Attributed string conversion
This commit is contained in:
parent
a4d791a995
commit
38d57b3f79
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@ -5,6 +5,10 @@ import PackageDescription
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let package = Package(
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name: "HTMLStreamer",
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platforms: [
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.iOS(.v13),
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.macOS(.v10_15),
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],
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products: [
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// Products define the executables and libraries a package produces, making them visible to other packages.
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.library(
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@ -0,0 +1,320 @@
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//
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// AttributedStringConverter.swift
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// HTMLStreamer
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//
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// Created by Shadowfacts on 11/24/23.
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//
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#if os(iOS)
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import UIKit
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#elseif os(macOS)
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import AppKit
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#endif
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struct AttributedStringConverter<Callbacks: AttributedStringCallbacks> {
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private let configuration: AttributedStringConverterConfiguration
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private var tokenizer: Tokenizer<String.Iterator>
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private let str = NSMutableAttributedString()
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private var actionStack: InlineArray3<ElementAction> = []
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private var styleStack: InlineArray3<Style> = []
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// The current run of text w/o styles changing
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private var currentRun: String = ""
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init(html: String, configuration: AttributedStringConverterConfiguration) where Callbacks == DefaultCallbacks {
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self.init(html: html, configuration: configuration, callbacks: DefaultCallbacks.self)
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}
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init(html: String, configuration: AttributedStringConverterConfiguration, callbacks _: Callbacks.Type = Callbacks.self) {
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self.configuration = configuration
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self.tokenizer = Tokenizer(chars: html.makeIterator())
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}
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mutating func convert() -> NSAttributedString {
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while let token = tokenizer.next() {
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switch token {
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case .character(let c):
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currentRun.append(c)
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case .comment:
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// ignored
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continue
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case .startTag(let name, let selfClosing, let attributes):
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let action = Callbacks.elementAction(name: name, attributes: attributes)
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actionStack.append(action)
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// self closing tags are ignored since they have no content
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if !selfClosing {
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handleStartTag(name, attributes: attributes)
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}
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case .endTag(let name):
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handleEndTag(name)
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// if we have a non-default action for the current element, the run finishes here
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if actionStack.last != .default {
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finishRun()
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}
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actionStack.removeLast()
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case .doctype:
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// ignored
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continue
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}
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}
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finishRun()
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return str
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}
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private mutating func handleStartTag(_ name: String, attributes: InlineArray3<HTMLStreamer.Attribute>) {
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switch name {
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case "br":
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currentRun.append("\n")
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case "a":
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// we need to always insert in attribute, because we need to always have one
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// to remove from the stack in handleEndTag
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// but we only need to finish the run if we have a URL, since otherwise
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// the final attribute run won't be affected
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let url = attributes.attributeValue(for: "href").flatMap(Callbacks.makeURL(string:))
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if url != nil {
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finishRun()
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}
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styleStack.append(.link(url))
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case "em", "i":
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finishRun()
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styleStack.append(.italic)
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case "strong", "b":
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finishRun()
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styleStack.append(.bold)
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case "del":
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finishRun()
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styleStack.append(.strikethrough)
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case "code":
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finishRun()
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styleStack.append(.monospace)
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case "pre":
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startBlockElement()
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finishRun()
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styleStack.append(.monospace)
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case "blockquote":
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startBlockElement()
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finishRun()
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styleStack.append(.blockquote)
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case "p":
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startBlockElement()
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default:
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break
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}
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}
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private mutating func startBlockElement() {
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if str.length != 0 || !currentRun.isEmpty {
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currentRun.append("\n\n")
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}
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}
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private mutating func handleEndTag(_ name: String) {
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switch name {
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case "a":
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if case .link(.some(_)) = styleStack.last {
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finishRun()
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}
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removeLastStyle(.link)
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case "em", "i":
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finishRun()
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removeLastStyle(.italic)
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case "strong", "b":
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finishRun()
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removeLastStyle(.bold)
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case "del":
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finishRun()
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removeLastStyle(.strikethrough)
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case "code":
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finishRun()
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removeLastStyle(.monospace)
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case "pre":
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finishRun()
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removeLastStyle(.monospace)
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case "blockquote":
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finishRun()
