Add Kotlin DSL to create Adapters (#68)

* First draft

* New ListAdapterDelegateDsl implementatino

* Moved dsl stuff in own submodule

* Removed unusded files

* Code duplication for adapter delegates

* Tests added

* Added dsl for other recyclerview releavant callbacks

* Updated README

* Updated Main Example

* Update

* More Docs

* Fix a test

* More assertions

* More Readme

* Better tests

README.md

@@ -1,11 +1,13 @@
 # AdapterDelegates
 Read the motivation for this project in [my blog post](http://hannesdorfmann.com/android/adapter-delegates).
 
+For Kotlin, there is a convenient DSL. Check out that section in the documentation below.
+
 ## Dependencies
 This library is available on maven central:
 
 ```groovy
-compile 'com.hannesdorfmann:adapterdelegates4:4.0.0'
+implementation 'com.hannesdorfmann:adapterdelegates4:4.1.0'
 ```
 [![Build Status](https://travis-ci.org/sockeqwe/AdapterDelegates.svg?branch=master)](https://travis-ci.org/sockeqwe/AdapterDelegates)
 
@@ -14,7 +16,7 @@ Please note that since 4.0 the group id has been changed to `adapterdelegates4`.
 ### Snapshot
 
 ```groovy
-compile 'com.hannesdorfmann:adapterdelegates4:4.0.1-SNAPSHOT'
+implementation 'com.hannesdorfmann:adapterdelegates4:4.1.1-SNAPSHOT'
 ```
 
