Github user afs commented on the issue:
https://github.com/apache/jena/pull/473
Jena is already extensible for results formats. See
`ResultSetWriterRegistry` and `ResultSetReaderRegistry`. I'm sorry there is old
code around but, well, time ... .
Adding `ResultsFormat.FMT_TEXT` to `mapResultsFormatToLang` breaks text
output. The text format needs prefix mapping for abbreviation and that is
bypassed if that change is made to `mapResultsFormatToLang`. Give it a try! For
`<< >>` output, abbreviated is good!
It would be like:
ResultsWriter.create()
.lang(ResultSetLang.SPARQLResultSetText)
.build()
.write(System.out, resultSet);
If `ResultSetWriterRegistry.writerText` used the `Context` to get a
optional prologue; that should work out if setting the prologue is rolled out
into `arq.query`.
It might be better for the long term is to break up `query.queryExec` into
steps with protected methods for the steps as well.
---
