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use super::*;
pub trait Pop<T>: Collection
{
/// Removes the last element from the collection and returns it, or [`None`] if it is empty.
fn pop(&mut self) -> Option<T>;
/// Removes and returns the last element from the collection if the predicate returns `true``,
/// or [`None`] if the predicate returns false or the collection is empty (the predicate will not be called in that case).
fn pop_if<F>(&mut self, predicate: F) -> Option<T>
where
F: FnOnce(&mut T) -> bool;
}
/*
pub trait TryPop<T> : Pop<T>
{
type Error: Debug;
/// Removes the last element from the collection and returns it, or an error.
fn try_pop(&mut self) -> Result<T, Self::Error>;
}
*/
pub trait PopFront<T>: Collection
{
/// Removes the first element and returns it, or [`None`] if the collection is empty.
fn pop_front(&mut self) -> Option<T>;
/// Removes and returns the first element from the collection if the predicate returns `true``,
/// or [`None`] if the predicate returns false or the collection is empty (the predicate will not be called in that case).
fn pop_front_if(&mut self, predicate: impl FnOnce(&mut T) -> bool) -> Option<T>;
}
/*
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct EmptyError;
*/
impl<T> Pop<T> for Vec<T>
{
fn pop(&mut self) -> Option<T> { self.pop() }
fn pop_if<F>(&mut self, predicate: F) -> Option<T>
where
F: FnOnce(&mut T) -> bool,
{
self.pop_if(predicate)
}
}
/*
impl<T> TryPop<T> for Vec<T>
{
type Error=EmptyError;
fn try_pop(&mut self) -> Result<T, Self::Error> { self.pop().ok_or(EmptyError) }
}
*/
impl<T> Pop<T> for VecDeque<T>
{
fn pop(&mut self) -> Option<T> { self.pop_back() }
fn pop_if<F>(&mut self, predicate: F) -> Option<T>
where
F: FnOnce(&mut T) -> bool,
{
self.pop_back_if(predicate)
}
}
impl<T> PopFront<T> for VecDeque<T>
{
fn pop_front(&mut self) -> Option<T> { self.pop_front() }
fn pop_front_if(&mut self, predicate: impl FnOnce(&mut T) -> bool) -> Option<T>
{
self.pop_front_if(predicate)
}
}
/*
impl<T> TryPop<T> for VecDeque<T>
{
type Error=EmptyError;
fn try_pop(&mut self) -> Result<T, Self::Error> { self.pop_back().ok_or(EmptyError) }
}
*/
impl<T> Pop<T> for BinaryHeap<T>
where
T: Ord,
{
fn pop(&mut self) -> Option<T> { self.pop() }
fn pop_if<F>(&mut self, predicate: F) -> Option<T>
where
F: FnOnce(&mut T) -> bool,
{
let Some(mut v) = self.pop()
else
{
return None;
};
if predicate(&mut v)
{
return Some(v);
}
self.push(v);
None
}
}
impl<T> Pop<T> for LinkedList<T>
{
fn pop(&mut self) -> Option<T> { self.pop_back() }
fn pop_if<F>(&mut self, predicate: F) -> Option<T>
where
F: FnOnce(&mut T) -> bool,
{
let Some(mut v) = self.pop_back()
else
{
return None;
};
if predicate(&mut v)
{
return Some(v);
}
self.push_back(v);
None
}
}
impl<T> PopFront<T> for LinkedList<T>
{
fn pop_front(&mut self) -> Option<T> { self.pop_front() }
fn pop_front_if(&mut self, predicate: impl FnOnce(&mut T) -> bool) -> Option<T>
{
let Some(mut v) = self.pop_front()
else
{
return None;
};
if predicate(&mut v)
{
return Some(v);
}
self.push_front(v);
None
}
}
/*
impl<T> TryPop<T> for LinkedList<T>
{
type Error=EmptyError;
fn try_pop(&mut self) -> Result<T, Self::Error> { self.pop_back().ok_or(()) }
}
*/
impl Pop<char> for String
{
fn pop(&mut self) -> Option<char> { self.pop() }
fn pop_if<F>(&mut self, predicate: F) -> Option<char>
where
F: FnOnce(&mut char) -> bool,
{
let Some(mut v) = self.pop()
else
{
return None;
};
if predicate(&mut v)
{
return Some(v);
}
self.push(v);
None
}
}
/*
impl<T> TryPop<T> for String<T>
{
type Error=EmptyError;
}
*/