132 lines
3.9 KiB
Swift
132 lines
3.9 KiB
Swift
//
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// TextConverter.swift
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// HTMLStreamer
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//
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// Created by Shadowfacts on 12/19/23.
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//
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import Foundation
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public struct TextConverter<Callbacks: HTMLConversionCallbacks> {
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private let configuration: TextConverterConfiguration
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private var tokenizer: Tokenizer<String.UnicodeScalarView.Iterator>!
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private var str: String!
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private var actionStack: [ElementAction] = []
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private var previouslyFinishedBlockElement = false
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private var currentElementIsEmpty = true
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private var currentRun = ""
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public init(configuration: TextConverterConfiguration = .init()) where Callbacks == DefaultCallbacks {
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self.init(configuration: configuration, callbacks: DefaultCallbacks.self)
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}
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public init(configuration: TextConverterConfiguration = .init(), callbacks _: Callbacks.Type = Callbacks.self) {
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self.configuration = configuration
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}
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public mutating func convert(html: String) -> String {
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tokenizer = Tokenizer(chars: html.unicodeScalars.makeIterator())
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str = ""
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while let token = tokenizer.next() {
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switch token {
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case .character(let scalar):
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currentElementIsEmpty = false
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previouslyFinishedBlockElement = false
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currentRun.unicodeScalars.append(scalar)
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case .characterSequence(let string):
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currentElementIsEmpty = false
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previouslyFinishedBlockElement = false
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currentRun.append(string)
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case .startTag(let name, let selfClosing, let attributes):
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currentElementIsEmpty = true
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previouslyFinishedBlockElement = false
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let action = Callbacks.elementAction(name: name, attributes: attributes)
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actionStack.append(action)
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handleStartTag(name, selfClosing: selfClosing, attributes: attributes)
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case .endTag(let name):
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handleEndTag(name)
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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 .comment, .doctype:
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break
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}
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}
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if previouslyFinishedBlockElement {
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if configuration.insertNewlines {
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currentRun.removeLast(2)
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} else {
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currentRun.removeLast(1)
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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, selfClosing: Bool, attributes: [Attribute]) {
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switch name {
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case "br":
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if configuration.insertNewlines {
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currentRun.append("\n")
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} else {
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currentRun.append(" ")
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}
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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 handleEndTag(_ name: String) {
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switch name {
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case "pre", "blockquote", "p", "ol", "ul":
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finishRun()
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finishBlockElement()
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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 finishBlockElement() {
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if !currentElementIsEmpty {
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previouslyFinishedBlockElement = true
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if configuration.insertNewlines {
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currentRun.append("\n\n")
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} else {
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currentRun.append(" ")
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}
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}
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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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str.append(currentRun)
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currentRun = ""
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}
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}
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public struct TextConverterConfiguration {
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public var insertNewlines: Bool
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public init(insertNewlines: Bool = true) {
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self.insertNewlines = insertNewlines
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}
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}
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