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
|
package moe.nea.blog.md
import moe.nea.blog.util.indentSize
import java.util.*
class MarkdownParser(source: String) {
private val lines = source.lines()
private var lineIndex = 0
private var blockIndents = 0
private val indentStack = Stack<Int>()
private val blockParsers = mutableListOf<BlockParser>()
private val inlineParsers = mutableListOf<InlineParser>()
private val preprocessors = Stack<LinePreProcessor>()
private var peekedLine: String? = null
fun findParserFor(line: String): BlockParser? {
return blockParsers.filter { it.detect(line) }
.maxByOrNull { it.prio }
}
fun readChildBlock(): MarkdownBlock? {
val peek = peekLine() ?: return null
val blockParser = findParserFor(peek) ?: ParagraphParser
return blockParser.parse(this)
}
fun pushPreProcessor(preProcessor: LinePreProcessor) {
peekedLine = null
preprocessors.push(preProcessor)
}
fun popPreProcessor() {
peekedLine = null
preprocessors.pop()
}
fun preProcessLine(string: String): String? {
var acc = string
for (processor in preprocessors) {
acc = processor.preprocess(lineIndex, acc) ?: return null
}
return acc
}
fun pushIndent(newIndent: Int) {
indentStack.push(blockIndents)
blockIndents += newIndent
peekedLine = null
}
fun popIndent() {
blockIndents = indentStack.pop()
peekedLine = null
}
fun unpeekLine() {
peekedLine = null
}
fun consumeLine(): String? {
val line = peekLine()
if (line != null) {
peekedLine = null
lineIndex++
}
return line
}
fun peekLine(): String? {
if (lineIndex !in lines.indices) return null
val line = peekedLine ?: preProcessLine(lines[lineIndex]) ?: return null
peekedLine = line
val indent = line.indentSize()
if (indent != null && indent < blockIndents) {
peekedLine = null
return null
}
return line.drop(blockIndents)
}
fun parseInlineTextUntil(
text: String,
initialLookback: MarkdownFormat,
breakout: (lookback: MarkdownFormat, remaining: String) -> Boolean
): Pair<List<MarkdownFormat>, String> {
val seq = mutableListOf<MarkdownFormat>()
var remaining = text
var lastToken: MarkdownFormat = initialLookback
while (remaining.isNotEmpty()) {
if (breakout(lastToken, remaining))
break
val (tok, next) = parseInlineTextOnce(lastToken, remaining)
seq.add(tok)
lastToken = tok
remaining = next
}
return seq to remaining
}
fun parseInlineTextOnce(lookback: MarkdownFormat, text: String): Pair<MarkdownFormat, String> {
require(text.isNotEmpty()) // TODO handle empty string
val parser = inlineParsers.find { it.detect(lookback, text) }
if (parser != null) {
return parser.parse(this, text)
}
if (text[0] == ' ') {
return Pair(Whitespace(), text.substring(1))
}
val nextSpecial = text.indexOfFirst { it in inlineParsers.flatMap { it.specialSyntax } || it == ' ' }
if (nextSpecial == 0) {
return Pair(Word(text.substring(0, 1)), text.substring(1))
}
if (nextSpecial == -1) {
return Pair(Word(text), "")
}
return Pair(Word(text.substring(0, nextSpecial)), text.substring(nextSpecial))
}
fun parseInlineText(text: String): MarkdownFormat {
val (tokens, rest) = parseInlineTextUntil(text, Begin()) { _, _ -> false }
require(rest.isEmpty())
return collapseInlineFormat(tokens, true)
}
private fun expandMarkdownFormats(sequence: List<MarkdownFormat>): List<MarkdownFormat> {
val elongated = mutableListOf<MarkdownFormat>()
for (markdownFormat in sequence) {
if (markdownFormat is FormatSequence) {
elongated.addAll(expandMarkdownFormats(markdownFormat.list))
} else {
elongated.add(markdownFormat)
}
}
return elongated
}
private fun collapseMarkdownFormats(
sequence: List<MarkdownFormat>,
trimWhitespace: Boolean
): MutableList<MarkdownFormat> {
val shortened = mutableListOf<MarkdownFormat>()
var last: MarkdownFormat = if (trimWhitespace) Whitespace() else Begin()
for (format in sequence) {
if (format is Whitespace && last is Whitespace) {
continue
}
last = format
shortened.add(format)
}
return shortened
}
fun collapseInlineFormat(sequence: List<MarkdownFormat>, trimWhitespace: Boolean): MarkdownFormat {
val formats = collapseMarkdownFormats(expandMarkdownFormats(sequence), trimWhitespace)
return formats.singleOrNull() ?: FormatSequence(formats)
}
fun readDocument(): Document {
val list = mutableListOf<MarkdownBlock>()
while (true) {
val block = readChildBlock() ?: break
list.add(block)
}
return Document(list)
}
fun addDefaultParsers() {
blockParsers.add(CodeBlockParser)
blockParsers.add(HeaderParser)
blockParsers.add(ListParser)
blockParsers.add(BlockQuoteParser)
inlineParsers.add(ItalicsParser)
inlineParsers.add(LinkParser)
inlineParsers.add(ImageParser)
}
fun getLineIndex(): Int {
return lineIndex
}
fun mergeBlocks(elements: List<MarkdownBlock>): MarkdownBlock {
return elements.singleOrNull() ?: BlockList(elements)
}
fun getIndent(): Int {
return blockIndents
}
}
|
