Macro munge::munge

source · [−]

macro_rules! munge {
    (@field($ptr:ident) $field:tt) => { ... };
    (@element($ptr:ident) $index:tt) => { ... };
    (@parse_binding mut $name:ident $(,)?) => { ... };
    (@parse_binding mut $name:ident, $($rest:tt)+) => { ... };
    (@parse_binding $body:tt $(,)?) => { ... };
    (@parse_binding $body:tt, $($rest:tt)+) => { ... };
    (@parse_binding $first:tt $($rest:tt)+) => { ... };
    (@bindings _) => { ... };
    (@bindings ..) => { ... };
    (@bindings $name:ident) => { ... };
    (@bindings mut $name:ident) => { ... };
    (@bindings { .. }) => { ... };
    (@bindings { $field:ident $(,)? }) => { ... };
    (@bindings { mut $field:ident $(,)? }) => { ... };
    (@bindings { $field:ident, $($rest:tt)+ }) => { ... };
    (@bindings { mut $field:ident, $($rest:tt)+ }) => { ... };
    (@bindings { $field:ident: $($body:tt)+ }) => { ... };
    (@bindings ( $($body:tt)+ )) => { ... };
    (@bindings [ $($body:tt)+ ]) => { ... };
    (@parse_field($ptr:ident, $field:ident, $value:ident) { $body:tt $(,)? }) => { ... };
    (@parse_field($ptr:ident, $field:ident, $value:ident) { $body:tt, $($rest:tt)+ }) => { ... };
    (@parse_field($ptr:ident, $field:ident, $value:ident) { $first:tt $($rest:tt)+ }) => { ... };
    (@parse_field($ptr:ident, $index:tt, $value:ident) ( $body:tt $(,)? ) $indices:tt) => { ... };
    (@parse_field($ptr:ident, $index:tt, $value:ident) ( $body:tt, $($rest:tt)+ ) $indices:tt) => { ... };
    (@parse_field($ptr:ident, $index:ident, $value:ident) ( $first:tt $($rest:tt)+ ) $indices:tt) => { ... };
    (@parse_field($ptr:ident, $index:tt, $value:ident) [ $body:tt $(,)? ] $indices:tt) => { ... };
    (@parse_field($ptr:ident, $index:tt, $value:ident) [ $body:tt, $($rest:tt)+ ] $indices:tt) => { ... };
    (@parse_field($ptr:ident, $index:ident, $value:ident) [ $first:tt $($rest:tt)+ ] $indices:tt) => { ... };
    (@fields($ptr:ident, $value:ident) _) => { ... };
    (@fields($ptr:ident, $value:ident) $field:ident) => { ... };
    (@fields($ptr:ident, $value:ident) { .. }) => { ... };
    (@fields($ptr:ident, $value:ident) { mut $field:ident $(,)? }) => { ... };
    (@fields($ptr:ident, $value:ident) { $field:ident $(,)? }) => { ... };
    (@fields($ptr:ident, $value:ident) { mut $field:ident, $($rest:tt)+ }) => { ... };
    (@fields($ptr:ident, $value:ident) { $field:ident, $($rest:tt)+ }) => { ... };
    (@fields($ptr:ident, $value:ident) { $field:ident: $($binding:tt)+ }) => { ... };
    (@fields($ptr:ident, $value:ident) ( .. ) $indices:tt) => { ... };
    (@fields($ptr:ident, $value:ident) ( $($binding:tt)* ) [ $index_first:tt $($index_rest:tt)* ]) => { ... };
    (@fields($ptr:ident, $value:ident) ( $($body:tt)* )) => { ... };
    (@fields($ptr:ident, $value:ident) [ .. ] $indices:tt) => { ... };
    (@fields($ptr:ident, $value:ident) [ $($binding:tt)* ] [ $index_first:tt $($index_rest:tt)* ]) => { ... };
    (@fields($ptr:ident, $value:ident) [ $($body:tt)* ]) => { ... };
    (@fields($ptr:ident, $value:ident) $first:tt $($rest:tt)*) => { ... };
    (@destructure { $($path:tt)* } $body:tt = $value:expr) => { ... };
    (@destructure { $($path:tt)* } $first:tt $($rest:tt)*) => { ... };
    (let $($tokens:tt)*) => { ... };
}

Expand description

Projects a MaybeUninit type to its MaybeUninit fields using destructuring.

Example

pub struct Example {
    a: u32,
    b: (char, f32),
}

let mut mu = MaybeUninit::<Example>::uninit();

munge!(let Example { a, b: (c, mut f) } = &mut mu);
assert_eq!(a.write(10), &10);
assert_eq!(c.write('x'), &'x');
assert_eq!(f.write(3.14), &3.14);
f = &mut MaybeUninit::uninit();

// SAFETY: `mu` is completely initialized.
let init = unsafe { mu.assume_init() };
assert_eq!(init.a, 10);
assert_eq!(init.b.0, 'x');
assert_eq!(init.b.1, 3.14);