/
ParmaCore.swift
217 lines (175 loc) · 6.01 KB
/
ParmaCore.swift
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
//
// ParmaCore.swift
// Parma
//
// Created by leonard on 8/16/20.
//
// Copyright (c) 2020 Leonard Chan <wxclx98@gmail.com>
//
// MIT license, see LICENSE file for details
import SwiftUI
import Down
public typealias Text = SwiftUI.Text
@available(iOS 13.0, macOS 10.15, *)
/// The main logic of Parma.
class ParmaCore: NSObject {
// MARK: - Class property
// Composer collections
private var inlineComposers: [Element : InlineElementComposer] = [:]
private var blockComposers: [Element : BlockElementComposer] = [:]
// Composers
private let plaintTextComposer = PlainTextComposer()
private let strongElementComposer = StrongElementComposer()
private let emphasisElementComposer = EmphasisElementComposer()
private let linkElementComposer = LinkElementComposer()
private let codeElementComposer = CodeElementComposer()
private let headingElementComposer = HeadingElementComposer()
private let paragraphElementComposer = ParagraphElementComposer()
private let imageElementComposer = ImageElementComposer()
private let listElementComposer = ListElementComposer()
private let listItemElementComposer = ListItemElementComposer()
private let unknownElementComposer = UnknownElementComposer()
// Generated views
private var views: Array<AnyView> = []
// Temporary storage
private var texts: Array<Text> = []
private var foundCharacters = ""
private var concatenatedText: Text {
return texts.reduce(Text(""), +)
}
// MARK: - Public property
var composedView: AnyView {
AnyView(
ForEach(0..<views.count, id: \.self) { index in
self.views[index]
}
)
}
/// The render for views.
var render: ParmaRenderable = ParmaRender()
/// The context for element composing.
let context = ComposingContext()
let rootNode: Document
// MARK: - Initialization
convenience init(_ markdown: String) throws {
let down = Down(markdownString: escapeContent(markdown))
let ast = try down.toAST()
guard let document = ast.wrap() as? DownDocument else {
fatalError("Expecting document. Bug in Down?")
}
self.init(rootNode: document)
}
init(rootNode: DownDocument) {
self.rootNode = rootNode
inlineComposers =
[
.text : plaintTextComposer,
.strong : strongElementComposer,
.emphasis : emphasisElementComposer,
.link : linkElementComposer,
.code : codeElementComposer,
]
blockComposers =
[
.paragraph : paragraphElementComposer,
.heading : headingElementComposer,
.image : imageElementComposer,
.list : listElementComposer,
.item : listItemElementComposer,
.unknown : unknownElementComposer
]
}
/// Start composing views.
func start() {
process(rootNode)
}
}
// MARK: - Private function
/// Sanitize input to prevent `<` and `>` from causing problems
private func escapeContent(_ rawContent: String) -> String {
enum EscapedCharacters: String, CaseIterable {
case leftAngleBracket = "<",
rightAngleBracket = ">"
func replacement() -> String {
switch self {
case .leftAngleBracket:
return "<"
case .rightAngleBracket:
return ">"
}
}
static func escapeString(_ string: String) -> String {
var escapedValue = string
self.allCases.forEach {
escapedValue = escapedValue.replacingOccurrences(of: $0.rawValue, with: $0.replacement())
}
return escapedValue
}
}
return EscapedCharacters.escapeString(rawContent)
}
// MARK: - XML parsing logic
extension ParmaCore: XMLParserDelegate {
func process(_ node: Node) {
didStartElement(node)
if let text = node as? DownText, let content = text.literal {
context.foundCharacters += content
} else {
for child in node.childSequence {
process(child)
}
}
didEndElement(node)
}
func didStartElement(_ node: Node) {
let element = node.element
if element != .unknown {
context.enter(in: element)
}
context.attributes = node.attributes
if element.isInline {
inlineComposers[element]?.willStart(in: context)
} else {
blockComposers[element]?.willStart(in: context)
}
}
func didEndElement(_ node: Node) {
let element = node.element
if element.isInline {
if let text = inlineComposers[element]?.text(in: context, render: render) {
if let superEl = context.superElement, superEl.isInline {
context.texts = []
context.texts.append(text)
} else {
context.texts = []
texts.append(text)
context.texts = texts
}
}
inlineComposers[element]?.willStop(in: context)
} else {
if let text = blockComposers[element]?.text(in: context, render: render) {
context.views.append(AnyView(text))
} else {
if texts.count != 0 {
context.views.append(AnyView(concatenatedText))
}
}
texts = []
context.texts = []
if let view = blockComposers[element]?.view(in: context, render: render) {
if context.stack.count > 1 {
context.views.append(view)
} else {
context.views = []
views.append(view)
}
}
blockComposers[element]?.willStop(in: context)
}
context.foundCharacters = ""
if element != .unknown {
context.leaveElement()
}
}
}