forked from GitHub-Mirror/riotX-android
54 lines
1.6 KiB
Kotlin
54 lines
1.6 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.matrix.android.internal.util
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import androidx.lifecycle.LiveData
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import androidx.lifecycle.MediatorLiveData
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object LiveDataUtils {
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fun <FIRST, SECOND, OUT> combine(firstSource: LiveData<FIRST>,
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secondSource: LiveData<SECOND>,
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mapper: (FIRST, SECOND) -> OUT): LiveData<OUT> {
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return MediatorLiveData<OUT>().apply {
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var firstValue: FIRST? = null
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var secondValue: SECOND? = null
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val valueDispatcher = {
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firstValue?.let { safeFirst ->
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secondValue?.let { safeSecond ->
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val mappedValue = mapper(safeFirst, safeSecond)
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postValue(mappedValue)
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}
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}
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}
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addSource(firstSource) {
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firstValue = it
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valueDispatcher()
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}
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addSource(secondSource) {
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secondValue = it
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valueDispatcher()
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}
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}
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}
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} |