47 lines
1.7 KiB
Swift
47 lines
1.7 KiB
Swift
//
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// PreferenceSlot.swift
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//
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// Copyright 2026 Brendan Szymanski <hello@bscubed.dev>
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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 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 General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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// SPDX-License-Identifier: GPL-3.0-or-later
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//
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import LuminateCore
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import Observation
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/// The observable cell backing one preference key.
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///
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/// One instance per key lets Swift Observation track each preference independently.
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@Observable @MainActor package final class PreferenceSlot<Value: PreferenceValue> {
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/// Invoked synchronously after every value write.
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@ObservationIgnored private let onChange: (Value?) -> Void
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/// The current value, or `nil` when the key has never been set.
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package var value: Value? {
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didSet { onChange(value) }
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}
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/// Creates a slot with an optional initial value and persistence hook.
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///
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/// - Parameters:
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/// - value: The value restored from storage, or `nil` when unset. Initialization does not
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/// invoke `onChange`.
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/// - onChange: Invoked synchronously after every subsequent value write.
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package init(_ value: Value?, onChange: @escaping (Value?) -> Void) {
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self.onChange = onChange
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self.value = value
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}
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}
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