 You also have to add the url to the snapshot repository:
@@ -200,6 +202,104 @@ public class DiffAdapter extends AsyncListDifferDelegationAdapter<Animal> {
 }
 ```
 
+## Kotlin DSL
+There are 2 more artifacts for kotlin users that allow you to write Adapter Delegates more convenient by providing a `DSL`:
+
+```
+implementation 'com.hannesdorfmann:adapterdelegates4-kotlin-dsl:4.1.0'
+
+// If you use Kotlin Android Extensions and synthetic properties (alternative to findViewById())
+implementation 'com.hannesdorfmann:adapterdelegates4-kotlin-dsl-layoutcontainer:4.1.0'
+```
+
+Now instead of creating your own class which extends `AdapterDelegate<T>` and implement the `onCreateViewHolder` and `onBindViewHolder` you can use the following Kotlin DSL to write the same `CatListItemAdapterDelegate` shown in the example above:
+
+
+```kotlin
+fun catAdapterDelegate(itemClickedListener : (Cat) -> Unit) = adapterDelegate<Cat, Animal>(R.layout.item_cat) {
+
+    // This is the initializer block where you initialize the ViewHolder.
+    // Its called one time only in onCreateViewHolder.
+    // this is where you can call findViewById() and setup click listeners etc.
+
+    val name : TextView = findViewById(R.id.name)
+    name.setClickListener { itemClickedListener(item) } // Item is automatically set for you. It's set lazily though (set in onBindViewHolder()). So only use it for deferred calls like clickListeners.
+
+    bind { diffPayloads -> // diffPayloads is a List<Any> containing the Payload from your DiffUtils
+        // This is called anytime onBindViewHolder() is called
+        name.text = item.name // Item is of type Cat and is the current bound item.
+    }
+}
+```
+
+In case you want to use kotlin android extensions and synthetic properties (as alternative to findViewById()) use `adapterDelegateLayoutContainer` instead of `adapterDelegate` like this:
+
+```kotlin
+fun catAdapterDelegate(itemClickedListener : (Cat) -> Unit) = adapterDelegateLayoutContainer<Cat, Animal>(R.layout.item_cat) {
+
+    name.setClickListener { itemClickedListener(item) } // no need for findViewById(). Name is imported as synthetic property from kotlinx.android.synthetic.main.item_cat
+
+    bind { diffPayloads ->
+        name.text = item.name
+    }
+}
+```
+
+As you see, thanks to Kotlin DSL you can write the same adapter in much less code.
+`isForViewType()` is implemented by checking the two generic parameters.
+In the example above it is `Cat instanceof Animal`.
+If you want to provide your own `isForViewType()` implementation you have to provide a parameter `on` and return true or false:
+
+```kotlin
+adapterDelegate<Cat, Animal> (
+    layout = R.layout.item_cat,
+    on = { item: Animal, items: List, position: Int ->
+        if (item is Cat && position == 0)
+            true // return true: this adapterDelegate handles it
+        else
+            false // return false
+    }
+){
+    ...
+    bind { ... }
+}
+```
+
+The same `on` parameter is available for `adapterDelegateLayoutContainer()` DSL.
+
+
+### Danger: Memory leaks!
+Never ever use a top level `val` to hold a reference as top level `val` are static and will hold a reference to the adapter delegate and underlying ViewHolder and underlying android context (like activity) forever.
+**Don't do this:**
+
+
+```kotlin
+// top level property inside CatDelegate.kt
+val catDelegate = adapterDelegate<Cat, Animal> {
+    ...
+    bind { ... }
+}
+```
+
+**Instead use top level functions:**
+
+```kotlin
+// top level function inside CatDelegate.kt
+fun catAdapterDelegate() = adapterDelegate<Cat, Animal> {
+   ...
+   bind { ... }
+}
+```
+
+## Pagination
+There is an additional artifact for the pagination library:
+
+```gradle
+implementation 'com.hannesdorfmann:adapterdelegates4-pagination:4.1.0'
+```
+
+Use `PagedListDelegationAdapter`.
+
 ## Fallback AdapterDelegate
 What if your adapter's data source contains a certain element you don't have registered an `AdapterDelegate` for? In this case the `AdapterDelegateManager` will throw an exception at runtime. However, this is not always what you want. You can specify a fallback `AdapterDelegate` that will be used if no other `AdapterDelegate` has been found to handle a certain view type.
 

app/build.gradle

@@ -1,4 +1,10 @@
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+
+androidExtensions {
+    experimental = true
+}
 
 android {
     compileSdkVersion rootProject.ext.compileSdk
@@ -36,5 +42,11 @@ dependencies {
 
     implementation project(':library')
     implementation project(':paging')
+    implementation project(':kotlin-dsl')
+    implementation project(':kotlin-dsl-layoutcontainer')
     implementation 'com.android.support.constraint:constraint-layout:1.1.3'
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+}
+repositories {
+    mavenCentral()
 }

app/src/main/java/com/hannesdorfmann/adapterdelegates4/sample/MainActivity.java

@@ -31,7 +31,8 @@ protected void onCreate(Bundle savedInstanceState) {
 
         RecyclerView rv = (RecyclerView) findViewById(R.id.recyclerView);
         rv.setLayoutManager(new LinearLayoutManager(this));
-        MainAdapter adapter = new MainAdapter(this, getAnimals());
+        MainListAdapter adapter = new MainListAdapter(this);
+        adapter.setItems(getAnimals());
         rv.setAdapter(adapter);
 
 

app/src/main/java/com/hannesdorfmann/adapterdelegates4/sample/MainListAdapter.kt

@@ -0,0 +1,18 @@
+package com.hannesdorfmann.adapterdelegates4.sample
+
+import android.app.Activity
+import com.hannesdorfmann.adapterdelegates4.ListDelegationAdapter
+import com.hannesdorfmann.adapterdelegates4.sample.adapterdelegates.AdvertisementAdapterDelegate
+import com.hannesdorfmann.adapterdelegates4.sample.adapterdelegates.DogAdapterDelegate
+import com.hannesdorfmann.adapterdelegates4.sample.adapterdelegates.GeckoAdapterDelegate
+import com.hannesdorfmann.adapterdelegates4.sample.adapterdelegates.SnakeListItemAdapterDelegate
+import com.hannesdorfmann.adapterdelegates4.sample.dsl.catAdapterDelegate
+import com.hannesdorfmann.adapterdelegates4.sample.model.DisplayableItem
+
+class MainListAdapter(activity: Activity) : ListDelegationAdapter<List<DisplayableItem>>(
+    AdvertisementAdapterDelegate(activity),
+    catAdapterDelegate(),
+    DogAdapterDelegate(activity),
+    GeckoAdapterDelegate(activity),
+    SnakeListItemAdapterDelegate(activity)
+)

app/src/main/java/com/hannesdorfmann/adapterdelegates4/sample/dsl/DslSample.kt

@@ -0,0 +1,20 @@
+package com.hannesdorfmann.adapterdelegates4.sample.dsl
+
+import android.util.Log
+import com.hannesdorfmann.adapterdelegates4.dsl.adapterDelegateLayoutContainer
+import com.hannesdorfmann.adapterdelegates4.sample.R
+import com.hannesdorfmann.adapterdelegates4.sample.model.Cat
+import com.hannesdorfmann.adapterdelegates4.sample.model.DisplayableItem
+import kotlinx.android.synthetic.main.item_cat.*
+
+// Example
+fun catAdapterDelegate() = adapterDelegateLayoutContainer<Cat, DisplayableItem>(R.layout.item_cat) {
+
+    name.setOnClickListener {
+        Log.d("Click", "Click on $item")
+    }
+
+    bind {
+        name.text = item.name
+    }
+}

app/src/main/java/com/hannesdorfmann/adapterdelegates4/sample/model/Animal.java

@@ -16,18 +16,26 @@
 
 package com.hannesdorfmann.adapterdelegates4.sample.model;
 
+import androidx.annotation.NonNull;
+
 /**
  * @author Hannes Dorfmann
  */
 public class Animal implements DisplayableItem {
 
-  private String name;
+    private String name;
+
+    public Animal(String name) {
+        this.name = name;
+    }
 
-  public Animal(String name) {
-    this.name = name;
-  }
+    public String getName() {
+        return name;
+    }
 
-  public String getName() {
-    return name;
-  }
+    @NonNull
+    @Override
+    public String toString() {
+        return name + " " + super.toString();
+    }
 }

app/src/main/java/com/hannesdorfmann/adapterdelegates4/sample/model/Cat.java

@@ -24,6 +24,4 @@ public class Cat extends Animal {
   public Cat(String name) {
     super(name);
   }
-
-
 }

build.gradle

@@ -1,13 +1,15 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
+    ext.kotlin_version = '1.3.40'
     repositories {
         google()
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.3.2'
+        classpath 'com.android.tools.build:gradle:3.4.1'
         classpath 'com.vanniktech:gradle-maven-publish-plugin:0.6.0'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files

gradle.properties

@@ -17,7 +17,7 @@
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
 # org.gradle.parallel=true
 
-VERSION_NAME=4.0.1-SNAPSHOT
+VERSION_NAME=4.1.0-SNAPSHOT
 VERSION_CODE=401
 GROUP=com.hannesdorfmann
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Sun Mar 31 17:59:48 CEST 2019
+#Wed Jul 03 19:42:09 CEST 2019
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.10.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.1.1-all.zip

kotlin-dsl-layoutcontainer/.gitignore

@@ -0,0 +1 @@
+/build