?> getQueryParameter(String name) {
// We want to reuse the param instances, so that changes to them apply throughout the whole query
if (!uniqueParams.containsKey(name)) {
uniqueParams.put(name, new QueryParameter<>(name));
}
return uniqueParams.get(name);
}
private QueryParameter<?> getQueryParameter(Integer position) {
// We want to reuse the param instances, so that changes to them apply throughout the whole query
if (uniqueParams.containsKey(position)) {
throw new QueryParserException("Parameter with position " + position + " already found in query " + query);
}
final QueryParameter<?> qp = new QueryParameter<>(position);
uniqueParams.put(position, qp);
return qp;
}
}