Merge pull request #2782 from MAJKFL/generic-parameter-list-function-scope

[SwiftLexicalLookup][GSoC] Add switch, generic parameter and function scopes.

Author: DougGregor

Sources/CMakeLists.txt

@@ -11,6 +11,7 @@ add_subdirectory(_SwiftSyntaxCShims)
 add_subdirectory(SwiftBasicFormat)
 add_subdirectory(SwiftSyntax)
 add_subdirectory(SwiftDiagnostics)
+add_subdirectory(SwiftLexicalLookup)
 add_subdirectory(SwiftLibraryPluginProvider)
 add_subdirectory(SwiftParser)
 add_subdirectory(SwiftParserDiagnostics)

Sources/SwiftLexicalLookup/CMakeLists.txt

@@ -0,0 +1,29 @@
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
+# Licensed under Apache License v2.0 with Runtime Library Exception
+#
+# See http://swift.org/LICENSE.txt for license information
+# See http://swift.org/CONTRIBUTORS.txt for Swift project authors
+
+add_swift_syntax_library(SwiftLexicalLookup
+  IdentifiableSyntax.swift
+  LookupName.swift
+  LookupResult.swift
+  SimpleLookupQueries.swift
+  
+  Configurations/FileScopeHandlingConfig.swift
+  Configurations/LookupConfig.swift
+  
+  Scopes/GenericParameterScopeSyntax.swift
+  Scopes/IntroducingToSequentialParentScopeSyntax.swift
+  Scopes/ScopeImplementations.swift
+  Scopes/ScopeSyntax.swift
+  Scopes/SequentialScopeSyntax.swift
+  Scopes/TypeScopeSyntax.swift
+  Scopes/WithGenericParametersScopeSyntax.swift
+)
+
+target_link_swift_syntax_libraries(SwiftLexicalLookup PUBLIC
+  SwiftSyntax)
+

Sources/SwiftLexicalLookup/IdentifiableSyntax.swift

@@ -25,6 +25,12 @@ import SwiftSyntax
   }
 }
 
+@_spi(Experimental) extension FunctionParameterSyntax: IdentifiableSyntax {
+  @_spi(Experimental) public var identifier: TokenSyntax {
+    secondName ?? firstName
+  }
+}
+
 @_spi(Experimental) extension ClosureShorthandParameterSyntax: IdentifiableSyntax {
   @_spi(Experimental) public var identifier: TokenSyntax {
     name
@@ -42,3 +48,15 @@ import SwiftSyntax
     name
   }
 }
+
+@_spi(Experimental) extension GenericParameterSyntax: IdentifiableSyntax {
+  @_spi(Experimental) public var identifier: TokenSyntax {
+    name
+  }
+}
+
+@_spi(Experimental) extension PrimaryAssociatedTypeSyntax: IdentifiableSyntax {
+  @_spi(Experimental) public var identifier: TokenSyntax {
+    name
+  }
+}

Sources/SwiftLexicalLookup/Scopes/GenericParameterScopeSyntax.swift

@@ -0,0 +1,91 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftSyntax
+
+/// Scope that introduces generic parameter names and directs
+/// futher lookup to its `WithGenericParametersScopeSyntax`
+/// parent scope's parent scope (i.e. on return, bypasses names
+/// introduced by its parent).
+@_spi(Experimental) public protocol GenericParameterScopeSyntax: ScopeSyntax {}
+
+@_spi(Experimental) extension GenericParameterScopeSyntax {
+  /// Returns names matching lookup and bypasses
+  /// `WithGenericParametersScopeSyntax` parent scope in futher lookup.
+  ///
+  /// ### Example
+  /// ```swift
+  /// let a = 23
+  /// func foo<A>(a: A) {
+  ///   a // <-- start lookup here
+  /// }
+  /// ```
+  /// When starting lookup at the `a` reference,
+  /// lookup first visits the code block scope associated
+  /// with the function's body. Then, it's forwarded to the
+  /// function declaration scope and then to generic parameter
+  /// scope (`WithGenericParametersScopeSyntax`).
+  /// Then, to ensure there is no infinite cycle,
+  /// this method passes lookup to function scope's parent scope
+  /// (in this case: file scope).
+  @_spi(Experimental) public func lookup(
+    _ identifier: Identifier?,
+    at lookUpPosition: AbsolutePosition,
+    with config: LookupConfig
+  ) -> [LookupResult] {
+    return defaultLookupImplementation(
+      identifier,
+      at: lookUpPosition,
+      with: config,
+      propagateToParent: false
+    )
+      + lookupBypassingParentResults(
+        identifier,
+        at: lookUpPosition,
+        with: config
+      )
+  }
+
+  /// Bypasses names introduced by `WithGenericParametersScopeSyntax` parent scope.
+  ///
+  /// ### Example
+  /// ```swift
+  /// let a = 23
+  /// func foo<A>(a: A) {
+  ///   a // <-- start lookup here
+  /// }
+  /// ```
+  /// When starting lookup at the `a` reference,
+  /// lookup first visits the code block scope associated
+  /// with the function's body. Then, it's forwarded to the
+  /// function declaration scope and then to generic parameter
+  /// scope (`WithGenericParametersScopeSyntax`).
+  /// Then, to ensure there is no infinite cycle,
+  /// we use this method instead of the standard `lookupInParent`
+  /// to pass lookup to the function scope's parent scope (in this case: file scope)
+  /// and effectively bypass names already looked up before.
+  private func lookupBypassingParentResults(
+    _ identifier: Identifier?,
+    at lookUpPosition: AbsolutePosition,
+    with config: LookupConfig
+  ) -> [LookupResult] {
+    guard let parentScope else { return [] }
+
+    if let parentScope = Syntax(parentScope).asProtocol(SyntaxProtocol.self)
+      as? WithGenericParametersScopeSyntax
+    {
+      return parentScope.lookupInParent(identifier, at: lookUpPosition, with: config)
+    } else {
+      return lookupInParent(identifier, at: lookUpPosition, with: config)
+    }
+  }
+}

