Code actions to convert between computed properties and zero-parameter functions

Sources/SwiftRefactor/CMakeLists.txt

@@ -10,14 +10,17 @@ add_swift_syntax_library(SwiftRefactor
   AddSeparatorsToIntegerLiteral.swift
   CallToTrailingClosures.swift
   ConvertComputedPropertyToStored.swift
+  ConvertComputedPropertyToZeroParameterFunction.swift
   ConvertStoredPropertyToComputed.swift
+  ConvertZeroParameterFunctionToComputedProperty.swift
   ExpandEditorPlaceholder.swift
   FormatRawStringLiteral.swift
   IntegerLiteralUtilities.swift
   MigrateToNewIfLetSyntax.swift
   OpaqueParameterToGeneric.swift
   RefactoringProvider.swift
   RemoveSeparatorsFromIntegerLiteral.swift
+  SyntaxUtils.swift
 )
 
 target_link_swift_syntax_libraries(SwiftRefactor PUBLIC

Sources/SwiftRefactor/CallToTrailingClosures.swift

@@ -152,12 +152,6 @@ extension FunctionCallExprSyntax {
   }
 }
 
-fileprivate extension Trivia {
-  var droppingLeadingWhitespace: Trivia {
-    return Trivia(pieces: self.drop(while: \.isWhitespace))
-  }
-}
-
 fileprivate extension Sequence {
   func dropSuffix(while predicate: (Element) -> Bool) -> [Element] {
     self.reversed().drop(while: predicate).reversed()

Sources/SwiftRefactor/ConvertComputedPropertyToStored.swift

@@ -82,15 +82,3 @@ public struct ConvertComputedPropertyToStored: SyntaxRefactoringProvider {
     return nil
   }
 }
-
-fileprivate extension TokenSyntax {
-  var trivia: Trivia {
-    return leadingTrivia + trailingTrivia
-  }
-}
-
-fileprivate extension Trivia {
-  var droppingTrailingWhitespace: Trivia {
-    return Trivia(pieces: self.reversed().drop(while: \.isWhitespace).reversed())
-  }
-}

Sources/SwiftRefactor/ConvertComputedPropertyToZeroParameterFunction.swift

@@ -0,0 +1,105 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#if swift(>=6)
+public import SwiftSyntax
+#else
+import SwiftSyntax
+#endif
+
+public struct ConvertComputedPropertyToZeroParameterFunction: SyntaxRefactoringProvider {
+  public static func refactor(syntax: VariableDeclSyntax, in context: Void) -> FunctionDeclSyntax? {
+    guard syntax.bindings.count == 1,
+      let binding = syntax.bindings.first,
+      let identifierPattern = binding.pattern.as(IdentifierPatternSyntax.self)
+    else { return nil }
+
+    var statements: CodeBlockItemListSyntax
+
+    guard let typeAnnotation = binding.typeAnnotation,
+      var accessorBlock = binding.accessorBlock
+    else { return nil }
+
+    var effectSpecifiers: AccessorEffectSpecifiersSyntax?
+
+    switch accessorBlock.accessors {
+    case .accessors(let accessors):
+      guard accessors.count == 1, let accessor = accessors.first,
+        accessor.accessorSpecifier.tokenKind == .keyword(.get), let codeBlock = accessor.body
+      else { return nil }
+      effectSpecifiers = accessor.effectSpecifiers
+      statements = codeBlock.statements
+      let accessorSpecifier = accessor.accessorSpecifier
+      statements.leadingTrivia =
+        accessorSpecifier.leadingTrivia + accessorSpecifier.trailingTrivia.droppingLeadingWhitespace
+        + codeBlock.leftBrace.leadingTrivia.droppingLeadingWhitespace
+        + codeBlock.leftBrace.trailingTrivia.droppingLeadingWhitespace
+        + statements.leadingTrivia
+      statements.trailingTrivia += codeBlock.rightBrace.trivia.droppingLeadingWhitespace
+      statements.trailingTrivia = statements.trailingTrivia.droppingTrailingWhitespace
+    case .getter(let codeBlock):
+      statements = codeBlock
+    }
+
+    let returnType = typeAnnotation.type
+
+    var returnClause: ReturnClauseSyntax?
+    let triviaAfterSignature: Trivia
+
+    if !returnType.isVoid {
+      triviaAfterSignature = .space
+      returnClause = ReturnClauseSyntax(
+        arrow: .arrowToken(
+          leadingTrivia: typeAnnotation.colon.leadingTrivia,
+          trailingTrivia: typeAnnotation.colon.trailingTrivia
+        ),
+        type: returnType
+      )
+    } else {
+      triviaAfterSignature = typeAnnotation.colon.leadingTrivia + typeAnnotation.colon.trailingTrivia
+    }
+
+    accessorBlock.leftBrace.leadingTrivia = accessorBlock.leftBrace.leadingTrivia.droppingLeadingWhitespace
+    accessorBlock.rightBrace.trailingTrivia = accessorBlock.rightBrace.trailingTrivia.droppingTrailingWhitespace
+
+    let body = CodeBlockSyntax(
+      leftBrace: accessorBlock.leftBrace,
+      statements: statements,
+      rightBrace: accessorBlock.rightBrace
+    )
+
+    var parameterClause = FunctionParameterClauseSyntax(parameters: [])
+    parameterClause.trailingTrivia = identifierPattern.identifier.trailingTrivia + triviaAfterSignature
+
+    let functionEffectSpecifiers = FunctionEffectSpecifiersSyntax(
+      asyncSpecifier: effectSpecifiers?.asyncSpecifier,
+      throwsClause: effectSpecifiers?.throwsClause
+    )
+    let functionSignature = FunctionSignatureSyntax(
+      parameterClause: parameterClause,
+      effectSpecifiers: functionEffectSpecifiers,
+      returnClause: returnClause
+    )
+
+    return FunctionDeclSyntax(
+      modifiers: syntax.modifiers,
+      funcKeyword: .keyword(
+        .func,
+        leadingTrivia: syntax.bindingSpecifier.leadingTrivia,
+        trailingTrivia: syntax.bindingSpecifier.trailingTrivia
+      ),
+      name: identifierPattern.identifier.with(\.trailingTrivia, []),
+      signature: functionSignature,
+      body: body
+    )
+  }
+}

