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Add const generics for customized arrayvec size #63

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Add const generics for customized arrayvec size #63

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5d513e4
Remove bench
foresterre Dec 3, 2022
e242d50
Add const generics for customized arrayvec size
foresterre Dec 3, 2022
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7 changes: 0 additions & 7 deletions Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -25,10 +25,3 @@ default = []
version = "1.5.1"
optional = true
default-features = false

[dev-dependencies]
criterion = "0.3"

[[bench]]
name = "peek_bench"
harness = false
37 changes: 0 additions & 37 deletions benches/peek_bench.rs
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41 changes: 18 additions & 23 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -120,32 +120,27 @@ use smallvec::SmallVec;
///
/// [`next`]: https://doc.rust-lang.org/core/iter/trait.Iterator.html#tymethod.next
/// [`Iterator`]: https://doc.rust-lang.org/core/iter/trait.Iterator.html
pub trait PeekMore: Iterator + Sized {
pub trait PeekMore<const S: usize = 16>: Iterator + Sized {
/// Create a multi-peek iterator where we can peek forward multiple times from an existing iterator.
fn peekmore(self) -> PeekMoreIterator<Self>;
fn peekmore(self) -> PeekMoreIterator<Self, S>;
}

impl<I: Iterator> PeekMore for I {
fn peekmore(self) -> PeekMoreIterator<I> {
impl<I: Iterator, const S: usize> PeekMore<S> for I {
fn peekmore(self) -> PeekMoreIterator<I, S> {
PeekMoreIterator {
iterator: self,

#[cfg(not(feature = "smallvec"))]
queue: Vec::new(),

#[cfg(feature = "smallvec")]
queue: SmallVec::new(),
queue: SmallVec::<[Self; S]>::new(),

cursor: 0usize,
}
}
}

/// Default stack size for SmallVec.
/// Admittedly the current size is chosen quite arbitrarily.
#[cfg(feature = "smallvec")]
const DEFAULT_STACK_SIZE: usize = 8;

/// This iterator makes it possible to peek multiple times without consuming a value.
/// In reality the underlying iterator will be consumed, but the values will be stored in a queue.
/// This queue allows us to peek at unconsumed elements (as far as the multi-peek iterator is concerned).
Expand All @@ -154,7 +149,7 @@ const DEFAULT_STACK_SIZE: usize = 8;
///
/// [consumes]: https://doc.rust-lang.org/core/iter/trait.Iterator.html#tymethod.next
#[derive(Clone, Debug)]
pub struct PeekMoreIterator<I: Iterator> {
pub struct PeekMoreIterator<I: Iterator, const S: usize> {
/// The underlying iterator. Consumption of this inner iterator does not represent consumption of the
/// `PeekMoreIterator`.
iterator: I,
Expand All @@ -165,7 +160,7 @@ pub struct PeekMoreIterator<I: Iterator> {
#[cfg(not(feature = "smallvec"))]
queue: Vec<Option<I::Item>>,
#[cfg(feature = "smallvec")]
queue: SmallVec<[Option<I::Item>; DEFAULT_STACK_SIZE]>,
queue: SmallVec<[Option<I::Item>; S]>,

/// The cursor points to the element we are currently peeking at.
///
Expand All @@ -177,7 +172,7 @@ pub struct PeekMoreIterator<I: Iterator> {
cursor: usize,
}

impl<I: Iterator> PeekMoreIterator<I> {
impl<I: Iterator, const S: usize> PeekMoreIterator<I, S> {
/// Get a reference to the element where the cursor currently points to. If no such element exists,
/// return `None` will be returned.
///
Expand Down Expand Up @@ -456,7 +451,7 @@ impl<I: Iterator> PeekMoreIterator<I> {
///
/// [`next()`]: struct.PeekMoreIterator.html#impl-Iterator
#[inline]
pub fn advance_cursor(&mut self) -> &mut PeekMoreIterator<I> {
pub fn advance_cursor(&mut self) -> &mut PeekMoreIterator<I, S> {
self.increment_cursor();
self
}
Expand All @@ -467,7 +462,7 @@ impl<I: Iterator> PeekMoreIterator<I> {
///
/// [`next()`]: struct.PeekMoreIterator.html#impl-Iterator
#[inline]
pub fn advance_cursor_by(&mut self, n: usize) -> &mut PeekMoreIterator<I> {
pub fn advance_cursor_by(&mut self, n: usize) -> &mut PeekMoreIterator<I, S> {
self.cursor += n;
self
}
Expand All @@ -477,7 +472,7 @@ impl<I: Iterator> PeekMoreIterator<I> {
pub fn advance_cursor_while<P: Fn(Option<&I::Item>) -> bool>(
&mut self,
predicate: P,
) -> &mut PeekMoreIterator<I> {
) -> &mut PeekMoreIterator<I, S> {
let view = self.peek();

