Index out of range during parsing Crash Fix (#229)

* #225

Fix for crash

* addressing comment

* updating newline with Character newline

rdar://114291306

* updating newline with Character newline

* updating newline with Character newline

* Added test case that parse different characters set which represent newline for Document

* indentation

* Renaming Test method

Author: Roshankumar350

Sources/Markdown/Block Nodes/Block Container Blocks/BlockDirective.swift

@@ -90,13 +90,14 @@ public extension BlockDirective {
     init<Children: Sequence>(name: String,
                              argumentText: String? = nil,
                              children: Children) where Children.Element == BlockMarkup {
-        let argumentSegments = argumentText?.split(separator: "\n",
-                                                   maxSplits: .max,
-                                                   omittingEmptySubsequences: false).map { lineText -> DirectiveArgumentText.LineSegment in
-                                                    let untrimmedText = String(lineText)
-                                                    return DirectiveArgumentText.LineSegment(untrimmedText: untrimmedText,
-                                                                                             range: nil)
-                                                   } ?? []
+        let argumentSegments = argumentText?.split(
+            omittingEmptySubsequences: false,
+            whereSeparator: \.isNewline
+        ).map { lineText -> DirectiveArgumentText.LineSegment in
+            let untrimmedText = String(lineText)
+            return DirectiveArgumentText.LineSegment(untrimmedText: untrimmedText,
+                                                     range: nil)
+        } ?? []
         try! self.init(.blockDirective(name: name,
                                        nameLocation: nil,
                                        argumentText: DirectiveArgumentText(segments: argumentSegments),

Sources/Markdown/Parser/BlockDirectiveParser.swift

@@ -537,7 +537,7 @@ private enum ParseContainer: CustomStringConvertible {
         }
 
         mutating private func print<S: StringProtocol>(_ text: S) {
-            let lines = text.split(separator: "\n", omittingEmptySubsequences: false)
+            let lines = text.split(omittingEmptySubsequences: false, whereSeparator: \.isNewline)
             for i in lines.indices {
                 if i != lines.startIndex {
                     queueNewline()

Sources/Markdown/Parser/LazySplitLines.swift

@@ -28,7 +28,7 @@ struct LazySplitLines: Sequence {
         private var source: URL?
 
         init<S: StringProtocol>(_ input: S, source: URL?) where S.SubSequence == Substring {
-            self.rawLines = input.split(separator: "\n", maxSplits: Int.max, omittingEmptySubsequences: false)
+            self.rawLines = input.split(omittingEmptySubsequences: false, whereSeparator: \.isNewline)
             self.index = rawLines.startIndex
             self.source = source
         }

Sources/Markdown/Walker/Walkers/MarkupFormatter.swift

@@ -38,7 +38,7 @@ fileprivate extension Markup {
 fileprivate extension String {
     /// This string, split by newline characters, dropping leading and trailing lines that are empty.
     var trimmedLineSegments: ArraySlice<Substring> {
-        var splitLines = split(separator: "\n", omittingEmptySubsequences: false)[...].drop { $0.isEmpty }
+        var splitLines = split(omittingEmptySubsequences: false, whereSeparator: \.isNewline)[...].drop { $0.isEmpty }
         while let lastLine = splitLines.last, lastLine.isEmpty {
             splitLines = splitLines.dropLast()
         }

Tests/MarkdownTests/Block Nodes/DocumentTests.swift

@@ -40,4 +40,23 @@ final class DocumentTests: XCTestCase {
         XCTAssertThrowsError(try Document(parsing: URL(fileURLWithPath: #file)
             .appendingPathComponent("doesntexist")))
     }
+ 
+    func testParseNewlineCharacters() {
+        let inputParagraphString = """
+        # First\n
+        ## Second\r
+        ### Third\r\n
+        """
+        let document = Document(parsing: inputParagraphString, options: [.parseBlockDirectives, .parseSymbolLinks])
+        let expectedDump = """
+                Document
+                ├─ Heading level: 1
+                │  └─ Text "First"
+                ├─ Heading level: 2
+                │  └─ Text "Second"
+                └─ Heading level: 3
+                   └─ Text "Third"
+                """
+        XCTAssertEqual(expectedDump, document.debugDescription())
+    }
 }