126 lines
3.9 KiB
Swift
126 lines
3.9 KiB
Swift
// Copyright © 2020 Metabolist. All rights reserved.
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import Foundation
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#if !os(macOS)
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import UIKit
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#else
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import AppKit
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#endif
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public struct HTML: Hashable {
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public let raw: String
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public let attributed: NSAttributedString
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}
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extension HTML: Codable {
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public init(from decoder: Decoder) throws {
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let container = try decoder.singleValueContainer()
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raw = try container.decode(String.self)
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if let cachedAttributedString = Self.attributedStringCache.object(forKey: raw as NSString) {
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attributed = cachedAttributedString
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} else {
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attributed = HTMLParser(string: raw).parse()
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Self.attributedStringCache.setObject(attributed, forKey: raw as NSString)
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}
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}
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public func encode(to encoder: Encoder) throws {
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var container = encoder.singleValueContainer()
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try container.encode(raw)
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}
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}
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private extension HTML {
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static var attributedStringCache = NSCache<NSString, NSAttributedString>()
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}
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// https://docs.joinmastodon.org/spec/activitypub/#sanitization
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private final class HTMLParser: NSObject {
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private struct Link: Hashable {
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let href: URL
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let location: Int
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var length = 0
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}
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private let rawString: String
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private let parser: XMLParser
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private let parseStopColumn: Int
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private var constructedString = ""
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private var attributesStack = [[String: String]]()
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private var currentLink: Link?
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private var links = Set<Link>()
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private static let containerTag = "com.metabolist.metatext.container-tag"
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private static let openingContainerTag = "<\(containerTag)>"
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private static let closingContainerTag = "</\(containerTag)>"
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init(string: String) {
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rawString = Self.openingContainerTag
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.appending(string.replacingOccurrences(of: "<br>", with: "<br/>"))
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.appending(Self.closingContainerTag)
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parser = XMLParser(data: Data(rawString.utf8))
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parseStopColumn = rawString.count - Self.closingContainerTag.count
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super.init()
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parser.delegate = self
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}
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func parse() -> NSAttributedString {
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parser.parse()
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let attributedString = NSMutableAttributedString(string: constructedString)
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for link in links {
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attributedString.addAttribute(.link,
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value: link.href,
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range: .init(location: link.location, length: link.length))
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}
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return attributedString
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}
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}
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extension HTMLParser: XMLParserDelegate {
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func parser(_ parser: XMLParser,
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didStartElement elementName: String,
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namespaceURI: String?,
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qualifiedName qName: String?,
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attributes attributeDict: [String: String] = [:]) {
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attributesStack.append(attributeDict)
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if elementName == "a", let hrefString = attributeDict["href"], let href = URL(string: hrefString) {
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currentLink = Link(href: href, location: constructedString.utf16.count)
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} else if elementName == "br" {
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constructedString.append("\n")
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}
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}
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func parser(_ parser: XMLParser,
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didEndElement elementName: String,
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namespaceURI: String?,
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qualifiedName qName: String?) {
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let attributes = attributesStack.removeLast()
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if attributes["class"] == "ellipsis" {
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constructedString.append("…")
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}
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if elementName == "a", var link = currentLink {
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link.length = constructedString.utf16.count - link.location
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links.insert(link)
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} else if elementName == "p", parser.columnNumber < parseStopColumn {
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constructedString.append("\n\n")
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}
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}
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func parser(_ parser: XMLParser, foundCharacters string: String) {
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if attributesStack.last?["class"] != "invisible" {
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constructedString.append(string)
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}
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}
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}
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