[DNM] Support box-drawing-based blocks

CodeGeneration/Sources/SyntaxSupport/Child.swift

@@ -52,7 +52,7 @@ public enum ChildKind {
   /// The child is a token that matches one of the given `choices`.
   /// If `requiresLeadingSpace` or `requiresTrailingSpace` is not `nil`, it
   /// overrides the default leading/trailing space behavior of the token.
-  case token(choices: [TokenChoice], requiresLeadingSpace: Bool? = nil, requiresTrailingSpace: Bool? = nil)
+  case token(choices: [TokenChoice], requiresLeadingSpace: Bool? = nil, requiresTrailingSpace: Bool? = nil, defaultAt: Int? = nil)
 
   public var isNodeChoices: Bool {
     if case .nodeChoices = self {
@@ -108,7 +108,7 @@ public class Child: NodeChoiceConvertible {
   /// A docc comment describing the child, including the trivia provided when
   /// initializing the ``Child``, and the list of possible token choices inferred automatically.
   public var documentation: SwiftSyntax.Trivia {
-    if case .token(let choices, _, _) = kind {
+    if case .token(let choices, _, _, _) = kind {
       let tokenChoicesTrivia = SwiftSyntax.Trivia.docCommentTrivia(
         from: GrammarGenerator.childTokenChoices(for: choices)
       )
@@ -230,9 +230,18 @@ public class Child: NodeChoiceConvertible {
   /// Grab the existing reference to that token from the global list.
   public var tokenKind: Token? {
     switch kind {
-    case .token(let choices, _, _):
-      if choices.count == 1 {
-        switch choices.first! {
+    case .token(let choices, _, _, defaultAt: let defaultIndex):
+      let defaultToken: TokenChoice?
+      if let defaultIndex {
+        defaultToken = choices[defaultIndex]
+      } else if let onlyToken = choices.only {
+        defaultToken = onlyToken
+      } else {
+        defaultToken = nil
+      }
+
+      if let defaultToken {
+        switch defaultToken {
         case .keyword: return .keyword
         case .token(let token): return token
         }

CodeGeneration/Sources/SyntaxSupport/CommonNodes.swift

@@ -64,7 +64,11 @@ public let COMMON_NODES: [Node] = [
     children: [
       Child(
         name: "leftBrace",
-        kind: .token(choices: [.token(.leftBrace)]),
+        kind: .token(choices: [
+          .token(.leftBrace),
+          .token(.leadingBoxCorner),
+          .token(.leadingBoxJunction),
+        ], defaultAt: 0),
         documentation: "The brace introducing the code block."
       ),
       Child(
@@ -74,7 +78,11 @@ public let COMMON_NODES: [Node] = [
       ),
       Child(
         name: "rightBrace",
-        kind: .token(choices: [.token(.rightBrace)]),
+        kind: .token(choices: [
+          .token(.rightBrace),
+          .token(.trailingBoxCorner),
+          .token(.trailingBoxJunction),
+        ], defaultAt: 0),
         documentation: "The brace closing the code block."
       ),
     ]

CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift

@@ -57,7 +57,11 @@ public let DECL_NODES: [Node] = [
     children: [
       Child(
         name: "leftBrace",
-        kind: .token(choices: [.token(.leftBrace)]),
+        kind: .token(choices: [
+          .token(.leftBrace),
+          .token(.leadingBoxCorner),
+          .token(.leadingBoxJunction),
+        ], defaultAt: 0),
         documentation: "The brace introducing the accessor block."
       ),
       Child(
@@ -75,7 +79,11 @@ public let DECL_NODES: [Node] = [
       ),
       Child(
         name: "rightBrace",
-        kind: .token(choices: [.token(.rightBrace)]),
+        kind: .token(choices: [
+          .token(.rightBrace),
+          .token(.trailingBoxCorner),
+          .token(.trailingBoxJunction),
+        ], defaultAt: 0),
         documentation: "The brace closing the accessor block."
       ),
     ]
@@ -1579,15 +1587,23 @@ public let DECL_NODES: [Node] = [
     children: [
       Child(
         name: "leftBrace",
-        kind: .token(choices: [.token(.leftBrace)])
+        kind: .token(choices: [
+          .token(.leftBrace),
+          .token(.leadingBoxCorner),
+          .token(.leadingBoxJunction),
+        ], defaultAt: 0)
       ),
       Child(
         name: "members",
         kind: .collection(kind: .memberBlockItemList, collectionElementName: "Member")
       ),
       Child(
         name: "rightBrace",
-        kind: .token(choices: [.token(.rightBrace)])
+        kind: .token(choices: [
+          .token(.rightBrace),
+          .token(.trailingBoxCorner),
+          .token(.trailingBoxJunction),
+        ], defaultAt: 0)
       ),
     ]
   ),
@@ -1972,7 +1988,11 @@ public let DECL_NODES: [Node] = [
       ),
       Child(
         name: "leftBrace",
-        kind: .token(choices: [.token(.leftBrace)])
+        kind: .token(choices: [
+          .token(.leftBrace),
+          .token(.leadingBoxCorner),
+          .token(.leadingBoxJunction),
+        ], defaultAt: 0)
       ),
       Child(
         name: "groupAttributes",
@@ -1981,7 +2001,11 @@ public let DECL_NODES: [Node] = [
       ),
       Child(
         name: "rightBrace",
-        kind: .token(choices: [.token(.rightBrace)])
+        kind: .token(choices: [
+          .token(.rightBrace),
+          .token(.trailingBoxCorner),
+          .token(.trailingBoxJunction),
+        ], defaultAt: 0)
       ),
     ],
     childHistory: [

CodeGeneration/Sources/SyntaxSupport/ExprNodes.swift

@@ -511,7 +511,11 @@ public let EXPR_NODES: [Node] = [
     children: [
       Child(
         name: "leftBrace",
-        kind: .token(choices: [.token(.leftBrace)])
+        kind: .token(choices: [
+          .token(.leftBrace),
+          .token(.leadingBoxCorner),
+          .token(.leadingBoxJunction),
+        ], defaultAt: 0)
       ),
       Child(
         name: "signature",
@@ -524,7 +528,11 @@ public let EXPR_NODES: [Node] = [
       ),
       Child(
         name: "rightBrace",
-        kind: .token(choices: [.token(.rightBrace)])
+        kind: .token(choices: [
+          .token(.rightBrace),
+          .token(.trailingBoxCorner),
+          .token(.trailingBoxJunction),
+        ], defaultAt: 0)
       ),
     ]
   ),
@@ -1949,7 +1957,11 @@ public let EXPR_NODES: [Node] = [
       ),
       Child(
         name: "leftBrace",
-        kind: .token(choices: [.token(.leftBrace)]),
+        kind: .token(choices: [
+          .token(.leftBrace),
+          .token(.leadingBoxCorner),
+          .token(.leadingBoxJunction),
+        ], defaultAt: 0),
         documentation: "The brace introducing the switch body."
       ),
       Child(
@@ -1959,7 +1971,11 @@ public let EXPR_NODES: [Node] = [
       ),
       Child(
         name: "rightBrace",
-        kind: .token(choices: [.token(.rightBrace)]),
+        kind: .token(choices: [
+          .token(.rightBrace),
+          .token(.trailingBoxCorner),
+          .token(.trailingBoxJunction),
+        ], defaultAt: 0),
         documentation: "The brace closing the switch body."
       ),
     ],

CodeGeneration/Sources/SyntaxSupport/GrammarGenerator.swift

@@ -43,7 +43,7 @@ struct GrammarGenerator {
       return "(\(choicesDescriptions.joined(separator: " | ")))\(optionality)"
     case .collection(kind: let kind, _, _, _):
       return "\(kind.doccLink)\(optionality)"
-    case .token(let choices, _, _):
+    case .token(let choices, _, _, _):
       if choices.count == 1 {
         return "\(grammar(for: choices.first!))\(optionality)"
       } else {

CodeGeneration/Sources/SyntaxSupport/TokenSpec.swift

@@ -137,6 +137,8 @@ public enum Token: CaseIterable {
   case infixQuestionMark
   case integerLiteral
   case keyword
+  case leadingBoxCorner
+  case leadingBoxJunction
   case leftAngle
   case leftBrace
   case leftParen
@@ -168,6 +170,8 @@ public enum Token: CaseIterable {
   case singleQuote
   case stringQuote
   case stringSegment
+  case trailingBoxCorner
+  case trailingBoxJunction
   case unknown
   case wildcard
 