Sources/SwiftLexicalLookup/IntroducingToSequentialParentScopeSyntax.swift Sources/SwiftLexicalLookup/Scopes/IntroducingToSequentialParentScopeSyntax.swift

@@ -176,7 +176,7 @@ import SwiftSyntax
   /// All names introduced by the closure signature.
   /// Could be closure captures or (shorthand) parameters.
   ///
-  /// Example:
+  /// ### Example
   /// ```swift
   /// let x = { [weak self, a] b, _ in
   ///   // <--
@@ -222,7 +222,7 @@ import SwiftSyntax
 
   /// Finds parent scope, omitting ancestor `if` statements if part of their `else if` clause.
   ///
-  /// Example:
+  /// ### Example
   /// ```swift
   /// func foo() {
   ///   if let a = x {
@@ -262,7 +262,7 @@ import SwiftSyntax
   /// Lookup triggered from inside of `else`
   /// clause is immediately forwarded to parent scope.
   ///
-  /// Example:
+  /// ### Example
   /// ```swift
   /// if let a = x {
   ///   // <-- a is visible here
@@ -290,6 +290,24 @@ import SwiftSyntax
       LookupName.getNames(from: member.decl)
     }
   }
+
+  /// Creates a result from associated type declarations
+  /// made by it's members.
+  func lookupAssociatedTypeDeclarations(
+    _ identifier: Identifier?,
+    at lookUpPosition: AbsolutePosition,
+    with config: LookupConfig
+  ) -> [LookupResult] {
+    let filteredNames = members.flatMap { member in
+      guard member.decl.kind == .associatedTypeDecl else { return [LookupName]() }
+
+      return LookupName.getNames(from: member.decl)
+    }.filter { name in
+      checkIdentifier(identifier, refersTo: name, at: lookUpPosition)
+    }
+
+    return filteredNames.isEmpty ? [] : [.fromScope(self, withNames: filteredNames)]
+  }
 }
 
 @_spi(Experimental) extension GuardStmtSyntax: IntroducingToSequentialParentScopeSyntax {
@@ -308,7 +326,7 @@ import SwiftSyntax
   /// Lookup triggered from within of the `else` body
   /// returns no names.
   ///
-  /// Example:
+  /// ### Example
   /// ```swift
   /// guard let a = x else {
   ///   return // a is not visible here
@@ -330,10 +348,10 @@ import SwiftSyntax
   }
 }
 
-@_spi(Experimental) extension ActorDeclSyntax: TypeScopeSyntax {}
-@_spi(Experimental) extension ClassDeclSyntax: TypeScopeSyntax {}
-@_spi(Experimental) extension StructDeclSyntax: TypeScopeSyntax {}
-@_spi(Experimental) extension EnumDeclSyntax: TypeScopeSyntax {}
+@_spi(Experimental) extension ActorDeclSyntax: TypeScopeSyntax, WithGenericParametersScopeSyntax {}
+@_spi(Experimental) extension ClassDeclSyntax: TypeScopeSyntax, WithGenericParametersScopeSyntax {}
+@_spi(Experimental) extension StructDeclSyntax: TypeScopeSyntax, WithGenericParametersScopeSyntax {}
+@_spi(Experimental) extension EnumDeclSyntax: TypeScopeSyntax, WithGenericParametersScopeSyntax {}
 @_spi(Experimental) extension ExtensionDeclSyntax: TypeScopeSyntax {}
 
 @_spi(Experimental) extension AccessorDeclSyntax: ScopeSyntax {
@@ -356,7 +374,95 @@ import SwiftSyntax
 
