dyn_vec/src/impls.rs

//! Implements `Debug`, `Default`, `Extend`, and `Deref`. Also implements `PartialEq` for various list-like types.

use crate::{DynVec, Extra};

use std::{
    fmt::Debug,
    mem::size_of,
    ops::{Deref, DerefMut},
    ptr::NonNull,
    slice,
    vec::Vec,
};

// #[cfg(any(doc, feature = "unstable"))]
// use std::ops::CoerceUnsized;

impl<T: ?Sized> Default for DynVec<T> {
    fn default() -> Self {
        Self::new()
    }
}

impl<T: ?Sized + Debug> Debug for DynVec<T> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_list().entries(self.iter()).finish()
    }
}

// DynVec<T> == DynVec<U>
impl<T: ?Sized + PartialEq<U>, U: ?Sized> PartialEq<DynVec<U>> for DynVec<T> {
    fn eq(&self, other: &DynVec<U>) -> bool {
        if self.len != other.len {
            return false;
        }
        for (el, el2) in self.iter().zip(other.iter()) {
            if el != el2 {
                return false;
            }
        }
        true
    }
}

impl<T: ?Sized + Eq> Eq for DynVec<T> {}

// DynVec<T> == [U]
impl<T: PartialEq<U> + ?Sized, U> PartialEq<[U]> for DynVec<T> {
    fn eq(&self, other: &[U]) -> bool {
        if self.len != other.len() {
            return false;
        }
        for (el, el2) in self.iter().zip(other.iter()) {
            if el != el2 {
                return false;
            }
        }
        true
    }
}

// [U] == DynVec<T>
impl<T: PartialEq<U> + ?Sized, U> PartialEq<DynVec<T>> for [U] {
    fn eq(&self, other: &DynVec<T>) -> bool {
        other == self
    }
}

// DynVec<T> == &[U]
impl<T: PartialEq<U> + ?Sized, U> PartialEq<&[U]> for DynVec<T> {
    fn eq(&self, other: &&[U]) -> bool {
        *self == **other
    }
}

// &[U] == DynVec<T>
impl<T: PartialEq<U> + ?Sized, U> PartialEq<DynVec<T>> for &[U] {
    fn eq(&self, other: &DynVec<T>) -> bool {
        *other == **self
    }
}

// DynVec<T> == &mut [U]
impl<T: PartialEq<U> + ?Sized, U> PartialEq<&mut [U]> for DynVec<T> {
    fn eq(&self, other: &&mut [U]) -> bool {
        *self == **other
    }
}

// &mut [U] == DynVec<T>
impl<T: PartialEq<U> + ?Sized, U> PartialEq<DynVec<T>> for &mut [U] {
    fn eq(&self, other: &DynVec<T>) -> bool {
        *other == **self
    }
}

// DynVec<T> == [U; N]
impl<T: PartialEq<U> + ?Sized, U, const N: usize> PartialEq<[U; N]> for DynVec<T> {
    fn eq(&self, other: &[U; N]) -> bool {
        *self == other[..]
    }
}

// [U; N] == DynVec<T>
impl<T: PartialEq<U> + ?Sized, U, const N: usize> PartialEq<DynVec<T>> for [U; N] {
    fn eq(&self, other: &DynVec<T>) -> bool {
        *other == self[..]
    }
}

// DynVec<T> == &[U; N]
impl<T: PartialEq<U> + ?Sized, U, const N: usize> PartialEq<&[U; N]> for DynVec<T> {
    fn eq(&self, other: &&[U; N]) -> bool {
        *self == other[..]
    }
}

// &[U; N] == DynVec<T>
impl<T: PartialEq<U> + ?Sized, U, const N: usize> PartialEq<DynVec<T>> for &[U; N] {
    fn eq(&self, other: &DynVec<T>) -> bool {
        *other == self[..]
    }
}

// DynVec<T> == &mut [U; N]
impl<T: PartialEq<U> + ?Sized, U, const N: usize> PartialEq<&mut [U; N]> for DynVec<T> {
    fn eq(&self, other: &&mut [U; N]) -> bool {
        *self == other[..]
    }
}

// &mut [U; N] == DynVec<T>
impl<T: PartialEq<U> + ?Sized, U, const N: usize> PartialEq<DynVec<T>> for &mut [U; N] {
    fn eq(&self, other: &DynVec<T>) -> bool {
        *other == self[..]
    }
}

// #[cfg(not(feature = "unstable"))]
impl<T: ?Sized> Extend<Box<T>> for DynVec<T> {
    fn extend<I: IntoIterator<Item = Box<T>>>(&mut self, iter: I) {
        for item in iter {
            // TODO: optmize
            self.push_box(item);
        }
    }
}

// #[cfg(feature = "unstable")]
// impl<T: ?Sized, U: ?Sized> Extend<Box<U>> for DynVec<T>
// where
//     Box<U>: CoerceUnsized<Box<T>>,
// {
//     fn extend<I: IntoIterator<Item = Box<U>>>(&mut self, iter: I) {
//         for item in iter {
//             // TODO: optmize
//             self.push_box(item);
//         }
//     }
// }

impl<T> Deref for DynVec<T> {
    type Target = [T];

    fn deref(&self) -> &Self::Target {
        if self.is_empty() {
            unsafe { slice::from_raw_parts(NonNull::dangling().as_ptr(), 0) }
        } else {
            unsafe { slice::from_raw_parts(self.get_ptr(0), self.len) }
        }
    }
}

impl<T> DerefMut for DynVec<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        if self.is_empty() {
            unsafe { slice::from_raw_parts_mut(NonNull::dangling().as_ptr(), 0) }
        } else {
            unsafe { slice::from_raw_parts_mut(self.get_ptr(0) as _, self.len) }
        }
    }
}

unsafe impl<T: Send> Send for DynVec<T> {}
unsafe impl<T: Sync> Sync for DynVec<T> {}

impl<T> From<Vec<T>> for DynVec<T> {
    fn from(std_vec: Vec<T>) -> Self {
        let mut vec = Self::new();
        let new_cap = (size_of::<T>() + size_of::<Extra<T>>()) * std_vec.len();
        unsafe {
            vec.realloc(new_cap);
        }

        for item in std_vec {
            unsafe { vec.push_raw_unchecked(&item) }
        }

        vec
    }
}

impl<T> From<DynVec<T>> for Vec<T> {
    fn from(mut vec: DynVec<T>) -> Self {
        let mut std_vec = Self::with_capacity(vec.len);

        for item in vec.iter() {
            std_vec.push(unsafe { (item as *const T).read() });
        }

        vec.len = 0;

        std_vec
    }
}