297916 - Expose RDF nsresults on Components.results

Status: RESOLVED WONTFIX

(Core Graveyard :: RDF, enhancement)

Description

[Axel Hecht]

We should expose some of the RDF nsresults from rdf.h to script, 
Components.results is the canonical candidate.

I wonder if we should prune NS_RDF_CURSOR_EMPTY while we're at it, that one
is dead. At least, that's one we're not supposed to expose.

List of stuff to expose:

/* Returned from nsIRDFDataSource::GetSource() and GetTarget() if the source/target
   has no value */
#define NS_RDF_NO_VALUE           NS_ERROR_GENERATE_SUCCESS(NS_ERROR_MODULE_RDF, 2)

/* Returned from nsIRDFDataSource::Assert() and Unassert() if the assertion (or
   unassertion was accepted by the datasource*/
#define NS_RDF_ASSERTION_ACCEPTED NS_OK

/* Returned from nsIRDFDataSource::Assert() and Unassert() if the assertion (or
   unassertion) was rejected by the datasource; i.e., the datasource was not
   willing to record the statement. */
#define NS_RDF_ASSERTION_REJECTED NS_ERROR_GENERATE_SUCCESS(NS_ERROR_MODULE_RDF, 3)

/* Return this from rdfITripleVisitor to stop cycling */
#define NS_RDF_STOP_VISIT         NS_ERROR_GENERATE_SUCCESS(NS_ERROR_MODULE_RDF, 4)

Comment 1

[Benjamin Smedberg]

I'm very worried about dependencies and duplication here. Let's do
Components.result right if we can.

Comment 2

[Mike Shaver (:shaver emeritus)]

Why are you "very worried" about duplication?  There are no dependencies that I
know of, since the categories are in nsError.h anyway.

Doing Components.results "right" is a fine thing, but I don't think that
duplicating a handful of error codes for RDF or Calendar or whatever is bad
enough to defer solving this  problem until someone rearchitects Components.results.

Comment 3

[Darin Fisher]

Maybe leverage nsIErrorService somehow?  nsNetError.h has the same issue, and it
is a much larger set of error codes to duplicate.

Comment 4

[Jan Matousek]

Workaround for JavaScript code:

const NS_RDF_NO_VALUE           = ((0x45 + 10) << 16) | 2;
const NS_RDF_ASSERTION_REJECTED = ((0x45 + 10) << 16) | 3;

or (to ensure that the ugly bit shift numbers are correct)

var ser = Components.classes["@mozilla.org/rdf/rdf-service;1"]
	.getService(Components.interfaces.nsIRDFService);
var obj = Components.classes["@mozilla.org/rdf/datasource;1?name=in-memory-datasource"]
        .createInstance(Components.interfaces.nsIRDFInMemoryDataSource);
var obj = obj.QueryInterface(Components.interfaces.nsIRDFDataSource);
var i = obj.GetTarget(ser.GetResource("urn:nothing"),
        ser.GetResource("urn:nothing"), true);
const NS_RDF_NO_VALUE = Components.lastResult;

But I don't think that there is lot of JavaScript code that actually will use it.