/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hp.hpl.jena.sparql.resultset;
import java.io.InputStream ;
import java.util.ArrayList ;
import java.util.Iterator ;
import java.util.List ;
import org.apache.jena.atlas.csv.CSVParser ;
import org.apache.jena.atlas.iterator.Iter ;
import org.apache.jena.atlas.iterator.Transform ;
import org.apache.jena.atlas.logging.FmtLog ;
import org.slf4j.Logger ;
import org.slf4j.LoggerFactory ;
import com.hp.hpl.jena.graph.Node ;
import com.hp.hpl.jena.graph.NodeFactory ;
import com.hp.hpl.jena.query.ResultSet ;
import com.hp.hpl.jena.sparql.ARQException ;
import com.hp.hpl.jena.sparql.core.Var ;
import com.hp.hpl.jena.sparql.engine.ResultSetStream ;
import com.hp.hpl.jena.sparql.engine.binding.Binding ;
import com.hp.hpl.jena.sparql.engine.binding.BindingFactory ;
import com.hp.hpl.jena.sparql.engine.binding.BindingMap ;
/** Convenient comma separated values - see also TSV (tab separated values)
* which outputs full RDF terms (in Turtle-style).
*
* The CSV format supported is:
* <ul>
* <li>First row is variable names without '?'</li>
* <li>Strings, quoted if necessary and numbers output only.
* No language tags, or datatypes.
* URIs are send without $lt;>
* </li>
* CSV is RFC 4180, but there are many variations.
* </ul>
* This code reads the file and treats everything as strings.
* <p>
* The code also allows for parsing boolean results where we expect the header to be a single string
* from the set: true yes false no
* </p>
* <p>
* Any other value is considered an error for parsing a boolean results and anything past the first line is ignored
* </p>
*/
public class CSVInput
{
// This code exists to support the SPARQL WG tests.
private static Logger log = LoggerFactory.getLogger(CSVInput.class) ;
public static ResultSet fromCSV(InputStream in)
{
CSVParser parser = CSVParser.create(in) ;
final List<Var> vars = vars(parser) ;
List<String> varNames = Var.varNames(vars) ;
Transform<List<String>, Binding> transform = new Transform<List<String>, Binding>(){
private int count = 1 ;
@Override
public Binding convert(List<String> row) {
if ( row.size() != vars.size() )
FmtLog.warn(log, "Row %d: Length=%d: expected=%d", count, row.size(), vars.size()) ;
BindingMap binding = BindingFactory.create() ;
// Check.
for (int i = 0 ; i < vars.size() ; i++ ) {
Var v = vars.get(i) ;
String field = (i<row.size()) ? row.get(i) : "" ;
Node n = NodeFactory.createLiteral(field) ;
binding.add(v, n);
}
count++ ;
return binding ;
}} ;
Iterator<Binding> bindings = Iter.map(parser, transform) ;
//Generate an instance of ResultSetStream using TSVInputIterator
//This will parse actual result rows as needed thus minimising memory usage
return new ResultSetStream(varNames, null, bindings);
}
private static List<Var> vars(CSVParser parser) {
final List<Var> vars = new ArrayList<>();
List<String> varNames = parser.parse1() ;
if ( varNames == null )
throw new ARQException("SPARQL CSV Results malformed, input is empty");
for ( String vn : varNames ) {
vars.add(Var.alloc(vn)) ;
}
return vars ;
}
public static boolean booleanFromCSV(InputStream in)
{
CSVParser parser = CSVParser.create(in) ;
final List<Var> vars = vars(parser) ;
if ( vars.size() != 1 ) {
throw new ARQException("CSV Boolean Results malformed: variables line='"+vars+"'") ;
}
if ( ! vars.get(0).getName().equals("_askResult")) {
FmtLog.warn(log, "Boolean result variable is '%s', not '_askResult'", vars.get(0).getName()) ;
}
List<String> line = parser.parse1() ;
if ( line.size() != 1 ) {
throw new ARQException("CSV Boolean Results malformed: data line='"+line+"'") ;
}
String str = line.get(0) ;
boolean b ;
if ( str.equalsIgnoreCase("true") || str.equalsIgnoreCase("yes") )
b = true ;
else if (str.equalsIgnoreCase("false") || str.equalsIgnoreCase("no"))
b = false;
else {
throw new ARQException("CSV Boolean Results malformed, expected one of - true yes false no - but got " + str);
}
List<String> line2 = parser.parse1() ;
if ( line2 != null ) {
FmtLog.warn(log, "Extra rows: first is "+line2) ;
}
return b ;
}
}