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use slice_trait::Slice;
#[const_trait]
pub trait SliceFind<T>: Slice<Item = T>
{
/// Performs a linear search for the first value that equals `x`.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// // v
/// let x = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3];
///
/// let i = x.find(&5).unwrap();
///
/// assert_eq!(i, 4);
/// assert_eq!(x[i], 5);
/// ```
fn find(&self, x: &T) -> Option<usize>
where
T: PartialEq;
/// Performs a linear search for the first value that satisfies the given predicate.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// // v
/// let x = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3];
///
/// let f = |&xn| xn > 5;
///
/// let i = x.find_by(f).unwrap();
///
/// assert_eq!(i, 5);
/// ```
fn find_by<'a, F>(&'a self, f: F) -> Option<usize>
where
F: FnMut(&'a T) -> bool /*+ ~const Destruct*/,
T: 'a;
/// Performs a linear search for the first value that matches the given key given a hashing function.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// // v
/// let x = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3];
///
/// let f = |&xn| xn % 2;
///
/// let i = x.find_by_key(&0, f).unwrap();
///
/// assert_eq!(i, 2);
/// ```
fn find_by_key<'a, B, F>(&'a self, b: &B, f: F) -> Option<usize>
where
F: FnMut(&'a T) -> B /*+ ~const Destruct*/,
B: PartialEq,
T: 'a;
/// Performs a linear search from the right for the first value that equals `x`.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// // v
/// let x = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3];
///
/// let i = x.rfind(&5).unwrap();
///
/// assert_eq!(i, 8);
/// assert_eq!(x[i], 5);
/// ```
fn rfind(&self, x: &T) -> Option<usize>
where
T: PartialEq;
/// Performs a linear search from the right for the first value that satisfies the given predicate.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// // v
/// let x = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3];
///
/// let f = |&xn| xn > 5;
///
/// let i = x.rfind_by(f).unwrap();
///
/// assert_eq!(i, 7);
/// ```
fn rfind_by<'a, F>(&'a self, f: F) -> Option<usize>
where
F: FnMut(&'a T) -> bool /*+ ~const Destruct*/,
T: 'a;
/// Performs a linear search from the right for the first value that matches the given key given a hashing function.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// // v
/// let x = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3];
///
/// let f = |&xn| xn % 2;
///
/// let i = x.rfind_by_key(&0, f).unwrap();
///
/// assert_eq!(i, 7);
/// ```
fn rfind_by_key<'a, B, F>(&'a self, b: &B, f: F) -> Option<usize>
where
F: FnMut(&'a T) -> B /*+ ~const Destruct*/,
B: PartialEq,
T: 'a;
}
impl<T> SliceFind<T> for [T]
{
fn find(&self, x: &T) -> Option<usize>
where
T: PartialEq
{
self.find_by(|e| e == x)
}
fn find_by<'a, F>(&'a self, mut f: F) -> Option<usize>
where
F: FnMut(&'a T) -> bool,
T: 'a
{
let l = self.len();
let mut i = 0;
while i < l
{
if f(&self[i])
{
return Some(i)
}
i += 1
}
None
}
fn find_by_key<'a, B, F>(&'a self, b: &B, mut f: F) -> Option<usize>
where
F: FnMut(&'a T) -> B,
B: PartialEq,
T: 'a
{
self.find_by(|e| f(e) == *b)
}
fn rfind(&self, x: &T) -> Option<usize>
where
T: PartialEq
{
self.rfind_by(|e| e == x)
}
fn rfind_by<'a, F>(&'a self, mut f: F) -> Option<usize>
where
F: FnMut(&'a T) -> bool,
T: 'a
{
let l = self.len();
let mut i = l;
while i > 0
{
i -= 1;
if f(&self[i])
{
return Some(i)
}
}
None
}
fn rfind_by_key<'a, B, F>(&'a self, b: &B, mut f: F) -> Option<usize>
where
F: FnMut(&'a T) -> B,
B: PartialEq,
T: 'a
{
self.rfind_by(|e| f(e) == *b)
}
}
#[cfg(test)]
mod test
{
#[test]
fn it_works()
{
}
}