Paging-Coroutine-DataSource-Wrapper. version-0.1.0-alpha

_Demo.kt

import androidx.paging.ItemKeyedDataSource
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers

class DemoDataSourceFactory() {
    fun create(coroutineScope: CoroutineScope) {
        val coroutineScope = CoroutineScope(Dispatchers.IO)
        val dataSource: ItemKeyedDataSource<String, String> = DemoDataSource(coroutineScope)
    }
}

@Suppress("FunctionName")
fun DemoDataSource(coroutineScope: CoroutineScope): ItemKeyedDataSource<String, String> {
    return DemoDataSource().loadImpl(coroutineScope)
}

class DemoDataSource : SuspendableItemKeyedDataSource<String, String> {

    override suspend fun loadInitial(
        params: ItemKeyedDataSource.LoadInitialParams<String>,
        callback: ItemKeyedDataSource.LoadInitialCallback<String>
    ) {
        // API Call
    }

    override suspend fun loadAfter(
        params: ItemKeyedDataSource.LoadParams<String>,
        callback: ItemKeyedDataSource.LoadCallback<String>
    ) {
        // API Call
    }

    override fun loadBefore(
        params: ItemKeyedDataSource.LoadParams<String>,
        callback: ItemKeyedDataSource.LoadCallback<String>
    ) {
        // API Call
    }

    override fun getKey(item: String): String {
        // API Call
    }
}

SuspendableItemKeyedDataSource.kt

import androidx.paging.ItemKeyedDataSource
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.SupervisorJob
import kotlinx.coroutines.plus
import kotlinx.coroutines.runBlocking
import kotlin.coroutines.CoroutineContext



interface SuspendableItemKeyedDataSource<Key, Value> {
    fun loadImpl(
        coroutineScope: CoroutineScope,
        coroutineContext: CoroutineContext = Dispatchers.IO
    ): ItemKeyedDataSource<Key, Value> {
        return InternalItemKeyedDataSource(
            coroutineScope = coroutineScope,
            coroutineContext = coroutineContext,
            dataSource = this
        )
    }

    suspend fun loadInitial(
        params: ItemKeyedDataSource.LoadInitialParams<Key>,
        callback: ItemKeyedDataSource.LoadInitialCallback<Value>
    )

    suspend fun loadAfter(
        params: ItemKeyedDataSource.LoadParams<Key>,
        callback: ItemKeyedDataSource.LoadCallback<Value>
    )

    fun loadBefore(
        params: ItemKeyedDataSource.LoadParams<Key>,
        callback: ItemKeyedDataSource.LoadCallback<Value>
    )

    fun getKey(item: Value): Key

    private class InternalItemKeyedDataSource<Key, Value>(
        coroutineScope: CoroutineScope,
        coroutineContext: CoroutineContext,
        private val dataSource: SuspendableItemKeyedDataSource<Key, Value>
    ) : ItemKeyedDataSource<Key, Value>() {
        private val job = SupervisorJob()
        private val scope = coroutineScope + coroutineContext + job
        override fun loadInitial(
            params: LoadInitialParams<Key>,
            callback: LoadInitialCallback<Value>
        ) {
            runBlocking(scope.coroutineContext) {
                dataSource.loadInitial(params, callback)
            }
        }

        override fun loadAfter(params: LoadParams<Key>, callback: LoadCallback<Value>) {
            runBlocking(scope.coroutineContext) {
                dataSource.loadAfter(params, callback)
            }
        }

        override fun loadBefore(params: LoadParams<Key>, callback: LoadCallback<Value>) {
            runBlocking(scope.coroutineContext) {
                dataSource.loadBefore(params, callback)
            }
        }

        override fun getKey(item: Value): Key = dataSource.getKey(item)
    }
}