if predicate(view) {
Expand All @@ -498,7 +493,7 @@ impl<I: Iterator> PeekMoreIterator<I> {
///
/// [`PeekMoreError::ElementHasBeenConsumed`]: enum.PeekMoreError.html#variant.ElementHasBeenConsumed
#[inline]
pub fn move_cursor_back(&mut self) -> Result<&mut PeekMoreIterator<I>, PeekMoreError> {
pub fn move_cursor_back(&mut self) -> Result<&mut PeekMoreIterator<I, S>, PeekMoreError> {
if self.cursor >= 1 {
self.decrement_cursor();
Ok(self)
Expand All @@ -520,7 +515,7 @@ impl<I: Iterator> PeekMoreIterator<I> {
pub fn move_cursor_back_by(
&mut self,
n: usize,
) -> Result<&mut PeekMoreIterator<I>, PeekMoreError> {
) -> Result<&mut PeekMoreIterator<I, S>, PeekMoreError> {
if self.cursor < n {
Err(PeekMoreError::ElementHasBeenConsumed)
} else {
Expand All @@ -533,7 +528,7 @@ impl<I: Iterator> PeekMoreIterator<I> {
/// The latter happens when the cursor position is smaller than the elements it has to move
/// backwards by.
#[inline]
pub fn move_cursor_back_or_reset(&mut self, n: usize) -> &mut PeekMoreIterator<I> {
pub fn move_cursor_back_or_reset(&mut self, n: usize) -> &mut PeekMoreIterator<I, S> {
if self.cursor < n {
self.reset_cursor();
} else {
Expand All @@ -545,7 +540,7 @@ impl<I: Iterator> PeekMoreIterator<I> {

/// Move the cursor to the n-th element of the queue.
#[inline]
pub fn move_nth(&mut self, n: usize) -> &mut PeekMoreIterator<I> {
pub fn move_nth(&mut self, n: usize) -> &mut PeekMoreIterator<I, S> {
self.cursor = n;
self
}
Expand Down Expand Up @@ -746,7 +741,7 @@ impl<I: Iterator> PeekMoreIterator<I> {
}
}

impl<'a, I: Iterator> Iterator for PeekMoreIterator<I> {
impl<'a, I: Iterator, const S: usize> Iterator for PeekMoreIterator<I, S> {
type Item = I::Item;

fn next(&mut self) -> Option<Self::Item> {
Expand All @@ -765,12 +760,12 @@ impl<'a, I: Iterator> Iterator for PeekMoreIterator<I> {
/// Uses [`ExactSizeIterator`] default implementation.
///
/// [`ExactSizeIterator`]: https://doc.rust-lang.org/core/iter/trait.ExactSizeIterator.html
impl<I: ExactSizeIterator> ExactSizeIterator for PeekMoreIterator<I> {}
impl<I: ExactSizeIterator, const S: usize> ExactSizeIterator for PeekMoreIterator<I, S> {}

/// Uses [`FusedIterator`] default implementation.
///
/// [`FusedIterator`]: https://doc.rust-lang.org/core/iter/trait.FusedIterator.html
impl<I: FusedIterator> FusedIterator for PeekMoreIterator<I> {}
impl<I: FusedIterator, const S: usize> FusedIterator for PeekMoreIterator<I, S> {}

/// This enumeration provides errors which represent lack of success of the [`PeekMoreIterator`].
///
Expand Down