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62 lines
1.9 KiB
Kotlin
62 lines
1.9 KiB
Kotlin
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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package org.mozilla.fenix.components
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import androidx.annotation.MainThread
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import androidx.annotation.VisibleForTesting
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import androidx.lifecycle.ViewModel
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import androidx.lifecycle.ViewModelProvider
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import androidx.lifecycle.ViewModelStoreOwner
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import androidx.lifecycle.get
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import mozilla.components.lib.state.Store
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/**
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* Generic ViewModel to wrap a State object for state restoration.
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*
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* @property store [Store] instance attached to [ViewModel].
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*/
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class StoreProvider<T : Store<*, *>>(
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val store: T,
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) : ViewModel() {
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companion object {
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fun <T : Store<*, *>> get(owner: ViewModelStoreOwner, createStore: () -> T): T {
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val factory = StoreProviderFactory(createStore)
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val viewModel: StoreProvider<T> = ViewModelProvider(owner, factory).get()
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return viewModel.store
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}
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}
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}
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/**
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* ViewModel factory to create [StoreProvider] instances.
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*
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* @property createStore Callback to create a new [Store], used when the [ViewModel] is first created.
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*/
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@VisibleForTesting
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class StoreProviderFactory<T : Store<*, *>>(
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private val createStore: () -> T,
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) : ViewModelProvider.Factory {
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@Suppress("UNCHECKED_CAST")
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override fun <VM : ViewModel> create(modelClass: Class<VM>): VM {
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return StoreProvider(createStore()) as VM
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}
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}
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/**
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* Helper function for lazy creation of a [Store] instance scoped to a [ViewModelStoreOwner].
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*
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* @param createStore Function that creates a [Store] instance.
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*/
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@MainThread
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fun <T : Store<*, *>> ViewModelStoreOwner.lazyStore(
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createStore: () -> T,
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): Lazy<T> {
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return lazy(mode = LazyThreadSafetyMode.NONE) {
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StoreProvider.get(this, createStore)
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}
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}
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