宏如何匹配除逗号以外的任何标记树?

Question

macro_rules! foo {
( $( $( $tok:tt )* ,)* ) => {
[ bar!( $( $tok )* ,)* ]
}
}

产生错误:local ambiguity when calling macro 'foo'。因为逗号','的类型是:tt。我需要一种方法来匹配除coma以外的所有标记树。

用法示例

foo!(
add t0 zero zero,
add t1 t0 a0,
lb t1 0(t1),
)

应该产生:

[
bar!(add t0 zero zero),
bar!(add t1 t0 a0),
bar!(lb t1 0(t1)),
]

Answer 1

大嚼救命!

macro_rules! foo {
(@accumulate [ $($accumulated:tt)* ] [ ]) => { [ $($accumulated)* ] };
(@accumulate [ $($accumulated:tt)* ] [ $($this_line:tt)* ] , $($rest:tt)* ) => {
foo! { @accumulate [
$($accumulated)*
bar!( $($this_line)* ),
] [] $($rest)* }
};
(@accumulate [ $($accumulated:tt)* ] [ $($this_line:tt)* ] $current:tt $($rest:tt)* ) => {
foo! { @accumulate [ $($accumulated)* ] [ $($this_line)* $current ] $($rest)* }
};
( $($t:tt)* ) => { foo! { @accumulate [] [] $($t)* } }
}