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use std::fmt;
macro_rules! compact_debug {
(
impl fmt::Debug for $ty:ident {
fn fmt(&$this:ident, f: &mut fmt::Formatter) -> fmt::Result {
let (default, default_name) = $e:expr;
[debug_the_fields($($field:ident)*)]
}
}
) => (
impl fmt::Debug for $ty {
fn fmt(&$this, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// Try printing a pretty version where we collapse as many fields as
// possible, indicating that they're equivalent to a function call
// that's hopefully enough to indicate what each value is without
// actually dumping everything so verbosely.
let mut s = f.debug_struct(stringify!($ty));
let (default, default_name) = $e;
let mut any_default = false;
// Exhaustively match so when fields are added we get a compile
// failure
let $ty { $($field),* } = $this;
$(
if *$field == default.$field {
any_default = true;
} else {
s.field(stringify!($field), $field);
}
)*
if any_default {
s.field("..", &crate::macros::DisplayAsDebug(default_name));
}
s.finish()
}
}
)
}
pub struct DisplayAsDebug<T>(pub T);
impl<T: fmt::Display> fmt::Debug for DisplayAsDebug<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(&self.0, f)
}
}