[SwiftLexicalLookup] Add dollar identifier, better extension handling and more ASTScope related fixes

Sources/SwiftLexicalLookup/CMakeLists.txt

@@ -11,9 +11,7 @@ add_swift_syntax_library(SwiftLexicalLookup
   LookupName.swift
   LookupResult.swift
   SimpleLookupQueries.swift
-
-  Configurations/FileScopeHandlingConfig.swift
-  Configurations/LookupConfig.swift
+  LookupConfig.swift
 
   Scopes/CanInterleaveResultsLaterScopeSyntax.swift
   Scopes/FunctionScopeSyntax.swift

Sources/SwiftLexicalLookup/Configurations/LookupConfig.swift → Sources/SwiftLexicalLookup/LookupConfig.swift

@@ -11,8 +11,6 @@
 //===----------------------------------------------------------------------===//
 
 @_spi(Experimental) public struct LookupConfig {
-  /// Specifies behavior of file scope.
-  @_spi(Experimental) public var fileScopeHandling: FileScopeHandlingConfig
   /// Specifies whether lookup should finish in the closest sequential scope.
   ///
   /// ### Example
@@ -33,41 +31,14 @@
   /// If `finishInSequentialScope` would be set to `false`, the only name
   /// returned by lookup would be the `a` declaration from inside function body.
   @_spi(Experimental) public var finishInSequentialScope: Bool
-  /// Specifies whether to include results generated in file and member block scopes.
-  ///
-  /// ### Example
-  /// ```swift
-  /// class X {
-  ///   let a = 42
-  ///
-  ///   func (a: Int) {
-  ///     let a = 123
-  ///
-  ///     a // <-- lookup here
-  ///   }
-  /// }
-  /// ```
-  /// When looking up at the specified position with `includeMembers`
-  /// set to `true`, lookup will return declaration from inside function body,
-  /// function parameter and the `a` declaration from `class X` member block.
-  /// If `includeMembers` would be set to `false`, the latter name would be omitted.
-  @_spi(Experimental) public var includeMembers: Bool
 
   /// Creates a new lookup configuration.
   ///
-  /// - `fileScopeHandling` - specifies behavior of file scope.
-  ///   `memberBlockUpToLastDecl` by default.
   /// - `finishInSequentialScope` - specifies whether lookup should finish
   ///   in the closest sequential scope. `false` by default.
-  /// - `includeMembers` - specifies whether to include results generated
-  ///   in file and member block scopes. `true` by default.
   @_spi(Experimental) public init(
-    fileScopeHandling: FileScopeHandlingConfig = .memberBlockUpToLastDecl,
-    finishInSequentialScope: Bool = false,
-    includeMembers: Bool = true
+    finishInSequentialScope: Bool = false
   ) {
-    self.fileScopeHandling = fileScopeHandling
     self.finishInSequentialScope = finishInSequentialScope
-    self.includeMembers = includeMembers
   }
 }

Sources/SwiftLexicalLookup/LookupName.swift

@@ -46,7 +46,7 @@ import SwiftSyntax
   }
 
   /// The name of the implicit declaration.
-  private var name: String {
+  private var name: StaticString {
     switch self {
     case .self:
       return "self"
@@ -86,17 +86,38 @@ import SwiftSyntax
   /// `self` and `Self` identifers override implicit `self` and `Self` introduced by
   /// the `Foo` class declaration.
   var identifier: Identifier {
+    Identifier(name)
+  }
+
+  /// Position of this implicit name.
+  @_spi(Experimental) public var position: AbsolutePosition {
     switch self {
-    case .self:
-      return Identifier("self")
-    case .Self:
-      return Identifier("Self")
-    case .error:
-      return Identifier("error")
-    case .newValue:
-      return Identifier("newValue")
-    case .oldValue:
-      return Identifier("oldValue")
+    case .self(let declSyntax):
+      switch Syntax(declSyntax).as(SyntaxEnum.self) {
+      case .functionDecl(let functionDecl):
+        return functionDecl.name.positionAfterSkippingLeadingTrivia
+      case .initializerDecl(let initializerDecl):
+        return initializerDecl.initKeyword.positionAfterSkippingLeadingTrivia
+      case .subscriptDecl(let subscriptDecl):
+        return subscriptDecl.accessorBlock?.positionAfterSkippingLeadingTrivia
+          ?? subscriptDecl.endPositionBeforeTrailingTrivia
+      case .variableDecl(let variableDecl):
+        return variableDecl.bindings.first?.accessorBlock?.positionAfterSkippingLeadingTrivia
+          ?? variableDecl.endPosition
+      default:
+        return declSyntax.positionAfterSkippingLeadingTrivia
+      }
+    case .Self(let declSyntax):
+      switch Syntax(declSyntax).as(SyntaxEnum.self) {
+      case .protocolDecl(let protocolDecl):
+        return protocolDecl.name.positionAfterSkippingLeadingTrivia
+      default:
+        return declSyntax.positionAfterSkippingLeadingTrivia
+      }
+    case .error(let catchClause):
+      return catchClause.catchItems.positionAfterSkippingLeadingTrivia
+    default:
+      return syntax.positionAfterSkippingLeadingTrivia
     }
   }
 }
@@ -110,6 +131,8 @@ import SwiftSyntax
   case declaration(NamedDeclSyntax)
   /// Name introduced implicitly by certain syntax nodes.
   case implicit(ImplicitDecl)
+  /// Dollar identifier introduced by a closure without parameters.
+  case dollarIdentifier(ClosureExprSyntax, strRepresentation: String)
 
