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Use copy/clone closures to simplify calendar test #47305

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Jan 12, 2018
Merged

Use copy/clone closures to simplify calendar test #47305

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61 changes: 14 additions & 47 deletions src/test/run-pass/impl-trait/example-calendar.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,9 @@
universal_impl_trait,
fn_traits,
step_trait,
unboxed_closures
unboxed_closures,
copy_closures,
clone_closures
)]

//! Derived from: <https://raw.githubusercontent.com/quickfur/dcal/master/dcal.d>.
Expand Down Expand Up @@ -234,54 +236,22 @@ impl Weekday {
}
}

/// Wrapper for zero-sized closures.
// HACK(eddyb) Only needed because closures can't implement Copy.
struct Fn0<F>(std::marker::PhantomData<F>);

impl<F> Copy for Fn0<F> {}
impl<F> Clone for Fn0<F> {
fn clone(&self) -> Self { *self }
}

impl<F: FnOnce<A>, A> FnOnce<A> for Fn0<F> {
type Output = F::Output;

extern "rust-call" fn call_once(self, args: A) -> Self::Output {
let f = unsafe { std::mem::uninitialized::<F>() };
f.call_once(args)
}
}

impl<F: FnMut<A>, A> FnMut<A> for Fn0<F> {
extern "rust-call" fn call_mut(&mut self, args: A) -> Self::Output {
let mut f = unsafe { std::mem::uninitialized::<F>() };
f.call_mut(args)
}
}

trait AsFn0<A>: Sized {
fn copyable(self) -> Fn0<Self>;
}

impl<F: FnMut<A>, A> AsFn0<A> for F {
fn copyable(self) -> Fn0<Self> {
assert_eq!(std::mem::size_of::<F>(), 0);
Fn0(std::marker::PhantomData)
}
}

/// GroupBy implementation.
struct GroupBy<It: Iterator, F> {
it: std::iter::Peekable<It>,
f: F,
}

impl<It, F> Clone for GroupBy<It, F>
where It: Iterator + Clone, It::Item: Clone, F: Clone {
fn clone(&self) -> GroupBy<It, F> {
where
It: Iterator + Clone,
It::Item: Clone,
F: Clone,
{
fn clone(&self) -> Self {
GroupBy {
it: self.it.clone(),
f: self.f.clone()
f: self.f.clone(),
}
}
}
Expand Down Expand Up @@ -331,14 +301,11 @@ impl<It: Iterator, F: FnMut(&It::Item) -> G, G: Eq> Iterator for InGroup<It, F,
}

trait IteratorExt: Iterator + Sized {
fn group_by<G, F>(self, f: F) -> GroupBy<Self, Fn0<F>>
where F: FnMut(&Self::Item) -> G,
fn group_by<G, F>(self, f: F) -> GroupBy<Self, F>
where F: Clone + FnMut(&Self::Item) -> G,
G: Eq
{
GroupBy {
it: self.peekable(),
f: f.copyable(),
}
GroupBy { it: self.peekable(), f }
}

fn join(mut self, sep: &str) -> String
Expand Down Expand Up @@ -382,7 +349,7 @@ fn test_spaces() {
fn dates_in_year(year: i32) -> impl Iterator<Item=NaiveDate>+Clone {
InGroup {
it: NaiveDate::from_ymd(year, 1, 1)..,
f: (|d: &NaiveDate| d.year()).copyable(),
f: |d: &NaiveDate| d.year(),
g: year
}
}
Expand Down