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Merged
merged 1 commit into from
Jul 14, 2025
Merged

Add nested emphasis support #15

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120 changes: 91 additions & 29 deletions Sources/SwiftParser/Languages/MarkdownLanguage.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -824,6 +824,77 @@ public struct MarkdownLanguage: CodeLanguage {
}
}

// Helper to parse inline content supporting nested emphasis/strong
static func parseInline(context: inout CodeContext, closing: Token, count: Int) -> ([CodeNode], Bool) {
var nodes: [CodeNode] = []
var text = ""
var closed = false
func flush() {
if !text.isEmpty {
nodes.append(CodeNode(type: Element.text, value: text))
text = ""
}
}
while context.index < context.tokens.count {
guard let tok = context.tokens[context.index] as? Token else { context.index += 1; continue }
// Check for closing delimiter first
if tok.kindDescription == closing.kindDescription {
var idx = context.index
var cnt = 0
while idx < context.tokens.count, let t = context.tokens[idx] as? Token,
t.kindDescription == closing.kindDescription {
cnt += 1; idx += 1
}
if cnt == count {
context.index = idx
flush()
closed = true
break
}
}

// Strong delimiter
if (tok.kindDescription == "*" || tok.kindDescription == "_") &&
context.index + 1 < context.tokens.count,
let next = context.tokens[context.index + 1] as? Token,
next.kindDescription == tok.kindDescription {
flush()
context.index += 2
let (inner, ok) = parseInline(context: &context, closing: tok, count: 2)
if ok {
let node = CodeNode(type: Element.strong, value: "")
inner.forEach { node.addChild($0) }
nodes.append(node)
continue
} else {
text += tok.text + next.text
continue
}
}

// Emphasis delimiter
if tok.kindDescription == "*" || tok.kindDescription == "_" {
flush()
context.index += 1
let (inner, ok) = parseInline(context: &context, closing: tok, count: 1)
if ok {
let node = CodeNode(type: Element.emphasis, value: "")
inner.forEach { node.addChild($0) }
nodes.append(node)
continue
} else {
text += tok.text
continue
}
}

text += tok.text
context.index += 1
}
flush()
return (nodes, closed)
}

public class StrongBuilder: CodeElementBuilder {
public init() {}
public func accept(context: CodeContext, token: any CodeToken) -> Bool {
Expand All @@ -838,24 +909,19 @@ public struct MarkdownLanguage: CodeLanguage {
}
}
public func build(context: inout CodeContext) {
let snap = context.snapshot()
guard let open = context.tokens[context.index] as? Token else { return }
context.index += 2
var text = ""
while context.index + 1 < context.tokens.count {
if let t1 = context.tokens[context.index] as? Token,
let t2 = context.tokens[context.index + 1] as? Token,
(t1.kindDescription == open.kindDescription && t2.kindDescription == open.kindDescription) {
context.index += 2
let node = CodeNode(type: Element.strong, value: text)
context.currentNode.addChild(node)
return
} else if let tok = context.tokens[context.index] as? Token {
text += tok.text
context.index += 1
} else { context.index += 1 }
let (children, ok) = MarkdownLanguage.parseInline(context: &context, closing: open, count: 2)
if ok {
let node = CodeNode(type: Element.strong, value: "")
children.forEach { node.addChild($0) }
context.currentNode.addChild(node)
} else {
context.restore(snap)
context.currentNode.addChild(CodeNode(type: Element.text, value: open.text + open.text))
context.index += 2
}
let node = CodeNode(type: Element.strong, value: text)
context.currentNode.addChild(node)
}
}

Expand All @@ -868,23 +934,19 @@ public struct MarkdownLanguage: CodeLanguage {
return false
}
public func build(context: inout CodeContext) {
let snap = context.snapshot()
guard let open = context.tokens[context.index] as? Token else { return }
context.index += 1
var text = ""
while context.index < context.tokens.count {
if let tok = context.tokens[context.index] as? Token,
tok.kindDescription == open.kindDescription {
context.index += 1
let node = CodeNode(type: Element.emphasis, value: text)
context.currentNode.addChild(node)
return
} else if let tok = context.tokens[context.index] as? Token {
text += tok.text
context.index += 1
} else { context.index += 1 }
let (children, ok) = MarkdownLanguage.parseInline(context: &context, closing: open, count: 1)
if ok {
let node = CodeNode(type: Element.emphasis, value: "")
children.forEach { node.addChild($0) }
context.currentNode.addChild(node)
} else {
context.restore(snap)
context.currentNode.addChild(CodeNode(type: Element.text, value: open.text))
context.index += 1
}
let node = CodeNode(type: Element.emphasis, value: text)
context.currentNode.addChild(node)
}
}

Expand Down
12 changes: 12 additions & 0 deletions Tests/SwiftParserTests/SwiftParserTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,18 @@ final class SwiftParserTests: XCTestCase {
XCTAssertEqual(result.root.children[2].type as? MarkdownLanguage.Element, .strong)
}

func testMarkdownNestedEmphasis() {
let parser = SwiftParser()
let source = "*a **b** c*"
let result = parser.parse(source, language: MarkdownLanguage())
XCTAssertEqual(result.errors.count, 0)
XCTAssertEqual(result.root.children.count, 1)
let em = result.root.children.first
XCTAssertEqual(em?.type as? MarkdownLanguage.Element, .emphasis)
XCTAssertEqual(em?.children.count, 3)
XCTAssertEqual(em?.children[1].type as? MarkdownLanguage.Element, .strong)
}

func testMarkdownCodeBlockAndInline() {
let parser = SwiftParser()
let source = "```\ncode\n```\ninline `code`"
Expand Down