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Jul 15, 2025
Merged

Implement nested list parsing #19

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255 changes: 204 additions & 51 deletions Sources/SwiftParser/Languages/MarkdownLanguage.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,8 @@ public struct MarkdownLanguage: CodeLanguage {
case text
case listItem
case orderedListItem
case unorderedList
case orderedList
case emphasis
case strong
case codeBlock
Expand Down Expand Up @@ -402,88 +404,239 @@ public struct MarkdownLanguage: CodeLanguage {
}
}

public class ListItemBuilder: CodeElementBuilder {
// MARK: - List Parsing

public class UnorderedListBuilder: CodeElementBuilder {
public init() {}
public func accept(context: CodeContext, token: any CodeToken) -> Bool {
guard let tok = token as? Token else { return false }
switch tok {
case .dash, .star, .plus:
if context.index + 1 < context.tokens.count,
let next = context.tokens[context.index + 1] as? Token,
case .text(let s, _) = next,
s.first?.isWhitespace == true {
if context.index == 0 { return true }
if let prev = context.tokens[context.index - 1] as? Token, case .newline = prev {
return true
}

private func lineIndent(before idx: Int, in context: CodeContext) -> Int? {
if idx == 0 { return 0 }
var i = idx - 1
var count = 0
while i >= 0 {
guard let tok = context.tokens[i] as? Token else { return nil }
switch tok {
case .newline:
return count
case .text(let s, _) where s.allSatisfy({ $0 == " " }):
count += s.count
i -= 1
default:
return nil
}
default:
break
}
return false
return count
}

private func isBullet(_ tok: Token) -> Bool {
switch tok {
case .dash, .star, .plus: return true
default: return false
}
}

public func accept(context: CodeContext, token: any CodeToken) -> Bool {
guard let tok = token as? Token, isBullet(tok) else { return false }
guard context.index + 1 < context.tokens.count,
let next = context.tokens[context.index + 1] as? Token,
case .text(let s, _) = next, s.first?.isWhitespace == true else {
return false
}
if let ind = lineIndent(before: context.index, in: context) { return ind >= 0 } else { return false }
}

public func build(context: inout CodeContext) {
context.index += 1 // skip bullet
var text = ""
while context.index < context.tokens.count {
if let tok = context.tokens[context.index] as? Token {
func parseList(_ level: Int) -> CodeNode {
let list = CodeNode(type: Element.unorderedList, value: "")
var isLoose = false
while context.index < context.tokens.count {
guard let bullet = context.tokens[context.index] as? Token, isBullet(bullet), lineIndent(before: context.index, in: context) == level else { break }
let (node, loose) = parseItem(level)
if loose { isLoose = true }
list.addChild(node)
}
list.value = isLoose ? "loose" : "tight"
return list
}

func parseItem(_ level: Int) -> (CodeNode, Bool) {
var loose = false
// skip bullet and following whitespace
context.index += 1
if context.index < context.tokens.count,
let t = context.tokens[context.index] as? Token,
case .text(let s, _) = t, s.first?.isWhitespace == true {
context.index += 1
}

let node = CodeNode(type: Element.listItem, value: "")
var text = ""
itemLoop: while context.index < context.tokens.count {
guard let tok = context.tokens[context.index] as? Token else { context.index += 1; continue }
switch tok {
case .newline:
case .newline:
context.index += 1
let node = CodeNode(type: Element.listItem, value: text.trimmingCharacters(in: .whitespaces))
context.currentNode.addChild(node)
return
// Check for blank line
if context.index < context.tokens.count, let nl = context.tokens[context.index] as? Token, case .newline = nl {
loose = true
context.index += 1
}
let start = context.index
var spaces = 0
if start < context.tokens.count, let sTok = context.tokens[start] as? Token, case .text(let s, _) = sTok, s.allSatisfy({ $0 == " " }) {
spaces = s.count
context.index += 1
}
if context.index < context.tokens.count, let next = context.tokens[context.index] as? Token, isBullet(next), spaces > level {
let sub = parseList(spaces)
node.addChild(sub)
if context.index < context.tokens.count, let nextTok = context.tokens[context.index] as? Token, isBullet(nextTok), (lineIndent(before: context.index, in: context) ?? 0) <= level {
break itemLoop
}
} else if context.index < context.tokens.count, let next = context.tokens[context.index] as? Token, isBullet(next), spaces == level {
context.index = start
break itemLoop
} else if spaces > level {
text += "\n"
} else if spaces < level {
context.index = start
break itemLoop
} else {
text += "\n"
}
case .eof:
let node = CodeNode(type: Element.listItem, value: text.trimmingCharacters(in: .whitespaces))
context.currentNode.addChild(node)
context.index += 1
return
break itemLoop
default:
text += tok.text
context.index += 1
}
} else { context.index += 1 }
}
node.value = text.trimmingCharacters(in: .whitespaces)
return (node, loose)
}

