1 files changed, 91 insertions, 0 deletions
diff --git a/src/main/kotlin/moe/nea/blog/md/ItalicsParser.kt b/src/main/kotlin/moe/nea/blog/md/ItalicsParser.kt
new file mode 100644
index 0000000..afecf79
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/ItalicsParser.kt
@@ -0,0 +1,91 @@
+package moe.nea.blog.md
+
+object ItalicsParser : InlineParser {
+    override fun detect(lookback: MarkdownFormat, rest: String): Boolean {
+        return lookback is Whitespace && "\\*+[^ ].*".toRegex().matches(rest)
+    }
+
+    override val specialSyntax: Set<Char>
+        get() = setOf('*')
+
+    override fun parse(parser: MarkdownParser, text: String): Pair<MarkdownFormat, String> {
+        var firstStarCount = 0
+        while (firstStarCount in text.indices) {
+            if (text[firstStarCount] != '*') break
+            firstStarCount++
+        }
+
+        if (firstStarCount < 1 || firstStarCount > 3) error("Invalid italics/bold sequence")
+
+        val isBold = firstStarCount >= 2
+        val isItalics = (firstStarCount % 2) == 1
+
+        val firstSequence = mutableListOf<MarkdownFormat>()
+        var remainingText = text.substring(firstStarCount)
+        var lastToken: MarkdownFormat = Begin() // TODO: dedicated begin token
+        while (true) {
+            val (element, next) = parser.parseInlineTextOnce(lastToken, remainingText)
+            remainingText = next
+            lastToken = element
+            firstSequence.add(element)
+            if (element !is Whitespace && next.startsWith("*")) break
+        }
+
+        var secondStarCount = 0
+        while (secondStarCount in remainingText.indices) {
+            if (remainingText[secondStarCount] != '*') break
+            secondStarCount++
+        }
+
+        if (secondStarCount > firstStarCount)
+            secondStarCount = firstStarCount
+        if (secondStarCount < 1) error("Invalid italics/bold sequence")
+
+        remainingText = remainingText.substring(secondStarCount)
+        var firstElement = parser.collapseInlineFormat(firstSequence)
+        if (secondStarCount == 2)
+            firstElement = Bold(firstElement)
+        if (secondStarCount == 1)
+            firstElement = Italics(firstElement)
+        if (secondStarCount == firstStarCount) {
+            if (isBold)
+                firstElement = Bold(firstElement)
+            if (isItalics)
+                firstElement = Italics(firstElement)
+            return Pair(firstElement, remainingText)
+        }
+
+        val secondSequence = mutableListOf<MarkdownFormat>()
+        lastToken = Begin()
+        while (true) {
+            val (element, next) = parser.parseInlineTextOnce(lastToken, remainingText)
+            remainingText = next
+            lastToken = element
+            secondSequence.add(element)
+            if (element !is Whitespace && next.startsWith("*")) break
+        }
+
+        var thirdStarCount = 0
+        while (thirdStarCount in remainingText.indices) {
+            if (remainingText[thirdStarCount] != '*') break
+            thirdStarCount++
+        }
+
+        if (thirdStarCount > firstStarCount - secondStarCount)
+            thirdStarCount = firstStarCount
+
+        remainingText = remainingText.substring(thirdStarCount)
+
+        if (thirdStarCount != firstStarCount - secondStarCount) {
+            error("Invalid italics/bold sequence")
+        }
+        var secondElement = parser.collapseInlineFormat(secondSequence)
+        var combined: MarkdownFormat = FormatSequence(firstElement, secondElement)
+        if (thirdStarCount == 1)
+            combined = Italics(combined)
+        if (thirdStarCount == 2)
+            combined = Bold(combined)
+        return Pair(combined, remainingText)
+    }
+
+}
+\ No newline at end of file