tag-vec 0.0.2

A vector used for storing tags
Documentation 
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use std::ops::{ BitAnd, BitOr, Not };

/// A trait for a type that can
/// work as a bitfield.
pub trait BitField: BitAnd<Output = Self> + BitOr<Output = Self> + Not<Output = Self> + Sized + Copy {
	/// Creates a bitfield with no bits
	/// set
	fn empty() -> Self;

	/// Sets a bit. Assumes that n is less than
	/// n_bits
	fn set_bit(&mut self, n: usize, state: bool);

	/// Gets a bit. Assumes that n is less than
	/// n_bits
	fn get_bit(&self, n: usize) -> bool;

	/// Returns the number of bits.
	fn n_bits() -> usize;
}

/// Implements the BitField trait for a numeric type
macro_rules! impl_bitfield {
	($t:ty, $bits:expr) => {
		impl BitField for $t {
			fn empty() -> Self { 0 }

			fn set_bit(&mut self, n: usize, state: bool) {
				if state {
					*self |= (1 << n);
				}else{
					*self &= !(1 << n);
				}	
			}

			fn get_bit(&self, n: usize) -> bool {
				*self & (1 << n) > 0
			}

			#[inline(always)]
			fn n_bits() -> usize { $bits }
		}
	}
}

impl_bitfield!(u8, 8);
impl_bitfield!(u16, 16);
impl_bitfield!(u32, 32);
impl_bitfield!(u64, 64);
impl_bitfield!(u128, 128);

#[cfg(test)]
mod test {
	use super::*;

	#[test]
	fn get_bits() {
		assert_eq!(0b00101u32.get_bit(0), true);
		assert_eq!(0b00101u32.get_bit(1), false);
		assert_eq!(0b00101u32.get_bit(2), true);
		assert_eq!(0b00101u32.get_bit(3), false);
	}

	#[test]
	fn set_bits() {
		let mut bits = 0b00000u32;
		bits.set_bit(5, true);
		assert_eq!(bits.get_bit(5), true);
		bits.set_bit(5, false);
		assert_eq!(bits.get_bit(5), false);
	}
}