if let ind = lineIndent(before: context.index, in: context) {
let list = parseList(ind)
context.currentNode.addChild(list)
}
}
}

public class OrderedListItemBuilder: CodeElementBuilder {
public class OrderedListBuilder: CodeElementBuilder {
public init() {}
public func accept(context: CodeContext, token: any CodeToken) -> Bool {
guard let tok = token as? Token else { return false }
if case .number = tok {
if context.index + 1 < context.tokens.count,
let dot = context.tokens[context.index + 1] as? Token,
case .dot = dot {
if context.index == 0 { return true }
if let prev = context.tokens[context.index - 1] as? Token, case .newline = prev {
return true
}

private func lineIndent(before idx: Int, in context: CodeContext) -> Int? {
if idx == 0 { return 0 }
var i = idx - 1
var count = 0
while i >= 0 {
guard let tok = context.tokens[i] as? Token else { return nil }
switch tok {
case .newline:
return count
case .text(let s, _) where s.allSatisfy({ $0 == " " }):
count += s.count
i -= 1
default:
return nil
}
}
return count
}

public func accept(context: CodeContext, token: any CodeToken) -> Bool {
guard let tok = token as? Token, case .number = tok else { return false }
guard context.index + 1 < context.tokens.count,
let dot = context.tokens[context.index + 1] as? Token, case .dot = dot else { return false }
if let _ = lineIndent(before: context.index, in: context) { return true }
return false
}

public func build(context: inout CodeContext) {
context.index += 2 // skip number and '.'
var text = ""
while context.index < context.tokens.count {
if let tok = context.tokens[context.index] as? Token {
func parseList(_ level: Int) -> CodeNode {
let list = CodeNode(type: Element.orderedList, value: "")
var isLoose = false
while context.index < context.tokens.count {
guard context.index + 1 < context.tokens.count,
let num = context.tokens[context.index] as? Token, case .number = num,
let dot = context.tokens[context.index + 1] as? Token, case .dot = dot,
lineIndent(before: context.index, in: context) == level else { break }
let (node, loose) = parseItem(level)
if loose { isLoose = true }
list.addChild(node)
}
list.value = isLoose ? "loose" : "tight"
return list
}

func parseItem(_ level: Int) -> (CodeNode, Bool) {
var loose = false
context.index += 2
if context.index < context.tokens.count,
let t = context.tokens[context.index] as? Token,
case .text(let s, _) = t, s.first?.isWhitespace == true {
context.index += 1
}

let node = CodeNode(type: Element.orderedListItem, value: "")
var text = ""
itemLoop: while context.index < context.tokens.count {
guard let tok = context.tokens[context.index] as? Token else { context.index += 1; continue }
switch tok {
case .newline:
context.index += 1
let node = CodeNode(type: Element.orderedListItem, value: text.trimmingCharacters(in: .whitespaces))
context.currentNode.addChild(node)
return
if context.index < context.tokens.count, let nl = context.tokens[context.index] as? Token, case .newline = nl {
loose = true
context.index += 1
}
let start = context.index
var spaces = 0
if start < context.tokens.count, let sTok = context.tokens[start] as? Token, case .text(let s, _) = sTok, s.allSatisfy({ $0 == " " }) {
spaces = s.count
context.index += 1
}
if context.index + 1 < context.tokens.count,
let nextNum = context.tokens[context.index] as? Token, case .number = nextNum,
let dot = context.tokens[context.index + 1] as? Token, case .dot = dot,
spaces > level {
let sub = parseList(spaces)
node.addChild(sub)
if context.index + 1 < context.tokens.count,
let nextBullet = context.tokens[context.index] as? Token, case .number = nextBullet,
let ndot = context.tokens[context.index + 1] as? Token, case .dot = ndot,
(lineIndent(before: context.index, in: context) ?? 0) <= level {
break itemLoop
}
} else if context.index + 1 < context.tokens.count,
let nextNum = context.tokens[context.index] as? Token, case .number = nextNum,
let dot = context.tokens[context.index + 1] as? Token, case .dot = dot,
spaces == level {
context.index = start
break itemLoop
} else if spaces > level {
text += "\n"
} else if spaces < level {
context.index = start
break itemLoop
} else {
text += "\n"
}
case .eof:
let node = CodeNode(type: Element.orderedListItem, value: text.trimmingCharacters(in: .whitespaces))
context.currentNode.addChild(node)
context.index += 1
return
break itemLoop
default:
text += tok.text
context.index += 1
}
} else { context.index += 1 }
}
node.value = text.trimmingCharacters(in: .whitespaces)
return (node, loose)
}

