Added possibility to get view types from the adapter to add support for GridLayoutManager.SpanSizeLookup

[meruiden]

Example usage:

private val loadingIndicatorType = adapter.getItemViewTypeFromClass(LoadingIndicator::class.java)

override fun getSpanSize(position: Int): Int {
    val itemType = adapter.getItemViewType(position)

    return if(itemType == loadingIndicatorType) {
        spanCount
    } else {
        1
    }
}

See #15

[idanatz]

Looks good.

a couple of final thins:

1. Before addressing the next bullets, pull from develop branch, I've made local changes before your PR and pushed them a few hours ago, after that address the issues below.

2. I know I wrote it but on seconds thought, change class UnsupportedClassException(msg: String = "Class must implement Diffable interface") : Throwable(msg) to class UnsupportedClassException(msg: String = "") : Throwable(msg) and move the msg "Class must implement Diffable interface" to the throw site. it's more understandable when reading the code to see the actual message.

3. Why is fun getItemViewTypeFromClass(clazz: Class<*>): Int? returning Int? ? getCreatorUniqueIndex returns Int, it will never be nullable.

4. add this documentation below /**

   • Retrieves the view type of an item with a given class.
   • Note that this class must implement the Diffable interface and the adapter must contain items of that class.
   • @throws UnsupportedClassException if the class does not implement the Diffable interface. / fun getItemViewTypeFromClass(clazz: Class<>): Int?

Note that there are some validations that need to be implemented now that the getItemViewType and getCreatorUniqueIndex are publicly accessible, but I will add them after this PR will be merged.

[meruiden]

Why is fun getItemViewTypeFromClass(clazz: Class<*>): Int? returning Int? ? getCreatorUniqueIndex returns Int, it will never be nullable.

Whoops that shouldn't be nullable indeed. I'll remove this

[meruiden]

Looks good.

a couple of final thins:

1. Before addressing the next bullets, pull from develop branch, I've made local changes before your PR and pushed them a few hours ago, after that address the issues below.
2. I know I wrote it but on seconds thought, change class UnsupportedClassException(msg: String = "Class must implement Diffable interface") : Throwable(msg) to class UnsupportedClassException(msg: String = "") : Throwable(msg) and move the msg "Class must implement Diffable interface" to the throw site. it's more understandable when reading the code to see the actual message.
3. Why is fun getItemViewTypeFromClass(clazz: Class<*>): Int? returning Int? ? getCreatorUniqueIndex returns Int, it will never be nullable.

4. add this documentation below /**

   • Retrieves the view type of an item with a given class.
   • Note that this class must implement the Diffable interface and the adapter must contain items of that class.
   • @throws UnsupportedClassException if the class does not implement the Diffable interface. / fun getItemViewTypeFromClass(clazz: Class<>): Int?

Note that there are some validations that need to be implemented now that the getItemViewType and getCreatorUniqueIndex are publicly accessible, but I will add them after this PR will be merged.

I pulled the latest changes from develop and changed the stuff you requested, merged all in to master and pushed.

[idanatz]

merged your PR, thanks! will be released as a minor version in a few days after il check everything is good.