@@ -207,6 +211,10 @@ public enum Token: CaseIterable {
       return .other(name: "integerLiteral", nameForDiagnostics: "integer literal")
     case .keyword:
       return TokenSpec(name: "keyword", nameForDiagnostics: "keyword", text: nil, kind: .keyword)
+    case .leadingBoxCorner:
+      return .punctuator(name: "leadingBoxCorner", text: "╗")
+    case .leadingBoxJunction:
+      return .punctuator(name: "leadingBoxJunction", text: "╣")
     case .leftAngle:
       return .punctuator(name: "leftAngle", text: "<")
     case .leftBrace:
@@ -269,6 +277,10 @@ public enum Token: CaseIterable {
       return .punctuator(name: "stringQuote", text: "\"")
     case .stringSegment:
       return .other(name: "stringSegment", nameForDiagnostics: "string segment")
+    case .trailingBoxCorner:
+      return .punctuator(name: "trailingBoxCorner", text: "╚")
+    case .trailingBoxJunction:
+      return .punctuator(name: "trailingBoxJunction", text: "╠")
     case .unknown:
       return .other(name: "unknown", nameForDiagnostics: "token")
     case .wildcard:

CodeGeneration/Sources/SyntaxSupport/Traits.swift

@@ -45,8 +45,16 @@ public let TRAITS: [Trait] = [
   Trait(
     traitName: "Braced",
     children: [
-      Child(name: "leftBrace", kind: .token(choices: [.token(.leftBrace)])),
-      Child(name: "rightBrace", kind: .token(choices: [.token(.rightBrace)])),
+      Child(name: "leftBrace", kind: .token(choices: [
+        .token(.leftBrace),
+        .token(.leadingBoxCorner),
+        .token(.leadingBoxJunction),
+      ], defaultAt: 0)),
+      Child(name: "rightBrace", kind: .token(choices: [
+        .token(.rightBrace),
+        .token(.trailingBoxCorner),
+        .token(.trailingBoxJunction),
+      ], defaultAt: 0)),
     ]
   ),
   Trait(

CodeGeneration/Sources/SyntaxSupport/Trivia.swift

@@ -232,4 +232,9 @@ public let TRIVIAS: [Trivia] = [
       Character("\u{2B7F}")
     ]
   ),
+
+  Trivia(
+    name: "BoxDrawing",
+    comment: #"Box-drawing characters which have no syntactic significance."#
+  ),
 ]

CodeGeneration/Sources/Utils/SyntaxBuildableChild.swift

@@ -74,7 +74,7 @@ extension Child {
     if token.text != nil {
       return ExprSyntax(".\(token.identifier)Token()")
     }
-    if case .token(let choices, _, _) = kind,
+    if case .token(let choices, _, _, _) = kind,
       case .keyword(let keyword) = choices.only
     {
       return ExprSyntax(".\(token.memberCallName)(.\(keyword.spec.memberCallName))")
@@ -100,7 +100,7 @@ extension Child {
   /// `precondition` statement that verifies the variable with name var_name and of type
   /// ``TokenSyntax`` contains one of the supported text options. Otherwise return `nil`.
   public func generateAssertStmtTextChoices(varName: String) -> FunctionCallExprSyntax? {
-    guard case .token(choices: let choices, requiresLeadingSpace: _, requiresTrailingSpace: _) = kind else {
+    guard case .token(choices: let choices, requiresLeadingSpace: _, requiresTrailingSpace: _, defaultAt: _) = kind else {
       return nil
     }
 

CodeGeneration/Sources/generate-swift-syntax/templates/swiftparser/ParserTokenSpecSetFile.swift

@@ -39,7 +39,7 @@ let parserTokenSpecSetFile = SourceFileSyntax(leadingTrivia: copyrightHeader) {
 
   for layoutNode in SYNTAX_NODES.compactMap(\.layoutNode) {
     for child in layoutNode.children {
-      if case let .token(choices, _, _) = child.kind, choices.count > 1 {
+      if case let .token(choices, _, _, _) = child.kind, choices.count > 1 {
         try! ExtensionDeclSyntax("extension \(layoutNode.kind.syntaxType)") {
           try EnumDeclSyntax(
             """

