NetNewsWire/Shared/Extensions/NSAttributedString+NetNewsW...

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//
// NSAttributedString+NetNewsWire.swift
// NetNewsWire
//
// Created by Nate Weaver on 2020-04-07.
// Copyright © 2020 Ranchero Software. All rights reserved.
//
import RSParser
#if canImport(AppKit)
import AppKit
typealias Font = NSFont
typealias FontDescriptor = NSFontDescriptor
private let boldTrait = NSFontDescriptor.SymbolicTraits.bold
private let italicTrait = NSFontDescriptor.SymbolicTraits.italic
private let monoSpaceTrait = NSFontDescriptor.SymbolicTraits.monoSpace
#else
import UIKit
typealias Font = UIFont
typealias FontDescriptor = UIFontDescriptor
private let boldTrait = UIFontDescriptor.SymbolicTraits.traitBold
private let italicTrait = UIFontDescriptor.SymbolicTraits.traitItalic
private let monoSpaceTrait = UIFontDescriptor.SymbolicTraits.traitMonoSpace
#endif
extension NSAttributedString {
/// Adds a font and color to an attributed string.
///
/// - Parameters:
/// - baseFont: The font to add.
func adding(font baseFont: Font) -> NSAttributedString {
let mutable = self.mutableCopy() as! NSMutableAttributedString
let fullRange = NSRange(location: 0, length: mutable.length)
let size = baseFont.pointSize
let baseDescriptor = baseFont.fontDescriptor
let baseSymbolicTraits = baseDescriptor.symbolicTraits
mutable.enumerateAttribute(.font, in: fullRange, options: []) { (font: Any?, range: NSRange, stop: UnsafeMutablePointer<ObjCBool>) in
guard let font = font as? Font else { return }
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let currentDescriptor = font.fontDescriptor
let symbolicTraits = baseSymbolicTraits.union(currentDescriptor.symbolicTraits)
var descriptor = currentDescriptor.addingAttributes(baseDescriptor.fontAttributes)
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#if canImport(AppKit)
descriptor = descriptor.withSymbolicTraits(symbolicTraits)
#else
descriptor = descriptor.withSymbolicTraits(symbolicTraits)!
#endif
let newFont = Font(descriptor: descriptor, size: size)
mutable.addAttribute(.font, value: newFont as Any, range: range)
}
return mutable.copy() as! NSAttributedString
}
private enum InTag {
case none
case opening
case closing
}
private enum Style {
case bold
case italic
case superscript
case `subscript`
case underline
case strikethrough
case monospace
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init?(forTag: String) {
switch forTag {
case "b", "strong":
self = .bold
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case "i", "em", "cite", "var", "dfn":
self = .italic
case "sup":
self = .superscript
case "sub":
self = .subscript
case "u", "ins":
self = .underline
case "s", "del":
self = .strikethrough
case "code", "samp", "tt", "kbd":
self = .monospace
default:
return nil
}
}
}
/// Returns an attributed string initialized from HTML text containing basic inline stylistic tags.
///
/// - Parameters:
/// - html: The HTML text.
/// - locale: The locale used for quotation marks when parsing `<q>` tags.