Sources/SwiftRefactor/ConvertZeroParameterFunctionToComputedProperty.swift

@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#if swift(>=6)
+public import SwiftSyntax
+#else
+import SwiftSyntax
+#endif
+
+public struct ConvertZeroParameterFunctionToComputedProperty: SyntaxRefactoringProvider {
+  public static func refactor(syntax: FunctionDeclSyntax, in context: ()) -> VariableDeclSyntax? {
+    guard syntax.signature.parameterClause.parameters.isEmpty,
+      let body = syntax.body
+    else { return nil }
+
+    let variableName = PatternSyntax(
+      IdentifierPatternSyntax(
+        leadingTrivia: syntax.funcKeyword.trailingTrivia,
+        identifier: syntax.name
+      )
+    )
+
+    let triviaFromParameters =
+      (syntax.signature.parameterClause.leftParen.trivia + syntax.signature.parameterClause.rightParen.trivia)
+      .droppingTrailingWhitespace
+
+    var variableType: TypeAnnotationSyntax?
+
+    if let returnClause = syntax.signature.returnClause {
+      variableType = TypeAnnotationSyntax(
+        colon: .colonToken(
+          leadingTrivia: triviaFromParameters + returnClause.arrow.leadingTrivia,
+          trailingTrivia: returnClause.arrow.trailingTrivia
+        ),
+        type: returnClause.type
+      )
+    } else {
+      variableType = TypeAnnotationSyntax(
+        colon: .colonToken(
+          leadingTrivia: triviaFromParameters,
+          trailingTrivia: .space
+        ),
+        type: TypeSyntax("Void").with(\.trailingTrivia, .space)
+      )
+    }
+
+    let accessorBlock = AccessorBlockSyntax(
+      leftBrace: body.leftBrace,
+      accessors: .getter(body.statements),
+      rightBrace: body.rightBrace
+    )
+
+    return VariableDeclSyntax(
+      modifiers: syntax.modifiers,
+      .var,
+      name: variableName,
+      type: variableType,
+      accessorBlock: accessorBlock
+    )
+  }
+}

Sources/SwiftRefactor/SyntaxUtils.swift

@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#if swift(>=6)
+public import SwiftSyntax
+#else
+import SwiftSyntax
+#endif
+
+extension TokenSyntax {
+  var trivia: Trivia {
+    return leadingTrivia + trailingTrivia
+  }
+}
+
+extension Trivia {
+  var droppingLeadingWhitespace: Trivia {
+    return Trivia(pieces: self.drop(while: \.isWhitespace))
+  }
+
+  var droppingTrailingWhitespace: Trivia {
+    return Trivia(pieces: self.reversed().drop(while: \.isWhitespace).reversed())
+  }
+}
+
+extension TypeSyntax {
+  var isVoid: Bool {
+    switch self.as(TypeSyntaxEnum.self) {
+    case .identifierType(let identifierType) where identifierType.name.text == "Void": return true
+    case .tupleType(let tupleType) where tupleType.elements.isEmpty: return true
+    default: return false
+    }
+  }
+}

Sources/SwiftSyntaxBuilder/ConvenienceInitializers.swift

@@ -403,7 +403,8 @@ extension VariableDeclSyntax {
     _ bindingSpecifier: Keyword,
     name: PatternSyntax,
     type: TypeAnnotationSyntax? = nil,
-    initializer: InitializerClauseSyntax? = nil
+    initializer: InitializerClauseSyntax? = nil,
+    accessorBlock: AccessorBlockSyntax? = nil
   ) {
     self.init(
       leadingTrivia: leadingTrivia,
@@ -414,7 +415,8 @@ extension VariableDeclSyntax {
       PatternBindingSyntax(
         pattern: name,
         typeAnnotation: type,
-        initializer: initializer
+        initializer: initializer,
+        accessorBlock: accessorBlock
       )
     }
   }