Add refactoring action to convert stored to computed properties

This is the first syntactic refactoring action that needs to perform a cursor info request on `codeAction/resolve`, so the majority of this PR is to add infrastructure for that.

Based on swiftlang#2496.

Co-Authored-By: Padmashree S S <padmashreess2006@gmail.com>

Author: ahoppen

Sources/SwiftLanguageService/CodeActions/ConvertCommentToDocComment.swift

@@ -39,7 +39,7 @@ extension ConvertCommentToDocComment: SyntaxRefactoringCodeActionProvider {
   static let title = "Convert Comment to Doc Comment"
 
   static func nodeToRefactor(in scope: SyntaxCodeActionScope) -> DeclSyntax? {
-    let cursorPosition = scope.snapshot.absolutePosition(of: scope.request.range.lowerBound)
+    let cursorPosition = scope.snapshot.absolutePosition(of: scope.requestedRange.lowerBound)
     guard let token = scope.file.token(at: cursorPosition) else {
       return nil
     }

Sources/SwiftLanguageService/CodeActions/ConvertStoredPropertyToComputed.swift

@@ -0,0 +1,55 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 Foundation
+@_spi(SourceKitLSP) import LanguageServerProtocol
+import SourceKitLSP
+import SwiftExtensions
+import SwiftRefactor
+import SwiftSyntax
+import SwiftSyntaxBuilder
+
+extension ConvertStoredPropertyToComputed: SyntaxRefactoringCodeActionProvider {
+  static let title: String = "Convert Stored Property to Computed Property"
+
+  static func nodeToRefactor(in scope: SyntaxCodeActionScope) -> VariableDeclSyntax? {
+    return scope.innermostNodeContainingRange?.as(VariableDeclSyntax.self)
+      ?? scope.innermostNodeContainingRange?.parent?.as(VariableDeclSyntax.self)
+  }
+
+  static func refactoringContext(
+    for node: VariableDeclSyntax,
+    in scope: SyntaxCodeActionScope
+  ) async -> SyntaxCodeActionContextResult<Context> {
+    guard node.bindings.contains(where: { $0.typeAnnotation?.type == nil }) else {
+      // All types are syntactically specified, we don't need to resolve the semantic type
+      return .context(Context())
+    }
+    guard let binding = node.bindings.only,
+      let identifier = binding.pattern.as(IdentifierPatternSyntax.self)?.identifier
+    else {
+      // We can only resolve type information for a single variable binding at the moment. If this is variable decl with multiple bindings, still
+      // offer the refactoring action and introduce placeholders for the type annotation.
+      return .context(Context())
+    }
+    if scope.resolveSupport?.canResolveEdit ?? false {
+      return .resolveEditLazily
+    }
+    // Cursor info reports type as `_` if it cannot determine the type.
+    if let type = try? await scope.cursorInfo(at: scope.snapshot.position(of: identifier.position)).only?.typeName,
+      type != "_"
+    {
+      return .context(Context(type: "\(raw: type)"))
+    }
+    return .context(Context())
+  }
+}

Sources/SwiftLanguageService/CodeActions/RemoveUnusedImports.swift

@@ -72,8 +72,14 @@ extension SwiftLanguageService {
 
     let syntaxTree = await syntaxTreeManager.syntaxTree(for: snapshot)
     guard
-      let node = SyntaxCodeActionScope(snapshot: snapshot, syntaxTree: syntaxTree, request: request)?
-        .innermostNodeContainingRange,
+      let node = SyntaxCodeActionScope(
+        resolveSupport: nil,
+        snapshot: snapshot,
+        syntaxTree: syntaxTree,
+        requestedRange: request.range,
+        swiftLanguageService: self
+      )?
+      .innermostNodeContainingRange,
       node.findParentOfSelf(ofType: ImportDeclSyntax.self, stoppingIf: { _ in false }) != nil
     else {
       // Only offer the remove unused imports code action on an import statement.

Sources/SwiftLanguageService/CodeActions/SyntaxCodeActionProvider.swift

@@ -16,50 +16,88 @@ import SourceKitLSP
 import SwiftRefactor
 import SwiftSyntax
 
+extension TextDocumentClientCapabilities.CodeAction.ResolveSupportProperties {
+  var canResolveEdit: Bool {
+    return self.properties.contains("edit")
+  }
+}
+
 /// Describes types that provide one or more code actions based on purely
 /// syntactic information.
 protocol SyntaxCodeActionProvider: SendableMetatype {
   /// Produce code actions within the given scope. Each code action
   /// corresponds to one syntactic transformation that can be performed, such
   /// as adding or removing separators from an integer literal.
-  static func codeActions(in scope: SyntaxCodeActionScope) -> [CodeAction]
+  static func codeActions(in scope: SyntaxCodeActionScope) async -> [CodeAction]
 }
 
