116 lines
2.9 KiB
Swift
116 lines
2.9 KiB
Swift
//
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// AutoCompleteViewModel+Trie.swift
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// Mastodon
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//
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// Created by MainasuK Cirno on 2021-5-18.
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//
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import Foundation
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struct Trie<Element: Hashable> {
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let isElement: Bool
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let valueSet: NSMutableSet
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var children: [Element: Trie<Element>]
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}
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extension Trie {
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init() {
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isElement = false
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valueSet = NSMutableSet()
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children = [:]
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}
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init(_ key: ArraySlice<Element>, value: Any) {
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if let (head, tail) = key.decomposed {
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let children = [head: Trie(tail, value: value)]
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self = Trie(isElement: false, valueSet: NSMutableSet(), children: children)
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} else {
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self = Trie(isElement: true, valueSet: NSMutableSet(object: value), children: [:])
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}
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}
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}
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extension Trie {
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var elements: [[Element]] {
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var result: [[Element]] = isElement ? [[]] : []
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for (key, value) in children {
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result += value.elements.map { [key] + $0 }
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}
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return result
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}
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}
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//extension Array {
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// var slice: ArraySlice<Element> {
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// return ArraySlice(self)
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// }
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//}
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extension ArraySlice {
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var decomposed: (Element, ArraySlice<Element>)? {
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return isEmpty ? nil : (self[startIndex], self.dropFirst())
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}
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}
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extension Trie {
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func lookup(key: ArraySlice<Element>) -> Bool {
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guard let (head, tail) = key.decomposed else { return isElement }
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guard let subtrie = children[head] else { return false }
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return subtrie.lookup(key: tail)
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}
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func lookup(key: ArraySlice<Element>) -> Trie<Element>? {
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guard let (head, tail) = key.decomposed else { return self }
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guard let remainder = children[head] else { return nil }
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return remainder.lookup(key: tail)
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}
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}
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extension Trie {
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func complete(key: ArraySlice<Element>) -> [[Element]] {
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return lookup(key: key)?.elements ?? []
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}
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}
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extension Trie {
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mutating func inserted(_ key: ArraySlice<Element>, value: Any) {
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guard let (head, tail) = key.decomposed else {
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self.valueSet.add(value)
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return
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}
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if var nextTrie = children[head] {
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nextTrie.inserted(tail, value: value)
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children[head] = nextTrie
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} else {
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children[head] = Trie(tail, value: value)
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}
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}
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}
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extension Trie {
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func passthrough(_ key: ArraySlice<Element>) -> [Trie<Element>] {
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guard let (head, tail) = key.decomposed else {
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return [self]
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}
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let passthroughed = children[head]?.passthrough(tail) ?? []
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if isElement {
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return passthroughed + [self]
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} else {
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return passthroughed
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}
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}
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var values: NSSet {
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let valueSet = NSMutableSet(set: self.valueSet)
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for (_, value) in children {
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valueSet.addObjects(from: Array(value.values))
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}
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return valueSet
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}
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}
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