 @_spi(Experimental) extension CatchClauseSyntax: ScopeSyntax {
   /// Implicit `error` when there are no catch items.
-  public var introducedNames: [LookupName] {
+  @_spi(Experimental) public var introducedNames: [LookupName] {
     return catchItems.isEmpty ? [.implicit(.error(self))] : []
   }
 }
+
+@_spi(Experimental) extension SwitchCaseSyntax: ScopeSyntax {
+  /// Names introduced within `case` items.
+  @_spi(Experimental) public var introducedNames: [LookupName] {
+    label.as(SwitchCaseLabelSyntax.self)?.caseItems.flatMap { child in
+      LookupName.getNames(from: child.pattern)
+    } ?? []
+  }
+}
+
+@_spi(Experimental) extension ProtocolDeclSyntax: ScopeSyntax {
+  /// Protocol declarations don't introduce names by themselves.
+  @_spi(Experimental) public var introducedNames: [LookupName] {
+    []
+  }
+
+  /// For the lookup initiated from inside primary
+  /// associated type clause, this function also finds
+  /// all associated type declarations made inside the
+  /// protocol member block.
+  ///
+  /// ### Example
+  /// ```swift
+  /// class A {}
+  ///
+  /// protocol Foo<A/*<-- lookup here>*/> {
+  ///  associatedtype A
+  ///  class A {}
+  /// }
+  /// ```
+  /// For the lookup started at the primary associated type `A`,
+  /// the function returns exactly two results. First associated with the member
+  /// block that consists of the `associatedtype A` declaration and
+  /// the latter one from the file scope and `class A` exactly in this order.
+  public func lookup(
+    _ identifier: Identifier?,
+    at lookUpPosition: AbsolutePosition,
+    with config: LookupConfig
+  ) -> [LookupResult] {
+    var results: [LookupResult] = []
+
+    if let primaryAssociatedTypeClause,
+      primaryAssociatedTypeClause.range.contains(lookUpPosition)
+    {
+      results = memberBlock.lookupAssociatedTypeDeclarations(
+        identifier,
+        at: lookUpPosition,
+        with: config
+      )
+    }
+
+    return results + defaultLookupImplementation(identifier, at: lookUpPosition, with: config)
+  }
+}
+
+@_spi(Experimental) extension GenericParameterClauseSyntax: GenericParameterScopeSyntax {
+  /// Generic parameter names introduced by this clause.
+  @_spi(Experimental) public var introducedNames: [LookupName] {
+    parameters.children(viewMode: .fixedUp).flatMap { child in
+      LookupName.getNames(from: child, accessibleAfter: child.endPosition)
+    }
+  }
+}
+
+@_spi(Experimental) extension FunctionDeclSyntax: WithGenericParametersScopeSyntax {
+  /// Function parameters introduced by this function's signature.
+  @_spi(Experimental) public var introducedNames: [LookupName] {
+    signature.parameterClause.parameters.flatMap { parameter in
+      LookupName.getNames(from: parameter)
+    }
+  }
+}
+
+@_spi(Experimental) extension SubscriptDeclSyntax: WithGenericParametersScopeSyntax {
+  /// Parameters introduced by this subscript.
+  @_spi(Experimental) public var introducedNames: [LookupName] {
+    parameterClause.parameters.flatMap { parameter in
+      LookupName.getNames(from: parameter)
+    }
+  }
+}
+
+@_spi(Experimental) extension TypeAliasDeclSyntax: WithGenericParametersScopeSyntax {
+  /// Type alias doesn't introduce any names to it's children.
+  @_spi(Experimental) public var introducedNames: [LookupName] {
+    []
+  }
+}

Sources/SwiftLexicalLookup/ScopeImplementations.swift Sources/SwiftLexicalLookup/Scopes/ScopeImplementations.swift

@@ -87,20 +87,18 @@ extension SyntaxProtocol {
   func defaultLookupImplementation(
     _ identifier: Identifier?,
     at lookUpPosition: AbsolutePosition,
-    with config: LookupConfig
+    with config: LookupConfig,
+    propagateToParent: Bool = true
   ) -> [LookupResult] {
     let filteredNames =
       introducedNames
       .filter { introducedName in
         checkIdentifier(identifier, refersTo: introducedName, at: lookUpPosition)
       }
 
-    if filteredNames.isEmpty {
-      return lookupInParent(identifier, at: lookUpPosition, with: config)
-    } else {
-      return [.fromScope(self, withNames: filteredNames)]
-        + lookupInParent(identifier, at: lookUpPosition, with: config)
-    }
+    let fromThisScope = filteredNames.isEmpty ? [] : [LookupResult.fromScope(self, withNames: filteredNames)]
+
+    return fromThisScope + (propagateToParent ? lookupInParent(identifier, at: lookUpPosition, with: config) : [])
   }
 
   /// Looks up in parent scope.

Sources/SwiftLexicalLookup/ScopeSyntax.swift Sources/SwiftLexicalLookup/Scopes/ScopeSyntax.swift

@@ -22,7 +22,7 @@ extension SequentialScopeSyntax {
   /// and included `IntroducingToSequentialParentScopeSyntax` children
   /// scopes that match the lookup.
   ///
-  /// Example:
+  /// ### Example
   /// ```swift
   /// func foo() {
   ///   let a = 1