/// A lexical token over Norg source.
public struct NorgToken: Equatable, Sendable {

  /// What a token represents.
  public enum Kind: Equatable, Sendable {

    // MARK: Block / line level

    /// A heading marker run (`*`…), carrying its level.
    case heading(level: Int)
    /// An unordered-list marker run (`-`…).
    case unorderedList(level: Int)
    /// An ordered-list marker run (`~`…).
    case orderedList(level: Int)
    /// A quote marker run (`>`…).
    case quote(level: Int)
    /// A definition marker run (`$`…).
    case definition(level: Int)
    /// A footnote marker run (`^`…).
    case footnote(level: Int)
    /// A table-cell marker run (`:`…).
    case tableCell(level: Int)
    /// A task status marker including its parentheses, eg. `(x)`.
    case taskStatus(TaskStatus)
    /// A weak delimiting line (`---`).
    case weakDelimiter
    /// A strong delimiting line (`===`).
    case strongDelimiter
    /// A horizontal rule (`___`).
    case horizontalRule
    /// A ranged-tag fence marker: the `@` of an opener and of `@end`.
    case tagDelimiter
    /// A ranged-tag header after `@` (name and parameters), eg. `code swift`.
    case tagName
    /// A raw body line inside a ranged tag (`@code` … `@end`).
    case verbatimBlock

    // MARK: Inline level

    /// An attached- or verbatim-modifier delimiter (`*`, `/`, `` ` ``, `$`, …);
    /// the style identifies which.
    case modifierDelimiter(InlineStyle)
    /// A run of text carrying a non-empty cumulative style (the content of one
    /// or more nested modifiers).
    case styledText(InlineStyle)
    /// An inline comment, markers included (`%…%`).
    case comment
    /// An escape: the backslash of `\x` (the escaped character is not a token).
    case escape
    /// A link/anchor delimiter: `{`, `}`, `[`, or `]`.
    case linkDelimiter
    /// A link/anchor location (inside `{…}`).
    case linkTarget
    /// A link/anchor description or label (inside `[…]`).
    case linkDescription
  }

  public let kind: Kind
  public let range: Range<String.Index>

  public init(kind: Kind, range: Range<String.Index>) {
    self.kind = kind
    self.range = range
  }
}