Store Token position in the produces quads

[BenjaminHofstetter]

Why do I need that:
After parsing a Turtle file, I lose all information about the source file. For better tooling support, I propose implementing some kind of "source maps" to trace back from quads to positions in the Turtle file.

For instance, in tools like https://shacl-playground.zazuko.com/, when encountering errors in SHACL validation reports, locating the error-causing triple requires human intervention. With source map information, editors could pinpoint the exact location in the Turtle file, aiding in error resolution. Implementing source maps would bridge the gap between parsed files and their source, enhancing tooling support. The tokenizer already generates tokens with line, start, and end information, laying the groundwork for this feature.

[RubenVerborgh]

This would be possible indeed, if the parser emits the context from the tokenizer in the quads.

We have no plans to take this up, but a pull request that puts this functionality behind a flag would be welcome, provided it has no performance impact when switched off.