if let ind = lineIndent(before: context.index, in: context) {
let list = parseList(ind)
context.currentNode.addChild(list)
}
}
}
Expand Down Expand Up @@ -1216,7 +1369,7 @@ public struct MarkdownLanguage: CodeLanguage {

public var tokenizer: CodeTokenizer { Tokenizer() }
public var builders: [CodeElementBuilder] {
[HeadingBuilder(), SetextHeadingBuilder(), CodeBlockBuilder(), IndentedCodeBlockBuilder(), BlockQuoteBuilder(), ThematicBreakBuilder(), OrderedListItemBuilder(), ListItemBuilder(), ImageBuilder(), HTMLBuilder(), EntityBuilder(), StrikethroughBuilder(), AutoLinkBuilder(), BareAutoLinkBuilder(), TableBuilder(), FootnoteBuilder(), LinkReferenceDefinitionBuilder(), LinkBuilder(), StrongBuilder(), EmphasisBuilder(), InlineCodeBuilder(), ParagraphBuilder()]
[HeadingBuilder(), SetextHeadingBuilder(), CodeBlockBuilder(), IndentedCodeBlockBuilder(), BlockQuoteBuilder(), ThematicBreakBuilder(), OrderedListBuilder(), UnorderedListBuilder(), ImageBuilder(), HTMLBuilder(), EntityBuilder(), StrikethroughBuilder(), AutoLinkBuilder(), BareAutoLinkBuilder(), TableBuilder(), FootnoteBuilder(), LinkReferenceDefinitionBuilder(), LinkBuilder(), StrongBuilder(), EmphasisBuilder(), InlineCodeBuilder(), ParagraphBuilder()]
}
public var expressionBuilders: [CodeExpressionBuilder] { [] }
public var rootElement: any CodeElement { Element.root }
Expand Down
32 changes: 29 additions & 3 deletions Tests/SwiftParserTests/SwiftParserTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -47,16 +47,42 @@ final class SwiftParserTests: XCTestCase {
let source = "- item1\n- item2"
let result = parser.parse(source, language: MarkdownLanguage())
XCTAssertEqual(result.errors.count, 0)
XCTAssertEqual(result.root.children.count, 2)
XCTAssertEqual(result.root.children.first?.type as? MarkdownLanguage.Element, .listItem)
XCTAssertEqual(result.root.children.count, 1)
let list = result.root.children.first
XCTAssertEqual(list?.type as? MarkdownLanguage.Element, .unorderedList)
XCTAssertEqual(list?.children.count, 2)
XCTAssertEqual(list?.children.first?.type as? MarkdownLanguage.Element, .listItem)
}

func testMarkdownOrderedList() {
let parser = SwiftParser()
let source = "1. first\n2. second"
let result = parser.parse(source, language: MarkdownLanguage())
XCTAssertEqual(result.errors.count, 0)
XCTAssertEqual(result.root.children.first?.type as? MarkdownLanguage.Element, .orderedListItem)
let list = result.root.children.first
XCTAssertEqual(list?.type as? MarkdownLanguage.Element, .orderedList)
XCTAssertEqual(list?.children.count, 2)
XCTAssertEqual(list?.children.first?.type as? MarkdownLanguage.Element, .orderedListItem)
}

func testMarkdownNestedList() {
let parser = SwiftParser()
let source = "- item1\n - sub\n- item2"
let result = parser.parse(source, language: MarkdownLanguage())
XCTAssertEqual(result.errors.count, 0)
let list = result.root.children.first
XCTAssertEqual(list?.type as? MarkdownLanguage.Element, .unorderedList)
XCTAssertEqual(list?.children.count, 2)
let sub = list?.children.first?.children.first
XCTAssertEqual(sub?.type as? MarkdownLanguage.Element, .unorderedList)
}

func testMarkdownLooseList() {
let parser = SwiftParser()
let source = "- a\n\n- b"
let result = parser.parse(source, language: MarkdownLanguage())
XCTAssertEqual(result.errors.count, 0)
XCTAssertEqual(result.root.children.first?.value, "loose")
}

func testMarkdownEmphasisAndStrong() {
Expand Down