translate first 3 sections

Author: Maples7

swift-6-beta.docc/LanguageGuide/Macros.md

@@ -1,55 +1,26 @@
-<!--
-要翻译的文件：https://github.com/SwiftGGTeam/the-swift-programming-language-in-chinese/blob/swift-6-beta-translation/swift-6-beta.docc/LanguageGuide/Macros.md
-Swift 文档源文件地址：https://docs.swift.org/swift-book/documentation/the-swift-programming-language/macros
-翻译估计用时：⭐️⭐️⭐️⭐️⭐️
--->
-
-# Macros
+# 宏
 
-Use macros to generate code at compile time.
+在编译时使用宏生成代码。
 
-Macros transform your source code when you compile it,
-letting you avoid writing repetitive code by hand.
-During compilation,
-Swift expands any macros in your code before building your code as usual.
+宏会在你编译你的源代码时对其进行转换，从而可以让你避免手动编写重复的代码。在编译过程中，Swift 会先展开代码中的所有宏，然后再像往常一样构建代码。
 
-![A diagram showing an overview of macro expansion.  On the left, a stylized representation of Swift code.  On the right, the same code with several lines added by the macro.](macro-expansion)
+![一个显示宏展开概貌的图表。左侧是 Swift 代码的风格化表示。右侧是由宏添加了几行的相同的代码。](macro-expansion)
 
-Expanding a macro is always an additive operation:
-Macros add new code,
-but they never delete or modify existing code.
+宏展开始终是一种加法操作：宏会添加新代码，但绝不会删除或修改现有代码。
 
-Both the input to a macro and the output of macro expansion
-are checked to ensure they're syntactically valid Swift code.
-Likewise, the values you pass to a macro
-and the values in code generated by a macro
-are checked to ensure they have the correct types.
-In addition,
-if the macro's implementation encounters an error when expanding that macro,
-the compiler treats this as a compilation error.
-These guarantees make it easier to reason about code that uses macros,
-and they make it easier to identify issues
-like using a macro incorrectly
-or a macro implementation that has a bug.
+每个宏的输入和宏展开的输出都会被检查，以确保它们是语法上有效的 Swift 代码。同样，你传给宏的值以及宏生成的代码中的值也会被检查，以确保它们具有正确的类型。此外，如果宏的实现在扩展宏时遇到错误，编译器会将其视为编译错误。这些保证让使用了宏的代码更容易被推导，也更容易发现诸如宏使用不当或宏实现中的错误这样的问题。
 
-Swift has two kinds of macros:
+Swift 有两种宏:
 
-- *Freestanding macros* appear on their own,
-  without being attached to a declaration.
+- *独立宏*可单独出现，无需被附加到任何声明中。
 
-- *Attached macros* modify the declaration that they're attached to.
+- *附加宏*会修改它被附加到的声明。
 
-You call attached and freestanding macros slightly differently,
-but they both follow the same model for macro expansion,
-and you implement them both using the same approach.
-The following sections describe both kinds of macros in more detail.
+附加宏和独立宏的调用方式略有不同，但它们都遵循相同的宏展开模型，并都使用相同的方法来实现。下面的章节将更详细地描述这两种宏。
 
-## Freestanding Macros
+## 独立宏
 
-To call a freestanding macro,
-you write a number sign (`#`) before its name,
-and you write any arguments to the macro in parentheses after its name.
-For example:
+要调用独立宏，需要在其名称前写入数字符号 (`#`)，并在名称后的括号中写入宏的参数。例如：
 
 ```swift
 func myFunction() {
@@ -58,36 +29,21 @@ func myFunction() {
 }
 ```
 
-In the first line,
-`#function` calls the [`function()`][] macro from the Swift standard library.
-When you compile this code,
-Swift calls that macro's implementation,
-which replaces `#function` with the name of the current function.
-When you run this code and call `myFunction()`,
-it prints "Currently running myFunction()".
-In the second line,
-`#warning` calls the [`warning(_:)`][] macro from the Swift standard library
-to produce a custom compile-time warning.
+在函数内的第一行中，`#function` 调用了 Swift 标准库中的 [`function()`][] 宏。当你编译此代码时，Swift 会调用该宏的实现，将 `#function` 替换为当前函数的名称。当你运行这段代码并调用 `myFunction()` 时，它会打印 “Currently running myFunction()”。在第二行中，`#warning` 调用了 Swift 标准库中的 [`warning(_:)`][] 宏，以生成一个自定义的编译时警告。
 
