/*
* 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 org.apache.jena.sparql.resultset;
import java.io.OutputStream ;
import java.io.PrintWriter ;
import java.io.Writer ;
import org.apache.jena.query.QuerySolution ;
import org.apache.jena.query.ResultSet ;
import org.apache.jena.query.ResultSetFactory ;
import org.apache.jena.query.ResultSetRewindable ;
import org.apache.jena.rdf.model.RDFNode ;
import org.apache.jena.shared.PrefixMapping ;
import org.apache.jena.sparql.core.Prologue ;
import org.apache.jena.sparql.serializer.SerializationContext ;
import org.apache.jena.sparql.util.FmtUtils ;
import org.apache.jena.util.FileUtils ;
/** <p>Takes a ResultSet object and creates displayable formatted output in plain text.</p>
*
* <p>Note: this is compute intensive and memory intensive.
* It needs to read all the results first (all the results are then in-memory)
* in order to find things the maximum width of a column value; then it needs
* to pass over the results again, turning them into output.
* </p>
* @see org.apache.jena.query.ResultSetFormatter for convenience ways to call this formatter
*/
public class TextOutput extends OutputBase
{
//?? ResultSetProcessor to find column widths over a ResultSetRewindable and to output text
protected SerializationContext context = null ;
//static final String notThere = "<<unset>>" ;
static final String notThere = " " ;
public TextOutput(Prologue prologue)
{ context = new SerializationContext(prologue) ; }
public TextOutput(PrefixMapping pMap)
{ context = new SerializationContext(pMap) ; }
public TextOutput(SerializationContext cxt )
{ context = cxt ; }
@Override
public void format(OutputStream outs, ResultSet resultSet)
{ write(outs, resultSet) ; }
/** Writer should be UTF-8 encoded - better to an OutputStream */
public void format(Writer w, ResultSet resultSet) {
PrintWriter pw = new PrintWriter(w) ;
write(pw, resultSet) ;
pw.flush() ;
}
private int[] colWidths(ResultSetRewindable rs) {
int numCols = rs.getResultVars().size() ;
int numRows = 0 ;
int[] colWidths = new int[numCols] ;
// Widths at least that of the variable name. Assumes we will print col headings.
for ( int i = 0 ; i < numCols ; i++ )
colWidths[i] = (rs.getResultVars().get(i)).length() ;
// Preparation pass : find the maximum width for each column
for ( ; rs.hasNext() ; ) {
numRows++ ;
QuerySolution rBind = rs.nextSolution() ;
int col = -1 ;
for ( String s1 : rs.getResultVars() )
{
col++;
String rVar = s1;
String s = getVarValueAsString( rBind, rVar );
if ( colWidths[col] < s.length() )
{
colWidths[col] = s.length();
}
}
}
rs.reset() ;
return colWidths ;
}
/** Textual representation : default layout using " | " to separate columns.
* Ensure the PrintWriter can handle UTF-8.
* OutputStream version is preferred.
* @param pw A PrintWriter
* @param resultSet ResultSet
*/
public void write(PrintWriter pw, ResultSet resultSet)
{ write(pw, resultSet, "| ", " | ", " |") ; }
/** Output a result set.
* @param outs OutputStream
* @param resultSet ResultSet
*/
public void write(OutputStream outs, ResultSet resultSet)
{ write(outs, resultSet, "| ", " | ", " |") ; }
/** Output a result set.
* @param outs OutputStream
* @param resultSet ResultSet
* @param colStart Left column
* @param colSep Inter-column
* @param colEnd Right column
*/
public void write(OutputStream outs, ResultSet resultSet, String colStart, String colSep, String colEnd)
{
PrintWriter pw = FileUtils.asPrintWriterUTF8(outs) ;
write(pw, resultSet, colStart, colSep, colEnd) ;
pw.flush() ;
}
/** Textual representation : layout using given separator.
* Ensure the PrintWriter can handle UTF-8.
* @param pw PrintWriter
* @param colSep Column separator
*/
public void write(PrintWriter pw, ResultSet resultSet, String colStart, String colSep, String colEnd) {
if ( resultSet.getResultVars().size() == 0 ) {
pw.println("==== No variables ====");
// return ;
}
ResultSetRewindable resultSetRewindable = ResultSetFactory.makeRewindable(resultSet);
int numCols = resultSetRewindable.getResultVars().size();
int[] colWidths = colWidths(resultSetRewindable);
String row[] = new String[numCols];
int lineWidth = 0;
for ( int col = 0 ; col < numCols ; col++ ) {
String rVar = resultSet.getResultVars().get(col);
row[col] = rVar;
lineWidth += colWidths[col];
if ( col > 0 )
lineWidth += colSep.length();
}
if ( colStart != null )
lineWidth += colStart.length() ;
if ( colEnd != null )
lineWidth += colEnd.length() ;
for ( int i = 0 ; i < lineWidth ; i++ )
pw.print('-') ;
pw.println() ;
printRow(pw, row, colWidths, colStart, colSep, colEnd) ;
for ( int i = 0 ; i < lineWidth ; i++ )
pw.print('=') ;
pw.println() ;
for ( ; resultSetRewindable.hasNext() ; ) {
QuerySolution rBind = resultSetRewindable.nextSolution();
for ( int col = 0 ; col < numCols ; col++ ) {
String rVar = resultSet.getResultVars().get(col);
row[col] = this.getVarValueAsString(rBind, rVar);
}
printRow(pw, row, colWidths, colStart, colSep, colEnd);
}
for ( int i = 0 ; i < lineWidth ; i++ )
pw.print('-') ;
pw.println() ;
resultSetRewindable = null ;
}
private void printRow(PrintWriter out, String[] row, int[] colWidths, String rowStart, String colSep, String rowEnd) {
out.print(rowStart);
for ( int col = 0 ; col < colWidths.length ; col++ ) {
String s = row[col];
int pad = colWidths[col];
StringBuffer sbuff = new StringBuffer(120);
if ( col > 0 )
sbuff.append(colSep);
sbuff.append(s);
for ( int j = 0 ; j < pad - s.length() ; j++ )
sbuff.append(' ');
out.print(sbuff);
}
out.print(rowEnd);
out.println();
}
protected String getVarValueAsString(QuerySolution rBind, String varName) {
RDFNode obj = rBind.get(varName);
if ( obj == null )
return notThere;
return FmtUtils.stringForRDFNode(obj, context);
}
@Override
public void format(OutputStream out, boolean answer) {
PrintWriter pw = FileUtils.asPrintWriterUTF8(out);
if ( answer )
pw.write("yes");
else
pw.write("no");
pw.flush();
}
}