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removeLastStyle(.blockquote)
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default:
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break
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}
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}
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// needed to correctly handle mis-nested tags
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private mutating func removeLastStyle(_ type: Style.StyleType) {
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var i = styleStack.index(before: styleStack.endIndex)
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while i >= styleStack.startIndex {
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if styleStack[i].type == type {
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styleStack.remove(at: i)
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return
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}
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styleStack.formIndex(before: &i)
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}
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}
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private lazy var blockquoteParagraphStyle: NSParagraphStyle = {
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let style = configuration.paragraphStyle.mutableCopy() as! NSMutableParagraphStyle
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style.headIndent = 32
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style.firstLineHeadIndent = 32
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return style
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}()
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private mutating func finishRun() {
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guard !currentRun.isEmpty else {
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return
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}
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if actionStack.contains(.skip) {
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currentRun = ""
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return
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} else if case .replace(let replacement) = actionStack.first(where: \.isReplace) {
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currentRun = replacement
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}
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var attributes = [NSAttributedString.Key: Any]()
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var currentFontTraits = Set<FontTrait>()
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for style in styleStack {
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switch style {
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case .bold:
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currentFontTraits.insert(.bold)
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case .italic:
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currentFontTraits.insert(.italic)
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case .monospace:
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currentFontTraits.insert(.monospace)
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case .link(let url):
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if let url {
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attributes[.link] = url
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}
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case .strikethrough:
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attributes[.strikethroughStyle] = NSUnderlineStyle.single.rawValue
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case .blockquote:
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attributes[.paragraphStyle] = blockquoteParagraphStyle
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currentFontTraits.insert(.italic)
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}
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}
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let baseFont = currentFontTraits.contains(.monospace) ? configuration.monospaceFont : configuration.font
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var descriptor = baseFont.fontDescriptor
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if currentFontTraits.contains(.bold) && currentFontTraits.contains(.italic),
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let boldItalic = descriptor.withSymbolicTraits([.traitBold, .traitItalic]) {
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descriptor = boldItalic
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} else if currentFontTraits.contains(.bold),
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let bold = descriptor.withSymbolicTraits(.traitBold) {
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descriptor = bold
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} else if currentFontTraits.contains(.italic),
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let italic = descriptor.withSymbolicTraits(.traitItalic) {
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descriptor = italic
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}
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#if os(iOS)
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attributes[.font] = UIFont(descriptor: descriptor, size: 0)
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#elseif os(macOS)
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attributes[.font] = NSFont(descriptor: descriptor, size: 0)
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#endif
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if !attributes.keys.contains(.paragraphStyle) {
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attributes[.paragraphStyle] = configuration.paragraphStyle
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}
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str.append(NSAttributedString(string: currentRun, attributes: attributes))
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currentRun = ""
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}
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}
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protocol AttributedStringCallbacks {
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static func makeURL(string: String) -> URL?
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static func elementAction(name: String, attributes: InlineArray3<Attribute>) -> ElementAction
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}
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enum ElementAction: Equatable {
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case `default`
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case skip
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case replace(String)
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var isReplace: Bool {
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if case .replace(_) = self {
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true
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} else {
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false
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}
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}
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}
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extension AttributedStringCallbacks {
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static func makeURL(string: String) -> URL? {
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URL(string: string)
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}
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static func elementAction(name: String, attributes: InlineArray3<Attribute>) -> ElementAction {
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.default
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}
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}
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struct DefaultCallbacks: AttributedStringCallbacks {
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}
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struct AttributedStringConverterConfiguration {
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#if os(iOS)
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var font: UIFont
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var monospaceFont: UIFont
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var color: UIColor
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#elseif os(macOS)
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var font: NSFont
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var monospaceFont: NSFont
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var color: NSColor
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#endif
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var paragraphStyle: NSParagraphStyle
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}
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#if os(macOS)
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private extension NSFontDescriptor {
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func withSymbolicTraits(_ traits: SymbolicTraits) -> NSFontDescriptor? {
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let descriptor: NSFontDescriptor = self.withSymbolicTraits(traits)
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return descriptor
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}
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}
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private extension NSFontDescriptor.SymbolicTraits {
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static var traitBold: Self { .bold }
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static var traitItalic: Self { .italic }
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}
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#endif
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private enum FontTrait {
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case bold
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case italic
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case monospace
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}
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private enum Style {
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case bold
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case italic
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case monospace
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case link(URL?)
