宏中的动态结构键

Question

有没有办法让这两个宏成为同一个宏？

macro_rules! bg_color_test {
    ($($color:path, $flag:literal),*$(,)?) => {
        let mut options = Options::default();
        options.text = String::from("my text");

        $(
            options.background = $color;
            assert_eq!(
                parse_args(vec![
                    "path/to/bin".to_string(),
                    "my text".to_string(),
                    "-b".to_string(),
                    $flag.to_string()
                ]),
                options
            );
        )*
    }
}
// used like below:
bg_color_test!(
    Colors::Red,"red",
    Colors::Green,"green",
    Colors::Blue,"blue",
);

还有这个：

macro_rules! color_test {
    ($($color:expr, $flag:literal),*$(,)?) => {
        let mut options = Options::default();
        options.text = String::from("my text");

        $(
            options.colors = $color;
            assert_eq!(
                parse_args(vec![
                    "path/to/bin".to_string(),
                    "my text".to_string(),
                    "-c".to_string(),
                    $flag.to_string()
                ]),
                options
            );
        )*
    }
}
// used like below:
color_test!(
    vec![Colors::Red],"red",
    vec![Colors::Green],"green",
    vec![Colors::Blue],"blue",
);

我正在为这个问题苦苦挣扎： options.background = $color; vs options.colors = $color;...不知道如何将其构建到宏中...

在宏中，我尝试在下面使密钥动态化：

options.$kind = $color; // syntax error
options[$kind] = $color; // syntax error
options.$($kind)* = $color; // empty expression error

我使用宏的方式是这样的：

bg_color_test!(
    "background", Colors::Red,"red",
    "background", Colors::Green,"green",
    "background", Colors::Blue,"blue",
);

哪个会给我：

error: no rules expected the token `"background"`
   --> tests/parse_args_test.rs:491:3
    |
464 | macro_rules! bg_color_test {
    | ------------------------ when calling this macro
...
491 |         "background", BgColors::Red, "red",
    |         ^^^^^^^^^^^^ no rules expected this token in macro call

error: could not compile `lib` due to previous error

Answer 1

我在用户 @pie_flavor 的帮助下在 Discord 上找到了答案。

我的错误是在宏调用中将关键参数视为 str，它应该是 ident 作为开始的参数。

所以将这两个宏合并在一起的最终代码是：

macro_rules! color_test {
    ($($kind:ident, $color:expr, $flag:literal, $flag_value:literal),*$(,)?) => {
        let mut options = Options::default();
        options.text = String::from("my text");

        $(
            options.$kind = $color;
            assert_eq!(
                parse_args(vec![
                    "path/to/bin".to_string(),
                    "my text".to_string(),
                    $flag.to_string(),
                    $flag_value.to_string()
                ]),
                options
            );
        )*
    }
}

这样使用：

color_test!(
    colors, vec![Colors::Red], "-c", "red",
    background, Colors::Green, "-b", "green",
);

宏中的动态结构键

Dynamic struct key in macro

rust

rust-macros