small_len 1.1.2

A small library for storing the length in the smallest internal type.
Documentation 
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use std::fmt::{Display, Formatter};
use crate::{from_bytes, from_length_bytes, length_bin_expr, length_not_expr, to_bytes, to_length_bytes};
use std::ops::{Add, BitAnd, BitOr, BitXor, Div, Index, IndexMut, Mul, Rem, Sub};

#[derive(Copy, Clone, Debug, PartialEq, Hash, PartialOrd, Ord, Eq)]
pub struct Length {
    pub(crate) index: usize
}

impl Length {
    #[inline]
    pub fn new(index: usize) -> Length {
        Length {
            index
        }
    }

    #[inline]
    pub fn index(&self) -> usize {
        self.index
    }

    from_length_bytes! { from_le_bytes: from_le_bytes, from_be_bytes: from_be_bytes }
    to_length_bytes! { to_le_bytes: to_le_bytes, to_be_bytes: to_be_bytes }
}

impl Display for Length {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.index)
    }
}


#[derive(Copy, Clone, Debug, PartialEq, Hash, PartialOrd, Ord, Eq)]
pub enum SmallLength {
    Byte(u8),
    Word(u16),
    Double(u32),
    Quad(u64),
}

impl Display for SmallLength {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            SmallLength::Byte(u) => write!(f, "{}", u),
            SmallLength::Word(u) => write!(f, "{}", u),
            SmallLength::Double(u) => write!(f, "{}", u),
            SmallLength::Quad(u) => write!(f, "{}", u),
        }
    }
}

impl Default for SmallLength {
    #[inline]
    fn default() -> Self {
        SmallLength::Byte(0)
    }
}

impl <T> Index<SmallLength> for Vec<T> {
    type Output = T;

    #[inline]
    fn index(&self, index: SmallLength) -> &Self::Output {
        &self[index.index()]
    }
}

impl <T> Index<Length> for Vec<T> {
    type Output = T;

    #[inline]
    fn index(&self, index: Length) -> &Self::Output {
        &self[index.index]
    }
}

use std::borrow::BorrowMut;

impl <T> IndexMut<SmallLength> for Vec<T> {
    fn index_mut(&mut self, index: SmallLength) -> &mut Self::Output {
        self[index.index()].borrow_mut()
    }
}

impl <T> IndexMut<Length> for Vec<T> {
    fn index_mut(&mut self, index: Length) -> &mut Self::Output {
        self[index.index].borrow_mut()
    }
}

length_not_expr!(SmallLength, Length);

length_bin_expr! {
    SmallLength;
    Add: add(+),
    Sub: sub(-),
    Mul: mul(*),
    Div: div(/),
    Rem: rem(%),
    BitAnd: bitand(&),
    BitOr: bitor(|),
    BitXor: bitxor(^)
}

length_bin_expr! {
    Length;
    Add: add(+),
    Sub: sub(-),
    Mul: mul(*),
    Div: div(/),
    Rem: rem(%),
    BitAnd: bitand(&),
    BitOr: bitor(|),
    BitXor: bitxor(^)
}

impl SmallLength {
    #[inline]
    pub fn index(&self) -> usize {
        match self {
            SmallLength::Byte(v) => *v as usize,
            SmallLength::Word(v) => *v as usize,
            SmallLength::Double(v) => *v as usize,
            SmallLength::Quad(v) => *v as usize,
        }
    }
}

impl SmallLength {
    from_bytes! { from_le_bytes: from_le_bytes, from_be_bytes: from_be_bytes }
    to_bytes! { to_le_bytes: to_le_bytes, to_be_bytes: to_be_bytes }
}