105 lines
3.9 KiB
Swift
105 lines
3.9 KiB
Swift
// Swiftified and further development by (c) 2022 and onwards The vChewing Project (MIT License).
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// Was initially rebranded from (c) Lukhnos Liu's C++ library "Gramambular 2" (MIT License).
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// ====================
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// This code is released under the MIT license (SPDX-License-Identifier: MIT)
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extension Megrez.Compositor {
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/// 幅位單元乃指一組共享起點的節點。
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public class SpanUnit {
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/// 節點陣列。每個位置上的節點可能是 nil。
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public var nodes: [Node?] = []
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/// 該幅位單元內的所有節點當中持有最長幅位的節點長度。
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/// 該變數受該幅位的自身操作函式而被動更新。
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public private(set) var maxLength = 0
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/// （該變數為捷徑，代傳 Megrez.Compositor.maxSpanLength。）
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private var maxSpanLength: Int { Megrez.Compositor.maxSpanLength }
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/// 該幅位單元內的節點的幅位長度上限。
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private var allowedLengths: ClosedRange<Int> { 1 ... maxSpanLength }
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/// 幅位乃指一組共享起點的節點。
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public init() {
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clear()
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}
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/// 清除該幅位單元的全部的節點，且重設最長節點長度為 0，然後再在節點陣列內預留空位。
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public func clear() {
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nodes.removeAll()
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for _ in 0 ..< maxSpanLength {
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nodes.append(nil)
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}
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maxLength = 0
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}
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/// 往該幅位塞入一個節點。
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/// - Parameter node: 要塞入的節點。
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/// - Returns: 該操作是否成功執行。
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@discardableResult public func append(node: Node) -> Bool {
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guard allowedLengths.contains(node.spanLength) else {
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return false
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}
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nodes[node.spanLength - 1] = node
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maxLength = max(maxLength, node.spanLength)
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return true
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}
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/// 丟掉任何不小於給定幅位長度的節點。
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/// - Parameter length: 給定的幅位長度。
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/// - Returns: 該操作是否成功執行。
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@discardableResult public func dropNodesOfOrBeyond(length: Int) -> Bool {
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guard allowedLengths.contains(length) else {
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return false
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}
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for i in length ... maxSpanLength {
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nodes[i - 1] = nil
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}
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maxLength = 0
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guard length > 1 else { return false }
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let maxR = length - 2
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for i in 0 ... maxR {
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if nodes[maxR - i] == nil { continue }
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maxLength = maxR - i + 1
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break
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}
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return true
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}
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/// 以給定的幅位長度，在當前幅位單元內找出對應的節點。
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/// - Parameter length: 給定的幅位長度。
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/// - Returns: 查詢結果。
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public func nodeOf(length: Int) -> Node? {
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guard allowedLengths.contains(length) else { return nil }
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return nodes[length - 1]
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}
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}
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// MARK: Internal implementations.
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/// 找出所有與該位置重疊的節點。其返回值為一個節錨陣列（包含節點、以及其起始位置）。
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/// - Parameter location: 游標位置。
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/// - Returns: 一個包含所有與該位置重疊的節點的陣列。
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internal func fetchOverlappingNodes(at location: Int) -> [NodeAnchor] {
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var results = [NodeAnchor]()
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guard !spans.isEmpty, location < spans.count else { return results }
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// 先獲取該位置的所有單字節點。
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for theLocation in 1 ... spans[location].maxLength {
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guard let node = spans[location].nodeOf(length: theLocation) else { continue }
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results.append(.init(node: node, spanIndex: location))
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}
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// 再獲取以當前位置結尾或開頭的節點。
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let begin: Int = location - min(location, Megrez.Compositor.maxSpanLength - 1)
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for theLocation in begin ..< location {
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let (A, B): (Int, Int) = (location - theLocation + 1, spans[theLocation].maxLength)
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guard A <= B else { continue }
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for theLength in A ... B {
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guard let node = spans[theLocation].nodeOf(length: theLength) else { continue }
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results.append(.init(node: node, spanIndex: theLocation))
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}
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}
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return results
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}
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}
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