seanghay

/**
 * ResultOf is a utility result class for handling data and exception.
 * It's useful for LiveData and fragment/activity communication.
 */
sealed class ResultOf<out T> {
    data class Success<out T>(val value: T) : ResultOf<T>()
    data class Failure(
            val message: String?,
            val throwable: Throwable?

seanghay

import androidx.annotation.IntRange;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.VisibleForTesting;

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.text.NumberFormat;
import java.util.Currency;
import java.util.Locale;

seanghay

export function isHexColorValid(hex: string): boolean {
    return /^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$/.test(hex);
}

seanghay

class PostsListAdapter: RecyclerView.Adapter<RecyclerView.ViewHolder>() {
  
  override fun onCreateViewHolder(
    parent: ViewGroup, 
    @LayoutRes viewType: Int
  ): RecyclerView.ViewHolder {
    val view = LayoutInflator.from(parent.context).inflate(viewType, parent, false)
    return when(viewType) {
      R.layout.item_post -> PostViewHolder(view)
      R.layout.item_header -> HeaderViewHolder(view)

seanghay

/* Copyright 2020 Seanghay Yath (@seanghay)
   SPDX-License-Identifier: Apache-2.0 */

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
  viewModel.posts.observe(viewLifecycleOwner, Observer {result ->
    
    val (items) = result.withDefault { postsFromDb() }
    adapter.submitList(items)                                        
    
  })

seanghay

/* Copyright 2020 Seanghay Yath (@seanghay)
   SPDX-License-Identifier: Apache-2.0 */

inline fun <T> ResultOf<T>.withDefault(value: () -> T): ResultOf.Success<T> {
    return when (this) {
        is ResultOf.Success -> this
        is ResultOf.Failure -> ResultOf.Success(value())
    }
}

seanghay

/* Copyright 2020 Seanghay Yath (@seanghay)
   SPDX-License-Identifier: Apache-2.0 */
   
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
  viewModel.posts.observe(viewLifecycleOwner, Observer {result ->
     result.map { it.posts.first() }.doIfSuccess { post -> 
       addToSomewhere(post)                                           
     }                                                  
  })
}

seanghay

/* Copyright 2020 Seanghay Yath (@seanghay)
   SPDX-License-Identifier: Apache-2.0 */
   
inline fun <reified T, reified R> ResultOf<T>.map(transform: (T) -> R): ResultOf<R> {
    return when (this) {
        is ResultOf.Success -> ResultOf.Success(transform(value))
        is ResultOf.Failure -> this
    }
}

seanghay

/* Copyright 2020 Seanghay Yath (@seanghay)
   SPDX-License-Identifier: Apache-2.0 */
   
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
  viewModel.posts.observe(viewLifecycleOwner, Observer {result ->
    
    result.doIfSuccess {items ->
      adapter.submitList(items)
    }                                             
    

seanghay

/* Copyright 2020 Seanghay Yath (@seanghay)
   SPDX-License-Identifier: Apache-2.0 */

inline fun <reified T> ResultOf<T>.doIfFailure(callback: (error: String?, throwable: Throwable?) -> Unit) {
    if (this is ResultOf.Failure) {
        callback(message, throwable)
    }
}

inline fun <reified T> ResultOf<T>.doIfSuccess(callback: (value: T) -> Unit) {