 [`function()`]: https://developer.apple.com/documentation/swift/function()
 [`warning(_:)`]: https://developer.apple.com/documentation/swift/warning(_:)
 
-Freestanding macros can produce a value, like `#function` does,
-or they can perform an action at compile time, like `#warning` does.
-<!-- SE-0397: or they can generate new declarations.  -->
+独立宏可以像 `#function` 所做的那样产出一个值，也可以像 `#warning` 所做的那样在编译时执行一个操作。
+<!-- SE-0397: 或者他们也可以生成新的声明。  -->
 
-## Attached Macros
+## 附加宏
 
-To call an attached macro,
-you write an at sign (`@`) before its name,
-and you write any arguments to the macro in parentheses after its name.
+要调用附加宏，需要在其名称前写入 at 符号 (`@`) ，并在名称后的括号中写入宏的参数。
 
-Attached macros modify the declaration that they're attached to.
-They add code to that declaration,
-like defining a new method or adding conformance to a protocol.
+附加宏会修改它们被所附加到的声明。它们为被附加到的声明添加代码，比如定义一个新的方法或者增加对某个协议的遵循。
 
-For example, consider the following code
-that doesn't use macros:
+例如，请看下面这段不使用宏的代码：
 
 ```swift
 struct SundaeToppings: OptionSet {
@@ -98,14 +54,9 @@ struct SundaeToppings: OptionSet {
 }
 ```
 
-In this code,
-each of the options in the `SundaeToppings` option set
-includes a call to the initializer,
-which is repetitive and manual.
-It would be easy to make a mistake when adding a new option,
-like typing the wrong number at the end of the line.
+在这段代码中，`SundaeToppings` 选项集中的每个选项都包括对初始化器的调用，这是重复的手动操作。这样在添加新选项时容易出错，比如在行尾键入错误的数字。
 
-Here's a version of this code that uses a macro instead:
+下面是该代码使用宏后的替代版本：
 
 ```swift
 @OptionSet<Int>
@@ -118,26 +69,19 @@ struct SundaeToppings {
 }
 ```
 
-This version of `SundaeToppings` calls an `@OptionSet` macro.
-The macro reads the list of cases in the private enumeration,
-generates the list of constants for each option,
-and adds a conformance to the [`OptionSet`][] protocol.
+此版本的 `SundaeToppings` 调用了 `@OptionSet` 宏。这个宏会读取私有枚举类中的 `case` 列表，生成每个选项的常量列表，并增加对 [`OptionSet`][] 协议的遵循。
 
 [`OptionSet`]: https://developer.apple.com/documentation/swift/optionset
 
 <!--
-When the @OptionSet macro comes back, change both links back:
+当 @OptionSet 宏回归后，把这俩链接改回来：
 
 [`@OptionSet`]: https://developer.apple.com/documentation/swift/optionset-swift.macro
 [`OptionSet`]: https://developer.apple.com/documentation/swift/optionset-swift.protocol
 -->
 
 
-For comparison,
-here's what the expanded version of the `@OptionSet` macro looks like.
-You don't write this code,
-and you would see it only if you specifically asked Swift
-to show the macro's expansion.
+作为对比，下面是 `@OptionSet` 宏展开后的版本的样子。这段代码不是由你自己编写的，只有当你特别要求 Swift 显示宏的展开时，你才会看到它。
 
 ```swift
 struct SundaeToppings {
@@ -158,12 +102,7 @@ struct SundaeToppings {
 extension SundaeToppings: OptionSet { }
 ```
 
-All of the code after the private enumeration
-comes from the `@OptionSet` macro.
-The version of `SundaeToppings`
-that uses a macro to generate all of the static variables
-is easier to read and easier to maintain
-than the manually coded version, earlier.
+私有枚举类之后的所有代码都来自于 `@OptionSet` 宏。使用宏生成所有静态变量的 `SundaeToppings` 版本比前面手动编码的版本更易于阅读和维护。
 
 ## Macro Declarations