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case strikethrough
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case blockquote
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var type: StyleType {
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switch self {
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case .bold:
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return .bold
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case .italic:
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return .italic
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case .monospace:
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return .monospace
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case .link(_):
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return .link
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case .strikethrough:
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return .strikethrough
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case .blockquote:
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return .blockquote
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}
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}
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enum StyleType {
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case bold, italic, monospace, link, strikethrough, blockquote
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}
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}
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extension Collection where Element == Attribute {
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func attributeValue(for name: String) -> String? {
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first(where: { $0.name == name })?.value
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}
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}
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@ -0,0 +1,195 @@
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//
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// AttributedStringConverterTests.swift
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//
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//
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// Created by Shadowfacts on 11/24/23.
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//
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import XCTest
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@testable import HTMLStreamer
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final class AttributedStringConverterTests: XCTestCase {
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#if os(iOS)
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private let font = UIFont.systemFont(ofSize: 13)
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private let monospaceFont = UIFont.monospacedSystemFont(ofSize: 13, weight: .regular)
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#elseif os(macOS)
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private let font = NSFont.systemFont(ofSize: 13)
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private lazy var italicFont = NSFont(descriptor: font.fontDescriptor.withSymbolicTraits(.italic), size: 13)!
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private lazy var boldFont = NSFont(descriptor: font.fontDescriptor.withSymbolicTraits(.bold), size: 13)!
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private lazy var boldItalicFont = NSFont(descriptor: font.fontDescriptor.withSymbolicTraits([.bold, .italic]), size: 13)!
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private let monospaceFont = NSFont.monospacedSystemFont(ofSize: 13, weight: .regular)
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#endif
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private let blockquoteParagraphStyle: NSParagraphStyle = {
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let style = NSParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle
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style.headIndent = 32
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style.firstLineHeadIndent = 32
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return style
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}()
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private func convert(_ html: String) -> NSAttributedString {
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convert(html, callbacks: DefaultCallbacks.self)
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}
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private func convert<Callbacks: AttributedStringCallbacks>(_ html: String, callbacks _: Callbacks.Type = Callbacks.self) -> NSAttributedString {
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let config = AttributedStringConverterConfiguration(
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font: font,
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monospaceFont: monospaceFont,
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color: .black,
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paragraphStyle: .default
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)
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var converter = AttributedStringConverter<Callbacks>(html: html, configuration: config)
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return converter.convert()
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}
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func testConvertBR() {
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XCTAssertEqual(convert("a<br>b"), NSAttributedString(string: "a\nb", attributes: [
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.font: font,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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}
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func testConvertA() {
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XCTAssertEqual(convert("<a href='https://example.com'>link</a>"), NSAttributedString(string: "link", attributes: [
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.font: font,
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.paragraphStyle: NSParagraphStyle.default,
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.link: URL(string: "https://example.com")!,
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]))
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XCTAssertEqual(convert("<a>link</a>"), NSAttributedString(string: "link", attributes: [
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.font: font,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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}
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func testConvertP() {
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XCTAssertEqual(convert("<p>a</p><p>b</p>"), NSAttributedString(string: "a\n\nb", attributes: [
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.font: font,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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}
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func testConvertEm() {
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XCTAssertEqual(convert("<em>hello</em>"), NSAttributedString(string: "hello", attributes: [
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.font: italicFont,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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XCTAssertEqual(convert("<i>hello</i>"), NSAttributedString(string: "hello", attributes: [
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.font: italicFont,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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}
