libspecr 0.1.41

standard library for specr lang
Documentation 
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use crate::*;

mod ops;
mod func;
mod to;
mod step;

pub use to::ToInt;

/// The external Bigint Type, which we use under the hood.
pub(crate) use num_bigint::BigInt;
use num_traits::ToPrimitive;

#[derive(Copy, Clone, Hash, GcCompat)]
/// Garbage collected big integer that implements `Copy` and supports construction in `const` contexts.
pub struct Int(IntInner);

// IntInner only exists to hide the enum implementation details.
#[derive(Copy, Clone, Debug, Hash, GcCompat)]
enum IntInner {
    Big(GcCow<BigInt>),
    /// i128 is used to contain u64 and i64.
    Small(i128),
}

impl<T: ToInt> From<T> for Int {
    fn from(t: T) -> Int {
        t.to_int()
    }
}

impl Int {
    /// Create an `Int` from a regular Rust integer.
    ///
    /// `const fn` cannot be generic but it turns out `u64` is all we need.
    pub const fn from_u64(i: u64) -> Int {
        // `as` conversion is guaranteed lossless
        Int(IntInner::Small(i as i128))
    }
}

impl Int {
    /// The number 0
    pub const ZERO: Int = Int::from_u64(0);
    /// The number 1
    pub const ONE: Int = Int::from_u64(1);

    pub(crate) fn into_inner(self) -> BigInt {
        match self.0 {
            IntInner::Big(x) => x.extract(),
            IntInner::Small(x) => x.into(),
        }
    }

    pub(crate) fn wrap(big: BigInt) -> Self {
        match big.to_i128() {
            Some(x) => Self(IntInner::Small(x)),
            None => Self(IntInner::Big(GcCow::new(big)))
        }
    }
}