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use slice_trait::Slice;
#[const_trait]
pub trait SliceTrim<T>: Slice<Item = T>
{
/// Returns a trimmed subslice, trimmed from both ends using a trimming predicate.
///
/// `trim` should return `true` for each element that should be trimmed.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// let a = [0, 0, 0, 1, 2, 3, 0, 0, 0];
///
/// let at = a.trim(|&e| e == 0);
///
/// assert_eq!(at, &[1, 2, 3]);
/// ```
fn trim<F>(&self, trim: F) -> &[T]
where
F: FnMut(&T) -> bool /*+ ~const Destruct*/;
/// Returns a trimmed subslice, trimmed from the left using a trimming predicate.
///
/// `trim` should return `true` for each element that should be trimmed.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// let a = [0, 0, 0, 1, 2, 3, 0, 0, 0];
///
/// let at = a.trim_front(|&e| e == 0);
///
/// assert_eq!(at, &[1, 2, 3, 0, 0, 0]);
/// ```
fn trim_front<F>(&self, trim: F) -> &[T]
where
F: FnMut(&T) -> bool /*+ ~const Destruct*/;
/// Returns a trimmed subslice, trimmed from the right using a trimming predicate.
///
/// `trim` should return `true` for each element that should be trimmed.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// let a = [0, 0, 0, 1, 2, 3, 0, 0, 0];
///
/// let at = a.trim_back(|&e| e == 0);
///
/// assert_eq!(at, &[0, 0, 0, 1, 2, 3]);
/// ```
fn trim_back<F>(&self, trim: F) -> &[T]
where
F: FnMut(&T) -> bool /*+ ~const Destruct*/;
/// Returns a mutable trimmed subslice, trimmed from both ends using a trimming predicate.
///
/// `trim` should return `true` for each element that should be trimmed.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// let mut a = [0, 0, 0, 1, 2, 3, 0, 0, 0];
///
/// let at = a.trim_mut(|&e| e == 0);
///
/// assert_eq!(at, &mut [1, 2, 3]);
/// ```
fn trim_mut<F>(&mut self, trim: F) -> &mut [T]
where
F: FnMut(&T) -> bool /*+ ~const Destruct*/;
/// Returns a mutable trimmed subslice, trimmed from the left using a trimming predicate.
///
/// `trim` should return `true` for each element that should be trimmed.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// let mut a = [0, 0, 0, 1, 2, 3, 0, 0, 0];
///
/// let at = a.trim_front_mut(|&e| e == 0);
///
/// assert_eq!(at, &mut [1, 2, 3, 0, 0, 0]);
/// ```
fn trim_front_mut<F>(&mut self, trim: F) -> &mut [T]
where
F: FnMut(&T) -> bool /*+ ~const Destruct*/;
/// Returns a mutable trimmed subslice, trimmed from the right using a trimming predicate.
///
/// `trim` should return `true` for each element that should be trimmed.
///
/// # Example
///
/// ```rust
/// use slice_ops::ops::*;
///
/// let mut a = [0, 0, 0, 1, 2, 3, 0, 0, 0];
///
/// let at = a.trim_back_mut(|&e| e == 0);
///
/// assert_eq!(at, &mut [0, 0, 0, 1, 2, 3]);
/// ```
fn trim_back_mut<F>(&mut self, trim: F) -> &mut [T]
where
F: FnMut(&T) -> bool /*+ ~const Destruct*/;
}
impl<T> SliceTrim<T> for [T]
{
fn trim<F>(&self, mut trim: F) -> &[T]
where
F: FnMut(&T) -> bool
{
self.trim_back(&mut trim).trim_front(trim)
}
fn trim_front<F>(&self, mut trim: F) -> &[T]
where
F: FnMut(&T) -> bool
{
let mut slice = self;
let mut range = slice.as_ptr_range();
while matches!(slice.first().map(&mut trim), Some(true))
{
unsafe {
range.start = range.start.add(1);
slice = core::slice::from_ptr_range(range.clone())
}
}
slice
}
fn trim_back<F>(&self, mut trim: F) -> &[T]
where
F: FnMut(&T) -> bool
{
let mut slice = self;
let mut range = slice.as_ptr_range();
while matches!(slice.last().map(&mut trim), Some(true))
{
unsafe {
range.end = range.end.sub(1);
slice = core::slice::from_ptr_range(range.clone())
}
}
slice
}
fn trim_mut<F>(&mut self, mut trim: F) -> &mut [T]
where
F: FnMut(&T) -> bool
{
self.trim_back_mut(&mut trim).trim_front_mut(trim)
}
fn trim_front_mut<F>(&mut self, mut trim: F) -> &mut [T]
where
F: FnMut(&T) -> bool
{
let mut slice = self;
let mut range = slice.as_mut_ptr_range();
while matches!(slice.first().map(&mut trim), Some(true))
{
unsafe {
range.start = range.start.add(1);
slice = core::slice::from_mut_ptr_range(range.clone())
}
}
slice
}
fn trim_back_mut<F>(&mut self, mut trim: F) -> &mut [T]
where
F: FnMut(&T) -> bool
{
let mut slice = self;
let mut range = slice.as_mut_ptr_range();
while matches!(slice.last().map(&mut trim), Some(true))
{
unsafe {
range.end = range.end.sub(1);
slice = core::slice::from_mut_ptr_range(range.clone())
}
}
slice
}
}
#[cfg(test)]
mod test
{
use crate::ops::SliceTrim;
#[test]
fn it_works()
{
let a = [0, 0, 0, 1, 2, 3, 0, 0, 0];
let at = a.trim(|&e| e == 0);
assert_eq!(at, &[1, 2, 3]);
}
}