82 lines
3.1 KiB
Kotlin
82 lines
3.1 KiB
Kotlin
/*
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* Nextcloud Android client application
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*
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* @author Chris Narkiewicz
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* Copyright (C) 2019 Chris Narkiewicz <hello@ezaquarii.com>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package com.nextcloud.client.logger.ui
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import com.nextcloud.client.core.AsyncRunner
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import com.nextcloud.client.core.Cancellable
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/**
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* This utility class allows implementation of as-you-type filtering of large collections.
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*
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* It asynchronously filters collection in background and provide result via callback on the main thread.
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* If new filter request is posted before current filtering task completes, request
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* is stored as pending and is handled after currently running task completes.
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*
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* If a request is already running, another request is already pending and new request is posted
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* (ex. if somebody types faster than live search can finish), the pending request is overwritten
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* by a new one.
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*/
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class AsyncFilter(private val asyncRunner: AsyncRunner, private val time: () -> Long = System::currentTimeMillis) {
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private var filterTask: Cancellable? = null
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private var pendingRequest: (() -> Unit)? = null
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private val isRunning get() = filterTask != null
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private var startTime = 0L
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/**
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* Schedule filtering request.
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*
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* @param collection items to appy fitler to; items should not be modified when request is being processed
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* @param predicate filter predicate
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* @param onResult result callback called on the main thread
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*/
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fun <T> filter(
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collection: Iterable<T>,
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predicate: (T) -> Boolean,
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onResult: (filtered: List<T>, durationMs: Long) -> Unit
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) {
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pendingRequest = {
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filterAsync(collection, predicate, onResult)
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}
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if (!isRunning) {
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pendingRequest?.invoke()
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}
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}
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private fun <T> filterAsync(collection: Iterable<T>, predicate: (T) -> Boolean, onResult: (List<T>, Long) -> Unit) {
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startTime = time.invoke()
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filterTask = asyncRunner.postQuickTask(
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task = { collection.filter { predicate.invoke(it) } },
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onResult = { filtered: List<T> ->
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onFilterCompleted(filtered, onResult)
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}
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)
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pendingRequest = null
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}
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private fun <T> onFilterCompleted(filtered: List<T>, callback: (List<T>, Long) -> Unit) {
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val dt = time.invoke() - startTime
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callback.invoke(filtered, dt)
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filterTask = null
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startTime = 0L
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pendingRequest?.invoke()
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}
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}
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