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func testConvertStrong() {
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XCTAssertEqual(convert("<strong>hello</strong>"), NSAttributedString(string: "hello", attributes: [
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.font: boldFont,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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XCTAssertEqual(convert("<b>hello</b>"), NSAttributedString(string: "hello", attributes: [
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.font: boldFont,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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}
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func testConvertBoldItalic() {
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XCTAssertEqual(convert("<strong><em>hello</em></strong>"), NSAttributedString(string: "hello", attributes: [
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.font: boldItalicFont,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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}
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func testIncorrectNesting() {
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let result = NSMutableAttributedString()
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result.append(NSAttributedString(string: "bold ", attributes: [
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.font: boldFont,
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]))
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result.append(NSAttributedString(string: "both", attributes: [
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.font: boldItalicFont,
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]))
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result.append(NSAttributedString(string: " italic", attributes: [
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.font: italicFont,
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]))
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result.addAttribute(.paragraphStyle, value: NSParagraphStyle.default, range: NSRange(location: 0, length: result.length))
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XCTAssertEqual(convert("<strong>bold <em>both</strong> italic</em>"), result)
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}
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func testDel() {
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XCTAssertEqual(convert("<del>blah</del>"), NSAttributedString(string: "blah", attributes: [
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.font: font,
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.paragraphStyle: NSParagraphStyle.default,
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.strikethroughStyle: NSUnderlineStyle.single.rawValue,
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]))
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}
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func testCode() {
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XCTAssertEqual(convert("<code>wee</code>"), NSAttributedString(string: "wee", attributes: [
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.font: monospaceFont,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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}
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func testPre() {
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XCTAssertEqual(convert("<pre>wee</pre>"), NSAttributedString(string: "wee", attributes: [
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.font: monospaceFont,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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}
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func testBlockquote() {
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XCTAssertEqual(convert("<blockquote>hello</blockquote>"), NSAttributedString(string: "hello", attributes: [
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.font: italicFont,
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.paragraphStyle: blockquoteParagraphStyle,
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]))
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XCTAssertEqual(convert("<blockquote><b>hello</b></blockquote>"), NSAttributedString(string: "hello", attributes: [
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.font: boldItalicFont,
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.paragraphStyle: blockquoteParagraphStyle,
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]))
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}
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func testSelfClosing() {
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XCTAssertEqual(convert("<b />asdf"), NSAttributedString(string: "asdf", attributes: [
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.font: font,
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.paragraphStyle: NSParagraphStyle.default,
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]))
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}
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func testMakeURLCallback() {
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struct Callbacks: AttributedStringCallbacks {
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static func makeURL(string: String) -> URL? {
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URL(string: "https://apple.com")
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}
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}
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let result = convert("<a href='https://example.com'>test</a>", callbacks: Callbacks.self)
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XCTAssertEqual(result, NSAttributedString(string: "test", attributes: [
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.font: font,
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.paragraphStyle: NSParagraphStyle.default,
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.link: URL(string: "https://apple.com")!,
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]))
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}
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func testElementActionCallback() {
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struct Callbacks: AttributedStringCallbacks {
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static func elementAction(name: String, attributes: InlineArray3<Attribute>) -> ElementAction {
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let clazz = attributes.attributeValue(for: "class")
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if clazz == "invisible" {
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return .skip
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} else if clazz == "ellipsis" {
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return .replace("…")
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} else {
|
||||
return .default
|
||||
}
|
||||
}
|
||||
}
|
||||
let skipped = convert("<span class='invisible'>test</span>", callbacks: Callbacks.self)
|
||||
XCTAssertEqual(skipped, NSAttributedString())
|
||||
let skipNestped = convert("<span class='invisible'><b>test</b></span>", callbacks: Callbacks.self)
|
||||
XCTAssertEqual(skipNestped, NSAttributedString())
|
||||
let skipNestped2 = convert("<b><span class='invisible'>test</span></b>", callbacks: Callbacks.self)
|
||||
XCTAssertEqual(skipNestped2, NSAttributedString())
|
||||
let replaced = convert("<span class='ellipsis'>test</span>", callbacks: Callbacks.self)
|
||||
XCTAssertEqual(replaced, NSAttributedString(string: "…", attributes: [
|
||||
.font: font,
|
||||
.paragraphStyle: NSParagraphStyle.default,
|
||||
]))
|
||||
}
|
||||
|
||||
}
|
||||
Loading…
Reference in New Issue