Created
July 11, 2020 22:24
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macro_rules! compile_expr { | |
($( | |
if #[$meta:meta] { | |
$( $stmt:tt )* | |
} $(else if #[$else_if_meta:meta] { | |
$( $else_if_stmt:tt )* | |
})* $(else { | |
$( $else_stmt:tt )* | |
})? | |
)+) => { | |
$( | |
#[cfg($meta)] | |
{ | |
$( $stmt )* | |
} | |
compile_expr! { | |
@inner | |
( $meta, ) | |
$(else if #[$else_if_meta] { | |
$( $else_if_stmt )* | |
})* $(else { | |
$( $else_stmt )* | |
})? | |
} | |
)+ | |
}; | |
(@recurse ($( $prev_metas:tt)* ) ($new_meta:meta) $( $rem:tt )*) => { | |
compile_expr! { | |
@inner | |
($( $prev_metas )* $new_meta,) | |
$( $rem )* | |
} | |
}; | |
(@inner | |
$prev_metas:tt | |
else if #[$meta:meta] { | |
$( $else_if_stmt:tt )* | |
} | |
$( $rem:tt )* | |
) => { | |
#[cfg(all(not(any $prev_metas), $meta))] | |
{ | |
$( $else_if_stmt )* | |
} | |
compile_expr! { | |
@recurse $prev_metas ($meta) $( $rem )* | |
} | |
}; | |
(@inner $prev_metas:tt | |
else { | |
$( $else_stmt:tt )* | |
} | |
) => { | |
#[cfg(not(any $prev_metas))] | |
{ | |
$( $else_stmt )* | |
} | |
}; | |
(@inner ($($prev_metas:tt)*)) => {}; | |
} |
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