Query support

[rorbech]

Initial implementation of query support

This mostly just implements the inner building blocks required to do actual queries, but is not trying to finalize the public query API. This task is tracked by #84

For now the query support is implemented as lazy as possible only triggering C-API calls when actually accessing objects. Inspired by JS/Swift SDK's, but not necessarily semantic equivalent, as maybe questions about building and executing queries are not settled yet.

class Realm {
    fun <T: RealmModel> objects(clazz: KClass<T>): RealmResults<T>
}

class RealmResult<T> : AbstractList<T> {
    // For accessing elements
    fun get(index: Int): T

    // For sub queries
    fun query(query: String, vararg args: Any): RealmResults<T>

    // Delete all objects referenced by this result
    fun delete()
}

• JVM support
• Native support

Closes #64

[rorbech]

I looked into the links, dug a bit into the Java implementation and tried to play with a lazy evaluated API to get some insight. The last commit holds an overly lazy implementation, that raises question about how to tweak doing the fluent queries, when to raise errors, etc.

Will try to do the basic blocks for Native and then we can maybe discuss the various choices in a meeting.

[nhachicha]

Nice stab at the query API, I only have one worry concerning throwing for an empty result as stated in the comments

[nhachicha]

for now, it's still required to provide a schema until #90 is fixed

[rorbech]

Requiring it here just ruins the ability to build the configuration fluently. As far as I remember there is already a check for the schema when building it.

[nhachicha]

maybe add the below to its own query test?

[rorbech]

I tried separating the tests a bit. The really annoying part is that we have to maintain it twice as we currently cannot trigger the common tests to run on Android (neither from UI) or by connectedAndroidTest.

[rorbech]

Besides somehow overcoming the above annoyance, I guess reorganizing test should maybe follow the actual design/implementation. This was merely a PR to show a basic round trip to the underlying query API.

[nhachicha]

Reminder to add a small synopsis of the query syntax (could be in another PR)

[rorbech]

I have put a very brief note, basically just pointing to JS. Think it makes most sense to start elaborating along with #84.