 /// Defines the scope in which a syntactic code action occurs.
 struct SyntaxCodeActionScope {
+  /// Whether the client supports the codeAction/resolve request.
+  ///
+  /// This is set to `nil` during the `codeAction/resolve` request.
+  var resolveSupport: TextDocumentClientCapabilities.CodeAction.ResolveSupportProperties?
+
   /// The snapshot of the document on which the code actions will be evaluated.
   var snapshot: DocumentSnapshot
 
-  /// The actual code action request, which can specify additional parameters
-  /// to guide the code actions.
-  var request: CodeActionRequest
-
   /// The source file in which the syntactic code action will operate.
   var file: SourceFileSyntax
 
+  /// The originally requested range in the original code action request.
+  ///
+  /// Generally, `range` should be preferred because it performs useful adjustments to extend the range to the start and end of tokens.
+  var requestedRange: Range<Position>
+
   /// The UTF-8 byte range in the source file in which code actions should be
   /// considered, i.e., where the cursor or selection is.
   var range: Range<AbsolutePosition>
 
   /// The innermost node that contains the entire selected source range
   var innermostNodeContainingRange: Syntax?
 
+  /// The language service from which this code action is going to be resolved.
+  ///
+  /// Used to to retrieve cursor info if necessary.
+  private let swiftLanguageService: SwiftLanguageService
+
   init?(
+    resolveSupport: TextDocumentClientCapabilities.CodeAction.ResolveSupportProperties?,
     snapshot: DocumentSnapshot,
     syntaxTree file: SourceFileSyntax,
-    request: CodeActionRequest
+    requestedRange: Range<Position>,
+    swiftLanguageService: SwiftLanguageService
   ) {
+    self.resolveSupport = resolveSupport
     self.snapshot = snapshot
-    self.request = request
+    self.requestedRange = requestedRange
     self.file = file
 
-    guard let left = tokenForRefactoring(at: request.range.lowerBound, snapshot: snapshot, syntaxTree: file),
-      let right = tokenForRefactoring(at: request.range.upperBound, snapshot: snapshot, syntaxTree: file)
+    guard let left = tokenForRefactoring(at: requestedRange.lowerBound, snapshot: snapshot, syntaxTree: file),
+      let right = tokenForRefactoring(at: requestedRange.upperBound, snapshot: snapshot, syntaxTree: file)
     else {
       return nil
     }
     self.range = left.position..<right.endPosition
     self.innermostNodeContainingRange = findCommonAncestorOrSelf(Syntax(left), Syntax(right))
+    self.swiftLanguageService = swiftLanguageService
+  }
+
+  /// Retrieve the cursor info in the code action's document at the given position.
+  ///
+  /// Because this can be an expensive operation, this should only be called after all syntactic checks and if the request does not support lazily
+  /// resolving of the `edit` properties.
+  func cursorInfo(at position: Position) async throws -> [CursorInfo] {
+    let compileCommand = await swiftLanguageService.compileCommand(
+      for: snapshot.uri,
+      fallbackAfterTimeout: true
+    )
+
+    return try await swiftLanguageService.cursorInfo(
+      snapshot,
+      compileCommand: compileCommand,
+      position..<position
+    ).cursorInfo
   }
 }
 

Sources/SwiftLanguageService/CodeActions/SyntaxCodeActions.swift

@@ -24,6 +24,7 @@ let allSyntaxCodeActions: [any SyntaxCodeActionProvider.Type] = {
     ConvertIfLetToGuard.self,
     ConvertIntegerLiteral.self,
     ConvertJSONToCodableStruct.self,
+    ConvertStoredPropertyToComputed.self,
     ConvertStringConcatenationToStringInterpolation.self,
     ConvertZeroParameterFunctionToComputedProperty.self,
     FormatRawStringLiteral.self,

Sources/SwiftLanguageService/CodeActions/SyntaxRefactoringCodeActionProvider.swift

@@ -11,10 +11,44 @@
 //===----------------------------------------------------------------------===//
 
 @_spi(SourceKitLSP) import LanguageServerProtocol
+@_spi(SourceKitLSP) import SKLogging
 import SourceKitLSP
 import SwiftRefactor
 import SwiftSyntax
 
