Headless Development in Fully Reactive Apps

HeadlessDevelopmentInFullyReactiveApps.kt

/*
 * Copyright (c) pakoito 2017
 *
 * 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.
 */

import com.pacoworks.dereference.ReplUtils.c
import com.pacoworks.dereference.ReplUtils.p
import com.pacoworks.dereference.ReplUtils.u
import com.pacoworks.dereference.ReplUtils.into

import com.pacoworks.dereference.ScreenState
import com.pacoworks.dereference.Idle
import com.pacoworks.dereference.Loading
import com.pacoworks.dereference.Success
import com.pacoworks.dereference.Failure

import com.pacoworks.dereference.Profile
import com.pacoworks.dereference.Email

import com.pacoworks.dereference.authIdle
import com.pacoworks.dereference.authLoading
import com.pacoworks.dereference.authSuccess
import com.pacoworks.dereference.authFailure

import com.jakewharton.rxrelay.PublishRelay
import rx.Observable
import rx.Subscriber
import rx.functions.Action1

// Initialize state

val state = c<ScreenState>(Idle)

val userInput = PublishRelay.create<Email>()

// Subscribe user input processing

authIdle(state, userInput, { email -> email.address.length > 5 }, state)

Email("Paco") into userInput

Email("Pacoworks") into userInput

// Subscribe server call that always fails and return to Idle

val errorSub = authLoading(state, { Observable.just(Failure("Wrong!")) }, state)

authFailure(state, state)

errorSub.unsubscribe()

// Subscribe server call that always succeeds and return to Idle

authLoading(state, { Observable.just(Success(Profile("Logged in!"))) }, state)

authSuccess(state, state)

ReplUtils.kt

/*
 * Copyright (c) pakoito 2017
 *
 * 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.
 */

import com.jakewharton.rxrelay.Relay

/**
 * A [SerializedRelay] backed by a [BehaviorRelay] used to represent the value of one piece of state over time
 */
typealias StateHolder<T> = SerializedRelay<T, T>

/**
 * Creates a new [StateHolder]
 */
fun <T: Any> createStateHolder(value: T): StateHolder<T> =
        SerializedRelay(BehaviorRelay.create<T>(value))

object ReplUtils {
    fun <T: Any> c(value: T, name: String = "StateHolder"): StateHolder<T> =
            createStateHolder(value)
                    .apply {
                        zipWith(skip(1), { one, two -> one to two })
                                .subscribe { (one, two) -> println("$name updated!\nFROM:\n$one\nINTO:\n$two\n") }
                    }

    fun <T: Any, U: Relay<T, T>> u(state: U, value: T): Unit =
            state.call(value)

    infix fun <T: Any, U: Relay<T, T>> T.into(state: U): Unit =
            u(state, this)

    fun <T: Any, U: Relay<T, T>> p(state: U): Unit =
            println(state.toBlocking().first().toString())
}