1 files changed, 61 insertions, 0 deletions
diff --git a/Sources/NorgKit/Models/DetachedModifier.swift b/Sources/NorgKit/Models/DetachedModifier.swift
new file mode 100644
index 0000000..1f28c36
--- /dev/null
+++ b/Sources/NorgKit/Models/DetachedModifier.swift
@@ -0,0 +1,61 @@
+/// A detached modifier with its marker, nestling level, task status (if set),
+/// and content.
+struct DetachedModifier {
+  let marker: Character
+  let level: Int
+  let status: TaskStatus?
+  let statusIndex: String.Index?
+  let content: Substring
+
+  /// Finds and parses a detached modifier if present. The accepting markers
+  /// is used to reduce the markers being parsed.
+  static func parse(_ line: Substring, accepting markers: ASCIIByteSet) -> DetachedModifier? {
+
+    let utf8 = line.utf8
+    let end = utf8.endIndex
+    var i = utf8.startIndex
+
+    while i < end, ASCIIHelper.isWhitespace(utf8[i]) { i = utf8.index(after: i) }
+    guard i < end else { return nil }
+
+    let markerByte = utf8[i]
+    guard markers.contains(markerByte) else { return nil }
+
+    var level = 0
+    var run = i
+    while run < end, utf8[run] == markerByte {
+      level += 1
+      run = utf8.index(after: run)
+    }
+
+    guard run < end, ASCIIHelper.isWhitespace(utf8[run]) else { return nil }
+
+    var rest = run
+    while rest < end, ASCIIHelper.isWhitespace(utf8[rest]) { rest = utf8.index(after: rest) }
+
+    var status: TaskStatus?
+    var statusIndex: String.Index?
+    var contentStart = rest
+    if rest < end, utf8[rest] == UInt8(ascii: "(") {
+      let markerPosition = utf8.index(after: rest)
+      if markerPosition < end {
+        let closePosition = utf8.index(after: markerPosition)
+        let statusByte = utf8[markerPosition]
+        if closePosition < end, utf8[closePosition] == UInt8(ascii: ")"),
+          let parsed = TaskStatus(markerByte: statusByte) {
+          status = parsed
+          statusIndex = markerPosition
+          contentStart = utf8.index(after: closePosition)
+        }
+      }
+    }
+
+    return DetachedModifier(
+      marker: Character(Unicode.Scalar(markerByte)),
+      level: level,
+      status: status,
+      statusIndex: statusIndex,
+      content: TextHelper.whitespaceTrimmed(line[contentStart...])
+    )
+  }
+}