import Foundation /// This is the main converter class in Aztec. /// It takes care of converting HTML text to NSAttributedString and vice-versa. /// public class HTMLConverter { // MARK: - Plugins & Parsing let pluginManager: PluginManager // MARK: - Initializers public init() { pluginManager = PluginManager() } init(with pluginManager: PluginManager) { self.pluginManager = pluginManager } // MARK: - Converters: HTML -> AttributedString /// If a value is set the character set will be used to replace any last empty line created by the converter. /// open var characterToReplaceLastEmptyLine: Character? let htmlToTree = HTMLParser() private(set) lazy var treeToAttributedString: AttributedStringSerializer = { return AttributedStringSerializer(customizer: pluginManager) }() // MARK: - Converters: AttributedString -> HTML private(set) lazy var attributedStringToTree: AttributedStringParser = { return AttributedStringParser(customizer: pluginManager) }() private(set) lazy var treeToHTML: HTMLSerializer = { return HTMLSerializer(customizer: pluginManager) }() // MARK: - Conversion Logic /// Converts an HTML string into it's `NSAttributedString` representation. /// /// - Parameters: /// - html: the html string. /// - defaultAttributes: the default attributes for the attributed string. /// /// - Returns: the attributed string that represents the provided HTML. /// func attributedString(from html: String, defaultAttributes: [NSAttributedString.Key: Any]? = [:]) -> NSAttributedString { let processedHTML = pluginManager.process(html: html) let rootNode = htmlToTree.parse(processedHTML) pluginManager.process(htmlTree: rootNode) let defaultAttributes = defaultAttributes ?? [:] var attributedString = treeToAttributedString.serialize(rootNode, defaultAttributes: defaultAttributes) if let characterToUse = characterToReplaceLastEmptyLine { attributedString = replaceLastEmptyLine(in: attributedString, with: characterToUse) } return attributedString } func replaceLastEmptyLine(in attributedString: NSAttributedString, with replacement: Character) -> NSAttributedString { var result = attributedString let string = attributedString.string if !string.isEmpty, string.isEmptyLineAtEndOfFile(at: string.count), string.hasSuffix(String(.paragraphSeparator)), let location = string.location(before: attributedString.length) { let mutableString = NSMutableAttributedString(attributedString: attributedString) let attributes = mutableString.attributes(at: location, effectiveRange: nil) mutableString.replaceCharacters(in: NSRange(location: location, length: attributedString.length-location), with: NSAttributedString(string: String(replacement), attributes: attributes)) result = mutableString } return result } /// Check if the given html string is supported to be parsed into Attributed Strings. /// /// In some cases, like pasting from the Notes app, the generated HTML will have a `` tag, and that /// is not yet supported. In those cases is preferible to abort html parsing. /// /// - Parameter html: The html string to check. /// - Returns: A bool value indicating if the given html string can be handled correctly. /// func isSupported(_ html: String) -> Bool { let processedHTML = pluginManager.process(html: html) let rootNode = htmlToTree.parse(processedHTML) return hasBodyNode(rootNode.children) == false } /// Converts an attributed string string into it's HTML string representation. /// /// - Parameters: /// - attributedString: the attributed string /// - prettify: whether the output should be prettified. /// /// - Returns: the HTML string that represents the provided `NSAttributedString`. /// func html(from attributedString: NSAttributedString, prettify: Bool = false) -> String { let rootNode = attributedStringToTree.parse(attributedString) pluginManager.process(outputHTMLTree: rootNode) let html = treeToHTML.serialize(rootNode, prettify: prettify) return pluginManager.process(outputHTML: html) } } // MARK: - Helpers private extension HTMLConverter { func hasBodyNode(_ nodes: [Node]) -> Bool { return hasBodyNode(ArraySlice(nodes)) } private func hasBodyNode(_ nodes: ArraySlice) -> Bool { if nodes.isEmpty { return false } switch nodes.first { case let element as ElementNode where element.name == Element.body.rawValue: return true default: return hasBodyNode(nodes.dropFirst()) } } }