CodeGeneration/Sources/generate-swift-syntax/templates/swiftsyntax/RawSyntaxValidationFile.swift

@@ -209,7 +209,7 @@ let rawSyntaxValidationFile = try! SourceFileSyntax(leadingTrivia: copyrightHead
                         }
 
                         ExprSyntax("assertAnyHasNoError(kind, \(raw: index), \(verifiedChoices))")
-                      case .token(choices: let choices, requiresLeadingSpace: _, requiresTrailingSpace: _):
+                      case .token(choices: let choices, requiresLeadingSpace: _, requiresTrailingSpace: _, defaultAt: _):
                         let choices = ArrayExprSyntax {
                           for choice in choices {
                             switch choice {

CodeGeneration/Tests/ValidateSyntaxNodes/ValidateSyntaxNodes.swift

@@ -57,7 +57,7 @@ fileprivate extension ChildKind {
       return choices.count == otherChoices.count && zip(choices, otherChoices).allSatisfy { $0.hasSameType(as: $1) }
     case (.collection(kind: let kind, _, _, _), .collection(kind: let otherKind, _, _, _)):
       return kind == otherKind
-    case (.token(let choices, _, _), .token(let otherChoices, _, _)):
+    case (.token(let choices, _, _, _), .token(let otherChoices, _, _, _)):
       return choices == otherChoices
     case (.node(let kind), .collection(kind: let otherKind, _, _, _)):
       return kind == otherKind
@@ -92,7 +92,7 @@ fileprivate extension Child {
     guard childIndex + 2 < node.children.count else {
       return false
     }
-    if case .token(choices: [.token(.colon)], _, _) = node.children[childIndex + 2].kind {
+    if case .token(choices: [.token(.colon)], _, _, _) = node.children[childIndex + 2].kind {
       return true
     } else {
       return false
@@ -173,7 +173,7 @@ class ValidateSyntaxNodes: XCTestCase {
   ///
   /// - Returns: A failure message if validation failed, otherwise `nil`
   private func validateSingleTokenChoiceChild(child: Child, in node: LayoutNode) -> String? {
-    guard case .token(choices: let tokenChoices, _, _) = child.kind, let choice = tokenChoices.only else {
+    guard case .token(choices: let tokenChoices, _, _, _) = child.kind, let choice = tokenChoices.only else {
       return nil
     }
     switch choice {
@@ -369,7 +369,7 @@ class ValidateSyntaxNodes: XCTestCase {
     var failures: [ValidationFailure] = []
     for node in SYNTAX_NODES.compactMap(\.layoutNode) {
       for child in node.children {
-        guard case .token(choices: let tokenChoices, _, _) = child.kind,
+        guard case .token(choices: let tokenChoices, _, _, _) = child.kind,
           tokenChoices.count > 1,
           tokenChoices.allSatisfy({ $0.isKeyword })
         else {

Sources/SwiftIDEUtils/SyntaxClassification.swift

@@ -136,6 +136,10 @@ extension RawTokenKind {
       return .integerLiteral
     case .keyword:
       return .keyword
+    case .leadingBoxCorner:
+      return .none
+    case .leadingBoxJunction:
+      return .none
     case .leftAngle:
       return .none
     case .leftBrace:
@@ -198,6 +202,10 @@ extension RawTokenKind {
       return .stringLiteral
     case .stringSegment:
       return .stringLiteral
+    case .trailingBoxCorner:
+      return .none
+    case .trailingBoxJunction:
+      return .none
     case .unknown:
       return .none
     case .wildcard:

Sources/SwiftIfConfig/ActiveSyntaxRewriter.swift

@@ -478,7 +478,7 @@ extension Trivia {
     for piece in pieces {
       switch piece {
       case .backslashes, .carriageReturnLineFeeds, .carriageReturns, .formfeeds, .newlines, .pounds, .spaces, .tabs,
-        .unexpectedText, .verticalTabs:
+        .unexpectedText, .verticalTabs, .boxDrawing:
         piece.write(to: &stream)
 
       case .blockComment(let text), .docBlockComment(let text), .docLineComment(let text), .lineComment(let text):