What is the purpose of from map in the Expansion Algorithm?

[timothee-haudebourg]

The Expansion Algorithm requires a boolean from map variable as input. Its value is never changed across the expansion algorithms and is always set to false. There are only 3 occurrences of this variable in the whole API document. It doesn't seem to be used.

[gkellogg]

Step 13.8.3.6 of the Expansion Algorithm should pass from map as true when invoking the algorithm recursively. This seems to have gotten lost in some update.

As noted in the algorithm introduction, it is used to control reverting to a previous context, which can interfere with the semantics of index- id- and type-maps.

Removing it from my implementation causes expand#tc013 and expand#tm008 to fail, along with the toRdf versions of these tests.

[iherman]

This issue was discussed in a meeting.

• RESOLVED: Add back from_map to 13.8.3.6 to recursive call for scoped contexts per api #478

View the transcript

Rob Sanderson: #478
Gregg Kellogg: We have a flag “from map” that was not used, but it is actually used, but got lost. It is required for inherited scoped context. If an implementation does not use this, it can not pass the tests. So this would require restoring the use of this flag to fix this.
Proposed resolution: Add back from_map to 13.8.3.6 to recursive call for scoped contexts per api #478 (Rob Sanderson)
Gregg Kellogg: +1
Rob Sanderson: +1
Ruben Taelman: +1
Benjamin Young: +1
Pierre-Antoine Champin: +1
Resolution #4: Add back from_map to 13.8.3.6 to recursive call for scoped contexts per api #478

[gkellogg]

@timothee-haudebourg This is fixed in #481. Please let us know if that satisfies your concern.

[timothee-haudebourg]

It's fine for the text, although it would be nice to have a test that catches the correct use of from map. I've been able to pass all the expansion tests without ever using this variable.

[gkellogg]

In my implementation, if I don't pass true for from map from the Create Term Definition algorithm, tests c013 and m008 fail.