EnvironmentValueMacro.swift

//===----------------------------------------------------------------------===//
//
// 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
import SwiftSyntaxMacros

public struct EnvironmentValueMacro: AccessorMacro {
  public static func expansion(
    of node: AttributeSyntax,
    providingAccessorsOf declaration: some DeclSyntaxProtocol,
    in context: some MacroExpansionContext
  ) throws -> [AccessorDeclSyntax] {
    guard
      case .argumentList(let arguments) = node.arguments,
      let argument = arguments.first
    else { return [] }

    return [
      """
      get { self[\(argument.expression)] }
      """,
      """
      set { self[\(argument.expression)] = newValue }
      """,
    ]
  }
}