   /// Syntax associated with this name.
   @_spi(Experimental) public var syntax: SyntaxProtocol {
@@ -120,6 +143,8 @@ import SwiftSyntax
       return syntax
     case .implicit(let implicitName):
       return implicitName.syntax
+    case .dollarIdentifier(let closureExpr, _):
+      return closureExpr
     }
   }
 
@@ -132,6 +157,8 @@ import SwiftSyntax
       return Identifier(syntax.name)
     case .implicit(let kind):
       return kind.identifier
+    case .dollarIdentifier(_, strRepresentation: _):
+      return nil
     }
   }
 
@@ -149,34 +176,9 @@ import SwiftSyntax
     case .declaration(let syntax):
       return syntax.name.positionAfterSkippingLeadingTrivia
     case .implicit(let implicitName):
-      switch implicitName {
-      case .self(let declSyntax):
-        switch Syntax(declSyntax).as(SyntaxEnum.self) {
-        case .functionDecl(let functionDecl):
-          return functionDecl.name.positionAfterSkippingLeadingTrivia
-        case .initializerDecl(let initializerDecl):
-          return initializerDecl.initKeyword.positionAfterSkippingLeadingTrivia
-        case .subscriptDecl(let subscriptDecl):
-          return subscriptDecl.accessorBlock?.positionAfterSkippingLeadingTrivia
-            ?? subscriptDecl.endPositionBeforeTrailingTrivia
-        case .variableDecl(let variableDecl):
-          return variableDecl.bindings.first?.accessorBlock?.positionAfterSkippingLeadingTrivia
-            ?? variableDecl.endPosition
-        default:
-          return declSyntax.positionAfterSkippingLeadingTrivia
-        }
-      case .Self(let declSyntax):
-        switch Syntax(declSyntax).as(SyntaxEnum.self) {
-        case .protocolDecl(let protocolDecl):
-          return protocolDecl.name.positionAfterSkippingLeadingTrivia
-        default:
-          return declSyntax.positionAfterSkippingLeadingTrivia
-        }
-      case .error(let catchClause):
-        return catchClause.body.positionAfterSkippingLeadingTrivia
-      default:
-        return implicitName.syntax.positionAfterSkippingLeadingTrivia
-      }
+      return implicitName.position
+    case .dollarIdentifier(let closureExpr, _):
+      return closureExpr.positionAfterSkippingLeadingTrivia
     }
   }
 
@@ -197,6 +199,17 @@ import SwiftSyntax
     return accessibleAfter <= lookUpPosition
   }
 
+  func refersTo(_ otherIdentifier: Identifier?) -> Bool {
+    guard let otherIdentifier else { return true }
+
+    switch self {
+    case .dollarIdentifier(_, let strRepresentation):
+      return strRepresentation == otherIdentifier.name
+    default:
+      return identifier == otherIdentifier
+    }
+  }
+
   /// Extracts names introduced by the given `syntax` structure.
   ///
   /// When e.g. looking up a variable declaration like `let a = a`,
@@ -221,6 +234,12 @@ import SwiftSyntax
       return tuplePattern.elements.flatMap { tupleElement in
         getNames(from: tupleElement.pattern, accessibleAfter: accessibleAfter)
       }
+    case .tupleExpr(let tupleExpr):
+      return tupleExpr.elements.flatMap { tupleElement in
+        getNames(from: tupleElement, accessibleAfter: accessibleAfter)
+      }
+    case .labeledExpr(let labeledExpr):
+      return getNames(from: labeledExpr.expression, accessibleAfter: accessibleAfter)
     case .valueBindingPattern(let valueBindingPattern):
       return getNames(from: valueBindingPattern.pattern, accessibleAfter: accessibleAfter)
     case .expressionPattern(let expressionPattern):
@@ -288,6 +307,8 @@ import SwiftSyntax
       return "declaration: \(strName)"
     case .implicit:
       return "implicit: \(strName)"
+    case .dollarIdentifier(_, strRepresentation: let str):
+      return "dollarIdentifier: \(str)"
     }
   }
 }