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convenience init(html: String, locale: Locale = Locale.current) {
let baseFont = Font.systemFont(ofSize: Font.systemFontSize)
var inTag: InTag = .none
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var tag = ""
var currentStyles = CountedSet<Style>()
var iterator = html.makeIterator()
let result = NSMutableAttributedString()
var attributeRanges = [ (range: NSRange, styles: CountedSet<Style>) ]()
var quoteDepth = 0
while let char = iterator.next() {
if char == "<" && inTag == .none {
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tag.removeAll()
guard let first = iterator.next() else { break }
if first == "/" {
inTag = .closing
} else {
inTag = .opening
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tag.append(first)
}
} else if char == ">" && inTag != .none {
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let lastRange = attributeRanges.last?.range
let location = lastRange != nil ? lastRange!.location + lastRange!.length : 0
let range = NSRange(location: location, length: result.mutableString.length - location)
attributeRanges.append( (range: range, styles: currentStyles) )
if inTag == .opening {
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if tag == "q" {
quoteDepth += 1
let delimiter = quoteDepth % 2 == 1 ? locale.quotationBeginDelimiter : locale.alternateQuotationBeginDelimiter
result.mutableString.append(delimiter ?? "\"")
}
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if let style = Style(forTag: tag) {
currentStyles.insert(style)
}
} else {
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if tag == "q" {
let delimiter = quoteDepth % 2 == 1 ? locale.quotationEndDelimiter : locale.alternateQuotationEndDelimiter
result.mutableString.append(delimiter ?? "\"")
quoteDepth -= 1
}
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if let style = Style(forTag: tag) {
currentStyles.remove(style)
}
}
inTag = .none
} else if inTag != .none {
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tag.append(char)
} else {
if char == "&" {
var entity = "&"
var lastchar: Character? = nil
while let entitychar = iterator.next() {
if entitychar.isWhitespace {
lastchar = entitychar
break;
}
entity.append(entitychar)
if (entitychar == ";") { break }
}
result.mutableString.append(entity.decodedEntity)
if let lastchar = lastchar { result.mutableString.append(String(lastchar)) }
} else {
result.mutableString.append(String(char))
}
}
}
result.addAttribute(.font, value: baseFont, range: NSRange(location: 0, length: result.length))
for (range, styles) in attributeRanges {
let currentFont = result.attribute(.font, at: range.location, effectiveRange: nil) as! Font
let currentDescriptor = currentFont.fontDescriptor
var descriptor = currentDescriptor.copy() as! FontDescriptor
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var symbolicTraits = currentDescriptor.symbolicTraits
if styles.contains(.bold) {
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let traits: [FontDescriptor.TraitKey: Any] = [.weight: Font.Weight.bold]
let attributes: [FontDescriptor.AttributeName: Any] = [.traits: traits]
descriptor = descriptor.addingAttributes(attributes)
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symbolicTraits.insert(boldTrait)
}
if styles.contains(.italic) {
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symbolicTraits.insert(italicTrait)
}
if styles.contains(.monospace) {
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symbolicTraits.insert(monoSpaceTrait)
}
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#if canImport(AppKit)
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descriptor = descriptor.withSymbolicTraits(symbolicTraits)
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#else
descriptor = descriptor.withSymbolicTraits(symbolicTraits)!
#endif
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func verticalPositionFeature(forSuperscript: Bool) -> [FontDescriptor.FeatureKey: Any] {
#if canImport(AppKit)
let features: [FontDescriptor.FeatureKey: Any] = [.typeIdentifier: kVerticalPositionType, .selectorIdentifier: forSuperscript ? kSuperiorsSelector : kInferiorsSelector]
#else
let features: [FontDescriptor.FeatureKey: Any] = [.featureIdentifier: kVerticalPositionType, .typeIdentifier: forSuperscript ? kSuperiorsSelector : kInferiorsSelector]
#endif
return features
}
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if styles.contains(.superscript) || styles.contains(.subscript) {
let features = verticalPositionFeature(forSuperscript: styles.contains(.superscript))
let descriptorAttributes: [FontDescriptor.AttributeName: Any] = [.featureSettings: [features]]
descriptor = descriptor.addingAttributes(descriptorAttributes)
}
var attributes = [NSAttributedString.Key: Any]()
attributes[.font] = Font(descriptor: descriptor, size: baseFont.pointSize)
if styles.contains(.strikethrough) {
attributes[.strikethroughStyle] = NSUnderlineStyle.single.rawValue
}
if styles.contains(.underline) {
attributes[.underlineStyle] = NSUnderlineStyle.single.rawValue
}
result.addAttributes(attributes, range: range)
}
self.init(attributedString: result)
}
}
/// This is a very, very basic implementation that only covers our needs.
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private struct CountedSet<Element> where Element: Hashable {
private var _storage = [Element: Int]()
mutating func insert(_ element: Element) {
_storage[element, default: 0] += 1
}
mutating func remove(_ element: Element) {
guard var count = _storage[element] else { return }
count -= 1
if count == 0 {
_storage.removeValue(forKey: element)
} else {
_storage[element] = count
}
}
func contains(_ element: Element) -> Bool {
return _storage[element] != nil
}
subscript(key: Element) -> Int {
get {
return _storage[key, default: 0]
}
}
}
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private extension String {
var decodedEntity: String {
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// It's possible the implementation will change, but for now it just calls this.
(self as NSString).rsparser_stringByDecodingHTMLEntities() as String
}
}