Add capability to convert stored property to computed property

Author: antigluten

Sources/SwiftRefactor/CMakeLists.txt

@@ -9,6 +9,7 @@
 add_swift_syntax_library(SwiftRefactor
   AddSeparatorsToIntegerLiteral.swift
   CallToTrailingClosures.swift
+  ConvertStoredPropertyToComputed.swift
   ExpandEditorPlaceholder.swift
   FormatRawStringLiteral.swift
   IntegerLiteralUtilities.swift

Sources/SwiftRefactor/ConvertStoredPropertyToComputed.swift

@@ -0,0 +1,45 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 ConvertStoredPropertyToComputed: SyntaxRefactoringProvider {
+  
+  public static func refactor(syntax: VariableDeclSyntax, in context: ()) -> VariableDeclSyntax? {
+    guard syntax.bindings.count == 1, let binding = syntax.bindings.first, let initializer = binding.initializer else {
+      return nil
+    }
+    
+    let body = CodeBlockItemSyntax(
+      item: .expr(initializer.value)
+    )
+    
+    let newBinding = binding
+      .with(\.initializer, nil)
+      .with(
+        \.accessorBlock,
+         AccessorBlockSyntax(
+          leftBrace: .leftBraceToken(trailingTrivia: .space),
+          accessors: .getter(CodeBlockItemListSyntax([body])),
+          rightBrace: .rightBraceToken(leadingTrivia: .space)
+         )
+      )
+    
+    return syntax
+      .with(\.bindingSpecifier, .keyword(.var, trailingTrivia: .space))
+      .with(\.bindings, PatternBindingListSyntax([newBinding]))
+  }
+}

Tests/SwiftRefactorTest/ConvertStoredPropertyToComputed.swift

@@ -0,0 +1,84 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 SwiftRefactor
+import SwiftSyntax
+import SwiftSyntaxBuilder
+import XCTest
+import _SwiftSyntaxTestSupport
+
+final class ConvertStoredPropertyToComputedTest: XCTestCase {
+  
+  func testRefactoringStoredPropertyWithInitializer1() throws {
+    let baseline: DeclSyntax = """
+      static let defaultColor: Color = .red
+      """
+    
+    let expected: DeclSyntax = """
+      static var defaultColor: Color { .red }
+      """
+    
+    try assertRefactorConvert(baseline, expected: expected)
+  }
+  
+  func testRefactoringStoredPropertyWithInitializer2() throws {
+    let baseline: DeclSyntax = """
+      static let defaultColor: Color = Color.red
+      """
+    
+    let expected: DeclSyntax = """
+      static var defaultColor: Color { Color.red }
+      """
+    
+    try assertRefactorConvert(baseline, expected: expected)
+  }
+  
+  func testRefactoringStoredPropertyWithInitializer3() throws {
+    let baseline: DeclSyntax = """
+      var defaultColor: Color = Color.red
+      """
+    
+    let expected: DeclSyntax = """
+      var defaultColor: Color { Color.red }
+      """
+    
+    try assertRefactorConvert(baseline, expected: expected)
+  }
+  
+  func testRefactoringStoredPropertyWithInitializer4() throws {
+    let baseline: DeclSyntax = """
+      var defaultColor: Color = Color()
+      """
+    
+    let expected: DeclSyntax = """
+      var defaultColor: Color { Color() }
+      """
+    
+    try assertRefactorConvert(baseline, expected: expected)
+  }
+}
+
+fileprivate func assertRefactorConvert(
+  _ callDecl: DeclSyntax,
+  expected: DeclSyntax?,
+  file: StaticString = #filePath,
+  line: UInt = #line
+) throws {
+  try assertRefactor(
+    callDecl,
+    context: (),
+    provider: ConvertStoredPropertyToComputed.self,
+    expected: expected,
+    file: file,
+    line: line
+  )
+}