Paged list controller (#533)

* EpoxyController that works with PagedList

This CL introduces a new class in epoxy-paging called
CachingPagingEpoxyController. This controller works with a PagedList
and caches models for each item. It still allows modifying the final
model list via an addModels API.

Fixes: 524
Test: PagedListModelCacheTest

* More docs and style fixes

* more docs & cleanup based on comments

* Rename caching paging to PagedListEpoxyController

* update sample not to add items randomly, it is confusing

blessedDeps.gradle

@@ -17,7 +17,9 @@ rootProject.ext.MIN_SDK_VERSION_LITHO = 15
 
 rootProject.ext.ANDROID_SUPPORT_LIBS_VERSION = "27.1.0"
 rootProject.ext.ANDROID_DATA_BINDING = "1.3.1"
-rootProject.ext.ANDROID_PAGING = "1.0.0-beta1"
+rootProject.ext.ANDROID_PAGING = "1.0.1"
+rootProject.ext.ANDROID_ARCH_TESTING = "1.1.1"
+rootProject.ext.ANDROID_TEST_RUNNER = "1.0.2"
 rootProject.ext.BUTTERKNIFE_VERSION = "8.8.1"
 rootProject.ext.SQUARE_JAVAPOET_VERSION = "1.11.1"
 rootProject.ext.SQUARE_KOTLINPOET_VERSION = "0.7.0"
@@ -44,6 +46,8 @@ rootProject.ext.deps = [
     androidDesignLibrary  : "com.android.support:design:$ANDROID_SUPPORT_LIBS_VERSION",
     androidRecyclerView   : "com.android.support:recyclerview-v7:$ANDROID_SUPPORT_LIBS_VERSION",
     androidPagingComponent: "android.arch.paging:runtime:$ANDROID_PAGING",
+    androidArchCoreTesting: "android.arch.core:core-testing:$ANDROID_ARCH_TESTING",
+    androidTestRunner     : "com.android.support.test:runner:$ANDROID_TEST_RUNNER",
     androidAnnotations    : "com.android.support:support-annotations:$ANDROID_SUPPORT_LIBS_VERSION",
     dataBindingCompiler   : "com.android.databinding:compiler:$ANDROID_PLUGIN_VERSION",
     dataBindingAdapters   : "com.android.databinding:adapters:$ANDROID_DATA_BINDING",

epoxy-paging/build.gradle

@@ -1,23 +1,26 @@
 apply plugin: 'com.android.library'
-
+apply plugin: 'kotlin-android'
 android {
   compileSdkVersion rootProject.COMPILE_SDK_VERSION
 
   defaultConfig {
     minSdkVersion rootProject.MIN_SDK_VERSION
     targetSdkVersion rootProject.TARGET_SDK_VERSION
+    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
   }
 }
 
 dependencies {
+  implementation rootProject.deps.kotlin
+  api rootProject.deps.androidPagingComponent
+  api project(':epoxy-annotations')
+  api project(':epoxy-adapter')
 
-  compile rootProject.deps.androidPagingComponent
-  compile project(':epoxy-annotations')
-  compile project(':epoxy-adapter')
+  androidTestImplementation rootProject.deps.junit
+  androidTestImplementation rootProject.deps.androidArchCoreTesting
+  androidTestImplementation rootProject.deps.androidTestRunner
 
-  testCompile rootProject.deps.junit
-  testCompile rootProject.deps.robolectric
-  testCompile rootProject.deps.mockito
+  kaptAndroidTest project(":epoxy-processor")
 }
 
 apply from: rootProject.file('gradle/gradle-maven-push.gradle')

epoxy-paging/src/androidTest/java/com/airbnb/epoxy/paging/Item.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.airbnb.epoxy.paging
+
+import android.support.v7.util.DiffUtil
+
+/**
+ * Dummy item for testing.
+ */
+data class Item(val id: Int, val value: String) {
+  companion object {
+    val DIFF_CALLBACK = object : DiffUtil.ItemCallback<Item>() {
+      override fun areItemsTheSame(oldItem: Item, newItem: Item) = oldItem.id == newItem.id
+
+      override fun areContentsTheSame(oldItem: Item, newItem: Item) = oldItem == newItem
+    }
+  }
+}

epoxy-paging/src/androidTest/java/com/airbnb/epoxy/paging/ListDataSource.kt

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.airbnb.epoxy.paging
+
+import android.arch.paging.PositionalDataSource
+
+/**
+ * Simple data source that works with a given list and its loading can be stopped / started.
+ */
+class ListDataSource<T>(
+    private val data: List<T>
+) : PositionalDataSource<T>() {
+  private var pendingActions = arrayListOf<() -> Unit>()
+  private var running = true
+
+  private fun compute(f: () -> Unit) {
+    if (running) {
+      f()
+    } else {
+      pendingActions.add(f)
+    }
+  }
+
+  fun start() {
+    running = true
+    val pending = pendingActions
+    pendingActions = arrayListOf()
+    pending.forEach(this::compute)
+  }
+
+  fun stop() {
+    running = false
+  }
+
+  override fun loadRange(params: LoadRangeParams, callback: LoadRangeCallback<T>) {
+    compute {
+      callback.onResult(
+          data.subList(params.startPosition, Math.min(data.size, params.startPosition + params.loadSize))
+      )
+    }
+  }
+
+  override fun loadInitial(params: LoadInitialParams, callback: LoadInitialCallback<T>) {
+    val start = computeInitialLoadPosition(params, data.size)
+    val itemCnt = computeInitialLoadSize(params, start, data.size)
+    callback.onResult(
+        data.subList(start, start + itemCnt),
+        start,
+        data.size
+    )
+  }
+}