danielgomezrico · October 9, 2019 13:38 · Oct 9, 2019 · Oct 9, 2019 · Oct 9, 2019
diff --git a/gistfile1.txt → gistfile1.kt b/gistfile1.txt → gistfile1.kt
diff --git a/gistfile1.txt b/gistfile1.txt
@@ -1,3 +1,10 @@
+package com.lahaus.utils.extensions
+
+import androidx.paging.DataSource
+import androidx.paging.PagedList
+import androidx.paging.PositionalDataSource
+import androidx.paging.RxPagedListBuilder
+import io.reactivex.Observable
 
 fun <T> List<T>.toObservablePagedList(): Observable<PagedList<T>> {
     val defaultConfig = PagedList.Config.Builder()
@@ -11,12 +18,18 @@ fun <T> List<T>.toObservablePagedList(): Observable<PagedList<T>> {
         .buildObservable()
 }
 
+/**
+ * src: https://gist.github.com/JoseAlcerreca/1e9ee05dcdd6a6a6fa1cbfc125559bba
+ */
 private fun <T> dataSourceFactory(itemList: List<T>): DataSource.Factory<Int, T> =
     object : DataSource.Factory<Int, T>() {
         override fun create(): DataSource<Int, T> =
             ListDataSource(itemList)
     }
 
+/**
+ * src: https://gist.github.com/JoseAlcerreca/1e9ee05dcdd6a6a6fa1cbfc125559bba
+ */
 private class ListDataSource<T>(private val itemList: List<T>) : PositionalDataSource<T>() {
 
     override fun loadRange(params: LoadRangeParams, callback: LoadRangeCallback<T>) {

diff --git a/gistfile1.txt b/gistfile1.txt
@@ -0,0 +1,30 @@
+
+fun <T> List<T>.toObservablePagedList(): Observable<PagedList<T>> {
+    val defaultConfig = PagedList.Config.Builder()
+        .setEnablePlaceholders(false)
+        .setPageSize(size)
+        .setMaxSize(size + 2)
+        .setPrefetchDistance(1)
+        .build()
+
+    return RxPagedListBuilder(dataSourceFactory(this), defaultConfig)
+        .buildObservable()
+}
+
+private fun <T> dataSourceFactory(itemList: List<T>): DataSource.Factory<Int, T> =
+    object : DataSource.Factory<Int, T>() {
+        override fun create(): DataSource<Int, T> =
+            ListDataSource(itemList)
+    }
+
+private class ListDataSource<T>(private val itemList: List<T>) : PositionalDataSource<T>() {
+
+    override fun loadRange(params: LoadRangeParams, callback: LoadRangeCallback<T>) {
+        itemList.subList(params.startPosition, params.startPosition + params.loadSize)
+            .toMutableList()
+    }
+
+    override fun loadInitial(params: LoadInitialParams, callback: LoadInitialCallback<T>) {
+        callback.onResult(itemList, 0)
+    }
+}