Sources/SwiftLexicalLookup/LookupResult.swift

@@ -20,6 +20,36 @@ import SwiftSyntax
   case fromFileScope(SourceFileSyntax, withNames: [LookupName])
   /// Indicates where to perform member lookup.
   case lookInMembers(LookInMembersScopeSyntax)
+  /// Indicates to lookup generic parameters of extended type.
+  ///
+  /// ### Example
+  /// ```swift
+  /// extension Foo {
+  ///   func bar() {
+  ///     let a = A() // <-- lookup here
+  ///   }
+  /// }
+  /// ```
+  /// For a lookup started at the marked position, `lookInGenericParametersOfExtendedType`
+  /// will be included as one of the results prompting the client
+  /// to lookup the generic parameters of of the extended `Foo` type.
+  case lookInGenericParametersOfExtendedType(ExtensionDeclSyntax)
+  /// Indicates this closure expression could introduce dollar identifiers.
+  ///
+  /// ### Example
+  /// ```swift
+  /// func foo() {
+  ///   let a = {
+  ///     $0 // <-- lookup here
+  ///   }
+  /// }
+  /// ```
+  /// When looking up for any identifier at the indicated position,
+  /// the result will include `mightIntroduceDollarIdentifiers`
+  /// result kind. If it's performed for a dollar identifier, `LookupName.dollarIdentifier`
+  /// with the appropriate identifier will be used in the
+  /// result associated with the closure expression inside `a`.
+  case mightIntroduceDollarIdentifiers(ClosureExprSyntax)
 
   /// Associated scope.
   @_spi(Experimental) public var scope: ScopeSyntax {
@@ -30,6 +60,10 @@ import SwiftSyntax
       return fileScopeSyntax
     case .lookInMembers(let lookInMemb):
       return lookInMemb
+    case .lookInGenericParametersOfExtendedType(let extensionDecl):
+      return extensionDecl
+    case .mightIntroduceDollarIdentifiers(let closureExpr):
+      return closureExpr
     }
   }
 
@@ -38,7 +72,9 @@ import SwiftSyntax
     switch self {
     case .fromScope(_, let names), .fromFileScope(_, let names):
       return names
-    case .lookInMembers(_):
+    case .lookInMembers(_),
+      .lookInGenericParametersOfExtendedType(_),
+      .mightIntroduceDollarIdentifiers(_):
       return []
     }
   }
@@ -53,6 +89,14 @@ import SwiftSyntax
     }
   }
 
+  /// Returns result specific for the particular `scope` kind with provided `names`
+  /// as an array with one element. If names are empty, returns an empty array.
+  static func getResultArray(for scope: ScopeSyntax, withNames names: [LookupName]) -> [LookupResult] {
+    guard !names.isEmpty else { return [] }
+
+    return [getResult(for: scope, withNames: names)]
+  }
+
   /// Debug description of this lookup name.
   @_spi(Experimental) public var debugDescription: String {
     var description =
@@ -87,6 +131,10 @@ import SwiftSyntax
       return "fromFileScope"
     case .lookInMembers:
       return "lookInMembers"
+    case .lookInGenericParametersOfExtendedType(_):
+      return "lookInGenericParametersOfExtendedType"
+    case .mightIntroduceDollarIdentifiers(_):
+      return "mightIntroduceDollarIdentifiers"
     }
   }
 }

Sources/SwiftLexicalLookup/Scopes/FunctionScopeSyntax.swift

@@ -12,13 +12,14 @@
 
 import SwiftSyntax
 
-protocol FunctionScopeSyntax: DeclSyntaxProtocol, WithGenericParametersScopeSyntax {
+@_spi(Experimental) public protocol FunctionScopeSyntax: DeclSyntaxProtocol, WithGenericParametersScopeSyntax {
   var signature: FunctionSignatureSyntax { get }
+  var body: CodeBlockSyntax? { get }
 }
 
 extension FunctionScopeSyntax {
   /// Function parameters introduced by this function's signature.
-  @_spi(Experimental) public var introducedNames: [LookupName] {
+  @_spi(Experimental) public var defaultIntroducedNames: [LookupName] {
     signature.parameterClause.parameters.flatMap { parameter in
       LookupName.getNames(from: parameter)
     } + (parentScope?.is(MemberBlockSyntax.self) ?? false ? [.implicit(.self(self))] : [])
@@ -33,7 +34,7 @@ extension FunctionScopeSyntax {
   ) -> [LookupResult] {
     var thisScopeResults: [LookupResult] = []
 
-    if !signature.range.contains(lookUpPosition) {
+    if body?.range.contains(lookUpPosition) ?? false {
       thisScopeResults = defaultLookupImplementation(
         identifier,
         at: position,