What to do with value entries outside value objects?

[timothee-haudebourg]

In my current implementation of the expansion algorithm, when the expanded node only contains value entries (i.e. @language or @direction entries), then it is dropped. In my interpretation of the JSON-LD syntax, this is more or less what is intended as the map is neither a node object nor a value object. This is also quite natural to do it this way with a typed implementation since node objects cannot include @language or @direction by construction.

I discovered that this is not what is described by the JSON-LD API document, where this doesn't seem to be really covered. It only covers the case where the map only contains a @language entry, in which case it is ignored:

If result is a map that contains only the entry @language, return null.

More complex cases are not covered. In the playground, only the d map is dropped in the following example:

{
  "http://a": {
    "@id": "http://a",
    "@language": "fr"
  },
  "http://b": {
    "@id": "http://b",
    "@language": "en",
    "@direction": "ltr"
  },
  "http://c": {
    "@id": "http://c",
    "@direction": "ltr"
  },
  "http://d": {
    "@language": "fr"
  },
  "http://e": {
    "@language": "en",
    "@direction": "ltr"
  },
  "http://f": {
    "@direction": "ltr"
  }
}

In my case, I drop d, e and f while removing the problematic entries in a, b and c. Is that a wrong interpretation of the expansion algorithm?

[pchampin]

I consider this as an oversight; this section should have been updated when we added the @direction keyword. @gkellogg @dlongley WDYT?

Also, it seems that we have no test case for step 18 (the one quoted by @timothee-haudebourg). The proposed snippet is a good candidate for such a test.