+/// Data that is included in a `CodeAction` response for which the client should resolve the edit lazily using a `codeAction/resolve` request.
+///
+/// This data allows us to re-construct the `SyntaxCodeActionScope`.
+struct UnresolvedCodeActionData: Codable, LSPAnyCodable {
+  /// A string representation of the syntax refactoring action's type.
+  let action: String
+
+  /// The document on which the code action should be applied.
+  let document: VersionedTextDocumentIdentifier
+
+  /// The range at which the code action was originally requested.
+  let range: Range<Position>
+
+  init<Metatype: SyntaxRefactoringCodeActionProvider>(
+    actionType: Metatype.Type,
+    document: VersionedTextDocumentIdentifier,
+    range: Range<Position>,
+  ) {
+    self.action = "\(Metatype.self)"
+    self.document = document
+    self.range = range
+  }
+}
+
+enum SyntaxCodeActionContextResult<Context> {
+  /// The cont
+  case context(Context)
+  /// Report a code action without the `edit` properties. The client is expected to send a `codeAction/resolve` request to resolve the edit.
+  ///
+  /// Must only be returned if the the client can resolve edits.
+  case resolveEditLazily
+}
+
 /// Protocol that adapts a SyntaxRefactoringProvider (that comes from
 /// swift-syntax) into a SyntaxCodeActionProvider.
 protocol SyntaxRefactoringCodeActionProvider: SyntaxCodeActionProvider, EditRefactoringProvider {
@@ -24,18 +58,45 @@ protocol SyntaxRefactoringCodeActionProvider: SyntaxCodeActionProvider, EditRefa
   /// scope.
   static func nodeToRefactor(in scope: SyntaxCodeActionScope) -> Input?
 
-  static func refactoringContext(for scope: SyntaxCodeActionScope) -> Context
+  /// Retrieve the refactoring context to refactor the given node in the given scope.
+  ///
+  /// Throwing an error from this method causes the code action to be reported without any workspace edits. The client is expected to send a
+  /// `codeAction/resolve` request when the user selects the code action in order to retrieve the semantic information and compute the actual edits.
+  static func refactoringContext(
+    for node: Input,
+    in scope: SyntaxCodeActionScope
+  ) async -> SyntaxCodeActionContextResult<Context>
 }
 
-/// SyntaxCodeActionProviders with a \c Void context can automatically be
-/// adapted provide a code action based on their refactoring operation.
 extension SyntaxRefactoringCodeActionProvider {
-  static func codeActions(in scope: SyntaxCodeActionScope) -> [CodeAction] {
+  static func codeActions(in scope: SyntaxCodeActionScope) async -> [CodeAction] {
     guard let node = nodeToRefactor(in: scope) else {
       return []
     }
 
-    guard let sourceEdits = try? Self.textRefactor(syntax: node, in: refactoringContext(for: scope)) else {
+    let context: Context
+    switch await refactoringContext(for: node, in: scope) {
+    case .context(let c): context = c
+    case .resolveEditLazily:
+      guard scope.resolveSupport?.canResolveEdit ?? false else {
+        logger.fault(
+          "Refactoring action \(Self.self) requested lazy resolution of edits but client cannot resolve edits"
+        )
+        return []
+      }
+      return [
+        CodeAction(
+          title: Self.title,
+          kind: .refactorInline,
+          data: UnresolvedCodeActionData(
+            actionType: Self.self,
+            document: VersionedTextDocumentIdentifier(scope.snapshot.uri, version: scope.snapshot.version),
+            range: scope.requestedRange
+          ).encodeToLSPAny()
+        )
+      ]
+    }
+    guard let sourceEdits = try? Self.textRefactor(syntax: node, in: context) else {
       return []
     }
 
@@ -53,9 +114,14 @@ extension SyntaxRefactoringCodeActionProvider {
   }
 }
 
+/// SyntaxCodeActionProviders with a `Void` context can automatically be adapted provide a code action based on their
+/// refactoring operation.
 extension SyntaxRefactoringCodeActionProvider where Context == Void {
-  static func refactoringContext(for scope: SyntaxCodeActionScope) -> Context {
-    return ()
+  static func refactoringContext(
+    for node: Input,
+    in scope: SyntaxCodeActionScope
+  ) -> SyntaxCodeActionContextResult<Context> {
+    return .context(())
   }
 }
 

Sources/SwiftLanguageService/CursorInfo.swift

@@ -28,6 +28,9 @@ struct CursorInfo {
   /// name and USR.
   var symbolInfo: SymbolDetails
 
+  /// A human-readable string representation of the symbol at the given location, eg. a variable's type.
+  var typeName: String?
+
   /// The annotated declaration XML string.
   var annotatedDeclaration: String?
 
@@ -39,10 +42,12 @@ struct CursorInfo {
 
   init(
     _ symbolInfo: SymbolDetails,
+    typeName: String?,
     annotatedDeclaration: String?,
     documentation: String?
   ) {
     self.symbolInfo = symbolInfo
+    self.typeName = typeName
     self.annotatedDeclaration = annotatedDeclaration
     self.documentation = documentation
   }
@@ -107,6 +112,7 @@ struct CursorInfo {
         receiverUsrs: dict[keys.receivers]?.compactMap { $0[keys.usr] as String? } ?? [],
         systemModule: module
       ),
+      typeName: dict[keys.typeName],
       annotatedDeclaration: dict[keys.annotatedDecl],
       documentation: dict[keys.docComment]
     )