Tusker/Pachyderm/Utilities/CharacterCounter.swift

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//
// CharacterCounter.swift
// Pachyderm
//
// Created by Shadowfacts on 9/29/18.
// Copyright © 2018 Shadowfacts. All rights reserved.
//
import Foundation
public struct CharacterCounter {
static let linkDetector = try! NSDataDetector(types: NSTextCheckingResult.CheckingType.link.rawValue)
static let mention = try! NSRegularExpression(pattern: "(@[a-z0-9_]+)(?:@[a-z0-9\\-\\.]+[a-z0-9]+)?", options: .caseInsensitive)
public static func count(text: String, for instance: Instance? = nil) -> Int {
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let mentionsRemoved = removeMentions(in: text)
var count = mentionsRemoved.count
for match in linkDetector.matches(in: mentionsRemoved, options: [], range: NSRange(location: 0, length: mentionsRemoved.utf16.count)) {
count -= match.range.length
count += instance?.configuration?.statuses.charactersReservedPerURL ?? 23 // default Mastodon link length
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}
return count
}
private static func removeMentions(in text: String) -> String {
var mut = text
for match in mention.matches(in: mut, options: [], range: NSRange(location: 0, length: mut.utf16.count)).reversed() {
let replacement = mut[Range(match.range(at: 1), in: mut)!]
mut.replaceSubrange(Range(match.range, in: mut)!, with: replacement)
}
return mut
}
}