forked from GitHub-Mirror/riotX-android
56 lines
1.7 KiB
Kotlin
56 lines
1.7 KiB
Kotlin
/*
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* Copyright 2019 New Vector Ltd
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package im.vector.riotredesign.core.utils
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import androidx.lifecycle.Observer
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open class LiveEvent<out T>(private val content: T) {
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var hasBeenHandled = false
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private set // Allow external read but not write
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/**
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* Returns the content and prevents its use again.
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*/
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fun getContentIfNotHandled(): T? {
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return if (hasBeenHandled) {
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null
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} else {
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hasBeenHandled = true
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content
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}
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}
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/**
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* Returns the content, even if it's already been handled.
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*/
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fun peekContent(): T = content
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}
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/**
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* An [Observer] for [LiveEvent]s, simplifying the pattern of checking if the [LiveEvent]'s content has
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* already been handled.
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*
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* [onEventUnhandledContent] is *only* called if the [LiveEvent]'s contents has not been handled.
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*/
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class EventObserver<T>(private val onEventUnhandledContent: (T) -> Unit) : Observer<LiveEvent<T>> {
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override fun onChanged(event: LiveEvent<T>?) {
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event?.getContentIfNotHandled()?.let { value ->
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onEventUnhandledContent(value)
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}
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}
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} |